View Full Version : Renovation of Celestion 66 Studio Monitors
http://www.jkwynn.co.uk/Project_Images/66/66_01.jpg
These are the Celestion 66 Studio Monitors I purchased off Fleabay. :D
They have very nice cabinets with good original grill cloth and badges, I got them for a ridiculously low price. The following is the story of their renovation back to full working order.
http://www.jkwynn.co.uk/Project_Images/66/66_02.jpg
They are an early version unofficially referred to as Mk I.
When you take the grills off they don't look so smart and certainly look their age.
http://www.jkwynn.co.uk/Project_Images/66/66_03.jpg
The drivers show all the signs of being stored for years unused.
The tweeter covers had unglued themselves and were lying inside the main grill covers.
http://www.jkwynn.co.uk/Project_Images/66/66_04.jpg
Here is where things get ugly, both bass drivers have perished surrounds, but I knew that when I bought them, that's why they were so cheap. Within a minute of winning them in an auction on Fleabay I also had an offer of £80 accepted for a pair of early 66 bass drivers that looked in great condition, they will be going in as soon as possible. Strangely enough the two original drivers still measure the correct resistance so I will keep them for now.
http://www.jkwynn.co.uk/Project_Images/66/66_05.jpg
That's the first cabinet stripped out and ready for work to start.
First thing I did was paint the horrible white glue line around the edge of the baffle board. Some satin black and an artists brush did the trick. The sides and back of the cabinet seem relatively stiff and resonance free. The top and bottom seem very boxy when you give them the old knuckle wrap - I will be applying a bitumen dead sheet to both.
As you can see my workshop - err kitchen - is in a bit of a mess at the moment, sooo many projects.
http://www.jkwynn.co.uk/Project_Images/66/66_06.jpg
That's the x-over, confirming they are an early (Mk I) version. It's taken as a wiring reference should I forget how it all goes back together. I will be keeping everything pretty much as original as a first step. Once I have got used to how they sound I will consider upgrades such as re capping and even the tweeter upgrades. For now I will simply renew the puny internal wiring and the binding posts, as one of my posts is broken.
More to follow………..
Nice cabinets......looking forward to following the renovation.
You won't be disappointed with the 66s.....currently listening to The Muswell Hillbillies through mine.
John - yes they were just too good to pass on, I had to pull the trigger.
Need a bit of work but I think they will tidy up nicely.
Never actually heard a set but everyone I speak to has good things to say about them - can't wait.
The Barbarian
14-04-2014, 09:56
Even thought the 'Ditton' fad is over with most people this should be very interesting thread, look forward to the finished article..
Wakefield Turntables
14-04-2014, 09:58
Even thought the 'Ditton' fad is over with most people this should be very interesting thread, look forward to the finished article..
Ouch! They ain't that bad.
That crossover is interesting Ken - all air-coed coils and point to point hard wired. It's odd that the coils aren't orientated a bit better though.
Mark - If I do a re-cap at some point it would be good to try and re-orientate the coils at the same time. (Possible phase II) ;)
Repositioning the coils isn't difficult, certainly not for someone with your DIY expertise :). As fas as caps are concerned, there only looks to be one electrolytic in the whole thing!
Well, I'd rather a pair of 66s than, say, a pair of LV OBX-R2s, to which, IMHO, the Celestions give a massive hiding. At massively reduced cost.
If you get them working well, they'll easily beat 90% of the speakers that were at this years Bristol Hi-Fi show. In my opinion, that is.
I think those big bundles of 6 and 9 caps are elctrolytics, to be honest I haven't had time to go there yet.
There is a huge thread generated over a period of about five years covering all kinds of 66 based stuff on diyaudio.
When you swap out the old electrolytics for modern polyprops you have to add a risistor in series to keep the values as original.
They give the values required. Lots of frequancy plots etc. I will get into all that later on, my immediate task is to get a working set to standard spec.
istari_knight
14-04-2014, 14:44
The tweeter caps are already film [the one's bundled together] the rest are all 'lytics.
Having been there & done it with a pair of 44 [near identical crossover] I would advise replacing the tweeter capacitors with decent modern polypropylene's & replacing the rest with Alcap low loss 'lytics from Falcon acoustics. In other words: get them back to "as intended" by Celestion first and then see how you feel about mods.
Wakefield Turntables
14-04-2014, 15:21
Have a look on diyaudio.com with regards restoration threads for the 66's I think this may help you;)
:lol: Rexton - have a read of my previous posting.
istari_knight - Thanks for the tip.
http://www.jkwynn.co.uk/Project_Images/66/66_07.jpg
Word has it that the 66's need to be up off the floor and well isolated for the bass to perform properly. I am fitting 3 of these "Soundcare" feet to each speaker base. They are like a spike which caries round its own floor cup/shoe, the big stainless washer is to prevent the fairly small diameter neck from biting into the veneer.
These will then stand on a custom made concrete plinth with a profile that matches the cabinet. This will have 4 adjustable spiked feet and a spirit bubble set into the centre, allowing the plinth to be levelled before putting the speakers in place.
http://www.jkwynn.co.uk/Project_Images/66/66_08.jpg
The Midrange Driver had its front plate removed and the crud cleaned from the inside and from the dome. This was then reassembled and tested, given a final polish and is ready to install.
http://www.jkwynn.co.uk/Project_Images/66/66_09.jpg
The ABR has been cleaned and is also ready to go back into the cabinet.
DarrenHW
15-04-2014, 08:00
Looking good! What did you use to clean the ABR?
Those drivers look brand new now. You can't beat a speaker restoration thread especially when it's a good big 'un being restored.
Darren - I leveled the worst of the blobs in the gunk on the ABR face with some 400 grade abrasive, carefully as its only made from Polystyrene. Then applied a light coat of water based satin black paint (Acrylic Wilko own brand) some paints will disolve the styrene but acrylic is safe. This gave the styrene and glue an even colour just paint this, not the rubber or centre disc. The rubber and bittumen centre disc was given a coat of black trim wax and buffed with a clean cloth when dry, this cleans and feeds the rubber and helps protect it from drying out and cracking, oh and it looks good too. :D
UPDATE:
http://www.jkwynn.co.uk/Project_Images/66/66_10.jpg
The replacement bass drivers arrived. The seller mounted them on plywood boards with spacers so the rubber surrounds wouldn't be under pressure. Then he wedged them face to face, diagonally in a thick polystyrene box, which was then in a stout cardboard box. I think the delivery guy could have dropped them from the van and kicked them to the door and they would have been undamaged - but I'm glad he didn't. They measure well and play music through the x-over so will just have a light clean up before being installed. Many of these drivers have had after market cone treatments applied these look original and unmolested.
Found out the tweeters are both blown, open circuit between contacts, I suspected they may have been so it's no biggie.
I've purchased a matched pair in pristine condition from a guy in California. When I say matched I mean they both measure exactly the same resistance. The base drivers are pretty close as well with only 0.1 Ohm difference between them.
http://www.jkwynn.co.uk/Project_Images/66/66_11.jpg
This is one of the x-over boards from my “Blackies”.
The values may be useful to some folks.
Thanks for sharing that, Ken. Love the fact that all the components are hard-wired, point to point - when done properly it's so much better than using PCBs.
I've not touched the crossovers yet on my 66s, but would quite like to upgrade the electrolytic capacitors with high-quality polys of the same value.
Which ones are the electrolytics? :)
Marco.
Marco - All bar the Tweeter caps are electrolytics.
I will be replacing them all with Polyprops.
When you replace the electrolytics you have to add a resistor in series with the Polyprop replacement.
These are ESR simulating resistors to bring the replacements (low ESR) up to the original values of the Electrolytics (high ESR).
If you don't do this the circuit will behave differently to the original.
The Tweeter caps, on mine anyway, are film caps with low ESR so no resistors required when these are replaced, they used a variety of makes and qtys bundled in parallel to make the total value required.
The bass coils and caps are a weak area regarding quality, apparently upgrading the coils with same value (mH) but approx half the dcR and changing lytics to props in this area will give tighter faster bass. The existing parts smear the sound.
There is lots about this on diyaudio.
I will be doing all this to mine but I am not touching the original x-overs. I am keeping these original and building new boards as every part will be changed and possibly a better layout on a bigger board. One point was raised over at diyaudio about coil interaction due to close proximity, the Celestion engineers were not fools and the circuits when new performed well, so maybe there was some interaction and was accounted for in values. If that was the case then giving better locations with similar values might produce worse results? It's a thought - if it ain’t broke don't fix it comes into mind here? Without building both versions and doing comparisons, it would be hard to guess about the outcome and who has the time for that amount of experimenting.
I will be drawing up a circuit with values and parts to use soon, need to clarify one or two things first with the 66 guru on diyaudio. “Alan-1-b” seems to have a handle on what makes these things tick. ;)
When I looked at coil interaction I found that it was quite easy to alter the mH rating by altering the distance and relationship between coils. If you have a spare coil and an LCR meter it is easy to see the changes happening in real time.
I would also add that reducing the DCR of coils will have as much, if not more, impact on the crossover than the ESR of newer caps - I would urge caution in this area.
YNWaN - Its because the coils have too high a dcR that lower values are sought. After looking at response curves this is what was thought to be part of the soloution. There is a lot of work going on at diyaudio for 66's, they are even modifying the circuit to allow for ageing drivers and inbalance in drivers between stereo pairs.
In terms of altering coil values by proximity (interaction), again it was muted that if normally "better" positions were used this may alter the interaction which surely must be taking place. This may have been allowed for in the circuit design. Its all quess work unless you do some experimenting with the actual coils to see if less interaction results in better or worse sound with the other component values unchanged.
66's are rated quite highly by many people so the circuit must be pretty good as is. :)
Hmm... So whilst Celestion may have had a cunning new interpretation of inductor interaction but they had significantly less understanding of inductor resistance - I suppose it's possible but seems unlikely to me. After all, you only have to increase the gauge of the wire used to lower the resistance of a coil (hardly a new concept) and I've never heard of a speaker manufacturer relying on coil interaction to alter values when it is easy enough to specify the actual value wanted. Anyway, irrespective, I'm sure you will have fun and make a nice job of your project.
"So whilst Celestion may have had a cunning new interpretation of inductor interaction but they had significantly less understanding of inductor resistance"
It's only a theory put forward, remember, most designs are not based on what is best or should be done but by what is affordable and we are allowed to do. The argument was that the size of the board and type of inductors may have been dictated by cost so the engineers may have had to work with the unwanted interaction best they could, low dcR air core inductors usually cost more, a lot more.
Like I say just a theory put out there, it could be total rubbish and moving the coils appart and reorienting them might have significant benefits. In theory it should, so long as there were no tweeks elsewhere to compensate for their close proximity and that really was the point being made.
With every change you make it's a gamble till you have the results, most of us can't afford to have too many go the wrong way so err on the cautious side.
I'm still gathering info and am firmly on the fence with some of this stuff so intrested in all points of view.
The first running of my speakers will have the std x-overs that came with them, I will be gentle with them and not turn the volume to eleven till I can create a new pair of x-over with fresh parts.
My replacement Tweeters are on route from the States, all my projects are on hold waiting for bits at the moment.
Marco - When you come to replace the two 72uf electrolytic caps in the bass section of the x-over you will find that it is a difficult value to find.
In my photo these are the two caps on the right, one above each of the big coils.
No one seems to make a 72uf Polyprop film cap and if they did it would be huge/pricey.
If you try and make it from x2 at 36uf again this is not a standard value, the only options seem to be Solen PB or Axon True Cap. Both are made by SCR in the same factory in France and are at the budget end of the Polyprop caps, but would still be a big improvement on the Lytics.
They are about $7 each for the Axon and $20 for the Solen (USD) you will need eight in total for the two boards. Humblehomemadehifi in the cap tests rated the Axon very marginally better, "more clarity". They are both +/- 5% but at humble he recond that Axon are closer to the nominal value - May have been batch variation on the samples he had.
These caps are a lot bigger than the originals and you need two to make up the value, they will not fitt the space on the board, another reason to make a new one.
I wouldn't recomend using caps of unequal value to make up the 72uf, there was a technical explanation for this on diyaudio, something about different foil lengths giving different times for the signal to pass through, combined = smeared sound, which kind of has some logic to it from my none expert viewpoint. The problem I find with the technical arguments is you can never get two techy people to agree on anything. :D One option proposed was to use single caps and make the one nearest the input 75uf and the other to 68uf (more easily available). people who had done this had reported good results and the tolerance on a 72 total (if 10%) was raised as an argument. I personally will be using two identical 36uf caps, measuring them and pairing from the total of eight needed to get the closest combined values.
I will also be replacing the thin interconnect wire used internally. Thought about this and considered 12awg/Teflon, then I came accross the Black Rhodium "Twist" speaker cable with Silicone prime insulation and no jacket. Its £3.50/m at mainscables R us and they have some with smeared lettering with 25% discount. The Silicon will help dampen vibration when used in the cabinet so seems made for the job.
It was reasonably well recieved as a main speaker cable and I know REXTON had very good things to say about it when he tried it as a main cable from the amp. So that seems to have sorted that one.
Pondering what make of caps to use for the other values re Price/performance. Sonicap GenI have been one of my long time favourites and seem to be used a lot in the 66 recaps. They didn't work well on my Tannoy Cheviots though and to my ears ClarityCap ESA were a much better match for that combination of driver/circuit and at a reasonable price.
istari_knight
24-04-2014, 11:47
Go the whole hog and take them active :eyebrows:
istari knight - Don't tempt me. :D
http://www.jkwynn.co.uk/Project_Images/66/66_12.jpg
The replacement Bass drivers have been completed and are ready to fit.
I cleaned the alloy with some "T-Cut" colour restorer on a plastic scouring pad, the green bit, I pulled it off the yellow foam part, it was polished off with a soft cloth.
I prefer the Black drivers to the natural, the colour is in the coating that was sprayed or brushed on by Celestion, its quite thick and rubbery, a bit like evo-stick contact cement when it has fully set. I didn't want to add any material and weight as the Bass unit contributes to the lower Mid Range and any additional coating would very probably ruin the output, so paint of any kind was out of the question. I decided to Dye the existing coating and did a test on the old driver to check for compatibility. I did this using two giant felt tip markers, the old permanent type of xylene marker that is Jet Black, none of this eco friendly Blue Black stuff that looks pants when you catch it in the light. I used the big 12mm chisel tip and quickly covered the cone. When the marker had dried, which only took a minute, I went over it with a lint free cloth moistened with some Isopropanol, this blends in any lines in the colour and gives a uniform finish. When the Iso had evaporated off I then applied a little Black Trim Wax to the cone and the rubber surround which was buffed off with a clean cloth. This gives a slight sheen to the finish and a little UV protection to the Marker colour. Again this adds nothing which will affect the acoustics. I did them one at a time and compared the sound of the cone between the one that was completed and the untouched one. When I scraped or tapped the cones they sounded the same so mission accomplished. The old driver in the background has had some after market treatment applied which is about 0.5mm thick and has made the dust cap solid, this will have added a lot of weight and I think the sound would have suffered. It was fashionable at one time to paint these products on to paper cones, luckily the samples I found were original and only had Celestions treatment applied.
Apologies for the loss of pictures on all my postings.
My web hosting site is changing servers and I am having teething problems.
:doh:
The Barbarian
24-04-2014, 19:01
Marco - When you come to replace the two 72uf electrolytic caps in the bass section of the x-over you will find that it is a difficult value to find.
Ansar do 75uF These are 5% which will do.
Yep, 75uf and 68uf are more like standard values and quite a few are available.
To me 75 + 5% = 78.75uf in worst case and is getting a bit far from the 72uf target, in reality they would probably never be that far out.
Not a name I've come accross but Ansar "Supersound" range is stocked at Crincklewood Electronics in the UK 75uf are about £35 a go plus postage.
Size = dia 55mm x L 83mm :eek:
istari_knight
24-04-2014, 21:36
Ansar Supersound are very good :thumbsup:
Thanks for the info on the caps, Ken - much appreciated. I'll sticky this thread for future reference.
Looks like things are progressing nicely with your own refurbishing project... I think you're going to end up with a really stonking pair of speakers! :)
Marco.
Thanks Marco
I only have room for one set of speakers, so it will be a shoot out between my Tannoy Cheviots and the 66's.
They are different designs and will do some things better than others so its the overall balance I will be looking at and which ever one I favour will be keepers.
Sorted out the Hosting issues - Normal service has resumed. :)
Ali Tait
25-04-2014, 08:26
Ansar Supersound are very good :thumbsup:
+1
The grill cloth which came on the speaker frames is the original and while it is in very good condition for 40+ years old there is one defect.
The Treble has a window cut in the metal mesh frame directly in front of it; presumably the metal was blocking the sound.
The cloth is unsupported in this are and is pinned in position by a few dabs of glue round the edge of the window, consequently the cloth does not stretch and move with the rest of the material.
The weave had become saggy and is not pulled tight so a few ripples can be seen.
On examination of the cloth, I could see it has quite thick strands of plastic thread running throughout it. These may have stretched over time and due to pressure when being cleaned.
Knowing that plastic has a memory and when warmed will try to return to its original shape I grabbed my hot air paint stripper. It’s a fierce tool I know so has to be applied cautiously, I held the trigger down and let the temperature stabilize then waved it across my out stretched hand to gauge the distance were it would be HOT but not scorching, I didn’t want to melt a hole through the irreplaceable cloth. I waved it around the area of the window and like magic I could see the ripples flatten out as the weave tensioned up.
It’s stood overnight and both grills have remained flat, if I press on the cloth in the window it is no longer floppy and has some spring to it when you push against it. Job done and they now look perfect.
This is not for the faint hearted if you have a saggy window (Ooo Err Missus) and try to fix it in this way be very cautious in applying the heat and as soon as you see it flatten stop heating it.
A hot air gun will burn a hole through the cloth in seconds if applied incorrectly.
If you have a hair dryer, use the hot setting, this may be enough heat to do the job.
As I am follicly challenged I don't own one and can't say for sure it will work as well.
