B&W DM2 polarity check

[Palmer67]

Anyone able to confirm driver polarity in these what I think are DM2a’s ? I am replacing the bad Coles tweeters and wanted to confirm polarity while I am digging around in them . If I use the red dot on the driver terminals = positive rule it appears both the mid and tweeter are wired in reverse polarity . I found a document here on AOS that suggests the opposite.

https://i.ibb.co/2ZLXPYX/DE6696-F4-F4-CE-4651-A883-CB9313-DB0710.jpg

https://i.ibb.co/zZQqQRh/EA2-B97-D3-041-A-480-D-949-C-DACA91-CC397-F.jpg

https://i.ibb.co/CVRhDcb/33188-D74-C144-4-CF5-B042-257-EAF6139-DC.jpg

https://i.ibb.co/jT0THVH/0473-FA4-B-3-EF6-4-D05-AD3-C-2-BDE98153132.png

https://i.ibb.co/SQpTjr8/BF81-D8-EF-C0-F5-4-DBC-B0-CF-BBC84-A957-F0-E.png

https://i.ibb.co/qyxhHmh/75-E1-CBC0-9-E8-B-4-B00-A1-E5-EE462-F709067.jpg



Any insight or confirmation would be greatly appreciated...

[Lawrence001]

Great speakers these, I haven't looked inside one for years. Spendorman is the resident expert on these, although I suspect a few of the regular members have a good knowledge.

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[Barry]

I have a pair of these in my AV system.

If you are replacing the original Coles tweeters, then I would follow the wiring 'as found'. It is not uncommon for some of the drive units to be connected out of phase in some speaker designs; however the circuit diagram you show suggests the DM2 is not one of those.

[Palmer67]

Yes it was in fact Audio Al’s refurb post from 2012 that brought to AOS and the schematics came from spendorman’s reply in the same thread

[spendorman]

Just been looking at the diagrams I have, DM2a has all units in phase, DM2 has the HF1300 reversed phase.

If diagrams needed, just PM me with your email.

There seems to be confusion as to which is a DM2 or DM2a. I consider the DM2a as the one with the switchable HF control. This may or may not be correct.

[Lawrence001]

I'm sure I've seen DM2s with the switch. Maybe the crossover change was the difference.

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[spendorman]

I've even thought that B&W produced DM2a's with DM2 labels on.

[spendorman]

An aside, those cabinets should come up pretty well with a light sanding and oiling or varnishing, veneer is quite thick on these speakers.

[Barry]

Would it help if you contacted B&W quoting the serial numbers of your speakers, to find out if they the DM2 or the DM2a versions?

[spendorman]

Would it help if you contacted B&W quoting the serial numbers of your speakers, to find out if they the DM2 or the DM2a versions?

Not a bad idea, worth trying, In 2009 when I contacted B&W, I provided them with info on early models that they did not have. The Guy I was dealing with was Stephen Wheately.

[Palmer67]

Thanks for all the info guys ! Spendorman I will take you up on that diagram offer . I’ll send you a note in a bit . Funny I was kinda wondering if anyone had info on the serial numbers and will contact B&W to see if they have anything. It for sure won’t hurt any . These are serial # 15835 A and 15836 B .

Unfortunately someone had sanded through the veneer on the top on one of the cabinets . It’s small enough I may leave it and refinish them without replacing the whole top veneer .

[spendorman]

Unfortunately someone had sanded through the veneer on the top on one of the cabinets . It’s small enough I may leave it and refinish them without replacing the whole top veneer .

A bit of filler correctly stained, can work wonders

[Palmer67]

Well I’ve been able to contact someone at B&W and I hope I’ll be able to get an answer soon .

While reviewing the schematics I’ve noticed my crossover never had the “C1” capacitor installed

https://i.ibb.co/MVDtvhG/CFA8-AA86-60-F9-4-A9-E-A255-0185406-F5-F15.jpg

https://i.ibb.co/SQpTjr8/BF81-D8-EF-C0-F5-4-DBC-B0-CF-BBC84-A957-F0-E.png