2. speakers
  3. 134439-109758

B&W DM70's - top end lacking

I have a pair of DM70’s.
They sound really good with vocal, blues and opera.
The bass is overblown with complex orchestral or progressive.

I am already replacing the bass units with Leak sandwich, as I found that the original units had not been repaired correctly.
They had some sort of home made surround made of thick paper with a 12 inch foam surround stuck on top.
The leaks seem to solve some of the bass issues.
I will get the bass units professionally repaired at some point.

Now to the treble units.
The mid and lower treble seems great, but things like symbols seem muted.
I was told that the electrostatic units had been repaired by One Thing, but now I am not so sure.

I am driving them with an Art Audio Quintet fed from a Conrad Johnson PV9a pre.
My CD is a Unison Unico and I am using a Focus One turntable just now.
Cables are from Chord. (Yes they do help a bit)

These are frustrating speakers, as when at their best, they sound so good.
First I need to know what to expect (especially from the treble).
Then I need to know how to fix any issues.

Sometimes they sound so so good and other times . . .
iscm
roberjerman
4,319 posts
 
I'd ditch them and get a pair of Infinity 2000A's. 12inch woofer, midrange cone, RTR electrostatic tweeters in a large box. Built from 1968 - 72 by Arnie Nudell! I have a pair I bought two years ago from the estate of a college professor in CA.     Near perfect condition, never abused!        Same design as your DM70's (but yours have been beaten up and will be expensive to restore!).
iscm OP
40 posts
 
Thanks  roberjerman
I am not ready to ditch them yet.
The leak bass units work OK now and I am sure that the surrounds on the original bass units can be fixed.

I really wanted to know from an owner what to expect from the treble and if mine need to be redone.
The boxes are in exceptional condition and not beaten up at all, but I did not want to pay for an electrostatic rebuild if it was not required.
ct0517's avatar
ct0517
2,041 posts
 
Hi Iscm

Well I never thought I would come across another owner of these speakers here. :^)

A few things I found for optimum setup and assuming your speakers are functional.

First are your’s version one or two? The recommended amp 25 - 100 watts. I would recommend at least 100 wpc due to that woofer. If using Solid State make sure its wattage doubles at 4 ohms as they dip to 4 ohms. The amplifier you are using appears to be 15 wpc - This is not enough to hear what they can do.
That appears to be problem one. You need more power.

Floor Setup
These speakers do not have matrix bracing so they MUST not be placed "as is" on a suspended wood floor. if they are on a suspended wood floor your description of

"the bass is overblown with complex orchestral or progressive"

is pretty accurate.

Solution.
They must be raised on a solid platform, to where the tweeter panel is level with your ears. This fixes two aspects.

It ensures the bass stays tight and clean, and the ESL panel is the most resolving. They like a larger space, do not put them up against walls. They should be free standing.  

Pic 21 on my virtual system shows how I had them setup.

B&W ESL DM70

I used them with and without external tweeters. If your room is heavily damped you may need external tweeters. They are the total opposite of B&W 801’s, in that they like an un damped room just like my Quad 57’s.

The thin curved ESL panel needs to be at ear level, but its shape does give a decent sized sweetspot.

Any ESL repair shop can fix the speakers if they need repairs.

Hope this helps. .

More to discover