SCREWS:
The screw inserts (T-Nuts) installed in the Baffle board are an imperial size, almost but not quite M5. Its so close that an M5 will go in a few turns before it jams. I want to fit new screws as the old zink plate has gone grey and in any case appart from the bass driver chassis everything else is black so black screws would be better for most fixings and stainless for the Bass driver. Imperial screws are available but not so much choice in finishes etc this side of the pond so I've changed over to M5. I didn't have to replace the T-Nuts, I just ran an M5 Tap through them while still installed and they work fine. :)
The Barbarian
25-04-2014, 12:17
Ansar Supersound are very good :thumbsup:
Too right James..Said this all along.
Ken, when it comes to the grilles, I've tried listening to the speakers with and without them over a long period of time, and in my opinion the 66s sound more balanced and natural with the grilles on.
See what you think, though! :)
Marco.
The Barbarian
25-04-2014, 12:55
Marco:
This is true with my vintage Castles, i always now leave the grills on.. But this is obviously bound to be a criminal offence to audio buffs
:lol:
Really nice pair of Ditton 66 right on my doorstep
http://www.ebay.co.uk/itm/141262731781?_trksid=p2055120.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Marco:
This is true with my vintage Castles, i always now leave the grills on.. But this is obviously bound to be a criminal offence to audio buffs
:lol:
:eyebrows: :eyebrows:
Marco.
Beobloke
25-04-2014, 15:38
I generally leave grilles on the speakers I'm using as I find wobbling drive units too distracting!
I'll sticky this thread...
Dirty boy...
:D
The Cheviots sound better with the grills on, I also find bare drivers distracting.
Barbarian - I have only measured one x-over but the two 72uf Lytics on this board are 65 and 77uf.
If these old caps were +/- 10% which was common, they are still in spec which is quite incredible for their age (presuming original).
+5% yes they would be +/- just quoted the biggest possible variance from the original 72 if a 75 was used, the minus value is as you point out moving closer towards the correct figure.
Just found out the dead sheet panels are out of stock for a week, so there will be a delay in fitting them, the Tweeters should have arrived by then.
http://www.jkwynn.co.uk/Project_Images/66/66_14.jpg
Yep, the replacement Tweeters arrived safely from California. They play music when connected to the crossover and sound the same, best as I can tell, they also measure exactly the same resistance which is great.
The only thing stopping me from building up the one speaker I dismantled, is the bitumen panels and binding posts, which will take a bit longer to arrive. :(
Done some initial work on the x-over design but this is very much a work in progress, I have seperated the Bass from the rest of the circuit, you couldn't fit it all on one board with the much larger caps. The Bass board will drop in where the stock item was located and use the same fixing points, the Mid/Tweeter board will go behind the Mid/Tweeter drivers and be fixed in exactly the same fashion, progress can be viewed via this link:
http://www.jkwynn.co.uk///Project_Images/66/66_X-Over.pdf
Still waiting on bitumen panels, no progress for nearly three weeks now.
I find this is the biggest time consumer on any project - waiting for bits to arrive. :steam:
DarrenHW
15-05-2014, 12:13
I find this is the biggest time consumer on any project - waiting for bits to arrive. :steam:
+1, currently killing time hoping that my new soldering iron will arrive today? Ordered it, resistors and some caps from Farnell yesterday, caps arrived via UPS this morning, resistors have literally just been posted through the door and I guess the iron's special delivery? I really hope it arrives as it's the last thing I need to partially recap (tweeter & mid) my 44's.
What capacitors will you be using for yours, Axon True Caps on your PDF? I've ordered Jantzen Cross Caps from Europe Audio (http://www.europe-audio.com/) dirt cheap, ordered Monday morning arrived Wednesday morning :).
Hi Darren
My current thinking is Axon True Cap for the 72uf (2 x 36uf) and Sonicap Gen I for the rest, but still reading up on what other folks have found works. The Sonicaps seem to have been used in a lot of the 66 recaps and I like them a lot in x-overs though not as coupling caps in my Phono stage. There seems to be various opinions on which is best, two 36uf to give exactly the required 72uf or a single cap approximately 72uf eg one position at 75uf and one at 68uf, the point being a single cap is better than a pair? Still thinking about that.
I use Europe Audio a lot, get my Jantzen coils their.
Jantzen Cross Caps don't come in the required values for mine.
DarrenHW
15-05-2014, 14:27
There seems to be various opinions on which is best, two 36uf to give exactly the required 72uf or a single cap approximately 72uf eg one position at 75uf and one at 68uf, the point being a single cap is better than a pair? Still thinking about that.
Yes, there are plenty of options for the 72uf, I did consider ordering 33uf & 39uf Jantzen's but Alan seem pretty adamant this is a compromise and there's no significant price difference from 36uf Axon's which seem to be the popular choice. Plus there are other components I want to buy from Part Connexion (e.g. Mills resistors, ordered Welwyn's for now) so gives me the excuse to order everything at once. What capacitors are you looking at for the 75/68 combo?
I'm picking up another pair of 44's next weekend so this will give me a benchmark to compare the modified pair to (I still plan on trying the SEAS tweeter), then they'll go on to be the rear speakers for the home cinema (providing I can shift the room around to accommodate them :scratch:).
Wow that will be some system when you sort it. No need for a Sub, I bet.
Not got as far as thinking about a make for a single 75 or 68uf cap but what ever they will be BIG and costly.
Alan seems to recomend single caps as ideal with multiples of the same value/make as next best, with multiples of different values as a last resort.
I'm trying to develop an opinion on which will be the best compromise:
A) Two identical caps giving the correct value.
B) One cap of approximately the correct value
Couple of things to consider.
If the approximate value part happens to be on the wrong side of its manufacturing tolerance, is the level of discrepancy acceptable.
What effect will using a pair of identical caps have on the ESR simulating resistor value? As it doesn't seem to be linked soley to the total capacitance value? Alan seems very busy and hasn't made any sugestions as yet.
These parts are quite expensive so I will not be rushing into it and shipping costs/time have to be factored in.
DarrenHW
15-05-2014, 16:45
Wow that will be some system when you sort it. No need for a Sub, I bet.
Yes, I'll still have a sub (will be investigating sealed as I have a ported sub which makes placement difficult) I even have it on for music may not be strictly stereo but I like it :rolleyes:.
Alan seems very busy and hasn't made any sugestions as yet.
No I've not heard from him recently, he replied to one of my posts, but not the last one concerning resistors. I couldn't get a WP4S in 1.8R so wanted to know if I could order a W22, he had suggested this in a previous post I really just wanted clarification as the Mills is 500v and the W22 is 200v, as the WP4S is 100v I guess this is fine (and I've ordered them anyway) but as you're more than aware I do like clarification.
These parts are quite expensive so I will not be rushing into it and shipping costs/time have to be factored in.
Agreed, I'm reluctant to follow in your footsteps with the Inductors due to the cost implication, are you planning on rewiring / if so with what? I was thinking of rewiring with speaker cable (Van Damme Blue 2.5).
Well no soldering iron delivered today, so I'll be under house arrest again tomorrow :steam:.
Darren - Yes I will be re wiring in fact some of the wire is in the same order I'm waiting on for bitumen panals (Wilmslow Audio).
They have my other items in stock but as its the bitumen panels I will be using first I told them to ship it all in one hit.
I am using Black Rhodium "Twirl" from binding posts to the two x-over Boards, I will be putting the bass filter on a seperate board due to the space needed for all the large replacement caps. This type of cable will also run from x-over to bass driver.
For the Mid/Tweeter x-over to drivers I will be using Black Rhodium "Twist" this is similar to the "Twirl" but smaller conductor.
These cables are tinned stranded copper (like the stock wire) with a thickish Silicon primary insulation, the two conductors are loosely twisted together to help reject interference and have no outer jacket. They are very flexible, withstand a lot of heat (soldering) and the silicon should help insulate from in-cabinet sound vibrations.
Rexton tried the "Twist" as a main speaker cable from the Amp and had very good things to say about it.
"Twist" retails at about £3.50/M and "Twirl" about £13.50/M if memory serves, I need 2m of each cable initially for std x-over and will need another 1m of "Twirl" when I go split boards. It seems a large price difference for a very small change with the two types but I do think the internal wiring is important, especially from binding posts to boards, why have an expensive main cable with a piece of bell wire as a link to the x-over, just doesn't make sense to me.
You could just use "Twist" throught, its conductors are thicker than the stock cable and it's a good price.
The cable is directional and marked at each end if you believe in that one :sofa:
I’ve added a link below to a PDF file I have put together of the original Celestion circuit drgs and parts list. I added a picture of each type for clarity.
66 Circuit Diagrams
http://www.jkwynn.co.uk/Project_Images/66/66_15.pdf
I thought this would make a good reference, I have certainly made good use of it.
There is a lot of misleading information around so I have put together the facts as best that I can – There was only ever one Celestion 66 produced which underwent continuous improvement during the course of its production life. Originally it was just called the Celestion 66 Studio Monitor and all the labels said just that. When it had a face lift the word “Ditton” was added into the description, probably to fall into line with the rest of the range at the time, Ditton 15, Ditton 44, etc.
There was never a MkI or MkII version, the earliest had painted fronts “Blackies” and after about two years production there was the face lift and this was changed to veneer “Woodies”. Changes such as moving from tag board to PCB x-overs did NOT coincide exactly with this change and many early Woodies had tag board x-overs as did the illustrations in the companies literature for the Woodies, see brochure below. The introduction of the MD500 mid range may have coincided roughly with the baffle board change but depending on how they carried out the change over and stock run down you could probably find them in both versions close to its introduction. The versions with MD500 should have had the PCB x-overs fitted as small changes to component values were made on these boards to cater for the slightly different characteristics of the driver, see the schematics in the PDF file above. The introduction of the bass driver with a larger dust cap came well after the facelift.
There was a much later Series Two 66 but this was a completely different loudspeaker having different drivers, x-over and cabinet and the ABR unit was on the rear face which makes identification strait forward. They really should have called this something else but were probably trying to make the most of the 66’s good reputation.
In an attempt to try and keep as much information in one place for anyone researching the 66’s I have added a link below to the brochure published for the introduction of the Woodies.
66 Brochure
http://www.jkwynn.co.uk/Project_Images/66/66_16.pdf
:)
Great work Ken, as usual ;)
The Barbarian
18-05-2014, 19:00
Ken:
Can you ask one of the Admin to put those Scans in the Knowledge section if that's ok with you
http://theartofsound.net/forum/forumdisplay.php?28-The-Knowledge
Andre - I've asked the question. If they are wanted I will send the files in.
This recapping lark is more complicated than it first appears.
There is no question that modern Polyprops sound better than Electrolytics, especially old elctrolytics. The thing is they are very different animals so substituting a superior Polyprop of the same value does not guarantee a better sound.
How can this be?
The Equivalent Series Resistance (ESR) on Lytics is quite high and very much a non linear value which is greatly affected by changes in temperature/current and frequency. The polyprops have a much lower ESR value and their performance is much flatter in regards to changes in frequency, current etc. This is normally a good thing and better for designers/software to work with and predict. Unfortunately it does not make them a good substitution for an electrolytic in all cases.
The standard fix is to add a resistor in series with the cap to make up to the old ESR value. The problem here is it’s a fixed value, so can only be a match for one point in the current/frequency effected slope. So it will never respond like an electrolytic across its full range, in fact just in a very small portion.
This seems to be born out in the threads I have read, users are initially really pleased, the Polyprops are cleaner more transparent and at certain frequencies sound much better, problem is they all end up coming back and get into endless tweaking because they have lost something from the originals. The ESR simulating resistors that are used seem to be of values that will be an approximate match around the x-over frequencies and this is the area where a mismatch will be most noticeable in terms of driver integration, but through out the rest of the frequency range there are going to be areas that have audibly changed from the originals and not necessarily in a good way.
These Celestion speakers are highly regarded in terms of their sound quality, Marco’s totally original set when in service at Scalford had praise from many people.
The best comment I think I found on the diyaudio 66 thread was from a Belgian contributor who said “I don’t want to improve the sound of my speakers, I like them the way they are”. He only wanted to renew the old caps with new electrolytics as the old ones had probably slipped out of spec and may also be letting driver damaging DC voltage through. It’s a valid point he was making, the Polyprops may be more transparent but are a bit of a square peg in a round hole when trying to replace Lytics and the down side of using them as direct replacements is probably as great as the benefits, though I’m sure the differences will vary between different circuit designs. In this particular case Celestion engineers did a great job in integrating the three drivers which were all working to the extremes of their frequency ranges, the mid driver at both ends, it wouldn’t take much to upset this balance.
I’m not saying you can’t design a better x-over using Polyprops, just that they may not work in the existing circuit design. Using them would involve a much more involved redesign of the circuit and plotting/tweaking of the response/impedance curves using measuring equipment and a high level of expertise, a far more complex process which most owners, me included, would not want to get into.
There are numerous other factors to be considered when comparing these two types of cap and how they perform in this circuit, but I think the general statement of upgrading x-overs by changing the elctrolytics for “better” Polyprops has to be questioned. If it aint broke don’t fix it comes to mind, again.
I am going to put my untouched x-overs back in and get used to how they sound.
As a first step I will change the Tweeter Caps to Sonicap Polyprops, these were film caps from the start so no issues, the Mid range electrolytics have values that can be got from the Mundorf 5% Electrolytic range and the Bass section could be Alcap 10% electrolytics which are supposed to sound similar to the original Elcap’s. This is a cost effective first step and these parts are of a size that would fit on to the original boards. The Alcaps are cheap enough (£1.10) to buy 10 or so and measure to find the closest 4 to the stated nominal value.
A theoretical 10% discrepancy is a big variation and even a 5% difference between x-overs would be too much for me.
These changes would need some extended listening tests to see if the sound was true to the original and was something I would be happy to live with long term. I think this more cautious approach will be the route I take, before considering more radical and expensive changes. ;)
Still waiting on the Bitumen panels from Wilmslow Audio (6 Weeks). Looking at their website it looks from the changed wording/picture/product dimensions/price that they are in the middle of changing suppliers for this product. If that’s the case why couldn’t they just be honest and say that this was causing a delay in stock availability? :steam:
walpurgis
24-05-2014, 14:54
Automotive bituminised sound deadening pads are the same stuff as offered (expensively) by speaker component suppliers. You'll find these on eBay at comparatively sensible prices.
Believe it or not Wilmslow Audio is approx half the price of the fleabay automotive supliers.
I don't want the flimsy 1.5/2mm thick sheets that are in abundance but don't really do much, it's the 3/4/5mm sheets which the automotive suppliers usually sell to the BOOM Box car audio fans at very high prices. The WA sheets I have on order are 3.5mm thick and the minimum I would consider using, I have searched for alternatives but there are not many people that stock thick bitumen sheets, pleanty of closed cell equivelents but I want the mass loading. ;)
Most interesting post #55, Ken - and NOTED! ;)
Marco.
http://www.jkwynn.co.uk/Project_Images/66/66_17.jpg
The parts order arrived so I can carry on with the work.
I fitted 3.5mm thick Bitumen sound absorbing pads to the top and bottom panels, for some reason these seem more resonant than the other faces.
http://www.jkwynn.co.uk/Project_Images/66/66_18.jpg
Before and after shots of the cleaned up terminal area with the new binding posts fitted.
DarrenHW
31-05-2014, 06:09
Eventually arrived then :champagne:!
Further to post #55 - I picked up another pair of 44's last weekend which (following the above post) I now plan to recap with Alcap Electrolytics. Your comments above hadn't occurred to me so thanks for posting, should make for an interesting (and very low cost) shoot out!
Good luck with the rest of the restoration, shouldn't be too long till you have them finished?
Hi Darren
If your x-overs have film caps in the Tweeter section then use film cap (Polyprop) replacements there.
If your Lytics are Low Loss usually marked LL then replace with LL Alcaps if like mine they are not then use the standard 50v Alcaps.
They need to be Non Polar or Bi Polar, same thing, the original Black/Red Elcaps are marked NP (This is more for anyone else reading this)
Falcon Acoustics do a matching service where they will sort there 10% lytics into 5% or 2% tolerance but obviously you pay extra for these.
I have come accross two posts elsewhere where they measured the 2% ones and the customers had sent them back as they said they were no where near 2% and were just ordinary 10% items. So take note of that and make of it what you want.
Try and keep everything like for like with the originals.
I'm certainly going to start that way.
If I then want to try replacing the Lytics I will do it one cap at a time and listen to the results before moving on to the next cap.
The most critical Lytic is the 24/30uf (depending on Mid range fitted) as its the only one in the signal path. Changing that will have the biggest effect, good or bad.
Edit: I keep forgeting you have 44's so I'm not sure where the component values differ, although the basic layout/circuit design looks the same.
I will be very intersted to hear your comments when comparing the two sets of speakers, one set recapped with like for like and the other "upgraded" with Polyprops.
http://www.jkwynn.co.uk/Project_Images/66/66_19.jpg
Before and after shots, the one on the right is now fully working.
We're into the holiday season so progress will be a bit erratic but I need to get the speaker on the left up to the same level and do some listening tests with the totally original x-overs. At least I have all the parts to complete the second unit so the job should be much quicker.
Superb stuff, Ken. I'm truly in awe at your patience, dedication and abilities! :clap: :youtheman:
Marco.
DarrenHW
04-06-2014, 09:52
Superb stuff, Ken. I'm truly in awe at your patience, dedication and abilities! :clap: :youtheman:
Marco.
+1 Looking great!
Thanks Marko/Darren - I think patience is a major factor in any DIY/restoration job. When things are going wrong, and beleive me I have a lot of that, walk away, have a brew and reflect on things. When you come back you usually do a much better job. This applies to everything from making an awkward solder joint to assembeling some fiddly components. :)
walpurgis
04-06-2014, 10:06
Coming along nicely Ken. Bet you're pleased. They'll be great once you've finished.
Gordon Steadman
04-06-2014, 10:27
Nice job you are doing. They will sound much better for having done the work yourself too:)
orbscure
04-06-2014, 10:41
Fantastic stuff Ken... I've been following this thread with a great deal of interest, so well done so far, it looks superb!
Thanks Gents,
I am pleased with the way things are going, but chomping at the bit to hear the finished article.
