View Full Version : Sq's system.
steviej233
26-02-2013, 09:12
They look awesome, job well done mate. :)
Spectral Morn
26-02-2013, 10:50
I think Mika just means was there baffle step correction built into the XO to start off with and did you alter the notch filter applied for this correction. There's no baffle step correction built into the XO, so there was nothing for Mark to adjust.
Here's today's pictures- they do look and sound mighty fine. The bass has defo become that little bit tighter and better damped and the mid and treble is just impeccable.
http://farm9.staticflickr.com/8384/8505559276_c248a628aa_b.jpg
http://farm9.staticflickr.com/8511/8504387823_77a49ccbcf_b.jpg
The man behind the work.
http://farm9.staticflickr.com/8093/8505507230_77ecb23bed_b.jpg
http://farm9.staticflickr.com/8112/8504400431_7fc570b474_b.jpg
http://farm9.staticflickr.com/8527/8504403757_22136798f5_b.jpg
http://farm9.staticflickr.com/8238/8504406903_904cf0b6a8_b.jpg
http://farm9.staticflickr.com/8370/8505519642_1c642218fa_b.jpg
http://farm9.staticflickr.com/8525/8504412775_5b2efff47e_b.jpg
http://farm9.staticflickr.com/8238/8504415805_def5b4a2da_b.jpg
http://farm9.staticflickr.com/8368/8505529718_92b921c072_b.jpg
http://farm9.staticflickr.com/8514/8504423667_7d17169bba_b.jpg
http://farm9.staticflickr.com/8086/8504426575_c6ae1b9b75_b.jpg
http://farm9.staticflickr.com/8506/8504429601_96105f57a0_b.jpg
http://farm9.staticflickr.com/8239/8505543804_b585675e38_b.jpg
http://farm9.staticflickr.com/8229/8505546586_954c22bb27_b.jpg
http://farm9.staticflickr.com/8516/8504439283_bf854629f5_b.jpg
http://farm9.staticflickr.com/8379/8504445481_58c1bd0efc_b.jpg
Those look stunning :stalks:
Regards Neil
Riislingen
26-02-2013, 12:14
Sweet Jesus, those beasts are just gorgeous !
Drooling non stop..:stalks:
They sound fabulous too :).
Lee Henley
26-02-2013, 18:53
Nice job they look fantastic
Have you been able to make any before/after FR measurements either on or off axis to see what has changed?
No; I could have, but I didn't even try to. It wasn't my intention to alter the frequency balance and I doubt it has changed much. The crossover components are all the same value, just better matched and closer tolerance. I measured the L-pads at my preferred settings and used resistors to emulate the same (but now fixed) settings.
However, a friend has the necessary gear (hi Dave :)) and I could get him to measure them.
When I've had a chance to catch my breath I think I'm going to try building an active crossover for the bass and run the mid and tweet passive (the wiring has been configured to facilitate this).
--------
Guy, I look forward to catching up this weekend :).
One of the records I listened to last night was 'Taking Tiger Mountain by Strategy', an early Brian Eno album - quite remarkable is how I would describe the experience. Despite being quite a noisy second hand record, it continuously demanded my attention with its subtle layering and dynamic contrasts. The Yamaha's are among the most revealing speakers I have ever heard (yes, EVER heard), but they aren't bright or hard. I've read that they are ruthlessly revealing, but that isn't true; they don't punish poor recordings, they just don't flatter them unrealistically.
In my teens i fell in love with The Velvet Underground; I've recently been buying up re-pressings of my favourite albums of theirs (some I only ever had tapes of). None of these Velvet Underground albums are technically great recordings, but the musicianship, the zeitgeist, comes over in the most compelling way I have ever experienced.!
There is a lot of love for vintage audio (and with much justification); but I didn't commit to these speakers because of a nostalgic dream or in recognition of their heritage. The only reason I 'bought in to' these speakers is because, quite randomly, I found myself loaned a pair and then, much to my surprise, found that I could not live without them!
Have just updated my thread with pics and explanation of the final assembly process. One wouldn't think it would have taken that long - but it took about six hours solid!
Should the tweeters not be on the inside - to improve imagery due to reflections on the baffle?
Fantastic standard of work. Glad it's been worth it for you.
Well, not according to the back panels which have an L and R after the serial number, designating left and right. Also, edge diffraction is the same whether the tweeters are inside or outside - at any rate, the anti-diffraction rings deal with that issue (imagery is actually extremely good - excellent even). As it happens, I have tried both orientations – tweeters to the outside gives a wider soundstage and central focus is still solid and consistent.
Yes, I'm pleased with the outcome, both in terms of finish and in terms of sound quality.
(the sharp eyed will see that the woofers have been fitted upside down compared to standard - this has been done intentionally to combat any cone sag that may have occurred)
Superb work.
Love the look of all of it.
Thanks Stu :). I've just added some quite OTT bases for the crossovers - 30mm Nero granite slabs (bevelled and polished), stainless steel ball bearings and acrylic location structure. They have come out better than I expected and I may well do something similar for the phonostage I am building.
sq225917
11-03-2013, 17:56
Finally a little bit of new for my own pair of speakers.
http://farm9.staticflickr.com/8385/8549717096_284003d244_b.jpg
I reckon thems be needing bigger back plates...
They do look propper lovely though,
Hum..I can do that tomorrow - how much bigger does it need to be?
Have you taken the old badge off then?
Will you be fitting a diffuser to your midrange drivers, Simon?
Hum..I can do that tomorrow - how much bigger does it need to be?
OK, have re-made them to sizes requested :)
sq225917
12-03-2013, 16:12
Nicely, I'll pop round later if I get the chance, not looking favourable at the minute though. Many 3D model to build.
sq225917
13-03-2013, 14:34
http://farm9.staticflickr.com/8371/8553740419_2a3d0635e9_b.jpg
And now my speakers with a new set of badges on them, very dapper...
They do look nice. What's the difference though between them now and #263 - was it the slightly bigger backing plates you were talking about doing?
Yep; there were already some aftermarket badges fitted to Simon's speakers and these were slightly bigger than the original Yamaha badges. As the aftermarket badges were nailed on in the corners, the back plates of my badges had to be a little bigger to cover the holes. All I did was re-make the black back plates a few mm larger. The glass look acrylic bit bolts to the black acrylic backplate and stands proud from it on 3mm spacers (it does look swanky :)). So although the badges look like they are bolted in place with hex head socket screws, they are actually just stuck to the baffle.
Ah yes - I can see now! Should've made it a "spot the difference" competition! ;)
Did you see this, Simon? Genuinely interested.
Will you be fitting a diffuser to your midrange drivers, Simon?
I think that's the plan - I've made some, but keep forgetting to bring them home.
sq225917
13-03-2013, 18:16
Sorry Martin I did indeed miss it. Yes I will be trying them as soon as Mark brings them round. I ran my ES14's with thick felt diffusers around tweeter and mids, the mids actually made the most difference.
Lovely work.
Might just have to get a badge made up for mine.
the mids actually made the most difference.
Very interesting! Keep us informed, as that seems like a relatively low cost mod to try out myself.
sq225917
23-03-2013, 17:10
Back on the phonostage build. I finally fitted the psu into a Naim style case today. I've put an extra loop into the power-in wiring just for now until I bolt the transformers in place, then I'll remove the connector block on the RHS and shorten up all the blue/brown wiring. and it'll be done.
http://farm9.staticflickr.com/8108/8583208064_f67989c942_c.jpg
Rare Bird
23-03-2013, 17:43
Hi Simon
Can't you scrap those Cable ties & tie down's, use lacing cord instead?
Hi Simon
Can't you scrap those Cable ties & tie down's, use lacing cord instead?
What would be the advantage of that? the cable ties are secure and have been done neatly (it looks to me).
Very neatly done Si. I don't know if this is your plan, but if you wanted, those terminal blocks could all be replaced with in-line crimp connectors (or just soldered).
(Lovely job of the back panel too ;))
Hmm... I did wonder if that was the angle you were coming from. I don't think that is Si's intention in this case - he probably wouldn't feel able to use toroidal transformers if a 'vintage' look was his intention.
sq225917
24-03-2013, 08:55
Lacing cord? I don't even know what that is. Is it something you use with valves and other sources of distortion?
Dingdong
24-03-2013, 09:19
It's what people used to tie cables together before tie-wraps.
I dont think Si was aiming for that butchered look for his phono! :D
http://www.achefshelp.com/up/images/recipes/demo/img/big_1280329991.jpg
Dingdong
24-03-2013, 10:46
I do like the lacing cord look. I shall have to have a practice and see if I can do a neat job of it.
Rare Bird
24-03-2013, 12:26
Lacing cord? I don't even know what that is. Is it something you use with valves and other sources of distortion?
http://theartofsound.net/forum/showthread.php?t=21199
:)
http://theartofsound.net/forum/showthread.php?t=21199
:)
Looks cool, but there's more 'stuff' near the wires, so if anything the cable ties are superior (if you believe in that sort of thing e.g. dielectric making a difference).
