View Full Version : B&W DM2 fettling
Hi all. Leading on from my recent experience with a pair of Ditton 44's I now realize the DM2's I currently own are unlikely to be bettered within a budget I can afford and as a consequence it would probably be wise to throw a little cash at them in a bid to wring out even more from them. I've taken note of the work James has carried out on the 44's and I feel the DM2's could benefit from a similar makeover. Apart from having to have a bass driver replaced due to a broken terminal 18 months ago they are more or less as they were when they left the factory back in 1972.
When we had the baffles off I did note that the wiring is of a reasonable quality and is connected to the drivers and crossovers via spade connectors, which might be the first port of call. From what I've read elsewhere, directly soldering the wiring to the terminal tabs and crossover can offer up some improvements in SQ, which sounds reasonable to me. If I choose to replace the internal wiring what should I be looking at as a replacement? I think I should steer clear of anything too fancy such as silver plated copper wire as the DM2's are already quite a lively sounding speaker in standard trim and I wouldn't want to push them into sounding brittle. I'd also like to replace the speaker terminals as the original fitment items are quite worn from over 40 years of use so recommendations would be welcome here also.
I have been informed that B&W installed good quality components onto DM2 crossover boards as a matter of course so in light of this, is it worth messing about with them at all? If so then some advice would be welcomed here as well although I would need to find someone to carry out this work for me as I am not confident enough in my own skills to carry out the work myself. I should note that these are DM2's and not DM2a's therefore there is no HF adjustment pot present. Not sure I'd want one to be honest as it is just another component in circuit to get in the way of the signal.
When we removed the front baffles from the speakers I noticed that a couple of the securing screws have begun to pull through the baffle board. Ideally I would prefer to fix this issue as eventually it will end up damaging the baffle board permanently. I've thought of two possible options, one is a quick fix and t'other would be to completely replace the baffle, however the latter option would probably be prohibitively expensive. The quick fix option would be to replace the existing screws with slightly longer items made from brass which would sit in raised brass ring washers (sorry, I don't know the proper term for these) which would not only prevent further damage to the baffles but should also look very smart.
Another slight cosmetic issue with this particular pair of DM2's is that there is some surface rust on the faceplates of both the Coles tweeters. This doesn't affect their performance in any way however it is a minor niggle for me whenever I remove the grills and one which I would dearly like to remedy. Other than replacing both units does anyone have any suggestions on how to get rid of the rust?
Just in case I have missed something I would welcome any other recommendations on how to improve these already wonderful sounding speakers... ;)
Thanks in advance
Dave...
Something I forgot to mention in my initial post regarding the Coles: Is there a drop in replacement for these units as I have heard they can be quite fragile?
istari_knight
01-11-2013, 15:54
Okay I'll go first :D
Personally I would replace the internal cables with the same cable you use between amp & speakers unless its silly thick in which case choose something as close as possible but smaller diameter... Replacing spades with solder connections makes no audiable difference but is undeniably a better connection & worth doing if inside them anyway. You have lots of choices with connection terminals, Michell used to make some lovely one's but I dont think you can get them anymore :( The binding posts fitted to the 44's were £5 for 4, the next step up would be something like CNC's which are about £16 per pair.
The B&W's are currently fitted with perfecly good inductors you dont need or want to fiddle with those, the capacitors are all MKT which is very good for a speaker of their vintage ! Even so improvements could be found replacing them with modern MKP's...When rejuvinating crossovers I usually use Jantzen capacitors due to smooth inoffensive sound & [relatively] low price, Jantzen Cross-Caps in parallel & Z-Standard in series. However, if I were upgrading a pair of speakers I intended to keep long term as you do I would be looking at Ansar SuperSound capacitors, they are damn good & I know many on here use them and like what they do... I keep reading good things about Clarity Cap ESA's but am yet to try them. The original resistors are bog standard wirewound jobbies that could be replaced with Mills non inductive types which may help that brittle colouration you experience sometimes ?
Is your baffle veneered of just the plain black version ? If the latter it sound like you could probably fill & re-spray ? I've removed oxidisation from Coles 4001 faceplates using brasso but they were the silver version... Not so sure what you could try if they're black :hmm:
Let's address an easy one for starters: I may have stumbled across a simple solution to spruce up the the Coles faceplate courtesy of my good lady, sticky backed felt discs with a hole in the centre to clear the dome. She is confident she can cut these by hand from some felt sheet she has in her stockpile of craft stuff, I just need to give her the measurements, These may even tame the top end slightly as well. The baffle is unfinished particleboard James so if I can source the brass screws and washer things I mentioned at least it will look a little tidier. I suppose I could always paint the baffles with matt black paint to smarten things up.
As far as the crossovers are concerned I would like them to be as good as they can be without breaking the bank, and seeing as I know nothing about how they work I will leave this to those in the know ;)
The speaker cable I use was manufactured by Sharkwire in the early noughties but is no longer available unfortunately, which is a shame as it is very good stuff indeed and it didn't cost me a penny. I've heard mention that Van Damme speaker cable is pretty good for internal wiring, I guess we'd probably be looking at their 2.5mm diameter cable for this job.
Coles were still in business last time I looked although they din't respond to emails. The later model has a plain black face plate but if you can get some thin felt around the dome to disguise the plate, I doubt it'll do the slightest bit of harm.
Any electrolytics in the crossover could be usefully replaced I think, plastic caps don't seem to go off the same. Internal wires are very short and in comparison to the thin coil and inductor wire the signal goes through, might not make a difference worth the effort. My 1974 BC2's had nasty thin tinned bell/instrument wire and Spendor did actually beef this up as the years went by. Push-on connectors aren't necessarily bad, as the crimped cables actually have no solder in the way. After 40 odd years though, anything could happen.
Good luck :) Have a look at the bass damping, which is where the DM2 could possibly be improved by todays standards.
istari_knight
02-11-2013, 12:32
To give you an idea of component cost Here's whats needed to refurb/upgrade one DM2 crossover :
Capacitors: [Voltage doesnt matter]
3 x 4.7uF
1 x 3.3uF
2 x 2.2uF
3 x 1.5uF
1 x 0.68uF
Resistors: [12w]
2 x 10ohm
1 x 33ohm
1 x 15ohm
Here's some suppliers:
HiFiCollective are good for Mills resistors but also have a nice selection of capacitors suitable for crossovers not to mention loads of posh fixings & fittings... http://www.hificollective.co.uk/componentshome.html
Audio-Components are Jantzen's UK distributor, their CrossCaps are the best value MKP capacitors around [what I used in the 44's HF crossover.] http://www.audio-components.co.uk/store/category.asp?CategoryID=2
Cricklewood Electronics sell the highly recommended Ansar SuperSound capacitors http://www.cricklewoodelectronics.co.uk/Cricklewood/home.php?cat=155
According to my workings out if you went for Ansar SuperSound caps & Mills resistors each crossover would cost £50.50 in replacement parts but that would undoubtedly be a lot less if you went with Jantzen caps... Depends how tight your budget is ? The Ansars are worth the extra IMO.
Cheers James, I shall mull this over. As for the technical stuff it has gone right over my head. I understand they are capacitors and that they come in various colours and values, what those values mean is beyond my ken unfortunately :lol:
Rare Bird
02-11-2013, 14:24
Dave:
Soon be November the 5th :lol:
Joking aside are your the 'DM2a' {Switch on the rear} ? Bypass that.
Nope André they are without switch, switchless, devoid of switchiness. They are ex-switched! :D
Andrew B
02-11-2013, 14:45
Hi Dave. I've had great results with rewiring speakers internally with Supra classic cable. It won't break the bank and maybe you can try more than one contender before getting the soldering iron out.
The threaded inserts (search under that term) for your front baffle can be had on EBay for peanuts. They are a doddle to fit and come in a range of sizes.
I'm as clueless as you when it comes to crossovers, so I'll not comment on stuff I don't understand.
All I'll say is that I've put money into things I intended to keep forever, only to gain nothing on the inevitable re-sale or worse still, devalued the item and faced a double-hit of lost outlay and lower resale price. Personally, I'd stick to things that don't cost a fortune and won't impact the resale value negatively.