I fired the single speaker up in my system with a Tannoy Cheviot on the other channel, but you can't really tell what they image like etc till you get a similar pair running together. Tried listening in mono through just the celestion on my Sugden amp and it definatley has a different sound to the Tannoy, I'm liking what I hear so far. :)
My Initial thoughts on the one 66 compared to a single Tannoy cheviot:
The Cheviots are standard cabinet and HPD315A driver, the x-overs were developed over a 12 month period and have ClarityCap ESA’s, mills resistors, Jantzen air core inductors. The 66’s are standard early drivers and x-over including all the old parts. They were standing on a paving slab with three soundcare feet on the cabinet base. I point this out because it’s not a fair comparison or any kind of head to head. Just using it to gauge my initial reaction to the 66 against a sound I am very familiar with.
66 Upper bass more punchy/percussive, snare drum blows have more impact. Tannoy goes deeper – That is a surprise.
66 top end is cleaner, cymbals have more detail, less splashy.
Mid range not as transparent as Tannoy.
Overall balance of 66 when listening to a piece is better, more enjoyable.
- The biggest down side I noticed, by far, was the lack of mid range transparency. The use of only one speaker won’t help with this, nor the ancient x-over parts.
I’ll give a proper listen when the other one is ready.
They'll be awesome Ken especially with a revised crossover I suspect.
istari_knight
19-06-2014, 15:50
Just caught up with this thread - You do lovely work sir !
- Thanks James.
Now that my Turntable project is completed I can concentrate on the 66’s
http://www.jkwynn.co.uk/Project_Images/66/66_20.jpg
The binding posts on the left are the "Standard" Wilmslow Audio items that I fitted. When I cut the thread to reduce it's length I discovered they are cast white metal, I had presumed they would be brass. The alloy is not the best of conductors so I fitted the ones on the right which where a Flebay purchase. They are solid brass (I checked) with a fairly thick Gold plating. The annoying thing is they where only 2/3 of the price of the first set with free postage and they arrived the day after I ordered them.
http://www.jkwynn.co.uk/Project_Images/66/66_21.jpg
The second speaker is back together, :champagne: so I now have a working pair with the totally stock x-overs installed. I will listen to these for a while before tinkering any further.
http://www.jkwynn.co.uk/Project_Images/66/66_22.jpg
The picture on the left shows the sagging cloth in front of the tweeters, the one on the right shows it after I applied some heat to tension the weave.
Now for some tunes :guitar: Next job is to cast some plinths for them to stand on.
orbscure
26-06-2014, 18:59
They look superb Ken... can't wait to hear what they sound like :eek:
istari_knight
28-06-2014, 13:15
- Thanks James.
Now that my Turntable project is completed I can concentrate on the 66’s
http://www.jkwynn.co.uk/Project_Images/66/66_20.jpg
The binding posts on the left are the "Standard" Wilmslow Audio items that I fitted. When I cut the thread to reduce it's length I discovered they are cast white metal, I had presumed they would be brass. The alloy is not the best of conductors so I fitted the ones on the right which where a Flebay purchase. They are solid brass (I checked) with a fairly thick Gold plating. The annoying thing is they where only 2/3 of the price of the first set with free postage and they arrived the day after I ordered them.
Can you post a link to the new one's Ken ? I always buy these which look similar: http://www.ebay.co.uk/itm/Speaker-Binding-Posts-Terminals-Connectors-2-Red-2-Black-Gold-Plated-/261189119715?pt=UK_Sound_Vision_Audio_Cable_Termin ations&hash=item3cd015aee3
Hi James
These are the item I just fitted, they look similar to yours except for thread length and no solder tag provided.
http://www.ebay.co.uk/itm/231092659984?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Edit: One thing to note is the fairly short post length which is required to fit in the Celestions recessed terminal location. The posts sit JUST below the surface so you can lie the speakers on their backs without fear of damaging the posts.
After listening to the pair of speakers it has confirmed my initial response to hearing just one. The bass does not go as deep as my Tannoy Cheviots. The upper bass and mid range is cleaner and faster than the Tannoys which sound soft and blurred in comparison. The top end, particularly the lower treble is more detailed and precise on the 66’s. These are not massive night and day differences but noticeable never the less. The Celestions bass sounds impressive but ultimately rolls off quicker.
Over all I prefer the presentation of the 66’s which to me is more believable. Snare drum has a much more percussive live sound. There is great tonal accuracy across the spectrum making instruments of all varieties come to life, and voices are portrayed extremely well. The lack of mid range trancparency which concerned me when listening to one speaker is not a factor when listening to the pair.
My Tannoys have had many hours of work on the x-overs which are about as good as they can get, using mills resistors, ClarityCap ESA’s and Jantzen air core coils and much experimentation. The Celestions have the original ELCAP electrolytic caps etc so my next step will be to look at some replacements and also to see what can be done to improve the bottom end.
One thing I will say about both these models of speaker is that they interact extremely well in my relatively small room without any bass boom or audible room resonances, even when played quite loud. :D In fact the stock Cheviot cabinets start to resonate before the room. The 66's cabinets do not seem as prone to resonate.
I'm not finished tweaking but it looks like the 66's will be the keepers.
walpurgis
28-06-2014, 20:12
That's strange. If you perceive the 66s not going as deep as the Cheviots in the bass, I'd think room acoustics may have something to do with this. Then Dittons have a very extended bottom end which I've heard in large rooms and I'd expect you to hear (feel?) good output to below 30Hz. The Cheviot rolls off progressively below 40Hz, although there is still output at 30Hz.
Geoff - It's not just perception.
There is so much bad information around on the 66's based upon opinion and rummer.
Because the upper bass of the 66's is quite pronounced and has high SPL at these frequencies they come accross with a lot of music as having great and abundant bass and people have expressed this oponion.
The fact of the matter is they roll off quickly so you don't get truly deep bass.
The -3db point for the Celestion 66's is A LOT higher than my Tannoy Cheviots for instance.
A quick look at both companies published frequency plots tells the story and for those who prefer it in text look at each companies brochures for what they say their speakers can do.
In fact Celestion don't quote a -3db point they state 50hz to 25kHz at +/- 4dB compared to Tannoys 40Hz to 20kHz at +/- 3dB.
Celestion state in their brochure 40Hz at -10 dB. :eek:
Its nothing to do with room accoustics, both sets of speakers were located in the same spot for my listening test and the published figures speak for themselves.
These reputations should allways be treated with a pinch of salt, like the one that Tannoy DC's don't do bass unless you go to 15" in huge exotic cabinets. Even with the modest Cheviot cabinet and 12" driver, they quite clearly do.
It didn't help that Celestion talked about the 66's as a full frequency 18hz to 35khz speaker in their publicity. If you turned the wick up to full and put your ear to the bass driver you probably could hear 18hz but not at any level worth mentioning at normal levels from your listening position.
I'm not knocking the 66's I like them a lot and prefer them over the Cheviots, but I appreciate that like the Cheviots, they are knot perfect and like all loudspeakers, have their limitations. ;)
In fact Celestion don't quote a -3db point they state 50hz to 25kHz at +/- 4dB compared to Tannoys 40Hz to 20kHz at +/- 3dB.
Celestion state in their brochure 40Hz at -10 dB. :eek:
That's interesting as it would correlate with my subjective experience of listening to the 66's.
Very nice job on the refurb by the way.
Strong mid-bass confused with deep bass. Happens a lot but it is just semantics, really. If we define 'deep bass' as below 40 HZ most speakers don't do it at all and those that do will mostly be well down in level. Fortunately most music doesn't have bass that deep and if it does it generally won't matter too much to the listening experience if it is not reproduced, some particular styles of music withstanding, of course.
Martin - this is so true, it's what happens above 40Hz that counts and purely from my perspective, I think the 66's shine.
I was curious so I dug out my test Tone CD and gave it a spin.
With the volume set at fairly loud but not an insane listening level on my Sugden I tried various tones.
20Hz Nothing.
24Hz Nothing.
28Hz Straining I could just here something was there.
32Hz Starting to come through but well down, less than half the loudness of when playing 56Hz.
40Hz Good level of sound and only slightly audibly lower than 56Hz.
56Hz And above is at full level.
The results seem to back up the specified frequency response. :)
I must remember to get one of those test cds, must come in handy on occasion.
istari_knight
29-06-2014, 17:54
Burn your own Martin: http://realtraps.com/test-cd.htm
Nice one. I'll need a cdr or dvdr disc, though.
istari_knight
29-06-2014, 18:44
Nice one. I'll need a cdr or dvdr disc, though.
Doh !
Martin - this is so true, it's what happens above 40Hz that counts and purely from my perspective, I think the 66's shine.
I was curious so I dug out my test Tone CD and gave it a spin.
With the volume set at fairly loud but not an insane listening level on my Sugden I tried various tones.
20Hz Nothing.
24Hz Nothing.
28Hz Straining I could just here something was there.
32Hz Starting to come through but well down, less than half the loudness of when playing 56Hz.
40Hz Good level of sound and only slightly audibly lower than 56Hz.
56Hz And above is at full level.
The results seem to back up the specified frequency response. :)
I wonder what the constraining factor really is here? The box size and drivers "look" mean enough to go lower.
No matter still a great loudspeaker and one of my personal faves.
Yes the test discs have many uses.
I check my HF hearing now and again. I am in my late 50's and my hearing ability has dropped by 1kHz in the last 12 months. :(
They always quote 20kHz as the limit for human hearing but in reality it's probably only very young children and a very few lucky adults who can hear this. Most folks by even their twenties will not hear 18kHz and if you can hear 16kHz by middle age you are lucky. It's one of those things that deteriorates from the day we are born - Doesn't everything :lol:
One good use for test tones is when auditioning a used pair of multi driver speakers as a possible purchase. It's difficult to hear individual drivers with a piece of music, but by selecting a tone mid way in the drivers range (presuming you know the x-over points) you can isolate say just the mid range driver. You can also compare the difference between individual left and right drivers when playing a single tone far easier than when hearing all drivers together, as with a music. It will give you some idea as to whether the individual drivers are working without distortion and that stereo pairs produce roughly the same output.
I've never tried this but I dare say you could also test bare drivers without a x-over. You wouldn't want to put full range music through a tweeter but a 10kHz tone would do nicely.
http://www.jkwynn.co.uk/Project_Images/66/66_23.jpg
This diagram shows the first stage of my intended x-over upgrade and as such is more of a capacitor parts refreshment. I have tried to keep the replacement caps as close as possible to the type they are replacing, avoiding ESR issues when replacing electrolitycs with polyprops etc. The tweeter film cap bundles are to be replaced with single Sonicap Gen1 200vdc film caps (Polyprops). The 4uf Elcap electrolytic used as a shunt in the midrange is to be renewed by an Alcap 50v electrolytic and the 72uf Elcap shunts in the bass section will be Alcap 100v electrolytics. Alcap are supposed to be the closest match tonally to the original Elcaps, I purchased them from Falcon Acoustics who graded the nominal 10% tolerance caps to +/- 2% for the 4uf 50v and +/- 5% for the 72uf 100v items at extra cost. I bought more than required and refined them further by picking the closest values from the bunch. The original 30uf (total) electrolytic in the midrange was a better quality item as it lies in the signal path. This is to be made up of two 15uf 70v 5% Mundorf ECAP's (electrolytic) again I purchased more than required and graded them for best match. Note that these electrolytics are all bi-polar.
This upgrade will protect the drivers from possibly leaky old caps but not involve changing the original boards, so is easily reversible and can also accept further changes if required. I am hoping the character of the speakers will not be altered by taking this path. The purchased caps have arrived (Sonicaps from USA) and are currently burning in prior to being fitted. I have used Sonicaps several times before in x-overs and know they take a lot of hours before smoothing out and sounding their best. Some say 180 hours but I thought they didn't change noticeably after 150 hours use. Major changes take place at around 70/90 hours so I will give them 96 hours burn prior to fitting and continue the process when installed in the x-overs/speakers. I find they tend to settle within about 8/10 hours when pre-burned this way, initially having a grainy treble which refines after this short period. Burning them in when fitted to the speakers takes for ever unless you run them 24/7 and the difference between virgin and run in caps is very noticeable. There is little point in trying to assess changes till they have settled.
I burn them in by attaching several in series to the positive speaker terminal on an amplifier and adding a 15 Ohm ceramic resistor in series on the end of the chain, as a load, before connecting that to the negative terminal. This way you can play a 24 hour FM radio station, turn the volume up to a reasonable level and without speakers connected, leave them switched on without disturbing anyone. I have an old Sony micro music system I use for this. All of the above is my way of doing things, other people may take a different approach, but it works for me. The caps will be ready to use in a few days and I will be installing them into the x-overs straight away. :)
http://www.jkwynn.co.uk/Project_Images/66/66_24.jpg
Before and after shots of one of the re-capped x-overs I completed today. :)
From the start, which was from removing the speakers from my system, to switching them back on for a listen, took 8 1/2 hours for the pair. I changed all the caps, which have been seated on hot melt adhesive. The thin multi strand cable used to make some of the connections was replaced by thick single strand tinned copper. They have only been playing for an hour so too early to make an assessment, but they do sound more transparent, that is immediately noticeable. I used Black Rhodium "Twirl" to connect the boards to the binding posts and Black Rhodium "Twist" from the boards to drivers.
walpurgis
15-07-2014, 20:28
Which one is which?
Just joking Ken :), it's a neat job.
Super work - as always. But (isn't there always a but), I would seriously reconsider the orientation of the inductors - definitely the three large ones.
I'm treading carefully Mark.
Changing things a bit at a time. To relocate/re-orientate the inductors correctly would need a new board/layout and better with two boards.
I would probably buy better inductors if doing that - I have a two board layout on the back burner using Jantzen coils, Polyprops throught and ESR resistors - its all drawn up parts listed and costed.
It will be moving away from the original design considerably though and I would like to keep things as original as possible for now.
I am just seeing what can be done with the minimum of changes and at a reasonable cost. So many people have dived in at the deep end on the 66's, lost the magic and ended up changing the Tweeter and even the Mid Range driver trying to "Improve" what was allready a very good speaker before they messed with it.
I'll see how this basic parts refresh works out and take things from there. ;)
Absolutely - makes total sense. Funny they positioned the inductors like that though. I can't be sure but they look like they are all air-cored already?
Yes - they are all air cored inductors. On these old coils the windings are strapped up with tape but are loose and can move around, the larger ones in particular and these are made of small diameter copper. They are glued down to the board and would be a PITA to remove without further loosening the windings. When I measured them they were not that close to the nominal value stated on the wiring diagram. Hence my thinking of using Jantzen air core with varnished windings, the coils are stuck together by the varnish which helps reduce vibrations and makes the coil pretty solid and robust.
Pre burned the caps but only got 5hrs use in the circuit so far, top end is cleaner not as harsh, generally the sound is more transparent, but the mid range is way back in the mix, not a lot comming through, or is it just being overpowered by the amount of treble the polyprops are letting through?
Early days, will see how things develop.
Ah yes, didn't realise the coils were constructed like that. I've looked into coil vibration. It can be very pronounced, even producing an audible sound! As you say, the Jantzen coils all use a baked varnish and the ones I measured were all very close to the stated value and even closer in value to each other. I notice that Mundorf charge extra of baked varnish but it's standard on all the Jantzen ones (P-core, air-core etc.).
The x-over parts have had time to settle in and I’ve had a good long listen to all kinds of music.
I can say without question that the speakers sounded better before the x-over was re-capped. :doh:
They became more transparent overall, but are just swamped with excessive treble, the mid range and bass are barely audible so the dynamics and slam which these speakers are capable of is now just a whimper. :(
I had read on another forum that a 66 owner had suffered loss of bass when re-capping. He had used polyprops + ESR simulating resistors where needed for treble/mid range and electrolytics for the big 72uf bass caps. He was advised that the Polyprops just let more of everything through and the bass was there but at a lower SPL. So as a temporary measure he fitted L-Pads to the tweeter and mid range and basically turned them down. Magic - he got the overall balance and dynamics back.
Applying this to my experience with a strident and very forward treble content, after fitting Polyprops to just the HF element and I could see where a solution could lie.
I wasn’t sure how much attenuation would be needed, but I had a box full of Mills resistors of various values to try out. First thing I did was to fit a couple of single terminal blocks in place between the last cap in the treble filter and the terminal tag for the wire going to the driver. This meant I could add a resistor in series and make quick changes of value with the x-over and speaker wiring all in place and without a soldering iron. There is enough slack in the bass driver leads to stand the driver on top of the baffle board (laid on its back) while I whip out a screw driver and change the resistor.
I started with a 1 ohm resistor and there was a huge improvement, but maybe I’d gone too far. I tried 0.5 Ohm and that wasn’t enough, so I dropped in 0.75 Ohm, made up of a parallel 1 & 3 Ohm. This was a revelation, that such a small change could have such a dramatic effect, I would not have believed it. The absolute Ideal may be around 0.85 Ohm but I’m very close.
The mid range and bass can now be heard and are making their contributions.
The following comments are made when comparing the original stock x-over with 40 year old parts, the mid range Lytic had 1973 printed on it, and the re-capped version with 0.75 Ohm series resistor added:
The bass is now more solid and better textured, evident when playing droning synthesised stuff like OMD’s English Electric album. Plenty of slam in Gershwin/Previns Piano Concerto in F with nice cymbal clashes and triangle but the sound is well proportioned now and the drivers are much better integrated. Strings sound good in REM’s Out of Time album. I have tried lots of music, horns, guitars, voices and all sound better than before.
The re-capped x-over now sounds substantially better than the original :D I am one happy bunny. Who would have thought that one piddling little resistor could turn the tables.
Things don’t stop here. I will be taking the 66’s to NEBO4 (bake off) and feel they can now show a little of what they are capable of. When they return I will be taking a close look at the mid range filter as I feel this is, comparatively, the weak point now.
The electrolytic that lie’s in the mid range signal path is crucial, Celestion used a different type of electrolytic for this component and I’m sure it was carefully selected for its properties. The pair of 15uf Mundorf lytics I used to make up the 30uf value just doesn’t sound as good, a bit mushy and slow, lacking dynamics compared to the crisp Sonicap polyprops in the treble.
Various folks mentioned Ansar “Supersound” caps earlier in the thread and gave positive comments. I did a bit more reading on them and found them reviewed by Tony Gee at http://www.humblehomemadehifi.com/Cap.html
his opinion was:
“they can be useful if you want to give a more open sound to a system that sounds a bit congested in the midrange and / or lower treble, in such a situation the Ansar open's things up nicely.”
Sounds like they were made for the job and they come in 30uf value which is not common.