Rare Bird
24-03-2013, 14:55
Doesnt look cool it looks right & neat.
They are not superior at all & i certainly don't buy all that dielectric stuff, i only use Teflon wire, for instance cos it don't melt when soldering no other reason :eyebrows:
sq225917
24-03-2013, 18:39
Lacing chord, oh aye that looks a bit ham shank!
Rare Bird
24-03-2013, 19:23
Yeh right :lol:
Lacing cord? I don't even know what that is. Is it something you use with valves and other sources of distortion?
Oi, behave! ;)
Marco.
sq225917
24-03-2013, 23:59
:-)
Absolutely BEAUTIFUL Yamaha's!!
Absolutely BEAUTIFUL Yamaha's!!
These:
http://farm9.staticflickr.com/8371/8553740419_2a3d0635e9_b.jpg
or these:
http://farm9.staticflickr.com/8527/8504403757_22136798f5_b.jpg
or both ;)...
My vote goes for both! :)
I say both too, but there's just something about the wood ones.....
realysm42
27-03-2013, 15:43
Nah, all about the black ones, impeccable work and attention to detail.
sq225917
27-03-2013, 18:23
It certainly isn't cheap chipboard kitchen worktop laminate that's for sure.... ;-)
realysm42
27-03-2013, 18:43
Did you guys do the finishing yourselves?
I did....
I did everything myself (I did a bit of Si's too ;))
sq225917
28-03-2013, 09:48
Badges and surrounds courtesy of Holterman. Lovely waxed wood courtesy of me.
steviej233
28-03-2013, 10:12
Definitely the black ones although I wouldn't say no to the wood ones!!! :)
For the cabinet exterior I still prefer my own NS-1000 pair in ebony but have to say that have been eyeballing this thread closely especially for the the xo, foams surrounds for the drivers and interior mods.
http://farm9.staticflickr.com/8341/8228002044_4b7758fb2c_c.jpg
So no need to panic if I sometime drop you a line and ask some guidance and spice things up for possibility to biamp/triamp the speakers.. :)
So no need to panic if I sometime drop you a line ...
No prob, line drop away.
Lovely waxed wood courtesy of me.
Yep, the wood look good :).
sq225917
28-07-2013, 17:15
Time to bring this one back from the dead.
I've been sat on a Krell KSA200 for a while, too many phonostages to build. It was tripping the protection board and needing a couple of driver transistors replacing, (which Jez Arkless did for me). It's just had all the PSU caps replaced with mahoosive Kendeils caps, £400 worth of the feckers. It's all up and running again but looking a little bit sorry inside from where one of the old PSU caps had let loose with a pint of electrolytic piss, So all the boards need taking out, washing down, rinsing with isopropyl before re-assembly. Given that I've previous on rebuilding Krell I'm going to give it a thorough overhaul as well with the following.
2x diode bridges 200v 35 amps.
All new PSU wiring, cap mounting studs and screws.
All new signal path wiring.
Replace the ballast resistors on the slow start board.
Replace all the electrolytics on each channel and the protection board.
Strip it and refinish the heatsinks, a couple of them have dings on the top that need polishing out before they are remounted out of sight upside down.
Then scrub every inch of metal to remove any residue of that exploding electrolytic.
I reckon there's 100 hours of work in there probably a couple of hundred quid but once done it will be as good as new and all set for another 30 years.
At which point I'l get bored with it, move on to another project and flog it like i did with my EAR 509's and my Krell KSP 7b pre-amp. Here's some pics.
http://farm6.staticflickr.com/5462/9382792027_8005ffc8c5_c.jpg
http://farm4.staticflickr.com/3720/9382793743_82caf07d39_c.jpg
http://farm3.staticflickr.com/2848/9385574350_125381e26a_c.jpg
http://farm6.staticflickr.com/5458/9382794617_faa572ec05_c.jpg
Retro, Moi?
walpurgis
28-07-2013, 17:20
Looks very good, I love Class A amps. Big bugger innit! Hope you've got a forklift. :)
The Yams look very nice too. Did you fit the foam diffusing rings?
Good combination NS1000s with a big Krell.
sq225917
28-07-2013, 17:21
Yeh, they are from Ynwan.
Bit of a monster there, goes well with the Yamaha's though :)
Sounds good too - very sweet in the mids.
337alant
28-07-2013, 18:13
Thats an impressive lump of an amplifier Simon how does it sound?. what were you using before?.
Post some internal shots as well Id like to see whats inside?.
I just bagged a pair of NS1000s from Ebay so look forward to hearing them :eyebrows:
Alan
sq225917
28-07-2013, 19:40
Bit of a monster there, goes well with the Yamaha's though :)
Yeh it's not a bad match with them, tonally it's cohesive and it plunges the depths of their bass. What that shot doesn't show though is the fact that even though the Yammies are a good foot from the back wall that amps still sticks out another foot in front of them- it huuuuuuuuuuuuuge.
Yep, it is absolutely massive - truly gigantic!
I just bagged a pair of NS1000s from Ebay so look forward to hearing them :eyebrows:
Alan
In my opinion, the NS1000M is one of the finest speakers ever built irrespective of age or cost - it's as simple as that!
sq225917
28-07-2013, 23:28
If they were the ones with the dragged off veneer on the bottom you got them at a good price. keep that bass drive well away from the floor and they are remarkably easy to position.
Alan, no shots yet, i'll do them as i strip it and replace the old electrolytics.
337alant
29-07-2013, 05:42
Simon,
Yes that’s the ones I won £488 they need some work on the cabinets and I intend to re veneer the whole cabinet in walnut, I’m just hoping the drivers are all OK, the Xover will need a referb anyway so thats no problem.
My room is not that big 4x4m so I will make some stands to get them up off the floor
Spured on by yours and Marks fantastic work Im quite excited
Alan
337alant
29-07-2013, 05:55
In my opinion, the NS1000M is one of the finest speakers ever built irrespective of age or cost - it's as simple as that!
that’s quite a statement Mark I hope you are right, I listened to a pair at Scalford Hall and I really liked them, they are hugh in real life as well much bigger than they look in photos, cant wait to get home, can't concentrate on my work :)
Alan
Don't worry Alan, I'm always right ;)
Seriously though, I appreciate that my statement was a bit nebulous but I stand by it.
Don't worry Alan, I'm always right ;)
Seriously though, I appreciate that my statement was a bit nebulous but I stand by it.
sez who? :)
the NS1000's aren't happy with 99.9% of amplifiers so once you find one that is happy driving them, hoooray you may be correct with your statement.
Nick has had a pair belonging to his friend in his Den for years sat doing nothing, one day the guy who owns them may wake up and decide to sell, I remain hopeful.
sez who? :)
Everyone knows - or will do eventually (perhaps you haven't received the memo yet).
the NS1000's aren't happy with 99.9% of amplifiers
Umm...not really. in fact, not at all. The NS-1000Ms are often used with flea powered valve amps and they will work with most amps - such an arrangement isn't to my taste but some like it.
you may be correct with your statement.
Well, certainly more correct than you are with yours ;).
walpurgis
29-07-2013, 10:08
I've not owned the NS1000, but I've heard them many times, driven by various amps. They seem at their best with big Class A solid state or hefty valve amps, but also giving decent results with smaller valve units. The top end is merciless with SS amps with any grittiness or hardness.
Personally I use a 70wpc A/B amp and it works very well for me. But I would agree that I think the Yamaha's work best with solid state.
I’ve heard the NS1000’s being powered with a few different amps including Jadis (100 watt) mono-blocks; modified Canary CA-608 with Border Patrol PSU; Luxman 505 (SS 100 watt), audiolab 8000a (SS 50) watt; and Leak TL12 (12 watt). To my ears the first three all sounded good. The audiolab was not too bad but didn’t reproduce the bass adequately (not enough depth or width). The Leak was completely unsuited to the Yamaha’s as the bass was a bit woolly and overall made the Yamaha’s signature sound unrecognisable. Whether I preferred the solid state amps or valves amps I’m not sure, but the Yamaha’s do seem to need plenty of power. What was interesting was the owner of the Leak was really happy with the sound, which drove it home to me just how personal hi-fi is.
The Grand Wazoo
29-07-2013, 17:26
I wonder if Yamaha themselves made an amp that worked well with them at the time?
Well Yamaha made them for monitoring in studios (and a lot of studios did use them) and at that time pretty much all studios used high powered transistor amps (class A/B).
Having said that, both the pairs being demonstrated at the last Pie show used valve amplification.
sq225917
29-07-2013, 21:40
I've not owned the NS1000, but I've heard them many times, driven by various amps. They seem at their best with big Class A solid state or hefty valve amps, but also giving decent results with smaller valve units. The top end is merciless with SS amps with any grittiness or hardness.
The top end will struggle to be merciless, there's nowt on them, by the time they hit 15k they are already falling off a cliff. I've used them with big class A and big class A/B, both 200 watt+, they sound no different on either to be honest. Stick some watts up them and they are happy, quality being more important than quantity, but flea powered valve amp with apoor damping factor need not apply.
walpurgis
29-07-2013, 22:14
by the time they hit 15k they are already falling off a cliff
According to the 1976 Hi-Fi choice loudspeaker reviews edition I have, the response on axis is within 6db from 70Hz to 20kHz, as is also shown on their graph.
walpurgis
29-07-2013, 22:16
I wonder if Yamaha themselves made an amp that worked well with them at the time?