I'm sure you'll have great fun and reap rewards whatever you decide to do.
Dave
Modern capacitors will likely have slightly better linearity with frequency and slightly lower distortion. If there are any p-core or ferrite cored inductors in the crossovers, change these to air core for the same value. Caps: Claritycap ESAa every time. Better imho than even the Jantzen Superior Z-caps and cheaper. Wiring: ANY ofc will do. OFC because it won't corrode and build up resistance over time. Multitrand because it needs to be relatively flexible. use 1.5 to 2mm2 section, that's plenty enough for the very short distances and will add b*gger all loop resistance...it doesn't have to be the same as your speaker cable. Solfer tag connections and if they use cheap and nasty speaker binding posts, change to something good like the gold plated OFC CMC items (about £15 per pair). Thats it. If you're not comfortable with sorting the crossovers, send them to me and I'll do it for you
Regards
Paul
Rare Bird
02-11-2013, 15:17
The below in Ansar 'Supersound' caps. {did all my speaker rebuilds in em & Martin T just done his Gale '401' in em}.. If you get them from Cricklewood electronics they will have the Ansar brand name on em.
4.7uF = £4.50 each
3.3uF = £3.50 each
2.2uF = £3.50 each
1.5uF = £3.50 each
0.68uF = £3.00 each
As for the Mills resistors always go for the higher wattage 'MRA12' ..
istari_knight
02-11-2013, 18:12
Agreed, Van Damme 1.5mm - 2.5mm would be perfect for the internal wiring. Have you compared the Ansars with Clarity Caps Paul ? For the relatively low values needed the ESA's might be a good bet.
Agreed, Van Damme 1.5mm - 2.5mm would be perfect for the internal wiring. Have you compared the Ansars with Clarity Caps Paul ? For the relatively low values needed the ESA's might be a good bet.
Hi James
Yes, I have both here in my spares bin and tbh, the Ansars are pretty good. Certainly excellent vfm and I prefer the Ansars to the SA range but prefer the ESAs to the Ansars. Considering the cost of the Ansars, they're excellent. As you suggest, if funds permit, some 250V ESAs wont break the bank and would be my choice almost every time depending on the circuit application.
istari_knight
03-11-2013, 12:24
Hi James
Yes, I have both here in my spares bin and tbh, the Ansars are pretty good. Certainly excellent vfm and I prefer the Ansars to the SA range but prefer the ESAs to the Ansars. Considering the cost of the Ansars, they're excellent. As you suggest, if funds permit, some 250V ESAs wont break the bank and would be my choice almost every time depending on the circuit application.
:thumbsup: I'll have to try some on my next project
Rare Bird
03-11-2013, 12:26
The best thing about the Ansars apart from the amazing value for money is they look very military, they look simular to the common Black Elcap caps you usually see residing in old speakers, perfect for vintage kit rebuilds. Ansar don't add any sound signature imho they just make the original design breathe more making everything sound more right if you get my meaning..
istari_knight
04-11-2013, 13:12
No Elcaps here :)
I know its a 2A crossover pictured but its the same apart from the switch & associated resistors...
Rare Bird
04-11-2013, 13:16
Hi James
I wasnt refering to the 'DM2' just that most the speakers of that vintage i have had were loaded with dem ELCAPz loike..
istari_knight
04-11-2013, 13:40
Hi James
I wasnt refering to the 'DM2' just that most the speakers of that vintage i have had were loaded with dem ELCAPz loike..
True, true... Their longevity seems vary wildly on speakers of similar age I dont know what causes them to "go off" lack of use maybe ? I remember the low loss Elcaps in those Castle Richmonds were 50%+ out of spec yet those in the Ditton 44's were all within 10% still :scratch:
surv1v0r
19-11-2013, 17:48
<snip>
All I'll say is that I've put money into things I intended to keep forever, only to gain nothing on the inevitable re-sale or worse still, devalued the item and faced a double-hit of lost outlay and lower resale price. Personally, I'd stick to things that don't cost a fortune and won't impact the resale value negatively.
<snip>As a (relatively) satisfied owner of a pair of second hand DM2s, I would echo this comment. I suspect that you could spend a lot of time and money replacing crossover components and replacing the internal wiring and notice no difference.
However, IF you do decide to go ahead and refurb your crossover, I would suggest you contact Jerry Bloomfield at Falcon Acoustics (sales@falconacoustics.co.uk>), he is INCREDIBLY helpful.
Good luck and I would love to hear what you do decide to do and how it works out.
As a (relatively) satisfied owner of a pair of second hand DM2s, I would echo this comment. I suspect that you could spend a lot of time and money replacing crossover components and replacing the internal wiring and notice no difference.
However, IF you do decide to go ahead and refurb your crossover, I would suggest you contact Jerry Bloomfield at Falcon Acoustics (sales@falconacoustics.co.uk>), he is INCREDIBLY helpful.
Good luck and I would love to hear what you do decide to do and how it works out.
Checking crossovers doesn't take long and is a good thing to do with any speaker older than 15 years or so old. Capacitors such as Solens or Ansars are relatively cheap and usually can be had in tighter tolrances (certainly to 5%) than many older capacitors, and it makes a heck of a positive difference bringing performance back by re-establishing the correct crossover points. Anything using electrolytics of that age has to be considered as requiring capacitor replacements IME (usually) PLUS some designs can be bettered very easily. For example, the DM2 used a well designed crossover but one which was badly laid out. By that I mean that the air cored inductors were all placed on the same axis, some very close to each other, which is inexcusably poor practice. By simply rotating selected inductors so that axis are all perpendicular can markedly improve performance.
Jerry is a very helpful chap and knows his stuff, but lets not forget that there are a few of us on AoS who are also happy to offer advice freely ;) (Speaker refurbishments are also part of my own business)
surv1v0r
20-11-2013, 18:24
<snip>
The DM2 used a well designed crossover but one which was badly laid out. By that I mean that the air cored inductors were all placed on the same axis, some very close to each other, which is inexcusably poor practice. By simply rotating selected inductors so that axis are all perpendicular can markedly improve performance.
<snip>How easy would this be to do? I attach a .JPG of my crossover.
11035
It shows that there are two black, one green, two white and one blue component. I take it that they are all inductors? Are ALL of them air cored or just the black and green ones to the left? As I understand it, the six green cylindrical and five brownish jobs should be OK?
Sorry if this is all a bit basic and do please feel free not to answer if you think my questions are too stupid to justify a response.
As to the "heck of a positive difference", I have to admit that I am expressing a personal opinion; I have no doubt that others will have much more sensitive hearing than I can now lay claim to ;)
istari_knight
20-11-2013, 18:39
You may find this interesting http://www.troelsgravesen.dk/coils.htm
The black & green one's are air core, the blue one is ferrite core but I'm not sure about the 2 large one's ? They look to have some epoxy or resin in the core... A ohms test would reveal all...
The Barbarian
20-11-2013, 20:03
I don't understand the need to swap out the inductors? :scratch:
istari_knight
20-11-2013, 20:14
I don't think there is. I posted that link as it visualizes what Paul was saying about the less than ideal inductor layout.
The Barbarian
20-11-2013, 21:15
Ok, however i do hear of a lot of people ripping out old inductors to replace with modern jobbies, ok some old designs do really have poor quality Inductors but these old B&W, the Dittons, early Castle etc really are good quality even though the bobbins look a bit gammy coloured..
In all honesty i do feel a lot of people go a bit mad sometimes.. Do you think these going a bit mad people loose sleep because they can't rewind the unit coils for modern wire :D
istari_knight
20-11-2013, 21:33
I just hope any prospective modders are honest with buyers if/when they sell up - I've had a few speakers now with completely bodged up crossovers :(
Power of the internet I suppose ? Speaking for myself, in the past if I didn't know sufficient amount to p*ss around with somethings inner workings I'd leave it well alone but now...
surv1v0r
20-11-2013, 21:38
In my youth I used to ride a motorcycle to work five days a week. At the weekends I would completely strip down some major component and rebuild it - just to make sure it was working better. After a year or two I could probably have completely stripped down and rebuilt the engine blindfolded.
