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.















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.