Yes B1 for a start, I'd imagine the CA-1000 would have done the job too.
sq225917
30-07-2013, 13:08
-6db is 1/4 as loud...
walpurgis
30-07-2013, 13:56
Yes I know, in energy terms, but not very audibly noticable.
Yes B1 for a start, I'd imagine the CA-1000 would have done the job too.
Used a CA1000 as well as the mk2. Not enough power or basic sound quality to give a half decent depth of soundstage. Going Class A helped with the latter, but the severe lack of power was then audible.
IMO and user experience, these things need loads of good clean Watts to make them anywhere near truly three dimensional, similar to passive ATC's I felt. The Linn LK2-80 I used was totally inappropriate I subsequently discovered once the 'Linn chip' had burned itself out in my brain - Gads, what was I thinking of :(
sq225917
30-07-2013, 16:01
I disagree, the 75 watts on offer from Mark's Nap 135's is more than enough to drive them to ear splitting levels and provides a level of precision to the soundstage that I've seldom heard. They don't go very deep front to back but that is a product of the ratio of their width to depth and the driver placement vs the lack of cabinet edge rounding- nothing to do with watts.
337alant
30-07-2013, 17:26
Simon is right they do fall a cliff above 15k
http://www.troelsgravesen.dk/Yamaha-NS1000.htm
Scroll down to the freqency plots and Troels knows a thing or 2 about measuring speakers :eyebrows:
Personally I cant hear anything above 12K so I dont need that bit anyway :lol::rolleyes:
Alan
The NS-1000S' are certainly easier to drive than the passive ATCs I have tried. As Si says, I find stereo placement to be really strong. As I recall, a lot of NS1000s came with a warning on the back not to exceed 70wpc.
sq225917
30-07-2013, 20:09
They fall off a cliff so much I've bought a set of Raals to mess about with replacing the tweeters.
Realistically I'm not going to modify these lovely cabinets no matter how bloody good the Raal's sound, so I'm likely looking at building a new set of speakers at some point. Raal's Audio-Tech mids and some thumping bloody bass drivers.
Reality is that there is so little music happening above 15kHz that its much more important to get this frequency and lower right over absolute frequency response.
I've not owned the NS1000, but I've heard them many times, driven by various amps. They seem at their best with big Class A solid state or hefty valve amps, but also giving decent results with smaller valve units. The top end is merciless with SS amps with any grittiness or hardness.
Grit and hardness is more likely to be the SS amp clipping than anything inherent in the sound of the amp. Plus it would be the midrange driver reproducing most of it, not the tweeter.
walpurgis
02-08-2013, 09:52
Percieved "grit and hardness" are often due to cable choices. Some can allow the sound to seem coarse, others can tailor in a smoother or cleaner presentation.
337alant
04-08-2013, 15:14
Si
What is the recommended height for speaker stands for the NS1000?, I was thinking of 300mm
Alan
The ones I built for my NS-1000Ms are about 300mm tall - but the speakers are tilted back about 2.5 degrees.
http://www.homebuilthifi.com/images/projects/4702/Yamaha_Stand_with_spikes2.jpg
http://www.homebuilthifi.com/project/4702
337alant
04-08-2013, 17:02
Thanks Mark and those stands look very nice ;)
I was also thinking of a 3 leg design but with the single leg at the front joined to the back with a T bar, Ive got some 50 x 50 RHS in the garage so I think ill knock some up when Im home :)
Alan
The uprights for mine are 50x50 I seem to recall. I don't use spikes on the top of mine now, I use a kind of ball joint type connection; a 12mm SS ball bearing rests in a 10mm hole in the top of the stand legs and then locates in a similar hole in a Delrin spacer - the speakers rest on those spacers and the height of those spacers creates the backward tilt. The backward tilt effectively makes the stands behave as if they are a bit taller and helps to time-align the drivers.
The height for the stands naturally depends of the listening position and the personal preference for the floor impact to the sound. My own stands for NS-1000s are approx. 45cms in height placing the listening axis somewhere to the upper part of the midrange driver..
337alant
05-08-2013, 16:00
Thanks Mika I will have to get Swmbo to measure from floor to ear whilst in the listening chair which Im sure will make her chuckle and she will tell me I'm off my trolley :D
But I'd like to get the tweeter at eye level if possible
Alan
There is some evidence that the optimum for the Yamaha's is for ear level to be between tweeter and mid driver.
sq225917
05-08-2013, 17:23
For those who are interested in thankless tasks.
http://farm6.staticflickr.com/5513/9443148835_4bd271ba57_c.jpg (http://www.flickr.com/photos/59684834@N08/9445936992/in/set-72157634946321928)
Click to view progress so far. I will add new shots daily.
Does it smell a bit fresher now?
sq225917
06-08-2013, 00:00
It's beginning to, it still largely smells like a favourite tobacco pipe.
There is some evidence that the optimum for the Yamaha's is for ear level to be between tweeter and mid driver.
True dat.
sq225917
06-08-2013, 17:24
http://farm6.staticflickr.com/5542/9453538292_4629f904ba_c.jpg
Half of the exterior casework for the amp.
Wakefield Turntables
06-08-2013, 19:53
WOW thats attention to detail. ;)
sq225917
06-08-2013, 20:02
No nut will be left unscrewed, no surface unwashed, unwiped and undried.
http://farm3.staticflickr.com/2828/9454455856_839c8b145d_c.jpg
Them caps are big buggers though..
http://farm8.staticflickr.com/7404/9451676495_822ee4f305_c.jpg
A real handful...
47,000 uF and there's six of them.
And when one of them pops, it makes a real mess.
http://farm6.staticflickr.com/5329/9451673705_edda08f0be_c.jpg
I'm hoping this will scrub up but I guess the pitting hints that it will need stripping and powder coating afresh.
Surely that's a can of beer disguised as a cap... :D
Whe you go for it Si, you REALLY go for it.
Looking forward to seeing the final result.
sq225917
07-08-2013, 07:08
There's no point in holding back. A totally stripped, cleaned, tested and electrically serviced Krell is going to sound better and look better than if I'd just settled for it with the bust bits replaced. Honestly, the smell was unbelievable and once it heats up it just fills the room.
Impressive work Simon like how perfectionist your approach is much like your Krell preamp refurb.
Can't see those Kendeil caps hurting over the next 20yrs or so...
sq225917
07-08-2013, 18:37
Cheers Neil. I have to admit I'm quite taken by the idea of owning a genuine piece of classic hifi, restoring it to as new condition and then releasing it back into the wild after a few months. Plenty more pics to follow later tonight.
Can't see those Kendeil caps hurting over the next 20yrs or so...
The Kendeils are good (i use them in my amps), but no electrolytic cap will be happy in that heat for ten years never mind twenty!
sq225917
07-08-2013, 19:54
http://www.flickr.com/photos/59684834@N08/9458655333/ click for the set.
http://farm8.staticflickr.com/7452/9458655333_969f96def6_c.jpg
Wakefield Turntables
07-08-2013, 20:12
bloody hell you really have ripped the $hit out of this one!
sq225917
08-08-2013, 06:54
Just wait until you see it tonight. Those heatsinks will be off, that transformer and the the loom will all be off the bottom panel and I'll have everything laid out in its correct place. I'm going to respray that bottom panel, even though you won't be able to see under the caps once it's assembled I'd know that the finish wasn't perfect and I can't have that.
I've been through all the caps now and only two of them show ESR that's high enough to be out of spec, and those are the two on the front relay board. That front relay board obviously gets pretty hot with that huge wirewound on it so I'm going to vent the board and remount the resistor so it sits a few mm higher for better air circulation. The heat from that resistor will be what has lead to the higher ESR on those two caps so fixing that should benefit the long term stability.
It's remarkable how well preserved all the parts are giving the operating temperatures of the heatsinks. Those side panels do go quite a way to shielding the main PSU caps and the main boards from the heat of the output stage.
You're certainly going a few extra miles with this. Has there been any desoldering or does it all come apart simply with a screwdriver and wrench? It seems to show the advantage due to a well engineered high-end amp in that it can be disassembled....even if heat management might have been better in the first place.
Arkless Electronics
08-08-2013, 10:22
Just wait until you see it tonight. Those heatsinks will be off, that transformer and the the loom will all be off the bottom panel and I'll have everything laid out in its correct place. I'm going to respray that bottom panel, even though you won't be able to see under the caps once it's assembled I'd know that the finish wasn't perfect and I can't have that.
I've been through all the caps now and only two of them show ESR that's high enough to be out of spec, and those are the two on the front relay board. That front relay board obviously gets pretty hot with that huge wirewound on it so I'm going to vent the board and remount the resistor so it sits a few mm higher for better air circulation. The heat from that resistor will be what has lead to the higher ESR on those two caps so fixing that should benefit the long term stability.
