B&W DM2 fettling

[synsei]

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...

[synsei]

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]

Okay I'll go first

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

[synsei]

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.

[DSJR]

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]

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/st...p?CategoryID=2

Cricklewood Electronics sell the highly recommended Ansar SuperSound capacitors http://www.cricklewoodelectronics.co...me.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.

[synsei]

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

[Rare Bird]

Dave:
Soon be November the 5th

Joking aside are your the 'DM2a' {Switch on the rear} ? Bypass that.

[synsei]

Nope André they are without switch, switchless, devoid of switchiness. They are ex-switched!

[Andrew B]

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.