I guess the good news was that it kept me off drugs, the bad news was that it wasn't so great for my sex life; I doubt that I could have coped without Rock and Roll.
I often wondered why I was never approached by a Japanese race team keen to capitalise on my experience . . . perhaps because they weren't as convinced of the improvements as I was ;)
Sorry for late response:
How easy or difficult the inductors in the photo above (Aaron's photo) would be to re-orientate depends on how they're held onto the circuit board. Some ferrites were attached using nylon bolts, some were epoxy glued in place whilst some were fixed with silicone or similar. If you can establish which might be the easiest to lift off the base, then those are the ideal candidates for moving. Air cores generally put out a stronger radiation field but by the same token are also more easily influenced by other magnetic fields and moving metal parts (such as vibrating conductive panels). By crossing their axis at 90 degrees to one another, you can get them fairly close (within 4 or 5 inches) without much impact on the signal. Ferrite cored inductors can be even closer as long as their axis are perpendicular. Tip: don't attempt to lift ferrite cored inductors that have been glued. The ferrite core and bobbin bases are surprisingly soft and fragile and will likely crack. Air cores are easier moved unless ferrites haven't been glued down. ..just be careful not to scrape any insulation varnish of coils when attempting to move either. If in doubt, leave well alone. If not confident on your DIY skills, leave well alone ;)
Re-examining the photo, a couple of the large ferrites (LHS) appear to be glued to base plates and these riveted in place. First thing is to de-solder the connections (other side of the board) then the rivets can be drilled out and rotating the inductors should be easy. you may need to solder additional lengths of copper wire in place to reach the connection points when done. Silicone into place and add a cable tie if needed.
surv1v0r
29-11-2013, 11:43
Many thanks for the reply Paul and in my turn, I apologise for my delay in replying - decorating the living room has had to take priority!
I get the impression that the air cored inductors are glued to the PCB, they are certainly VERY snug. I can't see any practical way of reorienting them and I certainly couldn't move them four to five inches apart without utilising some other form of mounting which really is most unlikely to happen. The two larger inductors are ferrite cored (I think?) and are as you suggest, attached to metal mounting plates.
I have recently been listening to the DM2s (which are not my main speakers) and I have to say that they do produce a very good sound. My only criticism would have to be that they aren't as clear on speech or vocals as my Kef Concertos are. I suspect that good as it is, the Celestion HF1300 is not as good in the mid-range as the Kef B110? I hadn't realised for ages that the DM2s are transmission line speakers although they do weigh an absolute ton so perhaps I should have guessed.
brian2957
29-11-2013, 11:56
Checking crossovers doesn't take long and is a good thing to do with any speaker older than 15 years or so old. Capacitors such as Solens or Ansars are relatively cheap and usually can be had in tighter tolrances (certainly to 5%) than many older capacitors, and it makes a heck of a positive difference bringing performance back by re-establishing the correct crossover points. Anything using electrolytics of that age has to be considered as requiring capacitor replacements IME (usually) PLUS some designs can be bettered very easily. For example, the DM2 used a well designed crossover but one which was badly laid out. By that I mean that the air cored inductors were all placed on the same axis, some very close to each other, which is inexcusably poor practice. By simply rotating selected inductors so that axis are all perpendicular can markedly improve performance.
Jerry is a very helpful chap and knows his stuff, but lets not forget that there are a few of us on AoS who are also happy to offer advice freely ;) (Speaker refurbishments are also part of my own business)
Yup and I've the recipient of Pauls excellent service and advice . I sent my Reag EL8 crossovers to him for repair and refurbishment . Over the last few days Paul has answered my numerous emails promptly ( within 30 mins. ) and has spent nearly 2 hours on the phone with me explaining all the options and giving me advice on how to get the best from my speakers . Paul has done all this work for a very good price indeed and the photos of the crossovers look superb . I guess the proof is in the listening so when I receive and refit them I'll post my findings on the forum . So far however Pauls service has been exemplary .
Taking our financial position into consideration I have decided that it might be best if I attempt to fettle the DM2's myself. Jo and I have discussed this at length and I reckon if I pace myself and don't over do it I can get the job done. It may take a week, it may take a month, or perhaps even longer, the trick is to not worry about deadlines and do what I am able to do, when I am able to do it ;)
My recent mishap with the Coles tweeters is what has driven me to this decision. To put it simply, I will need to open the cabs to fit the new tweeters anyhow so I may as well do the work planned on this thread whilst I am in there, and as Jo has succinctly pointed out, once complete I will experience such a sense of achievement and she is correct of course. I plan to work on one speaker at a time, taking photographs as I go along, however it has occurred to me since that they would not only be useful to document the work for myself, I could also post up my progress on here and do a bit of a write up to go with them ;)
walpurgis
07-12-2013, 22:27
Go for it Dave. Just take it steady and careful and you'll be OK! :)
Good decision Dave - look forward to seeing the photos.
I am almost ready to begin work on the DM2's and I am really looking forward to it. I have most of the supplies needed to complete the work but I require a little more information before I finally put them under the scalpel.
If a job's worth doing it's worth doing well so with that in mind, and after perusing Paul's (RFC) Rhapsody speaker thread and noting his use of felt on the Rhapsody's baffle fronts to improve the performance of the tweeter, I wondered whether this approach might benefit the DM2's too. I have been trawling ebay for 100% wool felt most of the weekend. Two 12" x 12" (30cm x 30cm) squares would be absolutely perfect but sourcing the good stuff with these dimensions and for a reasonable price has proved to be a bit of a problem. So far I have only found one seller who can supply 100% wool felt with the required dimensions in black at £2.99 a sheet, however it is a hand-made product which is 4mm - 5mm in thickness, is that too thick for such an installation? If it is then the only other option open to me is a 40% wool - 60% acrylic felt blend at the same price at just 1mm thickness. Would either of these be appropriate for the job?
Because a couple of the screws which secure the baffles into the cabinets have begun to pull themselves through the baffle material I have decided to employ cup washers to prevent further ingress. Again ebay came to my rescue and I discovered these (http://www.ebay.co.uk/itm/A2-Stainless-Steel-Solid-Machine-Turned-Finishing-Cup-Washers-For-Screws-Bolts-/161139903814?pt=UK_DIY_Material_Nails_Fixing_MJ&var=&hash=item2584afcd46) during my search. They are a machined stainless steel item and are a little more expensive than those more typically pressed from steel, brass or aluminium sheet. Personally I think they will look smarter when the grills are removed. My wish is to use the existing screws to save money however I have two questions: Firstly, will the existing screws be long enough to use with the cup washers, and secondly, can anyone tell me what size screws they are please (eg. #6 or #8 screws)? If I do need longer screws then what length and thread pitch would you advise using for this job?
I would like to replace the existing 4mm speaker binding posts with better quality fitments. Again, I don't want to go mad with money as funds are very limited and my preference would be for items manufactured entirely from gold plated brass. Since I have never been inside a pair of DM2's myself I have little idea whether the existing binding posts are secured directly to the rear baffle or are affixed to the crossovers, nor what their overall length is, information which is crucial so I can order the correct replacements, can anyone help here please? Ta!!! :)
Dave
you wont find it on Fleabay my friend. It must be one of the following grades: SAE F10, F11 or at a pinch, F7 manufactured to BS4060.
I have some here at 250 wide if any good to you and you can have it at cost price if that helps, as I want to make sure that you get the RIGHT stuff. It must be 97% pure wool minimum, and density should be below 0.22g/cm3. Thickness should be minimum 10mm to 12mm. Anything else wont do and denser wool felts (such as carpet underlays) will cause reflections (ie are NOT highly acoustically absorbant enough) which could well worsen response.