It's remarkable how well preserved all the parts are giving the operating temperatures of the heatsinks. Those side panels do go quite a way to shielding the main PSU caps and the main boards from the heat of the output stage.
I found that on the protection board, where I had to replace the faulty cap, most of the electrolytics showed considerably raised ESR compared to a new cap, if not enough to cause problems in the operation of the board. I had no reason to measure any others but I would be surprised if a full re-cap job did not show its worth.....
Wakefield Turntables
08-08-2013, 13:03
Can't wait for tonight's installment
sq225917
08-08-2013, 18:29
Jez,
The red Rhode's were never a low ESR cap in the first place, not compared to something like a Panasonic FC/FM. On closer inspection I've found 5 of them with cracks in the cases so I may as well replace the lot there's only a dozen or so of them in there and I have those values to hand in FC/FM Panasonics.
I lifted a leg on all the orange caps and measured them and they are all within spec. Seems like the 105 degree rating and DIN certification is worth something after all.
I've just keyed and sprayed the side panels in temp resist satin black. I'll do the bottom tomorrow.
Pics later, i've got a website launch that needs some attention.
sq225917
08-08-2013, 23:26
http://farm6.staticflickr.com/5464/9466646077_e5eab17c48_c.jpg
So that's one Krell KSa 200 minus the side panels that are hung up drying.
click for the full set http://www.flickr.com/photos/59684834@N08/9466646077/
I went round to sq's earlier today and the Krell was spread out over the entire room :). These amps were hardly cheap when new, but it has to be said that you do get quite a lot for your money and, unlike a lot of modern amps, they really are built in a way that suggests their specification is real! I find myself surprisingly impressed by the construction of the big Krell - I would certainly like to investigate a large ML amp.
sq225917
09-08-2013, 07:34
it looks like panasonic have a new electrolytic cap range, small footprint, low ESR, and up to 135 oC temp rated. Like like i've just found the replacement for those red Rhode's
sq225917
09-08-2013, 08:41
http://farm4.staticflickr.com/3742/9471761556_63aaaf4bf7_c.jpg
Nicely refinished, I hope the bottom panel comes out as well.
Yes indeed, that has turned out very well.
sq225917
09-08-2013, 17:32
It's the blutack balls in the threads that does it.... ;-)
Ah yes, that's precisely what I do :).
337alant
09-08-2013, 18:37
How does putting threads of blue tac on your balls make you better at spraying?:scratch::D
Nice finish that :eyebrows:
Alan
walpurgis
09-08-2013, 18:44
You don't mess about do you Simon. You've got well and truly stuck into this. Well done!
How does putting threads of blue tac on your balls make you better at spraying?:scratch::D
Nice finish that :eyebrows:
Alan
It stops the paint from going into the holes and clogging the threads.
sq225917
10-08-2013, 09:05
Time for some more metalwork finishing. There's plenty of work here.
http://farm3.staticflickr.com/2831/9478432012_da0e8abd2d_c.jpg
A close up shows it's not a pretty sight
http://farm3.staticflickr.com/2871/9478432810_a018974e62_c.jpg
Gotta cut through all that rust and pitting to get back to clean metal.
http://farm6.staticflickr.com/5459/9478433606_be272c6f4d_c.jpg
Here we are, all rust removed, all pitting sanded back to flat and all dust removed with a solvent wash. Time for tape.
http://farm6.staticflickr.com/5550/9478434502_f694f71927_c.jpg
Keyed and masked. (The bit you didn't seen is cleaning every single vent slot with a thick shoe lace soaked in thinners).
http://farm6.staticflickr.com/5349/9478435204_74c5897015_c.jpg
All sprayed, with my favourite sandy finish.
http://farm4.staticflickr.com/3782/9475648839_19b2228440_c.jpg
Flat as you like.
http://farm8.staticflickr.com/7368/9478437430_a3f6201eae_c.jpg
Looking good for a rattle can?
http://farm6.staticflickr.com/5341/9478438322_f34a3d217b_c.jpg
Tape mask cleaned off
http://farm4.staticflickr.com/3707/9475643139_8ec910ecd1_c.jpg
Now then, should i just fit these straight back on to my lovely resprayed bottom plate?
Of course not, these need wire wheeling and spraying too. Zinc primer with a clear lacquer or white smoothrite for a bit of bling?
http://farm6.staticflickr.com/5528/9478436066_240c227638_c.jpg
Wakefield Turntables
10-08-2013, 09:49
Yep this is one hell of a restoration. It puts my sansui au717 restoration to shame :(
Zinc primer with a clear lacquer or white smoothrite for a bit of bling?
Just silver spray will be fine - don't buy any I've got some.
Looking good matey :).
sq225917
11-08-2013, 09:36
http://farm8.staticflickr.com/7388/9482930581_630f612937_c.jpg
Polishing my nuts...
http://farm4.staticflickr.com/3819/9485705348_1025cc6d31_c.jpg
PSU caps refitted.
Just waiting on caps from Mouser to start recapping the boards then I can begin to reassemble it.
Admirable work Simon. Your lady must be quite laid back, I know a few women who would seriously object to having enourmous Krell amp rebuilds happening in their kitchen :)
sq225917
13-08-2013, 16:28
Kitchen? You're kidding, this thing would cover every work surface and the entire floor if I laid it out in our kitchen... She is very understanding though. She understands not to stick her friggin nose in my Hifi....
sq225917
14-08-2013, 09:44
http://farm4.staticflickr.com/3736/9498446596_3c0962840e_c.jpg
When you start looking closely at an amp you realise that at some point, someone has either been really lazy or are utterly clueless. This amp has single ended and balanced inputs, so there's +/-/gnd inputs. The + is white, the - is that little black wire next to it and the gnd is the big wire. Now which twunk has soldered the - input from the balanced input plug to the centre of the ground point on this pcb- dildo. So it will sound fine on the single ended input but if you use the balanced input you'll only get half a signal, literally, it will be 3db down on one channel in balanced mode. Here's what it should look like.
http://farm4.staticflickr.com/3667/9500258593_bab7c4f857_c.jpg
Ok, so it is reasonably complicated as they pair the GND wire from the XLR input with the signal shield from the short length of double core (red) signal input wire. But honestly anyone should spot that.
http://farm6.staticflickr.com/5344/9503055068_9f0636bea8_c.jpg
Not that it matters, they have all been desoldered anyway, and are waiting for a deflux before reassembly.
http://farm6.staticflickr.com/5521/9503058546_8de0221309_c.jpg
So we've got a 2x4" ground plane on the back of the boards, Nice! That's going to make removing the caps next to impossible with any soldering iron that can't weld steel. Mine might be 65 watt but It's no match for this.
http://farm4.staticflickr.com/3771/9498450172_3ce5014483_c.jpg
Fortunately Krell aren't stupid, when they solder in big capacitors they use 2mm vias between top and bottom of board. So with a jig to hold the pcb and a 1.5mm drill and a drill press you can drill right through the centre of the vias once you have removed the caps. Does it work?
http://farm8.staticflickr.com/7356/9498452700_e9c3162555_c.jpg
Hell yeh, it worked here and worked for the main boards as well. (no pics of those though drilled through, just the finished article) Yes I'll be trimming and resoldering that white wire.
http://farm8.staticflickr.com/7451/9503057308_e94796fde0_c.jpg
ah but are they really neat?
http://farm4.staticflickr.com/3783/9500255047_3c75bb7268_c.jpg
You bet your ass. One board done one more to do tonight then i can put this back together for the weekend.
But why replace all these caps surely they can't be that bad, it's only a little heat, surely?
http://farm8.staticflickr.com/7412/9495648817_92d8efc9a6_c.jpg
Well, no.
http://farm8.staticflickr.com/7283/9495652443_aefa59ecba_c.jpg
These have split cases, they all weigh significantly different amounts, implying some have dried out and their ESR is off the scale.
http://farm3.staticflickr.com/2837/9494028181_02edcda8e1_c.jpg
Once you start you simply have to do them all, there's no other realistic option. So this has 20 new main board smoothers added, 2 small signal caps, 6 new small signal caps on the relay board, 6x new massive psu cans and 2x small signal caps on the front relay board. all of them are 105 degree lifetime rated, some of them are 135 degree rated.
I'm fixing for this not to need the lid off it for another twenty years.
Arkless Electronics
14-08-2013, 10:26
Yeah replace the lot! It should last for years now and sound even better. I hadn't noticed that problem with the wiring of the inputs.... it wasn't one of the areas that was playing up and so hadn't warranted any attention... well spotted!
sq225917
14-08-2013, 13:14
Yeh, it was on the other channel to the one you sorted Jez. It really is the stupidest thing I've seen done to an amp in a long time. Either they were deaf or no one has used the balanced inputs since it was done.
sq225917
14-08-2013, 13:50
£1400 for this one on ebay. Incidentally from the same guy I got mine from.
http://i.ebayimg.com/t/KRELL-KSA-200-FULLY-WORKING-ORDER-MEGA-BEAST-/00/s/MTE5NFgxNjAw/z/W2QAAMXQGQRSCqc9/$(KGrHqZ,!oQFIGltnkrIBSCqc9ed6g~~60_12.JPG
I'm wondering why he has the bottom plate on the top of the amp though!