Fitting them will require an ESR resistor, 1.8 Ohms in series with the cap by all accounts and possibly involve attenuating the increase in mid range content afterwards and probably lead to re-doing the tweeter attenuation to get it all nicely balanced again. I will leave this till after NEBO4 as there are too many variables and things that can go wrong, which could leave me with a poor sounding speaker to take along.
Back on track and It’s all going in the right direction, there are many other things I could try, such as fitting better made coils in more suitable locations and replacing all the electrolytics with Polyprops, including the 72uf's which would be huge, these options start to get more complex and expensive to experiment with, so for now I will continue the small steps approach. ;)
walpurgis
17-07-2014, 18:43
I had a feeling these would keep you on the go for quite a while Mark. You'll get there and they'll be superb.
Ken - I like that term "plenty of slam". That's one of the reasons I like 66s so much. They are lively and dynamic and consequently I find them very engaging. The sound they produce is as close to an Apogee Duetta as many a box speaker can get.
With speakers as good as a 66 just making small changes to the x-over becomes a major issue. I say that having spent some time tuning my x-overs with the refurbisher. It is a blessing and a curse. However, once right, it's big smiles time:)
Enjoy. I'd buy a USB measurement mic (Dayton, UMIK...) and use a copy of HolmImpulse (free) if you haven't already done so - I haven't read all of the thread. You can then have a VERY interesting time correlating what you think you hear with what you measure.
You're a clever fella Ken and this is a wonderful restoration, well done sir (dead impressed with your solution to the saggy grill fabric btw) ;)
The Barbarian
19-07-2014, 03:57
http://www.jkwynn.co.uk/Project_Images/66/66_24.jpg
Before and after shots of one of the re-capped x-overs I completed today. :)
Ive not really kept up with this thread but why do people fit Electrolytics to these Re-builds, i personally would never use them or is it cash constraint due to high part values that made you fit them? However that does not explain the small one across the top of the board!
Ive not really kept up with this thread but why do people fit Electrolytics to these Re-builds, i personally would never use them or is it cash constraint due to high part values that made you fit them? However that does not explain the small one across the top of the board!
Because you cannot trade polys for electrolytics and expect the crossover point to remain the same. If they were voiced with electrolytics, then that's what you should use with a few exceptions. Also, some values manufacturer's used were fairly high in value and it could mean a lot of expense and more space usage than permissible by the current crossover housing in some speakers. Look closely at the photos and tell me where you can get a 72uF capacitor and what it would cost, then what the space usage would be with a grouped set of caps to make up that value, and also how would you deal with the difference in ESR between electrolytics and polys? The Alcap electrolytics available today can be supplied to tight tolerances and although they are not as stable or linear with temperature or frequency variation as Polys, they're pretty good. Add to that they cost very little and the question becomes "why not use them?"
Thanks for the comments gents.
Andre - I've fitted electrolytics where they were fitted in the first place.
If you just fit Polyprops where Lytics used to be you can compleatly screw up the circuit as Polyprops behave in a very different fashion.
You have to add additional resistors in series for every Poly prop fitted to try and make up for their lower ESR value, but this is only a partial fix as the Lytics are non linear and are effected by temperature, load and frequency in a major way compared to the Polyprops.
Circuits designed using Lytics have been tailored for the way they work.
If you replace all the Lytics with Polyprops you may have to compleatly re think the circuit design to maintain x-over points, impedance behavior and relative loudness of the driver combinations. It gets VERY complicated and without measuring equipment and the knowledge to use it, you can spend months going round in circles wondering why they don't sound the same as they used too. The Polyprops may sound cleaner and more transparent, but the balance and quite often the magic will have gone.
The reason I used the Polyprops in the HF section is that these were a film cap originaly that behaved more like a modern Polyprop.
The more I dabble with x-overs, the more I realize that these differences have major repercusions.
EDIT: Oooops I see Paul answered in a similar way while I was typing. Thanks for that Paul, you first raised my attention to this and I am finding with experimentation and actual results that it is the case.
The Barbarian
19-07-2014, 12:14
Because you cannot trade polys for electrolytics and expect the crossover point to remain the same. If they were voiced with electrolytics, then that's what you should use with a few exceptions.
Is that so :D Well ive rebuilt loads of vintage X -Overs with just PP they have always been a vast improvement. One thing i don't do & thats take advice from forum posters because i don't need to. I use one brand of PP always have always will do, all other sound cack to me regardless of their boutique price tag..
Let me think now Martin T re-built his Gale '401' crossovers with just PP guess what he's happy, i use three different pair of speakers with full PP rebuilds guess wat im more than happy.. Just done my mates speakers too guess what he's over the moon.
;)
Is that so :D Well ive rebuilt loads of vintage X -Overs with just PP they have always been a vast improvement. One thing i don't do & thats take advice from forum posters because i don't need to. I use one brand of PP always have always will do, all other sound cack to me regardless of their boutique price tag..
Let me think now Martin T re-built his Gale '401' crossovers with just PP guess what he's happy, i use three different pair of speakers with full PP rebuilds guess wat im more than happy.. Just done my mates speakers too guess what he's over the moon.
;)
Yes, that is so and just because you don't agree with it doesn't make it less so. You asked the question so why so aggressive when you're given the answer? Up to you if you ignore advice freely given and in an attempt to be helpful. :rolleyes:
Here's a pic of my (totally stock) 66s, in situ in our downstairs lounge, where about 75% of my listening is done these days:
http://imagizer.imageshack.us/v2/1024x768q90/674/55c269.jpg
:cool:
Marco.
Yes, that is so and just because you don't agree with it doesn't make it less so. You asked the question so why so aggressive when you're given the answer? Up to you if you ignore advice freely given and in an attempt to be helpful. :rolleyes:
Indeed.
Andre, your response to Paul, dude, was unnecessarily confrontational. He was only offering his relevant experience, in order to try and help, which although contrary to yours in this instance, was equally as valid :)
Marco.
Nice Walnut finish on the 66's Marco, suits the room.
Isolation platforms? Look different to the ones in the Scalford Pictures.
I need to knock some platforms up for NEBO4, I have the moulds 50% complete and will be casting them in concrete.
The design is 75mm thick and the same shape as the speaker, with the small flats on the two front edges. They have carpet spikes in each corner on the underside which are adjustable through holes in the top face and a leveling bubble mounted in the centre of the top face.
My speakers have 3 of those Soundcare spike/shoe assemblies fitted and these will sit on the Plinth.
Pictures of the plinth build will follow.
Hi Ken,
Cheers. They're pretty minty, although could do with a little attention here and there, in order to really bring them up like new! :)
The Mana 'platforms' are indeed different than those we used at Scalford. The ones pictured above are what's known as 'Mini Soundbases', designed to be used under tall floor-standing speakers, and suit the 66s perfectly.
At Scalford (as I didn't have the Mini Soundbases then) we used ones which are normally used under Krell power amps, so they were totally oversized, but fulfilled a purpose!
The 66s undoubtedly sound much better on top of some type of properly designed stands/plinths, rather than simply plonked on the floor, as they would've been originally used, and probably why some folk complained of 'boomy bass'. That just doesn't happen when they're properly supported and driven by an amplifier with suitable 'grip' and slam! :cool:
Look forward to seeing your plinth build in due course.
Marco.
It's a question you could ask about a lot of vintage speakers. Celestion did not just ship them out without listening. These are from well before the day of boxcalc and so forth. So what did the engineers do for stands when testing?
Probably just the castor feet. And bell-wire speaker cable.
It's called 'progess', Martin! ;)
Marco.
It's called 'progess', Martin! ;)
Marco.
My point was the boomy bass reports are probably down to something other than having the speakers plonked on the floor. Amplification most likely, trying to drive them with some weedy, underpowered thing.
I mean think about it, did they have this conversation back at Celestion in '73?
'How are those new flagship studio monitors coming along?'
'Okay but they are a bit boomy in the bass'
'Screw it lets ship them out anyway'
Which is not to say that you can't improve performance with the mana stands or whatever but I am sure I could plonk them straight down on my nice flat concrete floor and have no issues with boomy bass.
Yeah sure, however, the bass is nowhere near as tight and controlled, with the speakers just plonked on the floor, as it is with the Mana supports in situ - and that's regardless of what amplifier is being used.
Your point about amplifiers, however, is valid. I find that people's (bad) impressions of a lot of inherently excellent vintage gear, when they heard it first time round, is simply because of the original context they heard it in, perhaps with some 'less than excellent' partnering equipment of the day. Let's face it, as much as there are some vintage gems out there, there's also plenty of dross!
However, when said (inherently excellent) vintage gear is listened to in a modern context, with the use of proper stands, high-quality cables and better equipment, it can *really* shine!!
That's precisely why I always advocate the policy of combining the best of old and new technology, when building a system, as the sonic result can often be phenomenal, and achieved at far less cost overall than simply buying new....
:exactly:
Marco.
The Barbarian
20-07-2014, 09:23
Your point about amplifiers, however, is valid. I find that people's (bad) impressions of a lot of inherently excellent vintage gear, when they heard it first time round, is simply because of the original context they heard it in, perhaps with some 'less than excellent' partnering equipment of the day. Let's face it, as much as there are some vintage gems out there, there's also plenty of dross!
A lot of peoples bad impression of vintage gear is mainly due to ignorance.
You cannot just buy a vintage amp plug it in & expect glorious sound, it will nearly always sound poor due to the age of the components inside, the quality of the components inside & ultimately it has not been serviced for donkies years. but what do people do? yep they write i off as crap. Exacatly the same with vintage speakers. Bad crossover boards = bad sounding speakers.
Bit of advice for someone opting for vintage gear. It needs sorting out, in in some cases the cost can be more than a new modern amp. So if you plan buying old gear just because it may seem cheap please think twice.
A lot of peoples bad impression of vintage gear is mainly due to ignorance.
You cannot just buy a vintage amp plug it in & expect glorious sound, it will nearly always sound poor due to the age of the components inside, the quality of the components inside & ultimately it has not been serviced for donkies years. but what do people do? yep they write i off as crap. Exacatly the same with vintage speakers. Bad crossover boards = bad sounding speakers.
Bit of advice for someone opting for vintage gear. It needs sorting out, in in some cases the cost can be more than a new modern amp. So if you plan buying old gear just because it may seem cheap please think twice.
That's also valid and very good advice! :thumbsup:
Marco.
Bit of advice for someone opting for vintage gear. It needs sorting out, in in some cases the cost can be more than a new modern amp. So if you plan buying old gear just because it may seem cheap please think twice.
I don't think it will always need sorting out but most of the time that is probably true. If you want a vintage amp you might as well want it because it is vintage and not because it is going to be cheaper and/or better than a modern one.
But with vintage speakers it is a bit different because truly capable speakers, bought new, cost big money nowadays whereas you can pick up truly capable vintage speakers in perfect working order for a fraction of the money and even if you do need to re-do the crossovers it will still be fantastic value for money by comparison.
Leaving Andre's point aside, however, what I'm saying is slightly different (notwithstanding the fact that my 66s are totally stock, have been that way since I bought them 4 years ago, and sound superb with no crossover upgrades)...
My point is that, regardless of the very valid point Andre has made, 'back in the day' when all this stuff was being listened to, some of it was inherently excellent (such as 66s in question, and pretty much the whole of the Celestion range in those days), but some of it was also less than excellent, or indeed crap! The fact is, crap hi-fi existed back then then just as it does now.
Now, back in the 1970s, if you're trying to assess a pair of fundamentally excellent speakers with a less than excellent (or crap) amplifier and/or similar turntable upstream, all hooked up with shit bell-wire, and speakers just plonked on the floor, how are you ever going to appreciate just how good those speakers are.....?
Fast-forward to today, and partner those fundamentally excellent speakers with the best modern equipment, stands and cables, and WOW, all of a sudden you're able to hear the FULL potential of what those speakers are capable of!! And that's exactly what's happening with the 66s in my system, or in anyone else's where the best of old and new technology has been combined to superb effect - simples :cool:
Marco.
Leaving Andre's point aside, however, what I'm saying is slightly different (notwithstanding the fact that my 66s are totally stock, have been that way since I bought them 4 years ago, and sound superb with no crossover upgrades)...
My point is that, regardless of the very valid point Andre has made, 'back in the day' when all this stuff was being listened to, some of it was inherently excellent (such as 66s in question, and pretty much the whole of the Celestion range back then), but some of it was also less than excellent, or indeed crap.
Now, back in the 1970s, if you're trying to assess a pair of fundamentally excellent speakers with a less than excellent (or crap) amplifier and/or similar turntable upstream, how are you ever going to appreciate just how good those speakers are.....?
Fast-forward to today, and partner those fundamentally excellent speakers with the best modern equipment, stands and cables, and WOW, all of a sudden you're able to hear the full potential of what those speakers are capable of!! And that's exactly what's happening with the 66s in my system, or in anyone else's where the best of old and new technology has been combined to superb effect :cool:
Marco.
I know I am wandering a tad off topic but although I have not heard the Celestion 66's I can appreciate exactly where you are coming from Marco regarding old speakers and new amplification. My Spendor SP2's are fairly ancient, built in 1986 and were good back then when I bought them but since upgrading my system amplification and front end they have had a new lease of life and sound better than I can ever remember.
Problem I have now is thinking of a slightly larger pair of speakers for future needs, many of the Brave new world designs do not float my boat. Hence very interested in posts on AOS regarding "vintage" speakers:)
Now, back in the 1970s, if you're trying to assess a pair of fundamentally excellent speakers with a less than excellent (or crap) amplifier and/or similar turntable upstream, all hooked up with shit bell-wire, and speakers just plonked on the floor, how are you ever going to appreciate just how good those speakers are.....?
.
Except the 66 (or your Lockwoods for that matter) have always been highly rated, from when they were new models right up until now, 40 years on (more for the Lockies). It's not like we are just re-discovering these things after years of them being ignored as 'old crap'.
And don't forget they were designed and developed plonked on the floor with 'shit bellwire' cables. But yes, we can improve on this with more 'modern' thinking re cables and supports, I don't disagree for a second.
Really it is the flat earth outlook that marginalised these older designs to the point were only the true cognoscenti appreciated them. Small 2 way speakers with no bass so they sound 'fast' driven by expensive but low powered amps became 'the way to go' from the late eighties onwards, at least as far as the mainstream was concerned. A totally different presentation of the sound that led folk to believe the old way of doing speakers was inferior when IMO it was far superior.
Hi Jim,
I know I am wandering a tad off topic but although I have not heard the Celestion 66's I can appreciate exactly where you are coming from Marco regarding old speakers and new amplification. My Spendor SP2's are fairly ancient, built in 1986 and were good back then when I bought them but since upgrading my system amplification and front end they have had a new lease of life and sound better than I can ever remember.
So what does that tell you? That your SP2s are inherently excellent! If they weren't, they wouldn't be capable of revealing the sonic benefits of the superior kit upstream...
That's why one should never form rigidly held opinions about any vintage equipment, listened to 'back in the day', until one has assessed it in a modern (more optimised) context. DSJR, bless him, has a bad habit of doing that. No offence meant, Dave, but you know where I'm coming from... All I need to say is 'Goldring G800' or 'Shure M3D'! :eyebrows: ;)
Marco.
I have Goodmans Magisters. They are much cheaper to buy than Tannoy or Celestion. They have a 15 inch bass in a sealed cabinet. I found the original mid and treble to be a bit 'shouty'. I wondered if the voicing for older amplification and sources demanded this at the time. The higher frequencies also had to find their way through fairly thick grille material. With modern equipment it just seems too much and I have changed the mid and tweeter. I used polypropylene capacitors throughout. I have also deployed L-pads, yes I know, a purists nightmare, but I think the results are much better than the original sound. I have them on old school stands with casters and suffer no boominess. My previous pair of modern floorstanders had to be isolated from the suspended floor in order to achieve clean bass.
Hi Jim,
So what does that tell you? That your SP2s are inherently excellent! If they weren't, they wouldn't be capable of revealing the sonic benefits of the superior kit upstream...
That's why one should never form rigidly held opinions about any vintage equipment, listened to 'back in the day', until one has assessed it in a modern (more optimised) context. DSJR, bless him, has a bad habit of doing that. No offence meant, Dave, but you know where I'm coming from... All I need to say is 'Goldring G800' or 'Shure M3D'! :eyebrows: ;)
Marco.
Interestingly I had intended to replace my speakers as I upgraded my equipment, as I assumed because they were old they would easily be bettered by modern designs but they simply got better and better. What was interesting was their ability to reveal explicitly every change I made right down to details I was not even aware of such as cable placement, Turntable isolation (this was done in four steps) and obviously fundamental large component changes.
I have Goodmans Magisters. They are much cheaper to buy than Tannoy or Celestion. They have a 15 inch bass in a sealed cabinet. I found the original mid and treble to be a bit 'shouty'. I wondered if the voicing for older amplification and sources demanded this at the time. The higher frequencies also had to find their way through fairly thick grille material. With modern equipment it just seems too much and I have changed the mid and tweeter. I used polypropylene capacitors throughout. I have also deployed L-pads, yes I know, a purists nightmare, but I think the results are much better than the original sound. I have them on old school stands with casters and suffer no boominess. My previous pair of modern floorstanders had to be isolated from the suspended floor in order to achieve clean bass.
Andrew I am using Akais which also have 15 inch bass in sealed cab. Guess what a bass guitar sounds like a bass guitar and not just a bass 'sound' as it will through so many (obviously not all) modern speakers. IMO there is no adequate substitute for direct sound from a big driver, doesn't matter how many little 6 inch cones you line up or how many ports you use. I do find the Akais can be a bit shouty when not partnered correctly although I don't think that is down to the amplification, I do need to use sources that are very clean but not 'forward' sounding.
While they didn't have the luxury of modern computer programs, the engineers of the day were no fools, they did put man on the moon after all.
Good measuring and plotting equipment was available and I can't see them going to the trouble and expense of building an Anechoic chamber without making sure the speaker was well suported and adequatley wired.
Some truly classic designs came from this period and the engineers deserve due credit. :)
Except the 66 (or your Lockwoods for that matter) have always been highly rated, from when they were new models right up until now, 40 years on (more for the Lockies). It's not like we are just re-discovering these things after years of them being ignored as 'old crap'.