I have worked with felt underlay before so I knew it would be far too dense for this task, I had high hopes for the 5mm thick stuff though as it is hand teased 100% pure wool, I am staggered to discover that a minimum 10mm depth is needed however, and there was I worrying that 5mm might over-damp the tweeters output... :eek: I had hoped to utilize 30cm widths as that would be a perfect fit across the baffle Paul. I know some here would eschew aesthetics for functionality but I want this to look good too sir, any suggestions? :eyebrows:
Can you PM me a figure for this please Paul... Ta... ;)
You aren't damping anything Dave by applying the felt. Imaging is actually improved and on axis response is totally unaltered save for becoming less distorted as the out of phase reflections are eliminated. You are attenuating the soundwaves that travel across the surface of the baffle perpendicular to (and radiated by) the dome tweeter before they have a chance to diffract and reflect back towards you out of phase. Studies have shown that a 10mm thickness is about the minumum effective thickness for the wavelengths and their amplitudes (for normal listening levels). A 25 to 30mm wide strip should be ok. I'll PM you details.
You aren't damping anything Dave by applying the felt. Imaging is actually improved and on axis response is totally unaltered save for becoming less distorted as the out of phase reflections are eliminated. You are attenuating the soundwaves that travel across the surface of the baffle perpendicular to (and radiated by) the dome tweeter before they have a chance to diffract and reflect back towards you out of phase. Studies have shown that a 10mm thickness is about the minumum effective thickness for the wavelengths and their amplitudes (for normal listening levels). A 25 to 30mm wide strip should be ok. I'll PM you details.
Thanks dude. Should I treat the HF1300's too or leave well alone. I may have asked this before so forgive me if I have, my memory is not good these days... :eyebrows:
Depends entirely on the baffle Dave. If it sounds ok and they image ok, leave well alone and save your money. If you want to experiment, then you can only improve things as all speakers bar those with large rounded edges and offset tweeters will benefit.
I was considering having a go at updating the crossovers myself whilst I am inside the cabs until I costed the component list James kindly provided for me earlier in the thread. I choose TKD resistors and Ansar Supersound caps and the total came to 87 quid, money I just haven't got right now. I can afford to replace all the resistors with TKD's as the total there came to just £12, is this wise considering I won't be replacing the caps during this session or should I be patient, assemble all the components and do the lot in a one-er? I shall buy the caps in dribs and drabs until I have them all thus spreading the cost. It could be a while...
istari_knight
20-01-2014, 20:18
May I ask where sells high wattage TKD's at such a low price ?
May I ask where sells high wattage TKD's at such a low price ?
You could James but then I'd have to admit to being a pillock... :eyebrows: Basically I was looking at 2W TKD's instead of 12W, these being significantly more expensive... :doh:
mad-moon
23-01-2014, 10:03
Dave...I'm sure I have some sharkwire speaker cable in the depths of my cupboard...I'll have a dig later today and get back to you...Alan...
Let's address an easy one for starters: I may have stumbled across a simple solution to spruce up the the Coles faceplate courtesy of my good lady, sticky backed felt discs with a hole in the centre to clear the dome. She is confident she can cut these by hand from some felt sheet she has in her stockpile of craft stuff, I just need to give her the measurements, These may even tame the top end slightly as well. The baffle is unfinished particleboard James so if I can source the brass screws and washer things I mentioned at least it will look a little tidier. I suppose I could always paint the baffles with matt black paint to smarten things up.
As far as the crossovers are concerned I would like them to be as good as they can be without breaking the bank, and seeing as I know nothing about how they work I will leave this to those in the know ;)
The speaker cable I use was manufactured by Sharkwire in the early noughties but is no longer available unfortunately, which is a shame as it is very good stuff indeed and it didn't cost me a penny. I've heard mention that Van Damme speaker cable is pretty good for internal wiring, I guess we'd probably be looking at their 2.5mm diameter cable for this job.
istari_knight
23-01-2014, 11:57
You could James but then I'd have to admit to being a pillock... :eyebrows: Basically I was looking at 2W TKD's instead of 12W, these being significantly more expensive... :doh:
Damn, I thought you'd found a bargain site somewhere ! The stock one's fitted aren't bad at all so I would expect any improvements to be very subtle indeed.
Dave...I'm sure I have some sharkwire speaker cable in the depths of my cupboard...I'll have a dig later today and get back to you...Alan...
Thanks for the offer Alan but I have acquired 15m of Van Damme speaker cable for the job (I actually bought 10m but someone can't measure cable lengths properly)
Damn, I thought you'd found a bargain site somewhere ! The stock one's fitted aren't bad at all so I would expect any improvements to be very subtle indeed.
That's good to know James, thanks. I am going to leave the crossovers alone for now as I have run out of cash...
Good luck with your refurb,.... and dont feel too bad about the immediate lack of a crossover upgrade. I am sure the crossover can be improved with better components, but i am enjoying my DM2a very much, just in standard fettle.
Good luck with your refurb,.... and dont feel too bad about the immediate lack of a crossover upgrade. I am sure the crossover can be improved with better components, but i am enjoying my DM2a very much, just in standard fettle.
I was enjoying mine too Steve until I killed the supertweeters. Ah well, now I have an incentive to carry out the work and I'll be starting a thread once I get underway so keep 'em peeled ;)
surv1v0r
03-02-2014, 17:39
<snip>
I would like to replace the existing 4mm speaker binding posts with better quality fitments. Again, I don't want to go mad with money as funds are very limited and my preference would be for items manufactured entirely from gold plated brass. Since I have never been inside a pair of DM2's myself I have little idea whether the existing binding posts are secured directly to the rear baffle or are affixed to the crossovers, nor what their overall length is, information which is crucial so I can order the correct replacements, can anyone help here please? Ta!!! :)The crossover is mounted behind the plastic box through which the speaker binding posts pass. It is attached to the cabinet by means of a screw at each corner and uses six rubber grommets as stand-offs. The speaker binding posts pass through the plastic box, through the crossover PCB and are held in place by the nuts and washers above the blue inductor in the photo below.
11521 11522
The length of the post from where it abuts against the plastic box is 17mm - I can't see any obvious reason why it should not be longer. The threaded part that passes through the PCB is about 2.5mm in diameter, so if you fit a thicker post, you will have to drill out the hole in the plastic box and the PCB.
For what it is worth, Jerry Bloomfield of Falcon Acoustics gave me the following advice a while back:
The capacitors on the boards are all polyester or polycarbonates, they don’t degrade with age. We wouldn’t normally replace those, unless you are going for an “upgrade”, in which case you’re going to have some physical space issues as polypropylene caps are much larger. I’d recommend going for the ClarityCap option as they will produce the optimum result.
I would be inclined to worry more about the final load of wadding - in my case it is crumbling and I haven't been able to source a replacement - B&W were no help at all :(
The value of the components (ie electrical value) and tolerance matters FAR more than any foo branded names on them.
A crossover built with expensive components measuring 10% out on capacitance and inductance will sound FAR worse than one made using the correct value out of modest components.
Getting the design values right has the biggest impact of all. This audio forum trend for recommending fancy caps etc is something I'd advise against until the precise values for the components have firstly been established.
Manufacturers often come up with a design which is generic to a particular model of speaker based on component values built with sufficient tolerance to cover any variations between drivers. Very few are hand matched properly. The biggest upgrade you can achieve is to actually measure the impedance curves of the drivers and if you think an upgrade is worth doing, the ascribe new values to tighter tolerances based upon actual measurements, save the cash which would have been burnt on "Foo-sihness" and just spec 3% tolerance polyprops and 1% inductors. You dont need 630V ratings. 250v is more than enough. Sure, there's an argument for slightly lower distortion values at 630V but bedding in periods are longer and they're much more expensive generally speaking.
Thanks guys. I've decided to do this in two stages to make life easier. Stage one will involve fitting the Coles, replacement of the existing wiring with Van Damme Blue cable with 1.5mm diameter cores and hopefully I can replace the binding posts too, although these may have to wait until stage two as I don't have a drill and I can't afford to buy one just now. Stage two will involve the application of acoustic felt around the tweeters to tame any diffraction issues, the fitting of new binding posts if not done during stage one and a general sprucing up of the cabs. I'm in two minds whether to do anything to the crossovers or not but if so this will happen during stage two as well. For now though my priority is to get them back in working condition so I can sell the Skibo's which need far more space to breath than I can offer them...
surv1v0r
05-02-2014, 18:06
Here is a very lo-res image of a pair of standard speaker binding posts resting on a tape measure:
11529
I believe that it would be relatively easy slightly to relocate the crossover, pass better quality speaker binding posts through the plastic box at the rear of the speaker and then run a lead from the posts to the crossover and solder in place. This would obviate the need for you to take a drill to the crossover.