Arkless Electronics
14-08-2013, 15:08
Yeh, it was on the other channel to the one you sorted Jez. It really is the stupidest thing I've seen done to an amp in a long time. Either they were deaf or no one has used the balanced inputs since it was done.
Well I only used it unbalanced and it sounded great here... as you heard.
I wouldn't be surprised if you and Si aren't the only people to have used it since the cap went bang, so it probably hasn't been used balanced input.
I wonder if the other amp hasn't had the faceplate put on upside down. Either way it looks like the owner may have attempted a 'repair' on that one too - presumably a repair that worked (unlike the one he tried on your amp Si).
Just thinkin' - I bet Dan D'Agostino does the odd Google search every now and then. I wonder how he feels when he sees things like this?
TBH I had thought these old Krells were a bit shit. But hearing a KSA 300S driving some Ushers and some Apogee Calipers in the same day said nope, I'm a nice amp - still. So it should be worth all the effort.
sq225917
14-08-2013, 18:33
I spoke to him the other night he sent the one for sale off for repair to some guy in Manchester. It was caps on the protection board, cost him a small fortune. He hasn't recapped the psu in this one though, so there's a 400+ quid cost on top of the asking price.
Mine hadn't been working since the cap popped, so Jez was the first to hear it.
Spectral Morn
14-08-2013, 19:25
Nice work Simon, I doff my cap to you good sir. :cool:
Regards Neil
sq225917
14-08-2013, 20:07
Cheers Neil, I'm just off to do that 2nd board..
sq225917
14-08-2013, 23:54
http://farm4.staticflickr.com/3772/9513848772_0a5fc50945_c.jpg
First bit of signal wire replaced. Lovely bit of heavily shielded, twin core MIC cable.
http://farm8.staticflickr.com/7446/9511058635_53af6ff406_c.jpg
All trimmed to fit
http://farm6.staticflickr.com/5321/9513846950_24a69f1f75_c.jpg
Ooh, she's proper dirty..
http://farm3.staticflickr.com/2863/9513845990_efaa29a8e7_c.jpg
Why would you smoke in your hifi room?
http://farm6.staticflickr.com/5481/9511055971_d021347b88_c.jpg
More scraping and wiping.
http://farm4.staticflickr.com/3735/9511055139_46be1859e0_c.jpg
Nearly there now.
http://farm4.staticflickr.com/3750/9513843418_165489dc39_c.jpg
There you go, all clean.
http://farm6.staticflickr.com/5327/9511053413_3cbf14f770_c.jpg
Cleaned top and bottom
http://farm3.staticflickr.com/2854/9513841908_fec15584ee_c.jpg
20 year old apparently, who'da thunk it?
http://farm6.staticflickr.com/5506/9511050721_2461617159_c.jpg
I do like a nice shiny solder pool.
Right then just two more caps to do on this board then it's time for it all to start going back together...
Spectral Morn
15-08-2013, 08:28
Cheers Neil, I'm just off to do that 2nd board..
The talents of the folks of AOS - including your good-self - never fail to amaze me. Stripping, cleaning, refinishing and rebuilding anything never mind a Krell amplifier is very impressive. :cool:
Regards Neil
sq225917
15-08-2013, 09:40
In truth it's little more than undoing a few screws, tagging all the wire connections, some elbow grease and decent solder technique. There's no rocket science to it.
Spectral Morn
15-08-2013, 14:35
In truth it's little more than undoing a few screws, tagging all the wire connections, some elbow grease and decent solder technique. There's no rocket science to it.
Simon
I think you are being too modest and belittling the amount of work and knowledge that is going into your endeavour.
Regards Neil
sq225917
15-08-2013, 18:54
I used to modest, but I had to stop. I wasn't very good at it....
sq225917
15-08-2013, 19:35
http://farm6.staticflickr.com/5482/9519480570_9ebc3f0efd_c.jpg
New fittings for resistors.
http://farm6.staticflickr.com/5514/9519481774_9813361359_c.jpg
A little bit transformed.
http://farm6.staticflickr.com/5534/9516694029_f3a2a32d0c_c.jpg
looking good over that paint
http://farm6.staticflickr.com/5453/9516695403_9b0a55dd49_c.jpg
Quite pleased with that front section
http://farm8.staticflickr.com/7398/9519485884_ef2e2aebcb_c.jpg
Bloody pleased with these though
http://farm4.staticflickr.com/3701/9519487150_314aca1201_c.jpg
Protection board fitted, all new caps and washed relays.
http://farm3.staticflickr.com/2878/9519488560_64a58d2bc0_c.jpg
That big toe is just dying to get in there
http://farm8.staticflickr.com/7458/9519489760_d9112ce558_c.jpg
Output trannies mounted to resprayed side panel
http://farm4.staticflickr.com/3740/9519490936_e0b8d19ab7_c.jpg
Main board mounted
http://farm4.staticflickr.com/3754/9519492324_e97ba82066_c.jpg
Drivers mounted
http://farm3.staticflickr.com/2828/9516706605_880c14cfba_c.jpg
Nearly done. that side needs bolting up. The old input wires need striping from the back panel and the new ones soldering in. I'll be leaving the old PSU wiring on until next week, my old man is staying and the hifi room is the spare room with the bed settee.
bugger......
sq225917
15-08-2013, 23:24
All rebuilt. I still need to clean the carbon off the vents where the cap blew through the top plate and I need to replace the diode bridges and the diode bridge wiring and then it's done. But this will do for now.
http://farm4.staticflickr.com/3742/9517972615_0176ed6362_c.jpg
http://farm4.staticflickr.com/3775/9517971591_a560cabb7a_c.jpg
I reckon there's about 60 hours work in there all told and nearly £500 worth of new caps.
walpurgis
15-08-2013, 23:36
WOW!
I want to own that - I can't say more than that!
sq225917
15-08-2013, 23:52
Yeh but not until i finish that wiring and get the carbon off that lid.
sq225917
16-08-2013, 09:09
So the first switch on gave me a 'pop' as the protection board kicked in dumped the mains through a relay. I notice there's a strand of loose wire on the floor of the amp looking sorry for itself. That must have dropped in there while trimming wires to fit them. Looks like it arced across something or other. Time to take that back panel off and check all the wiring and make sure the back of the components are fouling the casework or each other. Thankfully the protection board did it's thing.
To be fair, I fully expected this to happen, something always slips past on such a big job.
Spectral Morn
16-08-2013, 09:30
So the first switch on gave me a 'pop' as the protection board kicked in dumped the mains through a relay. I notice there's a strand of loose wire on the floor of the amp looking sorry for itself. That must have dropped in there while trimming wires to fit them. Looks like it arced across something or other. Time to take that back panel off and check all the wiring and make sure the back of the components are fouling the casework or each other. Thankfully the protection board did it's thing.
To be fair, I fully expected this to happen, something always slips past on such a big job.
Sorry to hear that Simon - good luck on the clean up.
Regards Neil
Arkless Electronics
16-08-2013, 10:14
So the first switch on gave me a 'pop' as the protection board kicked in dumped the mains through a relay. I notice there's a strand of loose wire on the floor of the amp looking sorry for itself. That must have dropped in there while trimming wires to fit them. Looks like it arced across something or other. Time to take that back panel off and check all the wiring and make sure the back of the components are fouling the casework or each other. Thankfully the protection board did it's thing.
To be fair, I fully expected this to happen, something always slips past on such a big job.
Fingers crossed that it's not taken out anything during that "pop" :eek:
Nice job there Si.
sq225917
16-08-2013, 10:38
Cheers Jez, No signs of debris inside the amp and no smell or smoke. I'm pretty confident that it is just a short caused by the way one part has been fitted next to another or an exposed bit of wire. It might even be the bolt I fitted to the resistor under the protection board, (the one that only had one fitted previously) that actually looks like it could foul the back of the live pin on the IEC when reassembled.
I don't think it's anything to do with the rebuild itself, just the re-assembly. It was just a flash and a click, not a component letting go, i know what fried transistor sounds and smells like....
Love this thread! I still have my NS1000Ms which I have owned from new. When they were in my main system I had a Musical Fidelity A370 amp, my experience was more power = good with the Yams, I believe the failed tweeters many have experienced are due to the high harmonics resulting from clipping with an insufficiently powerful amp being enough to fry the tweeter .
Coincidentally my next amp was Krell KSA200B just like this, mind you I had 2 driving active Apogee Divas. I was working in France at the time and the heat from those amps meant the system was short term only in summer.
That speaker amp combo was a bit special but far too big when I moved back to the UK at the end of my contract.
Bravo for such a thorough re-build!
Ali Tait
16-08-2013, 20:45
Indeed, great job Simon, looks a grand job, love to hear a Krell sometime, never have.