Indeed - why else do you think I use that sort of kit? Unlike Andre, for example, who's into using vintage gear for the sake that it's vintage (which is fine, as I understand and appreciate exactly where he's coming from), I only entertain using it in my system if I consider that it's superior (or can be modified to be superior) to most modern equipment. I ain't on no nostalgia trip! :nono:
For me, it's ALL about obtaining maximum sonic performance/SPPV. In that respect, I couldn't give a tinker's cuss whether my gear was built in 'nineteen canteen' or 1999...
However, like Andre says, there are times when vintage kit needs lots of attention in order for it to perform to its sonic potential. Honestly, as highly rated as vintage Tannoys are (especially in Lockie cabs), if you'd heard them in stock form, before I had the crossovers modified, and compared them with how they sound now, you'd have chucked them in the bin originally! ;)
Now that raises an interesting point, regarding crossovers... Why have I gone to great lengths (and expense) modifying/upgrading the crossovers on the Tannoys, but not on the 66s? Well, apart from sheer laziness, the 66s sounded superb 'as is', when I first heard them, whereas the Tannoys most certainly didn't!
Why? Because crossover component technology came on a long way from the early 1960s (when Tannoy Monitor Golds first appeared on the scene), and the mid 1970s, when the 66s were born, so in that respect, the Celestions were inherently already more 'optimised' than the Tannoys. That's not to say, however, that one shouldn't replace certain components, through age, or modify the crossovers as Ken has done, to excellent effect.
But the fact is, the 66s were already more 'sorted' as a design than the Tannoys were, which is why I've been able to enjoy the Celestions in stock form without needing to tinker with them...
Returning to the issue of crossover component technology, just as what was around in the 1970s was significantly superior to what existed in the 1960s (and earlier), so it is with the quality of the components that are available today - in fact, when it comes to things like capacitors (aside from some highly sought after vintage P.I.O types), there is simply no comparison, although unfortunately, as Ken (and others) have found to their chagrin, electrical superiority doesn't always equate to sonic superiority! :eyebrows:
Really it is the flat earth outlook that marginalised these older designs to the point were only the true cognoscenti appreciated them. Small 2 way speakers with no bass so they sound 'fast' driven by expensive but low powered amps became 'the way to go' from the late eighties onwards, at least as far as the mainstream was concerned. A totally different presentation of the sound that led folk to believe the old way of doing speakers was inferior when IMO it was far superior.
Spot on - and that shit still irks me hugely to this day! It's also why we will continue to do all we can on AoS to remove the brainwashing and educate people as to the joys of going the vintage route!!
Right, I'm off to prepare the table outside for lunch, and enjoy the lovely sunshine.... :)
Marco.
Interestingly I had intended to replace my speakers as I upgraded my equipment, as I assumed because they were old they would easily be bettered by modern designs...
That's a fatal way of thinking, Jim, especially as 90% of the time it's untrue! Hey, at least you got there in the end ;)
Marco.
I have very mixed feelings with regard to capacitor ESR and how much of an issue it is when replacing capacitors in a crossover.
I have very mixed feelings with regard to capacitor ESR and how much of an issue it is when replacing capacitors in a crossover.
It depends entirely on the speaker crossover Mark. It is way more critical with some than others. For example, you replace the caps in say B&W CM1/2's with polys, you will ruin the speakers, period. I have had correspondence with B&W directly on this topic and their strong advice is NEVER to replace any electrolytics in their designs with polys for all the reasons that Ken and I have already raised. There are other simpler designs (mostly 1st order slopes) where the value of the cap, the impedance of the driver and the crossover point are way less critical. A lot depends on the original driver impedance and crossover point, but it does matter and it will make a (measurable) difference. People who try and outsmart the (smart) engineers who originally designed these things, especially without proper measurement, are imho, for the most part shooting in the dark. Sometimes they'll get lucky, mostly they wont. Most people would also never admit to mucking up their speakers. Each to their own, but my humble professional opinion is to think carefully...at least do a few sums and see what say a 1 ohm difference in ESR is likely to make for a series capacitor in terms of the filter to the crossover point and therefore the summed response. Who knows, in some cases it may be an improvement, but bear in mind that overall response depends on the behaviour of a particular filter design across a wide frequency range and often engineers from the '70s would use measurement to tweak cap values and positions and NEVER cookbook values. You cannot design a crossover on a cook book approach. We have the advantage of T-S parameters today but measurement is still how all good crossovers are designed and tweaked. It is a pre-requisite for matching left and right sides too. That and final listening tests. Sorry to hijack the topic Ken!
That's a fatal way of thinking, Jim, especially as 90% of the time it's untrue! Hey, at least you got there in the end ;)
Marco.
Absolutely right Marco, I can imagine just how many folk now regret chucking out their old Garrard and Thorens decks.
I know as I was one of them, had a Garrard 301, got chucked out and replaced by a Ceedee player:doh:
The Barbarian
20-07-2014, 12:26
Aye selling my 'TD124, Mk.II' once upon a time was a very big mistake as i so desperately want one again however since the asking prices are quite frankly a giant piss take i can't see this happening.
The whole process of going back to vinyl and analogue has been a giant leap forward for me:)
Sorry to hijack the topic Ken!
The topic has already been hijacked, had a course change to Beirut, landed and is sitting on the airstrip in a stand off with security forces and police ;)
But this is a speaker renovation tread so discussion of crossovers and re-building them is pretty much back on topic I think.
The whole process of going back to vinyl and analogue has been a giant leap forward for me:)
Amen to that ;)
I've a few customers and friends who have now dropped digital as their premier sources and get way more satisfaction from analogue. Be that the tactile nature of the medium, the ritual of selecting and playing (getting off one's arse so to speak in order to play something), the visual stimuli, the sound or a combination of all of the above. When challenged by others about the perfection that is (sic) digital, and the surface noise of vinyl, one chap quoted John Peel, "Life has surface noise mate" :lol:
If ESR in Elcectrolytic caps is dependant on frequency and temperature (and I'm not saying it isn't) how can it be emulated by placing a resistor (which won't change value with frequency or temperature) across a polypropylene?
I'm not advocating design by 'cook book' but plenty of designs were (and still are) designed in precisely this way. Many electrical engineers have no time for subjective assessment - as far as they are concerned, if the maths says it's right it is, no need to confirm that by listening. The idea that all 70's speakers were voiced by lengthy subjective evaluation is poetic and may well be so in some cases, but not true in all.
Answer to emulation: It can't be. It's an approximation.
Designs may be approximated too via cookbook recipes but they'll always be just that...ie approximations. things have moved on and most reputable speaker manufacturers measure things properly (and many always did). Why people insist that these things can be guessed is beyond me but there we are.
" Look, I've tried being helpful on this thread but it seems to invariably descend into mud slinging or confrontation where people have other ideas, so little point in contributing further. I do this for a living and thought that I could pass something useful on, no strings and all that. Sadly, I have been mistaken. Sorry and all that, but I'm not in this to be a target for people with an axe to grind for whatever reason. Its a sad inditement of AoS that some members have an axe to grind for whatever reason/agenda. Not that you have an agenda Mark (far from it).
.
I'm not seeing any mud-slinging or confrontation, Paul. People are allowed to politely disagree with you even though you are a professional in this area. Your contribution and expertise are welcome but AoS is discussion forum not a lecture theatre. If anyone oversteps or has overstepped the bounds of politeness then please let me know.
My Magisters have exactly the same crossover board as my Magnums. And yet they have different size cabinets and different bass drivers. The tweeter and mids were also used in other designs. So either the bass drivers and cabinets were carefully designed to use the same crossover, mid and tweeter somehow or the design allowed for a certain amount of latitude in the final sound. The latter is what I believe and is why, in this case, I have allowed myself to take liberties with my Magisters.
The Barbarian
20-07-2014, 13:51
I am not mud slinging either. My negativity against it is purely through experience in re-building many vintage X Overs throuh the years. I am fully aware of capacitors Specification through what i have read & learned on various electronics courses.
However the best Way to decide if a X-Over sounds right or has any ill effects with a full PP re-build is with my own earholes. As long as the original Cap value are used i see no potential danger to the original speaker design. Specifications must however count for something because some boutique caps sound aweful, some nice.
Upto now, i & other have had no issues so im afraid that the specification lark is swept under the carpet with me.
I'm not seeing any mud-slinging or confrontation, Paul. People are allowed to politely disagree with you even though you are a professional in this area. Your contribution and expertise are welcome but AoS is discussion forum not a lecture theatre. If anyone oversteps or has overstepped the bounds of politeness then please let me know.
I think the problem, as is often the case on forums, is confident people with educated and experienced opinions in audio not giving due respect or credence to the contrary opinions of others who fall into the same or a similar category as they do, in terms of education and experience... ;)
However, I'm not singling anyone out here as the 'culprit'. Therefore, I shall say no more other than that, please guys, let's remember that on AoS no-one's opinion on any subject is ever any 'more special', 'more important' or 'correct' that that of anyone else. There are no ‘know-it-alls’ here. We’re on a continual learning curve together in this game.
I don't want to have any more chit-chat about that matter (indeed continued off-topic remarks will be removed without further warning); just simply bear in mind what I’ve said in future when contributing here to discussions.
Now let's return to the thread topic, which is the renovation of Celestion 66 Studio Monitors. Ken, it's back over to you... :cool:
Cheers!
Marco.
When challenged by others about the perfection that is (sic) digital, and the surface noise of vinyl, one chap quoted John Peel, "Life has surface noise mate" :lol:
See my avatar ;)
Marco.
While they didn't have the luxury of modern computer programs, the engineers of the day were no fools, they did put man on the moon after all.
Good measuring and plotting equipment was available and I can't see them going to the trouble and expense of building an Anechoic chamber without making sure the speaker was well suported and adequatley wired.
Some truly classic designs came from this period and the engineers deserve due credit. :)
Excellent post.
The thing that annoys me about the truth of that post is that generally the facts will be disguised from your average 18 year old until they gain enough experience to realise it. Before they do, they'll probably waste countless £££s on modern gear when they could have done a lot better buying older kit.
walpurgis
20-07-2014, 22:20
Modern measuring equipment and computer modelling are great tools, but a good ear is still essential. It's subjective obviously, but I'm sure you can have a speaker measure superbly, but not sound necessarily 'right' or as expected.
The final arbiter in any audio design should always be one's ears!
Marco.
Modern measuring equipment and computer modelling are great tools, but a good ear is still essential. It's subjective obviously, but I'm sure you can have a speaker measure superbly, but not sound necessarily 'right' or as expected.
I have heard plenty of those, this is the problem when everything is now modelled on computers then built by a robot. Ok for building cars and vacuum cleaners, not so good for hifi components.
I suspect that when speakers and turntables where designed and constructed years ago there was a greater human input which generally involved a lot more listening and not so many graphs and analytical data.
Precisely - and that's probably a big reason why, with hi-fi equipment, in terms achieving the best sonic performance possible, we've gone backwards recently more than forwards! Who would ever have thought that the tinny-sounding cacophony, produced by a mobile phone, would one day be considered as 'hi-fi'...? :rolleyes:
The major advances in audio, in recent times, have largely been in terms of convenience, miniaturisation and improving portability, which is bad news for purists like us.... That's why going the (high-quality) vintage route, in terms of system building, often pays the greater dividends :)
Marco.
No-one could accuse Paul of building stuff with robots, unless there's something he's not telling us.... :eyebrows: Cue the title track to Terminator... :lol:
I certainly wasn't referring to Paul! I'm talking about the way hi-fi in general is going these days, compared to the way it was in its 'heyday', when most of the genuinely innovative stuff happened :)
Marco.
I know that silly, I was injecting some humour... I must have missed the vein... :D
Niento problemo :)
Marco.
http://www.jkwynn.co.uk/Project_Images/66/66_25.jpg
I need a solid stand for the speakers bass to perform at its best, so I set to on a mould for a cast concrete plinth.
The base board is melamine faced chip board, I sat the speaker on the board and drew round it with an indelible pen. The guide lines for the wood shuttering were drawn parallel to this with a slight increase in overall dimensions to allow for 12mm chamfered top edges.
The face contacting the board will be the top one of the plinth, the centres for the threaded inserts are marked out and the circle in the centre will have a disc stuck to it, creating a pocket for the spirit bubble to sit in.
I’ve made the shuttering and given it a coat of Danish oil to waterproof it, a second coat will be applied when the first one dries and after that dries it can be screwed back together. It makes it easier to remove the casting if the mould can be disassembled and the shuttering hasn’t got to be damaged as a second casting is needed to make the pair of stands.
I smell the whiff of another success, Ken! :)
Marco.
No thats just the whiff of the midnight oil you can smell Marco :eyebrows:.
I’m waiting for bits and pieces to arrive for the threaded inserts so I filled my time on some of the more trivial tasks.
http://www.jkwynn.co.uk/Project_Images/66/66_26.jpg
This is the pair of 30mm diameter bubble levels I purchased for the stands.
I painted the transparent sides and parts of the base Black, so that you won't see the concrete or any fixing adhesive through the clear material when in place.
http://www.jkwynn.co.uk/Project_Images/66/66_27.jpg
The set of badges on the left were being ignored by folks on Fleabay. After the seller had brought the starting price down on three successive auctions I made a sole bid and got them at a good price. I purchased these a few weeks after I bought the speakers, I was thinking about how I would make the stands and what the details would be even then.
I cut the “DITTON 22” part away to make plain badges for the stands. The badges will sit in pockets on the front chamfered edge and will of course add tremendously to the sound quality. :D
I'm still waiting on parts for the speaker plinths. :steam:
http://www.jkwynn.co.uk/Project_Images/66/66_28.jpg
I Know I said I was going to wait but the recessed mid range has been getting on my nerves, so I took out the pair of 15uf Mundorf Low Loss Lytics and dropped in the large 30uf Ansar "Supersound" PP cap with a 1.8 Ohm resistor to compensate for ESR. I changed the tweeter attenuating resistor from 0.75 to 0.82 Ohm while I was at it. You can see the terminal block elements I used to allow quick changes, I can swap resistors with the x-over still mounted in the cabinet.
The caps haven’t settled in yet but there is already more transparency and just more mid range period. Much better sounding than before but the thing is, the mid range seems to be the dominant force in the overall presentation now. :rolleyes:
I will let things run in a while and then have a proper listen before adjusting anything.
walpurgis
25-07-2014, 18:48
Nice dodge with the badges. Looks excellent.
Thanks Geoff
http://www.jkwynn.co.uk/Project_Images/66/66_29.jpg
The Acrylic tubing arrived so I can continue with the plinth. The tubing is I.D. 8mm x O.D. 12mm so an 8mm bolt will just slide through. The tube is used as a spacer for the stainless nuts/washers and an 80mm long csk machine screw is inserted from the underside to pull it all up nice and tight. The spacers have been adjusted so the top of the nut is just below the top of the mould and these will have some blu tac or similar stuffed in the top to stop cement getting down the ends. When the concrete sets and the screws are removed, the fixings will be anchored in the concrete and an M8 speaker spike can be inserted. By cutting a slot in the end of the spike with a hacksaw, the spike can be adjusted by inserting a long thin screw driver down the tube, who's open end will be on the top face of the plinth. By running a bead of silicon sealant down one side of the thread on the spike and rubbing it off with a finger, leaving just what is in the thread, you can make a form of thread lock. Leave the silicon to fully dry then insert the spike into the nut, you will need more than finger pressure to turn the thread, but once adjusted to the right height it will stay put without a lock nut and also without any unwanted vibration caused by chatter in the threads.
Nice job so far on the plinths, Ken! :clap:
It would be good if you could get your 66s 'optimally voiced' in time for NEBO, as I'm looking forward to comparing my stock jobbies against them and deciding whether or not I should leave them 'as is', and simply settle for an easy life [as I love how they sound now anyway]! ;)
Marco.
Marco - I will only have stage one compleated and sounding its best. I don't have time to complete stage two before NEBO4 and to listen to that when not opptimised would be pointless. I think I have stage one sorted barring any changes as the caps get more hours on them.
Stage One - Replacing the caps in the signal path (Series) with PP's and the caps in Parallel using Alcap lytics, all original values. This is the low cost option that uses just the stock x-over board so does not effect originality too much.
Stage Two - Also replace the parallel Lytics with PP's. This is a much more complicated affair as the shear size of the bass caps requires either a new board or a small additional board mounted adjacent. All these additional PP's will need ESR simulating resistors as well. Option one only requires a single ESR simulating resistor on each board. Ultimately stage two will have a tighter bass and cleaner mid range by a small margin, but will need a lot of work balancing out all the resistor values to achieve it.
http://www.jkwynn.co.uk/Project_Images/66/66_30.jpg
That's the first plinth poured, I will give it a few hours drying and then polish the top with a float.
When filling the mould I mixed a small amount of sand and cement and applied this first around edges and corners and of course the base of the inserts, to make sure the detail was picked up then the concrete mix was poured in and tamped down and levelled. Both were a strong mix and had PVA added to the metering water. PVA was applied neat to the inserts and spacers the night before and left to dry. A second coat was applied half an hour prior to adding the mortar/concrete, which will aid bonding. The mould had two coats of Danish Oil applied to seal the timber and a generous coating of furniture wax was rubbed over the internal surfaces as a mould release prior to casting.
The stock ones sound smooth and just a touch 'rich toned,' but not as warm/thick as Ditton 44's could do. I suspect the Ansar caps would be a hugely beneficial thing here and 'should' balance the speaker a touch more for modern tastes, or at least enhance clarity.
Labour of love this, got to admire it :)
The stock ones sound smooth and just a touch 'rich toned,'...
Mine don't!! ;)
Marco.
I wasn't criticising Marco, quite the opposite :)
I know you weren't - I was simply pointing out that mine don't sound how you describe :)
"Smooth and rich-toned", for me, suggests a form of euphonic coloration. The reality is that mine sound very detailed and open, fast, tight and punchy - and above all, as 'musical sounding' as the source programme material allows...
Marco.
It's a comparative so you have to have some reference point. Smooth and rich toned compared to an NS10? Or smooth and rich toned compared to a KEF104ab? If you see what I mean.
I know you weren't - I was simply pointing out that mine don't sound how you describe :)
"Smooth and rich-toned", for me, suggests a form of euphonic coloration. The reality is that mine sound very detailed and open, fast, tight and punchy - and above all, as 'musical sounding' as the source programme material allows...
Marco.