Here is an image of the connection on the PCB from which the leads are taken to the individual driver units:
11528
So far as replacing the existing wiring is concerned, you would probably want to solder the "Van Damme Blue cable with 1.5mm diameter cores" to the posts on the PCB and discard the connector which is used at present. Personally, I wouldn't bother since I am pretty well certain that I couldn't detect the difference but your experience may differ.
Here is a very lo-res image of a pair of standard speaker binding posts resting on a tape measure:
11529
I believe that it would be relatively easy slightly to relocate the crossover, pass better quality speaker binding posts through the plastic box at the rear of the speaker and then run a lead from the posts to the crossover and solder in place. This would obviate the need for you to take a drill to the crossover.
I'd been thinking along the same lines myself Aaron and frankly I think this would be my preferred option but I have not studied the inside of one of these speakers in any great detail as yet to help me determine how to proceed. I had hoped to start the work last weekend but life has got in the way, as is its wont, plus I am still waiting on a new bit to arrive for my Weller soldering station which I ordered seven days ago.
Here is an image of the connection on the PCB from which the leads are taken to the individual driver units:
11528
So far as replacing the existing wiring is concerned, you would probably want to solder the "Van Damme Blue cable with 1.5mm diameter cores" to the posts on the PCB and discard the connector which is used at present. Personally, I wouldn't bother since I am pretty well certain that I couldn't detect the difference but your experience may differ.
This is something else I've been mulling over. My preference would be to solder the wires directly onto the pins however if it turns out not to be too much of a faff to run the new cable into the existing plug then I may settle on this option..
Pablo Belgik
07-02-2014, 11:27
Hi, Synsei. I'm permitting myself to jump into the thread merely for the fact that I'm mighty impressed by DM2A speakers and anything pertaining to them and to their workings retain my interest, reason I'm following the thread. I believe there's a good reason to keeping these speakers alive and kicking. Mine are original "white satin" and in a few months, when I've retired from tired :lol: I'll take them apart and sand the cabinet and repaint them and put new speaker cloth on the baffle, etc. A full crossover recap isn't really anticipated, but since I got the speakers for a very reasonable price, I splurged on some spare (new) Coles as well as (used) Celestion HF-1300's and (used) spare crossovers, which I keep in a box (don't say I'm crazy; I already know that). Wish you perseverence with your project!
Paul
I'm glad I've inspired you to lavish some love on your DM2a's Paul, I wish you well with the project my friend... ;)
Right guys, I got the bug today and decided finally to begin work on the DM2's, so I grabbed one out of storage and began by removing and desoldering the damaged Coles driver, after which I unscrewed the front baffle to scope the lay of the land and then my bottle went. There is far too much inside those cabinets for me to screw up, so after a strong cup of coffee and a couple of cancer sticks the decision was made to just replace the Coles supertweeters and leave it at that. It took me all of 30 minutes to remove the old drivers and install the new ones and here sit the mended DM2's within my system, now all is right with the world again.
After a shaky start I had begun to warm to the ART Skibo's, especially after installing a set of RFC Reference Pluto IC's between my DAC and passive pre to compliment the Reference Neptunes which run from the pre to the power amp. This lead to a huge upgrade in SQ and an open, effortless musical delivery which can break hearts at a thousand paces, or so I thought. That is until the DM2's started strutting their funky stuff again this avo. As good as the Skibo's are they are no match for the DM2's in this room and system. I will report back in more detail on my gallery thread in a few days time but for now I need to rest my back as I am in bloody agony... :eyebrows:
brian2957
24-02-2014, 22:45
Are you using the DM2s with the t -amp / passive pre setup Dave ?
Are you using the DM2s with the t -amp / passive pre setup Dave ?
Not just now Brian, the 306 is back in circuit again. Too sore to faff about with anything else this evening but depending on how I am tomorrow I will attempt kickstart the T amp once again if I am able... ;)
brian2957
24-02-2014, 23:23
Ok mate , hope you get a good nights sleep.
Sent from my GT-S5830 using Tapatalk 2
Does anyone know how long it takes for a new pair of Coles tweeters to bed in? Although the DM2's are sounding fabulous there is a slight brittleness at extreme high frequencies which wasn't apparent with the old units in situ. I also noticed as I was fitting them that the new units differ slightly from the old in the design of their face plates...
Does anyone know how long it takes for a new pair of Coles tweeters to bed in? Although the DM2's are sounding fabulous there is a slight brittleness at extreme high frequencies which wasn't apparent with the old units in situ. I also noticed as I was fitting them that the new units differ slightly from the old in the design of their face plates...
The tweeters shouldn't take long at all Dave, if at all, to break in. There's nothing like the mechanical suspension or surrounds on woofers to bed-in. Basically a tweeter should sound as it will sound from the second it's installed, at least in my experience.
If it sounds markedly different to the old ones, that's because there must be a difference somewhere in some way shape or form (yes, obvious I know). You may want to double check things like sensitivity and impedance because if these do differ at all from the originals, then the crossover values you currently have won't be right. The other thing it could simply be (and more likely?) is that the new ones are simply performing as the old ones ought to have done if healthy, all other things being equal. You could raise the crossover point a little or add a damping L-Pad to reduce sensitivity a little. The face plate in itself shouldn't alter output unless it has gone from a flat flange to some form of waveguide shape (ie increased sensitivity). Give me a shout of the problem persists and we can discuss the issue.
The tweeters shouldn't take long at all Dave, if at all, to break in. There's nothing like the mechanical suspension or surrounds on woofers to bed-in. Basically a tweeter should sound as it will sound from the second it's installed, at least in my experience.
If it sounds markedly different to the old ones, that's because there must be a difference somewhere in some way shape or form (yes, obvious I know). You may want to double check things like sensitivity and impedance because if these do differ at all from the originals, then the crossover values you currently have won't be right. The other thing it could simply be (and more likely?) is that the new ones are simply performing as the old ones ought to have done if healthy, all other things being equal. You could raise the crossover point a little or add a damping L-Pad to reduce sensitivity a little. The face plate in itself shouldn't alter output unless it has gone from a flat flange to some form of waveguide shape (ie increased sensitivity). Give me a shout of the problem persists and we can discuss the issue.
Everything seems fine now Paul, the slight 'edge' I detected yesterday has gone now so whatever it was was very short lived and now the speakers are sounding sublime. I will contact you soon regarding the acoustic felt idea we were discussing a couple of months ago, I'll need to move the Skibo's on first though ;)
dantheman91
04-03-2014, 15:00
Hi Dave
I have finally had a chance to listen to these bad boys and i have got to say what a fantastic sound the produce with the newly serviced Quad 33 \ 405. The sure do like producing vocals to perfection well for 1973 its amazing but again old gear is best i think its a good match and you sure notice the super tweeter treble :eek: all i need now is a pair of stands i bought this combo of Xmas for my father and he loves it :D.
Hi Dave
I have finally had a chance to listen to these bad boys and i have got to say what a fantastic sound the produce with the newly serviced Quad 33 \ 405. The sure do like producing vocals to perfection well for 1973 its amazing but again old gear is best i think its a good match and you sure notice the super tweeter treble :eek: all i need now is a pair of stands i bought this combo of Xmas for my father and he loves it :D.
I'm so pleased for you Dan, that's a special combo you have there which should keep you well entertained for many years. Unfortunately one of the new Coles units I fitted to my DM2's stopped working yesterday evening so I'm a bit gutted just now. Be careful with yours fella as they are very delicate things which won't stand any abuse at all. I wouldn't mind if I had been blasting out Black Sabbath at seismic levels but I wasn't, it was Cassandra Wilson at a very low level as it was late at night and I have neighbours on both sides :(
istari_knight
04-03-2014, 15:12
Have you checked the internal wiring/connections Dave?
