B&w Dm4

[zeno]

I have a pair of old 1972 B&W DM4 speakers. They are in fairly good condition, but I would like to rebuild the xover. The inscriptions on the caps and coils in the original filter are gone over time...

Does anyone have a schematic of this three way filter? Or a clue where I could find it?

Marc

[jleaman]

Maybe you can email them and ask. Let them know what model and that you either want to buy the parts from them to repair them your self..

[zeno]

Yeah, good suggestion.
Did that too. But I am impatient... So I tried it at DIY too

[jleaman]

Right on Thumb's up for that one : O) This is the only forum that i hang out on all day sometimes..

But back to your speakers..

How do they sound. i almost bought a pair but i was told that i could build better pair for less money : O)

J'

[ingvar ahlberg]

Hi Marc
Havent got the schematic but x-over frequency from the 8" to the celestion hf1300 is 4000 Hz and to the Coles 401 supertweeter i think around 8000, mind You this was the mid seventies and my memory fades as the beard goes whiter. Realy nice speakers thou, need a bit of wall support not to become to lean in the bass.

[zeno]

Originally posted by JasonL


How do they sound. i almost bought a pair but i was told that i could build better pair for less money : O)

J'

They have been 'neglected' way too long, these B&W's!
So they tend to sound a bit harsh, no sweet top end. I do not remember how much my father paid for them in '74 but I do remember going to the shop with him and buy these speakers together with a Marantz receiver and a Revox open reel deck. Very 70s!
I still have the Revox (in mint conition) and the speakers. The Marantz went to a brother of mine.

If I remember well, these were very engaging speakers, even though their set up in my parents house wasn't perfect at all.

Wether or not you could build a better pair for less money than the price for a good pair of second hand B&W's depends of course on the money you want to spent on vintage items.

However I do think that speakers are very different nowadays from what was being engineered 30 years back. Most speakers are much more transparent e.g. an they can handle more power.

When I compare the DM's with the pair of AlonIV in y living room, there indeed is a world of difference.

I admit it, my question in the first post is just the first step back in time to my childhood.

[Duck-Twacy]

Once I almost bought these speakers, but I choose a pair of IMF super compact instead.

I guess you already found the user manual?

[george a]

Hi Zeno
This is a photo of my dm4 xover.
Pls pardon photo quality

Caps vaues left to right are as follows

Between yellow and green coil- 2.2uF on left 1.5uF on right
Row of 3 caps 1uF on left 0.68uF in middle and 3.3uf to right
Between black and white coils- 4.7uf on left 3.3uF on right
Caps have values molded onto them and appear to be 100volt
All coils appear to have no values marked –sorry
As to sound- very musical indeed- not bad for their vintage-probably still better than most consumer cr*p around these days- purchased at 2nd hand store- had to replace surrounds to woofers.

Hope this helps – pls let me know if I can add any further info.

[zeno]

Hi Georg a,

I checked the filter in my DM4's. They are screwed on the back of the speaker, identical to the xover on your picture. Is the xover in your DM4's sitting on the back of the baffle?

I noticed that the plastic domes of the so called 'super tweeter' are both damaged. They have a crack running almost entirely through the dome. I guess they have become brittle over the years and did not survive uninteded touching ...
A shame.

They do play very well though, even the high notes. I hooked them up tonight, put them close to the wall and started playing music.

Like them a lot!

[george a]

Hi Zeno

Yes PCB on back of front baffle, super tweeter under pcb in photo.
SAd to hear your tweetes damaged.
I know how good this unit can sound, dont know if you can still get replacement units - pehaps try wilmslow audio in UK ..?

I currently use them in rear channels of HT setup.


Cheers