Agree with your description of your speakers, having heard them.
http://www.jkwynn.co.uk/Project_Images/66/66_31.jpg
Out of the mould - The detail picked up pretty well, the chamfers on the top edge were worth the extra effort. :)
Yeah, has come out very well. Are you going to paint them (black)?
Yep, satin black acrylic (water based) Wilko own brand, boring I know but its what I used on the baffle boards so will tie in nice when the covers are off. I just use a gloss roller to apply it.
It's a comparative so you have to have some reference point.
Indeed... Mine is in terms of how real music sounds! ;)
Marco.
Agree with your description of your speakers, having heard them.
Churz, matey... I find them pretty close to being an 'open window': as in they simply sound as good as the source recording and components allow! ;)
Marco.
P.S Liking the plinths so far, Ken. Those should come up nice! :)
Marco.
Thanks Geoff
http://www.jkwynn.co.uk/Project_Images/66/66_29.jpg
The Acrylic tubing arrived so I can continue with the plinth. The tubing is I.D. 8mm x O.D. 12mm so an 8mm bolt will just slide through. The tube is used as a spacer for the stainless nuts/washers and an 80mm long csk machine screw is inserted from the underside to pull it all up nice and tight. The spacers have been adjusted so the top of the nut is just below the top of the mould and these will have some blu tac or similar stuffed in the top to stop cement getting down the ends. When the concrete sets and the screws are removed, the fixings will be anchored in the concrete and an M8 speaker spike can be inserted. By cutting a slot in the end of the spike with a hacksaw, the spike can be adjusted by inserting a long thin screw driver down the tube, who's open end will be on the top face of the plinth. By running a bead of silicon sealant down one side of the thread on the spike and rubbing it off with a finger, leaving just what is in the thread, you can make a form of thread lock. Leave the silicon to fully dry then insert the spike into the nut, you will need more than finger pressure to turn the thread, but once adjusted to the right height it will stay put without a lock nut and also without any unwanted vibration caused by chatter in the threads.
Don't suppose you want to loan/rent these moulds out to other keen 66 owners ( eg me) Ken?
Cheers
John
John - When I'm done making my second plinth you can have the mould. :)
Wait and see what you think of the finished articles, if you still want to use it, you will be doing me a favour taking it off my hands as I am short of storage space. You can pass it on to anyone else interested after you are done. (One mould use it twice).
Getting it to you will need thinking about as I see your in the Midlands but I'm sure we can find a way. :scratch:
Thanks Ken.....my 66s are on what I think might be granite chopping boards.
We'll be up your neck of the woods in middle of October to watch Leicester play at Newcastle....
Cheers
John
http://www.jkwynn.co.uk/Project_Images/66/66_32.jpg
That's the first of the plinths completed, spirit bubble set into the top and carpet spikes installed and adjusted through the four holes in the top face. Each plinth weighs over 20Kg.
http://www.jkwynn.co.uk/Project_Images/66/66_33.jpg
I'm pleased with the appearance, I think the base compliments the speaker.
The spikes have been adjusted so the base is only just clear of the carpet, which makes it look well anchored visually and not floating. The thickness of the base and the gap created by the "Soundcare" feet, have good proportions and work well together. It only remains for me to complete the second plinth which is out of the mould and requires finishing cosmetically.
istari_knight
02-08-2014, 09:09
Those look fantastic Ken, you do lovely work !
Yep - lovely job. Do the speakers just rest on the plinths?
The speaker base has three of these Soundcare feet fitted (a spike which carries its own shoe).
These have felt on the underside and they just sit on the plinth.
http://www.jkwynn.co.uk/Project_Images/66/66_07.jpg
I have to say that this has been one of the best threads on AOS ......nice work Ken.
Thanks everyone - Need to do the final tweeking of the x-overs in time for NEBO4 (bake off), they are very close to optimum I recon.
The speaker base has three of these Soundcare feet fitted (a spike which carries its own shoe).
These have felt on the underside and they just sit on the plinth.
http://www.jkwynn.co.uk/Project_Images/66/66_07.jpg
Ken, why 3 Soundcare feet per speaker base rather than 4?
Cheers
John
If you use 4 feet you have to adjust them for even minor variations in surface flatness or they will rock on three of the feet. If you don't have equal pressure on all four feet they don't contact correctly due to weight distribution in the rectangular layout pattern, which defeates the point in terms of creating good solid contact to produce good bass.
3 feet equally spaced don't have to be adjusted, they will allways sit with the weight on all the feet and will not rock. This is why a milking stool has three feet and a camera tripod etc. It is the most stable number possible.
The 3 feet I used are fixed on the bottom of the speaker and are equal height. In their make up they have a shoe attached that swivels to conform to any surface irregularities, which are few as the top surface of the plinth was, by design, moulded against the flat melamine base board, but still, it means they allways make optimum contact.
I leveled the first plinth using it's built in bubble and placed a speaker in position, I then put a spirit level on top of the speaker, it was perfectly level and did not rock having a very solid feel to it.
Long winded explanation, but I thought long and hard before making the decision. I also considered using three feet on the plinth but found through previous experience it wasn't needed, as there is sufficient weight and enough complience in the carpet/underlay for the four spikes to have a good amount of contact when adjusted correctly and no rocking. Once in position they are less likely to be moved and the speaker can be lifted on and off without any adjustment and remain stable, level and rock solid. ;)
Thanks Ken, very clear when explained. I should have listened more at school!
Cheers
John
I took the 66's to the NEBO4 bake off and they were well received.
See this link for how that went down: http://theartofsound.net/forum/showthread.php?33549-NEBO-4-(North-East-Bake-Off)/page5
When comparing them with Marco's totaly stock 66's there were areas that have improved and areas that need further attention (Mid Range integration). I will continue to work on that and post my results. :)
Hi there Ken, a little off topic , but enjoyed our conversation at Nebo 4 about the rationale behind your work on your 66's [sounded really full and listenable to me] especially the effect of resistor choice [not just value] made on the voicing of the speakers , gave me a lot food for thought on changing out of spec resistors on my old amps .Thanks for being generous with your time and accumulated knowledge , it was appreciated
No problemo Mick, these sort of events are allways a two way exchange of experiences and I picked up a lot of usefull tips on the day.
Ken, just reading this thread now. Had no idea how much work you'd put in. Having heard them I can say they're worth the effort and didn't realise the plinths were your own creations too. They really did look and sound the business. In terms of comparing them with Marco's I'd say whatever you've done on voicing the bass was just right for my ears, that was the key difference I observed given they were played in different systems. And I did tput some bass heavy stuff on at the end of the night too causing Mick's Radford to sweat a bit. In particular the Robbie Robertson track 1 from 'how to become clairvoyant'.
Good work mate. I'd be interested to see how you'd approach my old 15s.
Hi Rich
Taken on its own the bass sounds great and is probably slightly more emphasised than when turned out from the factory.
Listening to Marco's I just felt mine lacked a little richness in the mids, it's only a small point but I think worth persuing.
I'm a fussy bugger when it comes to speakers, I think the 66's have the capability to be my keepers, but I want them to be well balanced, I think they can be made to sound even better in this respect. ;)
Not posted for a while but I have reached a junction in the development so will bring things up to date.
Firstly, after many variations tried I have concluded that most of what is proposed over on the diyaudio forum, in the very large thread on the 66’s, just does not work.
This is not to take anything away from the hard work done, and I would not be at the point I am now without trying their suggestions. But after building them and trying all the options on values I have concluded that they are expensive and do not perform as well as the simple re-cap shown below. I repeat that this is based on building and trying what is suggested and after extensive listening tests and not just based on theory.
http://www.jkwynn.co.uk/Project_Images/66/66_34.jpg
After much experimenting over several months and trying Polyprops with/without ESR simulating resistors this is the best sounding set up I have found, for anyone wanting to keep the original boards/design. The Sonicap Gen 1 Polyprops are one of my favourites for HF applications and one of the few available in the exact value required as a single cap, but any good PP would do, avoid cheap ones like Solen for the Tweeter. The top three Alcap electrolytics are 100v versions. The 25uf in the Mid range is a Low Loss Item (important) and is for the MD500 mid range, if using the MF500 add an ordinary 5uf Alcap in parallel with this. I have both sets of drivers and found the earlier MF500 to be smoother and more refined in its presentation, the MD500 gives a more forward midrange and because of its rating will ultimately play louder. The 25uf was used as the correct 24uf is no longer available. This is now more complicated because I have been informed the 25uf is also no longer available, I must have purchased some of the last ones, so a parallel pair of LL will be needed to make up the correct 24uf or 30uf value depending on the type of Mid driver fitted.
http://www.jkwynn.co.uk/Project_Images/66/66_35.jpg
The circuit design used in the 66 is electrically resonant and the damping factor of the electrolytics used and their less than transparent presentation helps disguise it. The use of analogue sources at the time will also have helped the situation. This resonance accounts for the less than perfect top end by modern standards, and which I find particularly noticeable with digital sources, all my opinion here of course. Polyprops in the mid range really emphasize this top end weakness even with ESR compensating resistors fitted and without them sounds just plain terrible. As a longer term project I am now looking at what can be done to reduce this resonance effect. I have fitted Seas Tweeters (reversible), shown above, not that there is anything wrong with the HF2000, its just that the ferofluid damping in these modern units seems to reduce the resonance slightly and play cleaner, you have to adjust cap values to suit. I will be moving the circuit to the lower chamber and away from the big Bass driver magnet and re-positioning the coils to reduce interaction. The early air core coils that are fitted to my speakers are loosely wound and could be a source of mechanical resonance so new tighter wound and varnished coils will be used, again for originality the Celestion x-overs will be removed and kept intact, should I ever want to sell the speakers. I will try and isolate the resonance, which seems to be generated in the mid range band pass circuit and plays at a frequency in the range of the Tweeter and is still present when the mid driver is disconnected. So I will be splitting the circuit into its three separate filter components and isolating them. Each element will be wired separately back to the Amp (Tri-Wired), this may or may not help but is worth a try. To this end I am working on a design for a Logo/label to include three sets of binding posts which is shown above. There is a lot of work and experimenting to be done so I will just get on with it and post any worthwhile results. The speakers are probably sounding as good as they did when new, maybe better, but that doesn’t mean I can’t improve on this without the financial and constructional constraints which the original engineers had to deal with. I think it’s worth the effort as I really like the overall presentation of these speakers.
http://www.jkwynn.co.uk/Project_Images/66/66_34.jpg
Very impressive; a crossover based on Manchester United's much needed new 'Back Five' defence.
DarrenHW
28-09-2014, 11:15
Interesting. I've eventually serviced my Quad 405 and have spent this weekend burning it and the new inter connects in, this is the first time I've had a decent source (i.e. not an integrated picked up for a couple of quid at a car boot!) connected to my (DIYAudio) modified 44's. I think I'm experiencing similar issues to you with HF resonance, like you I have found this more obvious from CD than vinyl and have also experienced this in some cases, but to a lesser extent when connected to the AV receiver.
As I now have the 405 in service I can now turn my attention to my 44's. I have one pair which I have recapped the Tweeter and Mid with PP's and resistors as per the DIYAudio thread. I intend to recap the second pair of 44's with Electrolytics (I best get some 12uF's ordered before they're gone too!) in the Mid and can then compare them side by side. Your updated schematic show no resistors on the Tweeter caps (as per the original cross over) do you find it unnecessary in this configuration with new PP's for the Tweeter?
Is there a big difference with the Seas Tweeter's, will they be staying? It has always been my intention to try the Seas units as I will be incorporating either a 15XR or UL8 (I currently have both and I prefer the UL8 at present) as a centre speaker and would like to have matching tweeters in all speakers.
Hi Darren
The advice on diyaudio using PP's and resistors is Pants.
ESR is a variable, so trying to replicate it with a fixed value is only ever going to have a partial result.
Also the damping factor of the Lytics is not present in the PP's so resonance is higher.
It's a very long thread and I have wasted massive amounts of time trawling through it. My advice is, disregard the whole thing.
Bear in mind that the chap giving most of the advice has never owned a pair of 66's and the advice is based on general principles, a fact that he freely admits early on.
There is much inaccurate information early on about the various models and their differences. There was only ever one model, no mk II and the various changes did not happen together they were brought in gradually over the life of the product.
Also much of what is discussed is relating to people tweaking for defective hearing and/or defective drivers, it is very easy to miss the line in the massive amount of information that points this out and you end up following the wrong diagrams and parts values.
I tried using the correct information and found holes in the frequency response around the x-over regions when using the PP's/resistors. The Lytics sound a massive amount better, not just by a small amount. For general pop music you may not notice it, but put a concert grand piano on with a piece that runs up and down the scales and it is totally unrealistic badly timed and full of holes in the spectrum. It’s a good thing to test with.
When you change the mid range series cap to PP/resistor it increases the resonance and I have tried all the resistor combinations they suggest and many other things they have not tried. They have a frequency plot that shows how the increasing resistor value reduces the resonance. I would agree from my listening tests that it does do this, but at the expense of transparency the PP's end up sounding muffled and less transparent than the Lytics so it’s pointless. Changing the Parallel cap to PP/resistor increases the resonance even more.
The addition of these resistors has a big affect on the driver integration. The one on the Mids parallel cap makes a huge difference to the amount of upper mids/lower treble in the presentation and small changes to value make big audible changes. The one on the series cap effects the way the bass comes across. I only changed this by 0.2 Ohm and folks at Nebo4 were saying how much more present the Bass sounded compared to Marco’s untouched x-overs. The whole thing is balanced on a knife edge and it is very easy to screw them up. Just bang in the Lytics and they sound “RIGHT”.
I like the SEAS (19TFF1) tweeter a lot, it is very smooth and detailed and less prone to bring out the resonance of the x-over circuit. I am guessing because of the ferofluid damping - It is staying. My Sugden Amp is very clean sounding and the circuit resonance is very easy to pick out on Joni Mitchell – Blue CD which is a bit of a torture test. I use others and find Husky male voice also brings it out (REM etc).
Oh, the values for caps and the L-Pad values to use with this tweeter are all wrong on the diyaudio thread, tried them and they sounded crap. If you just hook the tweeter up to the standard circuit it sounds as good, but this is not optimum by any means (I’ve tried both). Just using an on-line calculator for the cap values and L-Pad gives much better integration and SQ, I used the ones on Europe Audio’s site.
For the stock HF2000 tweeter the PP’s in the HF filter do not need resistors, this is because the original caps were Polyester film caps (the early turquoise on mine) and behave in a very similar fashion to the modern PP’s. This was born out in listening. The original caps are long life for what it’s worth and sound reasonable, maybe on par with cheaper PP’s like Solen, but not as good as a quality PP.
I have taken a breather from the Mods as I have had the speakers appart several hundred times, sometimes four times in a day with all the stuff I have tried. Fitting terminal blocks for the key components was a big help for quick changes. ;)
Edit: The resonance is also very noticeable when playing my TV output through my DAC Magic.
DarrenHW
28-09-2014, 17:04
You make a compelling case for abandoning the PP's. I don't have any Joni Mitchell, my source of female vocal torture tests comes courtesy of fellow Canadian Martha Wainwright and she certainly upsets the 44's. I hadn't listened to any REM since plugging the 405 in so gave them a spin after reading your post. I too have issues with the lead vocal, not as pronounced as Martha Wainwright but still not right.
I've checked on Falcon Acoustics to see what Low Loss caps they still have in stock and have a bit of a problem. My original value is 27uF (this is also the case for the UL8's made up of 1x12 & 1x15), what would you suggest I do here? I could go 20 + 7 (27) / 16 + 12 (28) / 16 + 10 (26)? Since none are parallel I think sticking to 27 is probably the best way to go?
I'm glad you like the Seas, at least something positives came of the DIYAudio thread? Are you using the PP shown in your schematic above (4uF & 6uF) or is that just the schematic for stock HF2000's? The DIYAudio thread for 44's suggests 3uF & 11/12uF for the Seas? I did have a look at the calculator on Europe Audio but I don't know what I'm supposed to do :doh:.
Can't say I blame you for taking a break from the 66's. It must have been frustrating with all the combinations you've tried but at least your on your way to finishing them.
I'd stick with the value Celestion used, 27uf in your case.
To start using Polyprops throught you really need measuring equipment to see what is happening and probably change the basic circuit, maybe notch filters etc, it starts to get complicated. On the other hand the Alcaps work extremely well without any mods, remember they had lytics in from new and sounded pretty damn good. To try and replace the two 72uf in the bass with PP means new boards as well, a single cap or an identical parallel pair of this value takes up a lot of space. The one Lytic that might be worth experimenting with is the series cap in the mid range, as its in the signal path it will have a major influence on the overall sound, all the others just shunt to ground. When I get everything else to my satisfaction I may try working on just this component, I did have some success making this up from about 70% PP and 30% Lytic as a parallel pair, the ESR and damping factor of the Lytic helping the PP out. I may persue this further.
The 4 and 6uf on my diagram are for the HF2000. Sonicap are one of the few companies making both these values. Many people have used 3.9 for the 4.
I've got approx values in place for the Seas Tweeters at present made up of parallel pairs (from my parts bin) that are close but not exactly what I wanted to try. When I can afford it I will be getting some ClarityCap ESA from HFC. It is a pain getting the Sonicaps from the States, but they are very good. By the time all the shipping, taxes and import duty are paid it works out roughly that they cost the same number but in pounds rather than the dollar price on their site. The Seas needs an L-Pad and when I order caps I will get some fixed resistor pairs to make up approx -0.5db -1db and -1.5db. You have to work with the resistor values available and it comes out at -0.6db/-1.08db/-1.64db. It will probably be the smaller attenuation that is needed as they are not far out, but the slightly different cap values may alter this, one way or the other, so covering my bases and getting them all at once, to save on postage. Using MOX resistors and will change to Mills when the right values are established.
http://www.jkwynn.co.uk/Project_Images/66/66_36.jpg
The three sets of binding posts have been fitted along with my fake period label, it's amazing what you can do with an ink jet printer and a laminating machine. This will allow me to separate the three x-over elements and tri-wire or even go active and tri-amp if I get the urge. ;)
Wakefield Turntables
08-10-2014, 12:20
Maybe three intrinsic t-amps?
Rexton - That had crossed my mind.
eg:
Amptastic Mini-1 x3
Quad 303 x3
Pro-Ject Box Design x3
Cyrus Power x3
I was thinking along the lines of campact amps that could sit three abreast on my wider than normal shelf.