Have you checked the internal wiring/connections Dave?
Checked 'em after I soldered them James but not since. I daren't go into them now as I am very pi**ed off and liable to do some damage. I'm hoping that's all it is however it is unlikely as the solder joints were perfect...
istari_knight
04-03-2014, 15:19
Maybe it was faulty ? You did detect a tizzy quality...
Such things are rare but it does happen - If you were listening quietly & your amplifier wasn't clipping/outputting DC I can't see any other reason for it other than a manufacturing defect.
Maybe it was faulty ? You did detect a tizzy quality...
Such things are rare but it does happen - If you were listening quietly & your amplifier wasn't clipping/outputting DC I can't see any other reason for it other than a manufacturing defect.
James, can I give you a hug? :lol:
The only other thing I can think of is that when manipulating the wires to position them for soldering the other end may have pulled away from its position on the HF1300, I will check when I am in a better frame of mind. One thing I did notice just before it gave up the ghost was a strange 'buzzing' on the guitar in track two of Crosby & Nash's self-titled album, and again today I heard the same sound from the other speaker when playing the final track on Sam Brown's Of The Moment album. I hope the other one isn't going the same way. Incidentally, in both instances the volume was set to a very reasonable level and not blasting out... :scratch:
dantheman91
04-03-2014, 15:33
Hi
Don't worry no loud levels here we live in a flat :rolleyes:. I have read there delicate things but the problem with yours as James says eaither a manufacturing fault which is possible or maybe a wire has come loose have you moved them just a possibility? Although i can see why your giving them a wide birth
istari_knight
04-03-2014, 15:51
James, can I give you a hug? :lol:
The only other thing I can think of is that when manipulating the wires to position them for soldering the other end may have pulled away from its position on the HF1300, I will check when I am in a better frame of mind. One thing I did notice just before it gave up the ghost was a strange 'buzzing' on the guitar in track two of Crosby & Nash's self-titled album, and again today I heard the same sound from the other speaker when playing the final track on Sam Brown's Of The Moment album. I hope the other one isn't going the same way. Incidentally, in both instances the volume was set to a very reasonable level and not blasting out... :scratch:
http://i1154.photobucket.com/albums/p526/Lucie_Grace/hug2.gif (http://s1154.photobucket.com/user/Lucie_Grace/media/hug2.gif.html)
Hmm its a strange one. How did the originals die exactly ? I've had a similar problem before where the HF capacitor had significantly changed in value & was allowing far too much LF into the tweeters causing exactly that "buzzing" you describe.... Unlikely in the B&W's but it does sound very similar.
http://i1154.photobucket.com/albums/p526/Lucie_Grace/hug2.gif (http://s1154.photobucket.com/user/Lucie_Grace/media/hug2.gif.html)
Hmm its a strange one. How did the originals die exactly ? I've had a similar problem before where the HF capacitor had significantly changed in value & was allowing far too much LF into the tweeters causing exactly that "buzzing" you describe.... Unlikely in the B&W's but it does sound very similar.
I was fiddling with the earth lead on the TT with the volume control set to the 12 o'clock position and of course the input selector set to Phono. Yup yup, I should know better however I was practicing my 'numpty' skills that day...
istari_knight
04-03-2014, 20:04
Just re-reading this:
The only other thing I can think of is that when manipulating the wires to position them for soldering the other end may have pulled away from its position on the HF1300
Now I've not been inside DM2's so dont know how they're wired up internally but surely the Coles 4001 should have a separate + feed from the HF1300 ? If "daisy chained" the 4001 will be receiving frequencies intended for the HF1300.
Correct me if I've lost the plot :D
Mr Kipling
04-03-2014, 20:34
11733
Just re-reading this:
Now I've not been inside DM2's so dont know how they're wired up internally but surely the Coles 4001 should have a separate + feed from the HF1300 ? If "daisy chained" the 4001 will be receiving frequencies intended for the HF1300.
Correct me if I've lost the plot :D
It appeared not but I could be wrong, anyway after giving this some thought I can't have done this as it would have been apparent from the time I first fired them up. I'm in numpty mode again...
istari_knight
04-03-2014, 20:51
We'll just have to be patient & wait for you to have a look :D
If its not a wiring error you want to claim for a replacement... I know things aren't made to last like they used to be thats taking the Michael !
We'll just have to be patient & wait for you to have a look :D
If its not a wiring error you want to claim for a replacement... I know things aren't made to last like they used to be thats taking the Michael !
I am confident the unit is a duffer so I'll get onto Falcon Acoustics tomorrow to see what can be done...
istari_knight
04-03-2014, 22:51
:thumbsup: I'm sure Jerry will sort it out for you.
Spoke to Jerry just now and I am to send it back to him tomorrow and as he is paying Coles a visit on Monday he will take it down personally and have it tested while he is there, how about that for service? :)
istari_knight
05-03-2014, 17:11
Nice one :clap: Will be interesting to hear what Coles make of it.
walpurgis
20-03-2014, 23:41
Any progress Dave?
Any progress Dave?
Still waiting Geoff :(
surv1v0r
05-07-2014, 22:39
Any progress Dave?
No Aaron, I've been enjoying the Skibo's plus I feel I need to expand my knowledge a little more before I really get stuck into them.
walpurgis
14-07-2014, 20:43
Did you get all the drive units you were after Dave?
Yup, twice, well sort of. One of the Coles I ordered went 'phut' and it took a while for it's replacement to arrive. I will get around to sorting them out but for now there's no rush and besides, I am looking forward to working on the AS AV21's in another thread. If I cock those up then it's only cost me 20 quid ;)
I've just bought a pair of B&W DM2 a few weeks back.
I've put them through my Sansui 881 which is a 60wpc amp and I feel that the sound is somewhat closed and shunned?!? Also when pushed past 60% of volume the bass drivers start distorting. I figured out that the moving coil is hitting the back of the driver enclosure as it has little play in it. It might have been designed this way to limit the amount of volume is being pushed into them?!? Maybe?!?
Upon opening them up it looks like the DW200 bass driver have ben replaced ( with newer driver "tested may 1993") however they seem to have been replaced with like for like as they look identical to the original ones (which are not painted black) and fit perfectly into the panel but I wonder if the original DW 200 have the same limited play distance in the speaker coil.
I've put up some video to show them off.
1. B&W DM2 vs Monitor Audio Studio 2 vs Monitor Audio System R352
https://www.youtube.com/watch?v=P4BsrmC2I2E
2. B&W DM2 vs Monitor Audio Studio 2 vs Monitor Audio System R352
https://www.youtube.com/watch?v=6p-FflpamP4
3. B&W DM2 vs Monitor Audio Studio 2 vs Sony SS 1005 (B&W made)
https://www.youtube.com/watch?v=wLN0rJYxoUM
4. B&W DM2 vs Monitor Audio Studio 2 vs Sony SS 1005 B&W made
https://www.youtube.com/watch?v=_w6q234xG4k&t=21s
B&W DM2 speaker cone hitting the back magnet / casing
https://www.youtube.com/watch?v=nnuDfqB63_A
B&W DM2 A Speakers - What's on the inside.
https://www.youtube.com/watch?v=LnlNECMq3NI
These speakers are totally different designs yes, but I'm just finding my way around the hi-fi world trying out different things.
I wonder if anyone can tell from the last video whether the green capacitors, or whatever they are, they look out of shape due to ageing and if their upgrade / replacement would make any meaningful difference.
Here's a picture of the crossover of the other speaker I've just opened today.
30215
Been trying to remove the plastic knob from the HF potentiometer at the back now but it feels as though it's impossible to pull it out. I've sprayed tome WD forty at the base with the hope to loosen it up but no success, and I've been pulling hard on it. I will be taking the pliers to give it a little squeeze to see if that works.
Lawrence001
28-03-2022, 23:42
I've owned several pairs of these in the past and they are very nice speakers.