Frank, used to have an A370 myself. A good, but not great amp IMHO.
sq225917
16-08-2013, 23:01
Frank the Yams just have thin wire in the tweeter coils. So if you run them +3db and plays them loud they burn out. Easy to unwrap a turn off the coil to fix them.
Frank the Yams just have thin wire in the tweeter coils. So if you run them +3db and plays them loud they burn out. Easy to unwrap a turn off the coil to fix them.
Nice to know it is "easy" to fix, though I never ran them >0dB. I have seen a FR plot done by the guy who designed a crossover upgrade who's name I can't remember just now, showing early roll off (around 15kHz IIRC) or at least early for the 20-20k convention. I don't remember that from contemporary (obviously paper mags) long thrown away tests, though I am not sure if there is an age related or measurement technique/kit related explanation. Certainly I remember that one mag recommended -2 and -1 for mid and treble for flattest response. Back then though a speaker was considered in this country to sound "more natural" if it had a slowly drooping FR and all UK speakers were balanced like that AFAIK. It certainly led to German and French speakers having a bright reputation and for Japanese companies to balance their products for UK ears.
Frank, I'm pretty sure you are referring to Troels Gravesen (http://www.troelsgravesen.dk/Yamaha-NS1000.htm) who has measured the NS-1000Ms and also designed an alternative crossover. I'm not really sure about the crossover mods as they make the crossover more complex. I have heard a pair of Yamahas with them fitted but it was in an unfamiliar system and room; it's not easy to find reports of peoples experience with them either and nobody has compared them to just 'upgraded' crossovers as far as I am aware.
I know what you mean about drooping RF but it's not for me. I've replaced my adjustment pots with fixed value resistors but both the mid and tweet are effectively flat - I found that attenuating either did more than just alter the frequency response. We also measured the pots and found that they do still alter the impedance of the crossover as they are adjusted.
sq225917
17-08-2013, 18:04
Troels measurements show a Heavy roll off at 15k. This is part of the tweeter's make up, not applied from the crossover. His measurements were at 1m and room compensated. I have a set of Raals that I'll get round to trying instead of the Yamaha tweeter.
Frank, I'm pretty sure you are referring to Troels Gravesen (http://www.troelsgravesen.dk/Yamaha-NS1000.htm) who has measured the NS-1000Ms and also designed an alternative crossover. I'm not really sure about the crossover mods as they make the crossover more complex. I have heard a pair of Yamahas with them fitted but it was in an unfamiliar system and room; it's not easy to find reports of peoples experience with them either and nobody has compared them to just 'upgraded' crossovers as far as I am aware.
I know what you mean about drooping RF but it's not for me. I've replaced my adjustment pots with fixed value resistors but both the mid and tweet are effectively flat - I found that attenuating either did more than just alter the frequency response. We also measured the pots and found that they do still alter the impedance of the crossover as they are adjusted.
Thats it. I enjoyed reading about your NS1000M rebuild. I am not sure I would need more than 15kHz anyway. I listened to a frequency sweep recently and can only hear up to 12kHz unless I turn the volume up unrealistically, and I am unaware of whether my supertweeters are off or on, so not even connected any more.
I am continually amazed about how much talk there is about the top half an octave, where it is debateable whether much music exists anyway. Loads of speakers lack the last octave or octave and a half of bass and not only is that very definitely audible but great fun and massively missed, by me at least, if it isn't there.
Troels measurements show a Heavy roll off at 15k. This is part of the tweeter's make up, not applied from the crossover. His measurements were at 1m and room compensated. I have a set of Raals that I'll get round to trying instead of the Yamaha tweeter.
Yes I understood it wasn't in the crossover, was just speculating whether tweeters have lost something with age (can't imagine what), never had much output above 15kHz or whether it is his measuring microphone or something.
Sorry to have slightly hijacked your fascinating amp rebuild story....
sq225917
17-08-2013, 20:01
Aiui they were always like that.
sq225917
22-08-2013, 19:31
The old man toddles off tomorrow so i can crack on and find pout what I'd put back in the wrong place.
Thats it. I enjoyed reading about your NS1000M rebuild. I am not sure I would need more than 15kHz anyway. I listened to a frequency sweep recently and can only hear up to 12kHz unless I turn the volume up unrealistically, and I am unaware of whether my supertweeters are off or on, so not even connected any more.
I am continually amazed about how much talk there is about the top half an octave, where it is debateable whether much music exists anyway. Loads of speakers lack the last octave or octave and a half of bass and not only is that very definitely audible but great fun and massively missed, by me at least, if it isn't there.
I can't hear pure tones above 12kHz (probably less now), yet I can hear the effect of low-pass filtration at 15kHz on the sound of a violin. Although you cannot directly hear 15kHz, the harmonics and overtones of some instruments extend to these frequencies, and it is these harmonics and overtones that give the instrument its timbre.
Many years ago JBL produced a demonstration record called "Sessions". The effect of filtering out the high frequencies is one of the demonstration tracks.
http://www.adventuresinhifiaudio.com/19/06/2011/can%e2%80%99t-hear-those-high-frequencies-%e2%80%93-don%e2%80%99t-panic/
http://farm7.static.flickr.com/6017/6008147663_726e83d8a3.jpg
http://www.discogs.com/Various-Sessions/release/1025261
Click to view progress so far. I will add new shots daily.
That redefines the word 'painstaking' for me, Si. I'm impressed!
I can't hear pure tones above 12kHz (probably less now), yet I can hear the effect of low-pass filtration at 15kHz on the sound of a violin. Although you cannot directly hear 15kHz, the harmonics and overtones of some instruments extend to these frequencies, and it is these harmonics and overtones that give the instrument its timbre.
Many years ago JBL produced a demonstration record called "Sessions". The effect of filtering out the high frequencies is one of the demonstration tracks.
http://www.adventuresinhifiaudio.com/19/06/2011/can%e2%80%99t-hear-those-high-frequencies-%e2%80%93-don%e2%80%99t-panic/
http://farm7.static.flickr.com/6017/6008147663_726e83d8a3.jpg
http://www.discogs.com/Various-Sessions/release/1025261
Interesting, I would love to hear the examples but the links are probably too old or copyright has had them removed or something.
My experiment was at a higher frequency. A friend of mine who designs speakers brought along a pair of prototype supertweeters. I could not tell whether they were on or off. He could, but he is younger than I, and probably knew what to listen for.
BTW the fundamentals quoted in the article don't include piano. The lowest note on our piano has a fundamental of 31Hz, a lot lower than a contrabassoon, but not competing with organs pipe or electronic.
I still reckon I miss the commonly missing lower octave and a half (or more) at the bass end of most speakers than the top 1/2 octave...
Ali Tait
23-08-2013, 21:29
I can't hear pure tones above 12kHz (probably less now), yet I can hear the effect of low-pass filtration at 15kHz on the sound of a violin. Although you cannot directly hear 15kHz, the harmonics and overtones of some instruments extend to these frequencies, and it is these harmonics and overtones that give the instrument its timbre.
Many years ago JBL produced a demonstration record called "Sessions". The effect of filtering out the high frequencies is one of the demonstration tracks.
http://www.adventuresinhifiaudio.com/19/06/2011/can%e2%80%99t-hear-those-high-frequencies-%e2%80%93-don%e2%80%99t-panic/
http://farm7.static.flickr.com/6017/6008147663_726e83d8a3.jpg
http://www.discogs.com/Various-Sessions/release/1025261
Hence why super tweeters can make a huge difference to the presentation of a speaker.
sq225917
24-08-2013, 07:34
painstaking when it went 'pop' on first turn on. I'll get it sorted next week.
Ali Tait
24-08-2013, 12:35
Hope there's nowt major wrong Simon, you obviously spent a lot of time and effort on the amp.
sq225917
24-08-2013, 23:35
I have faith out was just an assembly issue, wires touching, exposed pcb track sort of thing.
Wakefield Turntables
25-08-2013, 10:54
yeah good luck with this 60 hours worth of graft for a puff of smoke is not good :( Hope you track the problem down.
sq225917
25-08-2013, 14:53
it's alive.....
Took the back panel off, gave it a brush to make sure there was nothing of that strand of wire left then let Dave turned it on, (lol). No drama, fired straight up, works perfectly, great channel balance, buckets of bass slam and more delicate treble you couldn't wish for.
I'll clean up with the PSU wiring and replace the diode bridges with new ones and fit my spanky new brass bolts for the PSU caps and she'll be all done.
My modded Mdac will be here on Tuesday as well, result.
Figlet108
25-08-2013, 15:37
Great result Simon - well done.
I've been quietly following your progress with admiration. I can only imagine how satisfying it feels :)
Spectral Morn
25-08-2013, 17:12
it's alive.....
Took the back panel off, gave it a brush to make sure there was nothing of that strand of wire left then let Dave turned it on, (lol). No drama, fired straight up, works perfectly, great channel balance, buckets of bass slam and more delicate treble you couldn't wish for.
I'll clean up with the PSU wiring and replace the diode bridges with new ones and fit my spanky new brass bolts for the PSU caps and she'll be all done.
My modded Mdac will be here on Tuesday as well, result.