It's not a definate path at the moment and is on the back burner till I see how the circuit splitting, tri-wiring and relocating away from the bass magnet works out.
Wakefield Turntables
08-10-2014, 14:25
What about installing them intrinsically, the aluminium casing of these amps should provide enough shielding?
Do you mean 'internally'?
Rexton - Presuming Internally. That is a possibillity but would require long RCA leads.
I'm still reading up on the subject, how individual driver gain and time delay can be adjusted etc.
It looks like the active x-over sits between the pre-amp and power amps on most set ups, they call this line level in some instances, which strictly speaking isn't true and the output from the pre-amp may be too high for the "T" amps, which are small intergrated units and their input sensitivity may be too high to cope. I think true power amps may be required. Like I said, I'm still looking into the subject, which is totally new to me and it's not a definate decision to adopt, just curious at this point.
I would be interested to hear from anyone that has experience with an active set up, especially a 3-way.
Very briefly looked at the mini-DSP system were a 3-way stereo set up plus Sub/s is possible. This seems an interesting system, most subs are baddly integrated as the gentle bass roll off of most speakers does not help. The ability to difine the cut off point and slope for the main speakers bass driver will make the integration of the sub far more seamless. Not saying I need a sub, but allways considering my options. :eyebrows:
http://www.jkwynn.co.uk/Project_Images/66/66_37.jpg
I needed a pair of tri-wire speaker leads so I can experiment with the external x-overs. Nothing too exotic for this try out, so I put together some DIY leads using Van Damme Tour Grade (6 x 2.5mm Square OFC). I would have used their Studio Grade but they don't do it in 6 way unfortunately. Inside the cabinet I have wired the Tweeter and Mid Range Drivers to the binding posts with Black Rhodium Twist and I used the thicker conductor of Black Rhodium Twirl for the Bass Driver.
spendorman
29-10-2014, 14:33
Rexton - That had crossed my mind.
eg:
Amptastic Mini-1 x3
Quad 303 x3
Pro-Ject Box Design x3
Cyrus Power x3
I was thinking along the lines of campact amps that could sit three abreast on my wider than normal shelf.
It's not a definate path at the moment and is on the back burner till I see how the circuit splitting, tri-wiring and relocating away from the bass magnet works out.
Three compact amps made me think of these, possibly not suitable though:
https://flic.kr/p/6RDwkq
spendorman
29-10-2014, 14:45
Rexton - That had crossed my mind.
eg:
Amptastic Mini-1 x3
Quad 303 x3
Pro-Ject Box Design x3
Cyrus Power x3
I was thinking along the lines of campact amps that could sit three abreast on my wider than normal shelf.
It's not a definate path at the moment and is on the back burner till I see how the circuit splitting, tri-wiring and relocating away from the bass magnet works out.
I have been playing round with a TPA 3116 chip amp, very impressed with the results, Basic assembled stereo board can be purchased for less than £10 inc. postage on ebay. It can give 50W RMS per channel. Running one right now in to my LS3/5a clones (genuine KEF units and KEF crossovers).
spendorman
29-10-2014, 16:43
Board in box here, seems good price:
http://www.ebay.co.uk/itm/Newest-TPA3116-HIFI-2-0-stereo-output-digital-audio-power-amplifier-50WX2-WLX-/271648077709?pt=UK_AudioTVElectronics_HomeAudioHiF i_Amplifiers&hash=item3f3f7cb78d
spendorman
29-10-2014, 16:47
Completed board here:
http://www.ebay.co.uk/itm/TPA3116-ClassD-Amplifier-Board-50W-50W-Filter-Capacitor-2-10000UF-DC18V-24V-/191367933497?pt=UK_AudioTVElectronics_HomeAudioHiF i_Amplifiers&hash=item2c8e6aee39
I use my speakers (three ways) part active with the mid and tweeter driven via a (analogue) passive crossover and the bass drivers driven actively via a digital crossover and class D amplification. In this case the digital crossover element is built into the front end of the power amp (Lab.gruppen IPD 1200). It's proven to be something of a revelation in terms of sound quality and flexibility and I would certainly recommend a similar course to you.
A friend has fully active Tannoys driven by chip amps very similar to the ones spendorman has linked to and they work remarkably well.
spendorman
30-10-2014, 09:31
I use my speakers (three ways) part active with the mid and tweeter driven via a (analogue) passive crossover and the bass drivers driven actively via a digital crossover and class D amplification. In this case the digital crossover element is built into the front end of the power amp (Lab.gruppen IPD 1200). It's proven to be something of a revelation in terms of sound quality and flexibility and I would certainly recommend a similar course to you.
A friend has fully active Tannoys driven by chip amps very similar to the ones spendorman has linked to and they work remarkably well.
I have a pair of Tannoy HPD315's but have not tried them on the TPA3116 amp as yet, I'm pretty sure it will work very well. The 3116 in to the clone LS3/5a's does impress me. I do have genuine Chartwell LS3/5a, but prefer the clones as I made the cabinets slightly bigger, and the bass is better in my view, being deeper and tighter.
An enthusiastic speaker builder friend heard the 3116/ LS3/5a clones combination, and was surprised at the good quality of sound .
Thanks for the tips guys.
For the time being I will persevere with tweeking the passive x-over using tri-wire inputs from a single stereo power amp and see how it pans out.
spendorman
31-10-2014, 15:16
Seems sensible to me. I'm impressed with your labels for the crossover terminals, nice touch. Can you explain how you did them? I would have thought that when you trim them to size they would come apart.
spendorman - I thought the same but did a test piece and the laminated plastic sticks to the surface of the paper not just to itself round the edges.
I printed two labels on a sheet of A4 Photo paper to get nice deep and solid blacks. I selected mid grey for the original silver and it matches well.
Laminated the whole A4 sheet, then cut the labels out using a scalpel and straight edge, cut the corner rads by hand.
I then punched the holes for the binding posts. I have a cheap set of gasket punches I bought off Fleabay, just punched straight through in one hit.
I then ran the labels through the laminating machine a couple of times to make sure the edges were stuck and the punched edges were flattened.
Job done
Note - I addapted existing type faces supplied in Corel Draw to make a match with my original labels, stretching, using Bold and also modifying the outline thicknes which when done on fonts makes the letters chunkier than normal, until I got a match. I actually matched a slightly later Logo used by Celestion which I prefered.
spendorman
31-10-2014, 16:03
Thank you, that is helpful.
I made some speaker badges by printing on to paper, sticking the paper to thin card with Pritt Stick, trimming and spraying with clear lacquer. Came out pretty good.
http://www.jkwynn.co.uk/Project_Images/66/66_38.jpg
Getting close now in terms of optimising the parts.
These are just some of the parts I tried, several electrolytic caps are not in the shot. The type and brand of cap is making a difference when it comes to reducing the effect of the resonant midrange circuit.
The Tri-Wiring also works better in this respect compared to a single run, quite noticeably better in fact.
Next step will be a new board layout and any final tweaking.
Part of the problem Ken might be the orientation and spacing of those inductors. If you can orientate the mid range one at bright angles (with axis not crossing each other) with the others (may involve changing more than one) it might help with the mid range issues.
Hi Paul
Re-spacing and positioning the coils is not guaranteed to work, but its about the only thing I've not tried. :)
My gut feeling is the resonance is inherant with the type of band pass filter used, but it is worth trying as you suggested, as new boards are being made anyway.
I'm in the process of doing just that. I was going to buy new coils but having spent a lot on experimenting allready I decided to re-use the stock items. I will have to carefully remove them from the board they are allready stuck to. Another reason for keeping them is that all my other part values have been derived using these, which do not measure to the exact values that Celestion quote on their drg. Getting new coils with the same Inductance and RCD values would be tricky, although not impossible to find within a very close margin (Jantzen air core) but would add another £60 to the build.
I'm finalising cap values/make and L-Pad values for driver attenuation at the moment and then doing an alternate layout on a much larger board (310 x 260mm). This is the largest that will fit through the ABR driver aperture. I have the Paxolin board and the brass eyelets arived this morning for making the solder points on the boards, so not far off.
The new board will sit behind the ABR unit away from the big Bass driver magnet and will have six 15mm diameter holes in it just below the centre so I can get to the six binding posts mounted behind it, so as to make the conections. I didn't want to move the binding posts for originality reasons. The two second largest coils (2.2mH) will be moved further away from the largest coil and turned on their side with the axis at 90 degrees to the large one. The other two small coils will be positioned away from these and avoiding their axis lines. That should do the trick.
I'll post some pictures when I get these boards done.
Need to get a wiggle on as I want them compleated and run in for NEBO5 on 10th January. :D
Thanks for the loan of the 66 base moulds Ken......ok mine still have a "little bit" of cosmetic work to do to match yours, but I'm happy with the results so far.
Anyone else want a loan of the moulds?
Cheers
John
http://i1300.photobucket.com/albums/ag89/Jrb1961/imagejpg1_zpsabec15e6.jpg (http://s1300.photobucket.com/user/Jrb1961/media/imagejpg1_zpsabec15e6.jpg.html)
http://www.jkwynn.co.uk/Project_Images/66/66_32.jpg
That's the first of the plinths completed, spirit bubble set into the top and carpet spikes installed and adjusted through the four holes in the top face. Each plinth weighs over 20Kg.
http://www.jkwynn.co.uk/Project_Images/66/66_33.jpg
I'm pleased with the appearance, I think the base compliments the speaker.
The spikes have been adjusted so the base is only just clear of the carpet, which makes it look well anchored visually and not floating. The thickness of the base and the gap created by the "Soundcare" feet, have good proportions and work well together. It only remains for me to complete the second plinth which is out of the mould and requires finishing cosmetically.
Hi Paul
Re-spacing and positioning the coils is not guaranteed to work, but its about the only thing I've not tried. :)
My gut feeling is the resonance is inherant with the type of band pass filter used, but it is worth trying as you suggested, as new boards are being made anyway.
I'm in the process of doing just that. I was going to buy new coils but having spent a lot on experimenting allready I decided to re-use the stock items. I will have to carefully remove them from the board they are allready stuck to. Another reason for keeping them is that all my other part values have been derived using these, which do not measure to the exact values that Celestion quote on their drg. Getting new coils with the same Inductance and RCD values would be tricky, although not impossible to find within a very close margin (Jantzen air core) but would add another £60 to the build.
I'm finalising cap values/make and L-Pad values for driver attenuation at the moment and then doing an alternate layout on a much larger board (310 x 260mm). This is the largest that will fit through the ABR driver aperture. I have the Paxolin board and the brass eyelets arived this morning for making the solder points on the boards, so not far off.
The new board will sit behind the ABR unit away from the big Bass driver magnet and will have six 15mm diameter holes in it just below the centre so I can get to the six binding posts mounted behind it, so as to make the conections. I didn't want to move the binding posts for originality reasons. The two second largest coils (2.2mH) will be moved further away from the largest coil and turned on their side with the axis at 90 degrees to the large one. The other two small coils will be positioned away from these and avoiding their axis lines. That should do the trick.
I'll post some pictures when I get these boards done.
Need to get a wiggle on as I want them compleated and run in for NEBO5 on 10th January. :D
Sorry for tardiness of late response Ken.
I'm not at all sure about electrical resonance as the cause of what you are hearing but am curious as to what you mean by that and why you think it is in any way a culprit? My experience of vintage factory supplied Celestion crossovers to date is that (being very polite about them) they were a very mixed bag indeed. They paid little or no attention to inductor spacing or orientation, or even how tightly the inductors were wound (some I have seen are very loose and a candidate for microphonic issues); the factory capacitors or circuits doing the rounds vary because often the values were made up of what they had to hand, so all in all, it takes some investigation to get the precise figures originally designed and tested for plus there (imho) is very little merit in replicating the existing layout or quality as it has such potential (as you are discovering) for improvement.
The best thing for most Celestion X-overs, if space and aesthetics allow, is to take them external (the same could be said for all crossovers), use optimum inductor spacing and orientation, junk the existing inductors and use only tight machine would modern equivalents. Electrolytics used much above 8 to 10KHz can safely be replaced with polys without having to be overly concerned about ESR differences. Typically from 10KHz onwards, 4 to 8 Ohm driver caps in poly will be around 0.1Ohm ESR which is similar to low loss electrolytics except that they wont suffer value drift to anything like the same degree with temperature rise.
I can't help but think that adopting standard, as they left the factory layout is a recipe for inductive coupling (and other issues) and until the layout and components are optimised then speculation about audible distortions wont really get to the heart of the matter. It may be worth using DATs or something similar to also do a rub and buzz test on both mid drivers and tweeters to rule out a possible driver issue. Acoustic measurement of each driver rolloff point is also a good idea (haven't you got a calibrated mic now?) as this will at least show you if there's any undue overlap in acoustic crossover points which may be resulting in audible phase differences about the crossover point. Lots of work I know, but to perfect crossovers for a worthwhile project such as this, it is worth the effort for the end result.
Hi paul
I have multiple drive units (eg 6 original tweeters not counting the Seas and 4 mid drivers) and they all measure well (very well) and sound fine.
If I disconnect two of the three in a cabinet and just listen to the tweeter or mid driver in isolation, the resonance is not there at all on the tweeters and only very slightly on the mid drivers.
Connect the tweeter and mids at the same time and resonance increases and comes mainly from the tweeters.
As for the coils, mine are not wound particularly tight so some mechanical resonance might be going on there. I am in the process of making new boards with better spacing, so that might help if interaction is the cause of any distortion.
My thoughts on the resonance being electrical came from reading about this type of band pass filter and that putting a cap and coil in series is electrically resonant the technicalities on tuning this resonance lost me but it made sense of what I am hearing. The resonance manifests as distorted raspy edginess to vocals in particular and occasionally on acoustic guitar and even certain trumpet notes. More noticeable at higher listening levels it drives me mad. Its not sibilance it sounds different.
As for Celestion using what ever was at hand for caps, I think it was a bit more structured than that. From what I have seen they changed cap types along the way as part of their other continuous developments and quite often cap changes coincide with other mods, they would order what was available at that time, and once changed rarely went back. You can almost age a speaker by the caps used.
Looking good John,
Just fill the minor cavities in the surface with Tetrion or any other cement based out door filler and rub it down lightly with medium grade paper on a block. It is easy to sand and the whole thing will then take a few coates of Acrylic (water based) paint applied with a small gloss roller. I just used Wilko brand satin black. Do not be tempted to give it a coat of PVA to seal prior to painting, this does not work and forms a poorely bonded skin that rubs off easily. Just apply the paint and the first coat sinks in to the porous surface and gets a good key.
If anyone wants to use the mould, arrange to pick it up from John, otherwise he will bin it, as I have no further use for it.
I have some instructions I printed out for John and could e-mail them to anyone wanting to have a go.
http://www.jkwynn.co.uk/Project_Images/66/66_39.jpg
This is my layout for the new board.
The High/Mid/Low filters have been separated and will connect to the three sets of binding posts already fitted. Coils have been re-spaced/oriented to avoid interaction.
Note: This is the biggest board that will go through the ABR aperture and is 310 x 260mm or 12 3/16" x 10 1/4".
You have to angle the board as it goes in, going from vertical (speaker laid on its back) and rotating to horizontal in its final location. This means the board has to be smaller than you might think. I have cut a piece of 3mm ply and tried it, it only just fits.
Note: It is mounted behind the ABR to get it away from the big magnet on the Bass driver.
Looks good Ken. Yes, a cap and coil in series can result in electrical resonance but it's usually damped sufficiently by the inductor impedance where designed in crossovers. I still think it's partly down to loose wound coils placed in the wrong orientation too close. Until those obvious defects are corrected, you'll not really establish whether is electrical resonance or not resulting in audible distortions, that was the point really.
I have a different view on Celestions having seen the inside of a fair few pairs now. It wasn't just them but many other manufacturers often used what was to hand to make values up...it was not quite as structured as some would like to think back in the day! ;) This would have affected the minority I suspect, which is why you still see most using the same values/make-up of values. One doesn't have to think too hard on this as they didn't take the trouble to wind coils tightly enough nor orientate them correctly. It would hardly be surprising then to learn that many manufacturers, Celestion included, may have used what was to hand when needed for making up values.
DarrenHW
10-12-2014, 16:37
Hi Ken,
I see you've reverted to polyprops for the Mid. I tried the Alcaps but ultimately preferred the PP's, although haven't tried PP's combined with a 4uF Alcap yet. Apologies if this is a stupid question but what are the pink rectangles in your schematic?
All the pink elements are inductors aren't they? Just orientated differently.
Darren - Yes just the coils mounted on their circumference so rectangular in plan view.
A PP works in the series location only in the midrange filter, don't add any ESR compensating resistors though.
The 24/30uf Elcap used in this location was LL so less ESR anyway.
In this location I've tried both PP and several make of electrolytic and combinations of both and different makes of PP.
The Ansar is my favourite of what I tried, and is not too big either. A Solen PP for instance, sounds similar to an Alcap Lytic in this location, very little difference between the two.
If you use a PP you will need the L-Pad in the mid range or the mids are too forward.
DarrenHW
11-12-2014, 07:17
Darren - Yes just the coils mounted on their circumference so rectangular in plan view.
So it was a stupid question :). Maybe this is too, but why 5 instead of 3?
A PP works in the series location only in the midrange filter, don't add any ESR compensating resistors though.
The 24/30uf Elcap used in this location was LL so less ESR anyway.
Interesting, I'll have to try it.
In this location I've tried both PP and several make of electrolytic and combinations of both and different makes of PP.
The Ansar is my favourite of what I tried, and is not too big either. A Solen PP for instance, sounds similar to an Alcap Lytic in this location, very little difference between the two.
Did you notice any difference in bass? I thought it noticeably tighter when using a PP instead of an Alcap but this was in a different pair of 44's so not sure if this was due to differences between the two (different cabinet construction, wiring and sound deadening).
If you use a PP you will need the L-Pad in the mid range or the mids are too forward.
I found the same myself, I thought the speakers had far better driver integration using the Alcaps, I wasn't sure if this was due to using a 27uF PP (as per the DIYAudio mod) as I used 3 x 10uF Alcaps (to keep with original values) in the second pair.
So it was a stupid question :). Maybe this is too, but why 5 instead of 3?
Interesting, I'll have to try it.
