B&W DM70 Standards

Hi Richard,

Yes the grill cloth that was on when i recived them was indeed of Tygan type, burgundy (open weave) but was very badly faded, torn and loose so has to be replaced,

i have kept the cloth that was on the ES panels to try and mach the same weave pattern, there is a major fabric suppliers near use in chorlton so i might have a drive there tomorrow to see what they have in stock.

I also noticed that when i removed the grill cloth for the drivers there was a rotten foam in between the grill baffle and cloth, what type of foam would this have been? and is it easy to source? lol i'm hopeless

[FlyingKipper]

The blue Tannoys are as far as I know original. I bought them secondhand like that.
It certainly looks "factory" or a professional job given the way the cloth is stapled to the frame.

Its a very thin cloth.

Clolour-wise I like them, although they clash with everything else in the room!

[Toppsy]

To be honest I would not spend a lot of time and money on these DM70 speakers. Just my opinion and others may choose differ. They are not the best of sounding speakers from reports I have read and to be honest a mate of mine who is familiar with these speakers commented he thought the boxes would burn very nicely!

I wouldn't go that far but I have not heard any hybrib speaker which partners electrostatic panels and a bass cone driver to integrate and work 100% successfully. And I have experimented with several ESL speakers and cone sub woofers.

But if these float your boat go for it.

Hi there Toppsy,

Im just replying to you with regards to the email discussion we had about the ES drive units and EHT boards (low volume and hum)

I decided to change both mains supply leads tonight and upon removing the neutral and earth wire from the mains transformer (faulty unit) i noticed that on the underside of the neutral wire the insulation had worn away and in its current place was touching the earth tag

Once i had finished i plugged the unit in and the hum had gone! i just have to wait now till i have re-built the ES panels to test it fully.

I also recived the circuit diagram (PDF) and a whole load of information on the DM70's from B&W today quite interesting stuff

If anyone is interested in having a look at the circuit Diagram for the DM70's i will be more than happy to send it to you (PM me your Email)

Thanks Mathew

[Shane]

Although I've never heard DM70s, I can see where Matthew's coming from. As a teenager in 1970 the DM70 Continentals had the same sort of effect on me as a Lamborghini Miura. Both are deeply flawed and can be criticised endlessly from the performance point of view, but they both still make me go weak at the knees. DM70Cs, Lecson AC1/AP3, Transcriptors Hydraulic Reference. Still neatly costed out in the back of my English exercise book, and with looks like that who cares what it sounds like?:p


I have to admit that they were displaced from my dream system shortly afterwards by Gale 401As. Fickle, fickle...

[david counter]

Originally Posted by Shane

Although I've never heard DM70s, I can see where Matthew's coming from. As a teenager in 1970 the DM70 Continentals had the same sort of effect on me as a Lamborghini Miura. Both are deeply flawed and can be criticised endlessly from the performance point of view, but they both still make me go weak at the knees. DM70Cs, Lecson AC1/AP3, Transcriptors Hydraulic Reference. Still neatly costed out in the back of my English exercise book, and with looks like that who cares what it sounds like?:p


I have to admit that they were displaced from my dream system shortly afterwards by Gale 401As. Fickle, fickle...

you should have tried living with them,

dominated the room like a pair of washing machines, divorce was mentioned more than once, wouldn't have been so bad if they'd sounded OK

[Richard]

Meanwhile, back in the workshop....

I've just had cause to recover a pair of grilles and found this site extremely helpful,

http://www.humanspeakers.com/howto/grill-cloth.htm

Followed it exactly and they have come out perfectly! It is based upon the more modern fabric with a bit of stretch in it. The woven-in stretch is better than lycra types I've used in the past (which go baggy after a while). This time I used speaker cloth from Wilmslow audio which many will recognise instantly as the type used since the late 70's on many commercial brands. Note there is a right and a wrong side to the fabric...

Glue was UHU All Purpose Solvent Free glue £1.95 tube from John Lewis. Sets like solvent impact types, clear and flxible, but takes longer, doesn't string, and can be wiped off with a damp cloth whilst working. Laid a bead approx 3mm wide (as in his pics) then smoothed it to about 10mm wide leaving quite a thick layer. Warmed it with a hairdryer for 5 mins till it just started skinning. That gave me plenty of tack to hold the cloth and a full 20 mins use time for stretching and adjusting. The pair took an hour in total after the usual agonising and cutting the cloth.

Mathew, that foam will be simple lightweight yellow plastic type and rots due to UV. I'm not sure I'd include it this time.

Rich

[Ali Tait]

You gonna build the EPI 1000's Richard? Go on,you know you want to..

[Yellow]

Originally Posted by Cobblers

........

I doubt that the original engineers for those speakers will still be at B&W these days!........

Well, I used to work at B&W, and I know that one or two of their Engineers are still there from the days when these speakers were sold.

Have you thought about a brown grille cloth? Personally, I would go with black, but the thickness of the original cloth may make the new thinner-cloth grille sound more treble-happy, as the thicker material will have damped out some of the top end. If so, you may need to add a small series resistor to the HF to compensate.
Can you hear any HF-level difference listening to the speakers with or without the grilles?

Neil.

[Cobblers]

Originally Posted by Yellow

Well, I used to work at B&W, and I know that one or two of their Engineers are still there from the days when these speakers were sold.

Neil.

B&W were extremely helpful and sent me a load of info (for free) on the then ancient DM12's back in the mid/late 90's, they also sent me info to bypass the protection mechanism on the crossover.

Oddly enough they worked well with push pull valves (like the LS3/5a) but were very different to modern B&W's with closed box loading, Bextrene 7 inch drivers and silk dome tweeters.
They were marketed as a mini monitor and would today be regarded as a large standmount.