I agree the bass speakers have been replaced as the originals had some sort of doping on them whereas these look like smooth plastic.
What the impact on the sound is I'm not sure, but the speakers set to A sounded like they have bass and treble with no midrange. Hard to tell but if that was these I'd guess either the bass speaker isn't going as high as the original (seems unlikely, it might have a different sensitivity but it doesn't strike me as one that would roll off below 1kHz). Or the Celestion HF1300 isn't working, which might explain a lack of upper midrange. That could be either a faulty unit, wiring or the selector at the back isn't engaging.
Easiest way to tell is to play it quietly and put your ear near to each driver, you should be able to tell if any isn't working. I used a choir for the supertweeter as it was hard to tell. It sounds like a hiss as much as anything.
I'm trying to remember if mine had the nasty itchy loft insulation material behind the woofer I'm pretty sure they didn't. (May have had a nice wool instead though it was too long ago to remember.) I'd take that out and see how they sound. It might be blocking the transmission line too much. They definitely had that flat folded material underneath don't take that out
Regarding the sticky knob, I think it might have a little black cap on the end, try getting it off with a sharp knife under the cap and you will see a screw inside which lets you take the knob off. I could be wrong it was many years ago I did all this.
Many thanks Lawrence for the tip regarding the removal of the plastic cap. I wouldn't have guessed in a million years. I've pulled it off till my fingers hurt
The the HF1300 has been tested as well as the super-tweeter and they are both working. I've covered one with a cloth and listened to the other and they are both working for sure.
Don't know what to say. I think the best way of to find out would be to find an original pair and do a swap around of the bass drivers or the whole drivers unit and see how it performs. It might be that the ageing crossover play a role in it as well. Don't know really. Had a second look at the cones in the bass drivers and indeed the original ones (a few on sale on ebay) have been some sort of paint/coating on them.
Don't know if removing the dampening material will do anything as it would leave a hollow space inside. I would be tempted to try, it's just that I don't want to work those screws up too many times. I might try out tomorrow.
walpurgis
29-03-2022, 08:01
Bypassing the potentiometer should elevate the output across the HF region by a few DB.
The bottoming out of the bass driver suspension is probably normal and not something to worry about.
Bypassing the potentiometer should elevate the output across the HF region by a few DB.
The bottoming out of the bass driver suspension is probably normal and not something to worry about.
surprised by that I would have said they should not make that noise when pushed in, never known a working speaker make that sound.
I'd say they need a complete re-build or break them for parts. Good speakers when in top shape but there's better out there.
could you come up with some examples that would be a good match for the Sansui 881's 60wpc?
Although I like the MA Studio 2 in the videos, unfortunately they're not suitable for a large room as they also lack bass even though for a smaller room they would be a good match.
I'm looking at a budged between 100 - 200$ preferably something more vintage so that I would hopefully get a good deal. Got these DM2's for £50 with a bit of luck lol. MA Studio 2 paid £72 for them but had to change the twitter foils. MA R352 £30. You get the point, bargain hunter lol
walpurgis
30-03-2022, 16:33
There's not much around capable of use in a larger room at that sort of money. You might find some vintage Goodmans Magnum K2 or Wharfedale Dovedale III in usable condition, both are sensitive and don't need loads of power to go loud. Good punchy bass on these with the 12 inch drivers. Both a bit of a classic of their time.
could you come up with some examples that would be a good match for the Sansui 881's 60wpc?
Although I like the MA Studio 2 in the videos, unfortunately they're not suitable for a large room as they also lack bass even though for a smaller room they would be a good match.
I'm looking at a budged between 100 - 200$ preferably something more vintage so that I would hopefully get a good deal. Got these DM2's for £50 with a bit of luck lol. MA Studio 2 paid £72 for them but had to change the twitter foils. MA R352 £30. You get the point, bargain hunter lol
KEF Calinda for £170 here https://www.ebay.co.uk/itm/255277855601?hash=item3b6fbef371%3Ag%3AVJYAAOSwOfF huJyy&LH_BIN=1&LH_ItemCondition=3000
They like a big room and your amp will have no bother driving them.
I've decided to keep the DM2's but I'm looking to upgrade the main mid-bass drivers DW 200/2.
Currently looking at these 8" JBL mid-bass drivers on eBay that were fitted in their Professional 3310 cinema speaker setup.
It's a 2 way speaker design with crossover frequency at 2.5kHz just as the DM2 and a frequency range between 40hz to 20.000kHz.
3063630637
https://www.ebay.co.uk/itm/144765884033#vi-desc-maincntr
Another option seems to be 8" Dalesford bextrene from the 70's.
Does anyone have any experience with upgrading the mid-bass driver of B&W's DM2?
spendorman
07-11-2022, 06:18
I've decided to keep the DM2's but I'm looking to upgrade the main mid-bass drivers DW 200/2.
Currently looking at these 8" JBL mid-bass drivers on eBay that were fitted in their Professional 3310 cinema speaker setup.
It's a 2 way speaker design with crossover frequency at 2.5kHz just as the DM2 and a frequency range between 40hz to 20.000kHz.
3063630637
https://www.ebay.co.uk/itm/144765884033#vi-desc-maincntr
Another option seems to be 8" Dalesford bextrene from the 70's.
Does anyone have any experience with upgrading the mid-bass driver of B&W's DM2?
I looked at using the DM2 bass unit in my LS3/6 but found it too coloured in the mid, the Dalesfords were better in this respect. Also tried the DM4 bass unit, similar problem.
Although coloured in the mid, the DM2 bass unit works quite well in the DM2, same applies to he DM4 unit in the DM4.
Not sure of any differences (if any) between DM2 and DM2A bass units.
spendorman
07-11-2022, 06:29
I've just bought a pair of B&W DM2 a few weeks back.
I've put them through my Sansui 881 which is a 60wpc amp and I feel that the sound is somewhat closed and shunned?!? Also when pushed past 60% of volume the bass drivers start distorting. I figured out that the moving coil is hitting the back of the driver enclosure as it has little play in it. It might have been designed this way to limit the amount of volume is being pushed into them?!? Maybe?!?
Upon opening them up it looks like the DW200 bass driver have ben replaced ( with newer driver "tested may 1993") however they seem to have been replaced with like for like as they look identical to the original ones (which are not painted black) and fit perfectly into the panel but I wonder if the original DW 200 have the same limited play distance in the speaker coil.
I've put up some video to show them off.
1. B&W DM2 vs Monitor Audio Studio 2 vs Monitor Audio System R352
https://www.youtube.com/watch?v=P4BsrmC2I2E
2. B&W DM2 vs Monitor Audio Studio 2 vs Monitor Audio System R352
https://www.youtube.com/watch?v=6p-FflpamP4
3. B&W DM2 vs Monitor Audio Studio 2 vs Sony SS 1005 (B&W made)
https://www.youtube.com/watch?v=wLN0rJYxoUM
4. B&W DM2 vs Monitor Audio Studio 2 vs Sony SS 1005 B&W made
https://www.youtube.com/watch?v=_w6q234xG4k&t=21s
B&W DM2 speaker cone hitting the back magnet / casing
https://www.youtube.com/watch?v=nnuDfqB63_A
B&W DM2 A Speakers - What's on the inside.
https://www.youtube.com/watch?v=LnlNECMq3NI
These speakers are totally different designs yes, but I'm just finding my way around the hi-fi world trying out different things.
I wonder if anyone can tell from the last video whether the green capacitors, or whatever they are, they look out of shape due to ageing and if their upgrade / replacement would make any meaningful difference.
Here's a picture of the crossover of the other speaker I've just opened today.
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Been trying to remove the plastic knob from the HF potentiometer at the back now but it feels as though it's impossible to pull it out. I've sprayed tome WD forty at the base with the hope to loosen it up but no success, and I've been pulling hard on it. I will be taking the pliers to give it a little squeeze to see if that works.