Good news Simon :) :cool:
Regards Neil
sq225917
25-08-2013, 18:07
http://farm3.staticflickr.com/2891/9593534628_6ed0d4d698_c.jpg
Here's the new 20 amp diode bridges with their +/- wiring. That's an AA battery for scale, I don't have much fear these will overheat....
Rare Bird
25-08-2013, 18:08
I Thought you would have gone for bridge rectifiers made from individual Diodes!
I Thought you would have gone for a full wave bridge rectifiers made from individual Diodes!
Not in an early Krell or something else like an early Pass Labs. There are also claimed advantages e.g. matching of diodes.
sq225917
25-08-2013, 18:32
Andre at 20 amps (US) you need the thermal mass to bolt down to dissipate the heat. I was tempted by the IXYS silicon bridges, but at £100 each, nah......
Rare Bird
25-08-2013, 18:46
I just thought that's what serious Hi-Fi guys did automatically :eyebrows: but i understand.. Yeh ive seen those IXYS Packages i think they are German..
The Black Adder
25-08-2013, 19:25
Eeee, sithi tha doin a reyt good job o that sunshine! :) - spot on!
Rare Bird
25-08-2013, 19:27
Aye reyt goowd amps dem towd Krells
sq225917
25-08-2013, 20:48
http://farm4.staticflickr.com/3785/9591883633_dceb94f129_c.jpg
460 miles of driving
105 hours of unscrewing, removing, twisting, cutting, scrubbing, wiping, rubbing, spraying, wire brushing, polishing, screwing and soldering.
16 crimp fittings
12 brass screws
4 metres of solder
3 foot of solder wick
6 pints of PSU caps
3 metres of wire
36 small signal caps
50cm of heatshrink
2 tins of isopropyl cleaner
1 tin of flex remover
10 grazed knuckles
1 squashed toe
1 arse flapping moment
and it's job done...
Yeah, nice job, I thought it sounded jolly good :).
sq225917
26-08-2013, 16:01
Right then no more after this I promise.
http://farm3.staticflickr.com/2888/9598289153_a0d61e7b90_c.jpg
Dirty vent slots, back/centre and RHS where the PSu cap has let loose and the electrolytic has carbonized the anodizing.
http://farm4.staticflickr.com/3726/9598292521_b78f51d8f9_c.jpg
With the help of a cordless drill, some bamboo kebab skewers and a bottle of T-cut (fine) I was able to polish out all the carbon without damaging the anodizing.
Now it's done...
The Black Adder
27-08-2013, 09:31
Champion! :)
Yep, I really like it - except for three minor issues:
1/ it is absolutely vast
2/ it is very heavy indeed
3/ it is like having a three bar electric fire turned on in the room
:)
Ali Tait
27-08-2013, 10:33
I'll give ye a fiver for it.
sq225917
27-08-2013, 11:44
I'll give ye a fiver for it.
Which bit?
That's absolutely astonishing work, Simon (in the same order as Marks Yamaha rebuild). I am most jealous of your abilities, I can only guess how it feels to have completed it.
I sincerely hope it sounds utterly wonderful, as it should, given your hard work, time, dedication and attention to detail. That must be one of the finest classic Krells in the world right now. Congratulations!
sq225917
27-08-2013, 12:46
Thanks Alan. I would be very surprised if there isn't someone out there somewhere that has a similarly serviced, component updated and casework refinished Krell, they are I believe more than worthy of such lavish attention to detail. I'd hate to think how much someone would charge for the work though...
Rare Bird
27-08-2013, 12:50
I used to fancy one of those old Aragon '24K' Pre-Amp/'4004' power-Amp..
Yep, I really like it - except for three minor issues:
1/ it is absolutely vast
2/ it is very heavy indeed
3/ it is like having a three bar electric fire turned on in the room
:)
Just like my Mark Levinson ML-2s; and you need two of them!
sq225917
27-08-2013, 13:09
I used to fancy one of those old Aragon '24K' Pre-Amp/'4004' power-Amp..
Yeh there's plenty of old quality out there, most stuff built these days doesn't match up in terms of sheer build quality.
Ali Tait
27-08-2013, 13:34
Which bit?
:D
Seriously, a grand job mate. Never heard a Krell, like to sometime.
Yeh there's plenty of old quality out there, most stuff built these days doesn't match up in terms of sheer build quality.
I had a look at the Krell website - there is a hell of a lot less in their power amps these days!
sq225917
27-08-2013, 15:02
I think that depends on the model. They try to hide the fact the amps are pure Class A monsters in talk about the cascoded output stage design. They still make massive amps, they've just found a more novel way to eliminate crossover distortion that sheer brute force.
I had a look at the Krell website - there is a hell of a lot less in their power amps these days!
There's quite a bit more inside, just a hell of a lot less heatsinks!
sq225917
27-08-2013, 19:13
There's a lot more management and a lot less action in them...
Spectral Morn
27-08-2013, 19:20
Nicely done :cool:
Regards Neil
Fantastic thread this,really interesting stuff,how about rebuilding some vintage Quad electrostatics next Simon ?
sq225917
27-08-2013, 22:27
Rebuilding Quads is a bit too specialist for me, too many things to go wrong and most materials are only available bulk or from expensive specialists. Could probably make a good stab at some solid frames but the panels are best left to those with the rigs to stretch them.
There's quite a bit more inside, just a hell of a lot less heatsinks!
A lot less everything from the pictures I looked at!
Ali Tait
28-08-2013, 12:42
Good repair kits for Quads available here-
http://www.eraudio.com.au/ESL_Repair_Kits/Quad_57_Kit/quad_57_kit.html
sq225917
28-08-2013, 14:50
My Mdac just arrived back from Mr Westlake. Finally I have hifi.....
Rare Bird
28-08-2013, 14:57
Sorry if im acting thick Simon but wht is an MDAC?
sq225917
28-08-2013, 15:42
An Audiolab Mdac, designed by John Westlake and in this case, extensively rebuilt and upgraded by the designer.
Sovereign
28-08-2013, 23:06
Did you go for the Toy upgrade?
sq225917
29-08-2013, 01:09
I did indeed, it's just warming through downstairs before a serious listen. I need to buy a new USb cable though, god knows where that has gone.
What's the Toy upgrade?
http://mdac.referata.com/wiki/Main_Page#Present_upgrades_.28available.29
Oh right, thanks. Does changing four resistors warrant being classed as a different variant?
it's alive.....
Great result, Si. The only thing I would quibble with is the idea that you'll sell it on. If I had put such loving care into such a great amp, I would not be letting it go :)
sq225917
29-08-2013, 13:24
Oh right, thanks. Does changing four resistors warrant being classed as a different variant?
Well one option has 4 Charcrofts in it and the other has 16, but both options have further differences built in to accomodate these parts. In my case there's about 60 new parts in there.
sq225917
29-08-2013, 13:31
Martin, It's just another amp I'm not precious about it. My hifi has no space for a power amp as i don't wish to buy a pre-amp. My current amp is a two source integrated with a pre-amp section tacked on. I can switch the pre-amp off by running it at 0db which i do for my Mdac and then use it to attenuate my phonostage as required.
I'm thinking about what a fair price would be, they tend to go 1400-1500 with no service or recap and there's 500 quids worth of new parts in here. I'm not sure what people would expect to pay for a completely rebuilt minter.
Anyway, next project
http://farm4.staticflickr.com/3709/9622895090_6058dbe929_c.jpg
Time to sort out those tweeters in the Yamaha's.. and what better to replace them with than a pair or of the worlds best ribbons?
http://farm8.staticflickr.com/7371/9622892030_b6dc10f548_c.jpg
I'm just fiddling about at the minute the XO is 4th order, set at 4.4k, it seems a little too steep, I'll measure it up tomorrow and see how it sits.
http://farm8.staticflickr.com/7444/9622888644_87568ce27e_c.jpg
Guess which coil I wound and which I bought? Yes that's right the shit looking one was purchased and the bang tidy green one was hand wound... ;-)
I'm Really jealous Simon,is this the pair on eBay a couple of weeks back ? I got out snipped yet again :doh:
sq225917
29-08-2013, 14:23
Yup. that's them. No sniping though. Just bid once, bid late, bid your max.
Lol yeah i know :doh: I thought my £425 would have been enough though ....enjoy them awesome sounding things
sq225917
29-08-2013, 15:51
That was a little optimistic, they are close to 1400 new.
I'm surprised they didn't sell for more like £1000 - £425 was extremely optimistic!
As for the Krell, it has to be worth £2.5k.
sq225917
29-08-2013, 17:41
More fiddling, 2nd order and dropped it down to 4k, seems about right, might need the mid attenuating a shade.
Is it more natural at 2nd order Si?
I'm just listening to it now :). The original crossover is 2nd order - the RAALs are unquestionably VERY posh ribbons.
I'm just listening to it now :). The original crossover is 2nd order - the RAALs are unquestionably VERY posh ribbons.