Did you notice any difference in bass? I thought it noticeably tighter when using a PP instead of an Alcap but this was in a different pair of 44's so not sure if this was due to differences between the two (different cabinet construction, wiring and sound deadening).
I found the same myself, I thought the speakers had far better driver integration using the Alcaps, I wasn't sure if this was due to using a 27uF PP (as per the DIYAudio mod) as I used 3 x 10uF Alcaps (to keep with original values) in the second pair.
A classic case of what happens when electrolytics are replaced with polys in certain positions , where adding L-pads to tame perceived brightness does not address the crossover frequency slope shift that the ESR and ESR slope with frequency gives with electrolytics compared with polys. In the lower mids, the differences may only be 0.5 Ohms or so but that's enough to throw phase integration out by shifting crossover point upwards. Also, it means adding more components into the signal path (l-pad) when sticking to the Alcaps avoids this. Sticking with close tolerances, matching manufacturers tried and tested exact values ("near enough" can often not be near enough), using like for like in the LF and lower MF positions for electrolytics good layout and quality of inductors. If these things are adhered to, the end result should be as good or better than when the speakers left the factory.
Reffc is right Darren, any deviation from original values or cap type is going to effect x-over point/slope.
So my choices in the mid range are a compromise but one I feel I can live with.
"Maybe this is too, but why 5 instead of 3?" There has allways been 5 coils in the Celestion 66 circuit.
I am just re-using the originals.
I found the 30uf Ansar PP cap gave more body/depth/texture to the mids, the Solen I tried did not and I prefered the Alcap Lytic over this.
Strangely the bigest impact I found on percieved bass was in the HF caps. I am using the Seas tweeter now but the same thing applied when I had the originals in use. I know the various parts of the filter inter act but I could not hazard a guess as to what is happening. Also sound is a mixture of frequencies, a drum strike has bass content but it also has higher frequencies that give it shape and snap/slam difining its edges.
My experimenting went like this, two Sonicap Gen1's for the tweeter values was very clean and transparent, maybe too forward in the treble, but very focused, Piano sounded very realistic at the top, the bass was there but nothing special. Two ClarityCap ESA's and the treble softened, too much for my liking and piano notes lacked that percusive hammer sound you get higher up the scale, mids were very realistic male voices had great texture and realism and Bass had more presence and depth. I liked the best bits of both but not the bad so started experimenting with mixtures of caps. I put a ClarityCap ESA in the large value HF and Sonicap for the smaller value. This was much better and kind of got the best of both, but still felt a little too forward, Joni Mitchell's voice was shrill and piercing at times. I reversed the makes eg Sonicap large Clarity small which was worse. So I kept the Clarity cap large value and dropped an Ansar Supersound in for the smaller, now we are cooking, It had natural tone to piano, good percussive action on the keys, voices both male and female sounded right and bass texture and slam seemed to jump up a notch. This voicing did it for me, I never listen to how good something sounds but how realistic it sounds, you can kid yourself that something that sounds pleasent and easy on the ear is better, but when you put something on that you can relate to and have a referance point for like acoustic instruments and voices you spot that something is not quite right. This mix can be quite spookey at times, I have my Satalite TV's audio playing through my system via a DAC and the other day I went to answer my mobile which was on the coffee table in front of me, to discover the sound was actually on the TV program. When I was in the kitchen on another occassion I thought someone was knocking at my front door, to dicover it was on the radio 4 play I was listening to. I know we all strive to get this kind of realism, but there are times when it raises the hair on the back of my neck. Don't get me wrong, my speakers are sounding good, I can still hear the resonance on certain tracks though, which means I tend to avoid playing them, this is why I am still faffing about. I could hear the same thing on Marco's speakers and it has even been measured on the diyaudio thread, if you use PP's with ESR compensating resistors it seem to bring it out to the point were it was visible on plots. It was at this point I gave up on using them and looked for an alternative approach. ;)
DarrenHW
11-12-2014, 16:52
"Maybe this is too, but why 5 instead of 3?" There has allways been 5 coils in the Celestion 66 circuit.
I am just re-using the originals.
Another stupid question then, sorry :rolleyes:.
Glad you're making progress with your crossovers and that the 66's are winning you over.
They won me over first time I heard them. :D
I just want them to be the best they can be, as I will probably have them for a long time.
The basic character, which is what I like, has not changed, I am just tweaking the fine detail.
http://www.jkwynn.co.uk/Project_Images/66/66_40.jpg
These are the circuit boards I made from "Paxolin" sheet.
Brass eyelets with 3mm through holes have been fitted for use as point to point solder contacts. The six large holes just off centre line up with the six binding posts I have already fitted to the cabinet. The boards will be secured using 16mm M4 stand off's, this will position them just above the block of wood on the rear face of the lower compartment, that Celestion added for mounting the binding posts. Plus give additional clearance to accommodate the plastic spacer bar that each pair of binding posts I have fitted is secured by.
As ever, very nicely made. I'm surprised that you bothered with the eyelets though - you could just have small holes, thread the lead and wires through, and point to point solder it all together on the other side.
YNWaN - I have learned the hard way, that even at this late stage, expect to modify further.
This arangement allows easy part changing without disturbing the main circuit, speaker connections etc.
I've even changed some parts on this type of board whithout re-moving the board from the cabinet and just worked through the driver aperture.
No rear access is required so keeps it simple and tidy after multiple mods and takes some of the strain off the parts as they are soldered to a fixed point. If you do as you sugested you can end up with loose parts that wiggle about as they have no direct connection to the board. ;)
If you do as you sugested you can end up with loose parts that wiggle about as they have no direct connection to the board. ;)
Well I would fix the components separately to the board - but if this solution works for you, was just wondering. .
I'm waiting till after the hollidays before building the new boards, I want to try some Visiton caps in the lash up first to see how they sound.
Meanwhile I have been trying the circuit Tri-Amped.
http://www.jkwynn.co.uk/Project_Images/66/66_41.jpg
This is the Power Amp I purchased second hand.
It's a Rotel RMB-1066, I wouldn't call it HiFi more like MidFi, but it’s a cheap way into Tri-Amping or Active crossovers. This model was mainly sold for home cinema use, where folks wanted to get into separates and split the amplification from the receiver/control section. It has several features that make it attractive for multi channel music use though.
First it is set up as 3 pairs of channels, so it's like having 3 Stereo Power Amps in one box
Second, each pair has it's own gain control, the pots are adjusted using a screwdriver and are located between the front fins, as indicated on the picture. For three way speakers this allows adjustment of each driver pair from one pot, so left and right bass drivers can be adjusted together as an example. Once drivers are initially matched for sensitivity the volume is controlled from your pre-amp.
Third is the RCA inputs, one pair of inputs for each pair of channels, again more like a stereo amp x3 which is good for going Active.
Lastly the input pairs can be linked by sliding a couple of switches so that one pair of inputs serves all three amp sections, saving on cable runs etc and useful for Tri-Amping from a single pair of outputs on a Pre-Amp.
This is a very versatile piece of kit, you can also bridge any pair of channels to increase the power in that section but reducing it to single channel. So you can have 6,5,4,or 3 channel output depending on which pairs you bridge. Power output is 60W/8 Ohm x6 or 150w/8 Ohm x3 (Bridged).
It doesn't sound bad at all, quite nice really and it has cleaned up the Tweeter circuit, no distortion getting through at all, now each one has it's own amp channel.
The mids still have the same distortion, which pretty much confirms the source of the problem, what ever it is, lies there. Lets hope when I move the coils appart it resolves it. I have taken the L-Pads out from the circuit and have adjusted the driver levels using the Amps gain controls, sooo easy to get the voicing the way you prefer it.
The Visaton Low Loss bi polar electrolytics arrived a few days back and I’ve been doing some comparisons for the 30uf Series cap using purley LL Lytics. (15+15uf)
I have listened to and my order of preference is:
1). Visaton
2). Mundorf
3). Alcap
To me, the Visaton and Mundorf are better on all counts than the Alcaps, period.
With my first and second choices the decision is less cut and dry and as with a lot of this type of comparison, my favourite changed from track to track, so it will depend on what voicing you prefer. I will try and describe the difference which is subtle and not dramatic:
Compared to the Visaton, the Mundorf is a touch warmer/softer sounding, so gives good timber to acoustic guitar body for example. It’s not quite as crisp being a little less transparent, less dynamic with not quite the same punch. This makes trumpet sound less convincing for instance. Voices however are slightly smoother and less prone to highlight the resonance.
Both these caps are good, I came down on the side of the Visaton for being more realistic with some instruments, it’s slightly more transparent, it just conveys a little more energy and emotion, but it is a small difference.
Next is to try a mix of the Visaton and Polyprop............
http://www.jkwynn.co.uk/Project_Images/66/66_43.jpg
The parts have been fitted to the new boards and then located in the bottom chamber, behind the ABR unit.
Burning everything in now before any critical listening.
I ended up with a mixture for the 30uf series cap of about 7.5% Ansar Supersound PP & the remainder using a pair of Visaton LL electrolytics, so thats the bundle of three in the lower right corner.
Got them ready in time for NEBO 5 bake off this Saturday - phew :D.
Really nice build - super work :).
Neat work as ever Ken and light years in layout ahead of the factory crossovers (why they couldn't do them like this I'll never know). Must admit,I like the Mundorf 'lytics. A cut above some new production bipolar electrolytics. Must do some measurement comparisons to see if it can be traced as to why they sound a little smoother.
Reffc - Hi Paul, you were right about the coils audibly interacting.
I had the parts lashed up on the original boards, with the closer spacing. When I have moved to the bigger boards and wider spacing, without any other changes the sound is cleaner. It's early days and things have to settle in but that much is evident after only an hours playing time.
I like the Mundorf Lytics and have tried the Visiton which I feel are slightly more transparent and dynamic, but I'm talking about very small difrences, they are both good and like you say the Mundorf is a bit smoother. Both these work well with 5 to 8% polyprop in the mix. 10% is too much, Ansar and ClarityCap ESA both worked well for me in this way, the small amount of PP brings a touch of refinement plus extra dynamics and welly depending where they are used of course. They just bring things to life without the problems associated with changing the whole Lytic for a PP.
Yep, fantastic stuff as usual, Ken. When you’re eventually ‘done’ with this project, and have optimised everything about the 66s to your exacting standards (and worked out a suitable cost), you’ll have a commission from me to do mine! ;)
Marco.
:thumbsup::thumbsup:
Reffc - Hi Paul, you were right about the coils audibly interacting.
Umm... I did mention it way back in post #6 of this very thread.....
I'm glad it has all worked out though :) :thumbsup:.
Mark - Coil Spacing - Yes You were about the fifth to mention it to me and I was allways open to the possibility after reading the test results on Troels Gravesen's site a good while back. Trouble was no one seemed to have tried it and this mod meant throwing originality out the window, so I was a bit hesitant.
It has cleaned up the sound, but only marginally, other things make as much or a bigger difference, internal wiring for instance. The early air core coils I have were wound quite loose, so that may also be effecting results, but renewing them would mean more expense with no guarantee of improvement. Having said that, one of the guys on diyaudio has replaced his early coils with the later ones wound on plastc bobbins and he recons there was a small improvement by doing this. All these things seem to be chipping away at the problem, but not really getting to the root of it.
The speakers are sounding very good, but I'm still not completely happy, I genuinely belive the drivers are capable of better and it is the x-over design that is the weak link. Changing to the Seas Tweeter makes a slight improvement to the top end, but it's not really necessary as the original unit is very good, this was more about long term sustainability as build quality on the originals was not fantastic and finding good second hand replacements will get harder.
Now I have a 6 channel Amp I may try going Active, or see if someone with a programable DSP will patch it in to my system for a try, just to see what kind of a difference that would make.
I don't belive an active solution is a cure all but with this speaker set up it may work, the drivers are pretty well matched and the x-over circuit is very simple with no notch filters or zoble networks, not even an L-Pad used, so the active circuit would just be providing the high and low pass filters. An easily adjustable DSP would also allow some exsperimenting with x-over points.
The bass crosses at 500Hz but this driver is also used in the ditton 25 and crosses at 2kHz in that application (if memory serves). Raising this a small amount would relieve the mid driver of some of it's low end duty where it is at it's limit. The Seas tweeter is flat way below the 5khz crossover point so again this could be reduced. I feel the 66 has a little too much emphasis on the mids and maybe tweeking the crossover points could give a more natural presentation. It would be trial and error and may not reep any benefits, but is up there to try. Once crossover points are established/confirmed a simple analogue opamp based active crossover could be constructed.
It's a major step to take but this hobby is all about stepping up to the challenge, so why not.
That's on the cards for after NEBO5.
Mark - Coil Spacing - Yes You were about the fifth to mention it to me and I was allways open to the possibility after reading the test results on Troels Gravesen's site a good while back. Trouble was no one seemed to have tried it and this mod meant throwing originality out the window, so I was a bit hesitant.
It has cleaned up the sound, but only marginally, other things make as much or a bigger difference, internal wiring for instance. The early air core coils I have were wound quite loose, so that may also be effecting results, but renewing them would mean more expense with no guarantee of improvement. Having said that, one of the guys on diyaudio has replaced his early coils with the later ones wound on plastc bobbins and he recons there was a small improvement by doing this. All these things seem to be chipping away at the problem, but not really getting to the root of it.
The speakers are sounding very good, but I'm still not completely happy, I genuinely belive the drivers are capable of better and it is the x-over design that is the weak link. Changing to the Seas Tweeter makes a slight improvement to the top end, but it's not really necessary as the original unit is very good, this was more about long term sustainability as build quality on the originals was not fantastic and finding good second hand replacements will get harder.
Now I have a 6 channel Amp I may try going Active, or see if someone with a programable DSP will patch it in to my system for a try, just to see what kind of a difference that would make.
I don't belive an active solution is a cure all but with this speaker set up it may work, the drivers are pretty well matched and the x-over circuit is very simple with no notch filters or zoble networks, not even an L-Pad used, so the active circuit would just be providing the high and low pass filters. An easily adjustable DSP would also allow some exsperimenting with x-over points.
The bass crosses at 500Hz but this driver is also used in the ditton 25 and crosses at 2kHz in that application (if memory serves). Raising this a small amount would relieve the mid driver of some of it's low end duty where it is at it's limit. The Seas tweeter is flat way below the 5khz crossover point so again this could be reduced. I feel the 66 has a little too much emphasis on the mids and maybe tweeking the crossover points could give a more natural presentation. It would be trial and error and may not reep any benefits, but is up there to try. Once crossover points are established/confirmed a simple analogue opamp based active crossover could be constructed.
It's a major step to take but this hobby is all about stepping up to the challenge, so why not.
That's on the cards for after NEBO5.
Hi Ken, Never heard the Celestion 66's so looking forward to hearing yours at NEBO5.
Be nice to hook your Croft Pre up to them with my Power amp, will have to see if there is time to do that.
Be nice to hook your Croft Pre up to them with my Power amp, will have to see if there is time to do that.
Yeah that would be great, not sure what I,m hooking it up with yet but expect all will be resolved on the day!:)
Yeah that would be great, not sure what I,m hooking it up with yet but expect all will be resolved on the day!:)
Steve has asked me to be there early as I am up first. (I live local to the venue)
Once I have demo'd my kit you are welcome to splice your Croft Pre into it. You will have the choice of the Celestion 66's or my Tannoy Cheviots. I'm sure we could find a turntable to add to it as I would love to here the built in phono stage, the Croft is on my wish list. ;)
Steve has asked me to be there early as I am up first. (I live local to the venue)
Once I have demo'd my kit you are welcome to splice your Croft Pre into it. You will have the choice of the Celestion 66's or my Tannoy Cheviots. I'm sure we could find a turntable to add to it as I would love to here the built in phono stage, the Croft is on my wish list. ;)
Hi Ken,
I may not be up early but should be there around 11am, so if we could fit phono stage into your system later that would be great.
Would like very much to hear both speakers.:)
Ken, make sure you demo it again later, so I can have a listen, as I probably won’t be there until midday :)
Marco.
Will certainly try Marco - We have an even greater amount of kit comming this time and I have a feeling we will run out of time trying some of the combinations.
Its important we set up as many systems as possible so we can move from one to another without wasted time, even if these systems are combined efforts.
This is what I liked about the Owston meet I attended, the multiple set ups and initial 3 track rule meant we heard a hell of a lot of kit within the timeframe.
Better to keep any further Nebo stuff for that thread. :D
I think one of the primary advantages I found when I started using a DSP crossover (in my case just for the bass driver but still) is the flexibility it allowed with crossover adjustment. You can save a whole host of adjustments and compare them in a way that would take months using any other method.
I know what you mean Mark.
The miniDSP 4x10 is very tempting due to that ability to experiment and also to carry it over to other projects.
Something just feels wrong about playing a vinyl set up through a set of digital filters though. :)
That's probably me just being a die hard for analogue.
Siegfried Linkwitz seems pretty impressed with the miniDSP offerings from what he has written on his site and he recomends the 4x10 unit as a direct alternative for his own ASP design for his flagship LX521, nuff said.
I suppose cost has a part to play, I can knock up a fixed frequency analogue 3 way active x-over, including power supply/Tranny for about £110. This would use ready made modules, a lot less if you buy the parts and populate the boards yourself. It wouldn't have a case to put it in at that price, but I could fix the parts to a piece of chip board, try it out and see if I like what I hear.
The miniDSP is closer to £500 if I remember correctly, so more of a commitment.
I've not heard a speaker system powered by one of these units but I'm open minded about it till something I hear tells me otherwise. ;)
Well you can hear mine if you like although it doesn't use the MiniDSP solution but is built into the amp that drives the bass unit.
I'm very analogue centric myself which is why it is only the bass that I apply the DSP to - but the gains are very persuasive.
Hi Mark
The DSP you are using for bass, is that on your Yamaha NS-1000m?
I read your Build thread for those, great job.
What amplification are you using for them these days?
I am currently interested in a pair that need a bit of cabinet work.
EDIT: The cabinets were not as bad as I thought, had a good listen and ended up buying them. - Great Speakers.
Hi yes, Yamaha NS-1000M actively driven in the bass by Lab.grupen IPD1200 using DSP and digital crossover - mid and tweeter powered by Naim Nap135's through passive crossover.
yes, great speakers - I'm sure you will enjoy yours :).
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