I believe that the DM2 bass unit shown in the video is faulty. Possibly a damaged voice coil/ former.
spendorman
07-11-2022, 06:34
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Apologies for replying to a very old post, but I believe that this crossover might be from DM2 Mk2, very different to DM2 crossover.
walpurgis
07-11-2022, 08:05
The suggested JBL bass driver would at least need to match the DM2 unit in exact dimensions, sensitivity, impedance curve and tonal characteristics to be a compatible substitute. I think this would be unlikely.
I believe that the DM2 bass unit shown in the video is faulty. Possibly a damaged voice coil/ former.
Don't know whether damaged voice coil or limiting design. It does play well without distortion until it hits the back plate.
It comes to an abrupt end which means that the travel distance is too short. The rubber surround is narrower which gives it less flexibility (maybe this has been done in purpose?!?). On the plus side, the magnet is at least 750g heavier as the chassis is identical to that of the B&Ws DW200.
I was thinking whether it's worth taking them apart to replace the rubber surround with a wider one and add a thick metal ring / plate between the magnet and the existing back plate in order to widen the travel distance of the cone / core tube assembly.
If anyone has experience with refurbishing drivers maybe they could let me know whether such upgrade would be possible or make sense.
close-up view of the driver
https://youtu.be/MIXDwRNceNo
in operation
https://youtu.be/Lv4HPK8inoY
spendorman
07-11-2022, 09:53
Don't know whether damaged voice coil or limiting design. It does play well without distortion until it hits the back plate.
It comes to an abrupt end which means that the travel distance is too short. The rubber surround is narrower which gives it less flexibility (maybe this has been done in purpose?!?). On the plus side, the magnet is at least 750g heavier as the chassis is identical to that of the B&Ws DW200.
I was thinking whether it's worth taking them apart to replace the rubber surround with a wider one and add a thick metal ring / plate between the magnet and the existing back plate in order to widen the travel distance of the cone / core tube assembly.
If anyone has experience with refurbishing drivers maybe they could let me know whether such upgrade would be possible or make sense.
close-up view of the driver
https://youtu.be/MIXDwRNceNo
in operation
https://youtu.be/Lv4HPK8inoY
I have had 4 pairs of DM2 / DM2a, none have been like this. Still have three pairs.
Does the other speaker do this?
Still reckon damaged unit.
Could be that unit was assembled with wrong coil/ former, or just badly assembled.
spendorman
07-11-2022, 10:31
I bought my first pair of DM2's about 17 years ago for £50, the guy selling had just bought a large pair of PMC's, he did a comparison for me, the DM2's stood up very well. I thought to myself that I'd rather have the DM2's and the remaining cash than the PMC's.
walpurgis
07-11-2022, 16:33
The driver looks wrong. The cone is smooth and not coated. I would not think B&W would still have been offering replacement drivers by 1993. I think those may have been cannibalised from a later model.
I have had 4 pairs of DM2 / DM2a, none have been like this. Still have three pairs.
Does the other speaker do this?
Still reckon damaged unit.
Could be that unit was assembled with wrong coil/ former, or just badly assembled.
they both behave in the same way.
I've been looking around since I bought this pair a few months ago and managed to find a few for sale.
This guy here is selling the same exact driver.
https://www.ebay.co.uk/itm/363958105598?mkevt=1&mkpid=0&emsid=e11051.m43.l1123&mkcid=26&ch=osgood&euid=f6964c35044c4653a0600889c7be56fe&bu=43684479253&osub=-1%7E1&crd=20221010082336&segname=11051
Naturally I've pose him the question. His reply was that I'm asking too much from these speakers and that I should be adding a subwoofer to take away some of the bass off the DM2s.
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Lawrence001
08-11-2022, 00:10
I suspect you are driving them too hard, speakers of this age weren't made to play that sort of music at high volume. If the cone is hitting the backstop it's a sure sign.
you may also be driving the amp into clipping which will make things worse. You might have damaged the speakers yourself.
I think you should look at more modern speakers for what you want to do with them.
I suspect you are driving them too hard, speakers of this age weren't made to play that sort of music at high volume. If the cone is hitting the backstop it's a sure sign.
you may also be driving the amp into clipping which will make things worse. You might have damaged the speakers yourself.
I think you should look at more modern speakers for what you want to do with them.
The DM2 are recommended to be run by an amplifier rated 20W to 60W.
Sansui 881 is rated 60W. Also the original drivers (DW200/2) don't make that knocking sound although they distort at high volume but this might be down to Sansui THD.
I would be interested to find out if anyone in the community has listened to these later 90's version of the bass drivers and how did they find them.
Lawrence001
09-11-2022, 07:14
Maybe the longer voice coil former was designed to stop the driver distorting at high volumes to prevent damage to the coil.
The amp might be rated to 60W but you can get more out of it if you clip it. It's not a volume limiting figure. The distortion you are getting is a sure sign of clipping unless it's faulty.
If you find yourself turning an amp up to distortion levels it means you need a more powerful amp. And if you want to listen at those volumes you need a pair of speakers that can handle that output, ie not these.
walpurgis
09-11-2022, 08:23
The DM2 should go loud enough for any 'normal' listening without the bass driver bottoming out.
walpurgis
09-11-2022, 08:37
If you want to consider an alternative to the B&W's, you could look at the Celestion Ditton 25, it has similar tonal characteristics through the upper mid and treble as it also uses HF1300 units but in pairs in each speaker (and the very fine HF2000). The 12 inch main driver offers far greater bass ability.
Maybe the longer voice coil former was designed to stop the driver distorting at high volumes to prevent damage to the coil.
The amp might be rated to 60W but you can get more out of it if you clip it. It's not a volume limiting figure. The distortion you are getting is a sure sign of clipping unless it's faulty.
If you find yourself turning an amp up to distortion levels it means you need a more powerful amp. And if you want to listen at those volumes you need a pair of speakers that can handle that output, ie not these.
Thanks Lawrence.
I think your point makes total sense.
Good that you laid straight the distorsion clipping relation. Maximum clean volume can be achieved at around 1pm position on the volume dial from what I understand.
I was also thinking that some distorsion may come up earlier than that depending on the THD of the amplifier. I also have a Tandberg TR 2060 which has lower THD (0.07) than the Sansui (0.3) but haven't put the DM2s through that one yet. From what I read on various forums the DM2s require clean robust power and my guess is that this is due to the weight / inneficiency of the Bextrene drivers. So theoretically the original DW200 who are not limited by the core tube length might be able to go slightly louder than the ones above. Either way the volume is plenty for normal listening situations at home as Geoff pointed out.
Lawrence001
09-11-2022, 14:48
Output power is not just a function of the knob position.
A 4 ohm speaker will hit 60W at a lower position than an 8 ohm speaker.
A less efficient speaker will sound quieter when you hit 60W.
IIRC B&W used to quote a high 95dB figure but for 3.6 watts not 1 for some reason. I did the calcs and they came out at mid 80s IIRC someone correct me if I'm wrong!
If you listen to them at the volume in you tube you should get a more modern amp and speaker. People didn't listen to such high dynamic music at such high volumes then. Except at gigd and discotheques of course [emoji23]
walpurgis
09-11-2022, 15:05
YouTube probably compress audio files.
spendorman
09-11-2022, 21:38
A nice Bextrene coned 8" unit is the Richard Allan HP8B, similar sounding to the Dalesford Bextrene units, perhaps very slightly better mid.
https://live.staticflickr.com/65535/50835047468_1a923c8a68_o.jpg (https://flic.kr/p/2ks7UxE)RA HP8B (2) (https://flic.kr/p/2ks7UxE) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr
https://live.staticflickr.com/65535/50835858062_9f7a0547fc_o.jpg (https://flic.kr/p/2ksc4vq)RA HP8B (1) (https://flic.kr/p/2ksc4vq) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr
Thanks for that.
Any ideas in which speakers these have been used?
spendorman
13-11-2022, 22:11
Thanks for that.
Any ideas in which speakers these have been used?
Fairy obviously, some of the Richard Allan models, I'm not sure which.
I believe that the LS3/6 uses a version of this unit, if one looks at the chassis of an LS3/6 bass unit, the chassis is identical to the HP8B.
I intend to use the HP8B in my LS3/6 that presently have the Dalesfords in.
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