Certainly look (and are priced) for it. Would be very interesting to hear yours & Simon's thoughts between various order filters. :)
sq225917
30-08-2013, 00:10
Mark didn't hear the 4th order filter. It was too fast and seemed like it lacked overlap with the mid. I'll measure them both tomorrow.
sq225917
30-08-2013, 12:04
Ok, a few tweaks later. I've ended up dropping the crossover point for the tweeter to 4k from the 4.4k of the original Yammy XO and It's back to a 2nd order rolloff. It sounds very good, though i imagine it measures pretty poor. I'll get into all that next week. I'm just going to live with the ribbons for a week and see how I fel about the difference.
sq225917
31-08-2013, 09:27
The next project just arrived back. A 24v, biphase turntable power supply, with phase offset, frequency and voltage being adjustable in 0.1 degree, 0.1hz and 0.01v incemenents. I built the pcb up for this ages ago but never completed the full assembly and the wiring of the USB micro controller. It's a bit of a monster as the outputs are two 40w chip amps driven in class A. The specs for it beat all the usual suspects, Hercules/Mose, Valhalla/Lingo, Armageddon etc, I just need to slap a Linn Pulley on a Rega motor.
pics to follow
I can do that for you :).
sq225917
31-08-2013, 11:02
I need the Rega motor first, and I'd prefer to get a scrappy Linn motor than pull the pulley off my brand new unused one.
That was a little optimistic, they are close to 1400 new.
You can get them new @£1000 was hoping we could have got a group buy going a while back but interest seemed to fissile out in the end
sq225917
01-09-2013, 15:00
Waiting on front panel switches for the TT-PSU, I'll probably leave it until I have all the parts rather than stop/starting with it.
Messed about a bit with REW today and the Raal ribbons. I was running them in at 4k just as a start off, REW highlighted some thing I couldn't hear. There was a dip at 4k- of course there was they are run at 180 degree to the mids and I had dropped the crossover point so they were sucking out at the XO point, about 4db down for 200hz either side of 4k. So it's back to the original 4.4k to see how that measures up.
What REW did point out that is just insane is how far the mid goes up. I woul;d never have guessed, though I can clearly hear it with just the mid in circuit but these buggers go up to 12k. So there's significant overlap from about 500hz to 12k on the mid and tweeter. No bloody wonder Troels re-made the XO's so that they were forth order electrical.
It's looking increasingly like if I want to improve things with these tweeters I can't just fiddle with their roll in I'm going to have to adjust the Mid XO as well to match their roll-off as well. At that point I'm basically redoing the whole XO so it migth just be less hassle to replace the whole thing with Troels design and then sort out the Raals at the end of that. it's not the quick fix project I was hoping for- but then again they never are.
sq225917
01-09-2013, 15:01
Is that for the Amorphous core versions?
I know Troels specification if you want to do that.
sq225917
01-09-2013, 19:22
Ok, so I can't leave well enough alone, or I'm a sucker for punishment. Either way, here's some graphs.
http://farm6.staticflickr.com/5453/9645580829_075531634f_c.jpg
Two measurements of mid and tweeter. The red line is the standard alignment of mid/tweeter and the green line shows the null created by inverting phase of tweeter. The green line response is also indicative of the width of the handover region between tweeter and mid. Despite the 4.4k crossover frequency the tweeter does go down to around 1K and the mid most definitely still has output up at 12K. Maybe steeper active filters might help improve things, narrowing the handover region and improving the response.
http://farm6.staticflickr.com/5443/9648814312_54e1171b07_c.jpg
When we look at the summed response, (this time measured at seated position and gated to remove reflections) we see that the response is actually pretty damn flat, and this is with the mid range unit attenuated a little on the L-pad. I could reduce the attenuation another db to bring the mids up. Thing is, I tried it like that previously and I prefer the sound like this. The rising response above 12k isn't an issue, my hearing is well down beyond 16k so a a couple of db up there makes no difference.
I'll solder the Yamaha tweeters back in later this week and run the measurements again, I have the mic position marked on the carpet. But so far so good. My ears tell me it sounds different to the Yamaha tweeters and my measurements tell me that its accurate, so hopefully it's adding the sparkle I want above 10k and without the shortcomings and rapid response fall off above 12k of the Yamaha tweeter.
sq225917
01-09-2013, 19:36
Smoothing is 1/6th octave.
sq225917
02-09-2013, 08:53
http://farm4.staticflickr.com/3829/9653863334_97b5e9ded6_c.jpg
The Yamaha tweeter is the green line. Quite a bit rougher between 1-12k and then drops off a cliff. It's fair to assume that the Raals are staying. I still think that steeper filters are the order of the day and I believe that playing about with the mid-range diffusor will also deliver a slightly flatter response.
sq225917
02-09-2013, 11:19
http://farm8.staticflickr.com/7410/9654630202_69ae8fd171_c.jpg
A quick spectrogram, pretty flat, not massively damped, quite even in decay time, overall a lively room without any really obvious flaws. There's a fair chunk of 50hz in the room, but I know that's coming from my amp.
sq225917
06-09-2013, 22:45
Back to the phonostage. I've been waiting on Mark sourcing some suitable front panel material for the psu and two amp channels. Finally the goods have arrived and he's laser etched me up two beauties.
http://farm3.staticflickr.com/2882/9690326950_666e83dc7c_c.jpg
The amp channels get laser etched, satin black, anodized aluminium face plates.
http://farm4.staticflickr.com/3668/9687083261_e07324aa10_c.jpg
The dual mono psu chassis gets the same but this time in smoked black acrylic.
They both look proper posh, like proper from a manufacturer posh...
I might even listen to a few records this weekend and bask in their beauty.
Nice work. When I was constructing projects as an impoverished twenty-something, quality of finish was always my bugbear as good cases and control knobs etc. were hard to come by or very expensive. Mind you, I was very good at Letraset for the front panels :)
Arkless Electronics
07-09-2013, 01:03
Yep, Mark's shit hot at this kinda stuff ;) Nice work!
That's a great job with the graphics, I'm really liking that.
Mind you, I was very good at Letraset for the front panels :)
Yeah :), I also remember hours with the Letraset (not sure if it exists any more).
I've designed fancy back panels too - just waiting for the materials to be delivered (on back order apparently)
http://i62.photobucket.com/albums/h90/markemark_2006/Hi-Fi/backpanelsgroup_zps24464d18.jpg
sq225917
25-09-2013, 17:10
http://farm4.staticflickr.com/3700/9936264686_3fa25c5ab1_c.jpg
One project ends and another starts. Though to be honest I'm far from finished with the tweeters on the Yamahas, in fact I just started messing about with the time alignment on them.
Anyway on to the project at hand. I started this nearly 18 months ago and never completed the build. I've since finished it and should have a suitable low voltage motor with me tomorrow So what is it?
Well, now that you ask... it's a new TT speed controller for an ac synchronous motor. It's kind of funky though. Whereas soemthing like the usual digital speed controller provides you with an accurate 50hz sinewave to drive your motor with a 90 degree offset this goes a little further. I can adjust the frequency of the drive sinewave in 0.1hz steps, so I can accommodate any size of platter/drive pulley, so it will work with any deck. I can adjust the drive voltages of each phase of the motor with 25 turn trim pots, so I can notionally trim a little 2nd harmonic that exists when both drive phases are the same voltage, (I'm not a great believer in this being important though). But importantly I can trim the phase offset between the two drive phases in 0.1hz steps. This means I can perfectly dial in the actual phase offset required by my specific motor, rather than just settling for a nominal value from the manufacturer that doesn't take into account production quality variance in the windings etc.
And not just that but I can also set a ramp up and slow down speed in hz/second to control the speed up and slow down of the platter to eliminate chatter on start up/stop. Oh yeh, did I forget to mention that all of this is controllable by a USb interface and will run on any windows machine. SO just set it and forget it. I'm hoping it will give me an improvement over my current Naim Armageddon clone set-up. The synthesised sine wave should be cleaner than the UK mains. I'll be happy if it is as good as the Armageddon clone, as at the very least it means I'll get 45rpm back again which I miss with the current set up.
More details and measurements once the motor arrives and my tame engineer turns me a pulley.
sq225917
30-09-2013, 12:40
http://farm6.staticflickr.com/5485/10018647523_7a414934d0_c.jpg
So the new 16v motor has a pulley for it now courtesy of Mark, just like the LP12 pulley, in fact you couldn't tell them apart. It's a bob-on job.
http://farm4.staticflickr.com/3752/10018570006_751dae5bc4_c.jpg
It's still a bit of a lash up at the minute. I'm still deciding whether the 16v motor is going to stay or if I'm going to use two transformers to step the output back up to the 110v needed by my LP12 motor. I can't tell them apart audibility in terms of presentation, apart from the fact that my 45 rpm is now 45rpm and not running slow as it was with the added drag from the silicon fluid in the bearing. That's the benefit of this controller I can adjust everything, voltage, phase, frequency, quadrature and trim them all by tiny amounts.
I'll take some measurements later this week when the step-ups arrive, then decide which motor I'll use. One thing is for sure, this has replaced my Geddon clone, convenience and functionality have trumped simplicity...
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