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surv1v0r 1st March 2013 08:31 AM

Where can I find schematics for speaker crossovers?
In a thread about a B&W DM4 problem, system7 has included a graph showing resistance and a schematic for the crossover. I wondered where these details could be found in relation to other speakers, specifically the B&W DM2 and the Kef DN12 - any suggestions (T27, B110, B139)?

Don Bunce 1st March 2013 05:56 PM

Google is your friend...

system7 1st March 2013 06:10 PM

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Those of us who have dug around for speaker details with the Google search engine know where to find stuff. :D

KEF stuff can be found here:
Technical Details of KEF Crossovers

You have KEF Concertos, DN12 SP1004 crossover updated by Falcon Acoustics who are pretty good. You might also find new crossover components at Wilmslow Audio:
KEF Concerto B139B B110A T27A network DN12 SP1004
Concerto Upgrade Crossovers

See those old Non-polar electrolytic capacitors dry out with age and degrade. :mad:

I presume you aren't terribly interested in B&W designs, but I dug up some stuff at The Art of Sound Forum - Powered by vBulletin. You have to join to see the scans in "The Knowledge." B&W themselves publish good documentation too.

The below KEF Concerto stuff should look familiar. Hope it helps. :cool:

Edit: You are on it, Don! LOL

KatieandDad 1st March 2013 06:12 PM

All B&W speaker service manuals are available from B& I'll dig out the link and post it when I find it.

That took about 20 seconds on Google.

Moderators, I do wish you could make this link sticky as it is asked so many times and the information is freely available.

system7 1st March 2013 06:44 PM

Hate to say this KatieandDad, but old B&W stuff is a pig to find. :D

B&W Group North America Service & Support - Owner's Manuals & Drawings

No use at all for the DM2 details. We rely on ENTHUSIASTS here to dig inside. :cool:

This is the well liked B&W DM-2A, but it must be different from the older DM2.

surv1v0r 1st March 2013 06:58 PM


Originally Posted by KatieandDad (
All B&W speaker service manuals are available from B& <snip>

Thanks for that. Sadly the information for the DM2 is pretty sketchy. There is an impedance graph (which looks pretty "all over the place" to my untutored eyes) but it isn't great quality and it isn't really possible to read it. Thanks anyhow.

Some time ago I did try contacting B&W with an enquiry about replacing the sound dampening material inside the DM2s (there are three different varieties) but they said that there was nobody there any longer who knew anything about them.

Thanks for the Kef stuff system7 & Don. I am aware of the Falcon Acoustics crossovers and they do look good, particularly the 5aB.

Anyhow, thanks to all for the various replies - I will try to make better use of Google in future

system7 1st March 2013 07:35 PM

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If I have an old cabinet with old and worn-out drivers, I usually measure the bass cutout and volume and wonder if I can fit modern drivers. :D

Maybe something like the Troels Gravesen Classic three way could be done in a biggish box:
3-Way Classic

I suspect the SEAS CA18RNX might be too small, but George Krilov has some nice designs:
DIY loudspeaker "OPTIMA" - YouTube

See, diyaudio has only your imagination as it's limit! :cool:

KatieandDad 1st March 2013 07:37 PM

The DM2 is on that site, just go down a bit to the older stuff.

I've found both the DM2A and the DM2/II.

Cal Weldon 1st March 2013 07:41 PM


Originally Posted by KatieandDad (
Moderators, I do wish you could make this link sticky as it is asked so many times and the information is freely available.


I have sent this to the backroom for consensus. In the future please hit the report post button when you wish to communicate with us. We don't just magically see every post. :)

KatieandDad 1st March 2013 07:44 PM

Cheers Carl. I just find it frustrating when the same questions get asked over and over again.

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