B&W CM2 Refoam

[AngelAT]

Hello AKs,

I would like to share with you my first refoaming experience.
I got a nice pair of B&W CM2 speakers but somehow they were not sounfing very well lately. Furthermore, the white rubber/fiaom on one of them broke - a small piece broke off. The original rubber/foam was somehow hard and the cone of the speaker was moving but not very easy.

I decided to try my first refoam. Read alot over the inet and found out that there is not much info about this model refoaming. I found that there are two options - to replace the white foam/rubber with rubber or with foam surrounds.
Locally I found foam surrounds and ordered them - 165 mm (6.5 inch).
The removal of the mid/bass unit from the body of the loudspeaker in not difficult - I just had to unscrew the bolts holding the aluminium plate (and also the grid) and then unscrew the four screws of the mid/bass drive unit.

Made sure to mark the connecting cables.

Then I had to remove the old surrounds - they were very fragile. Breaking like egg shell. Removing them from the metal frame was not a problem. I had to use an exacto knife to carefully remove the remainings from the kevlar cone. Used some alcohol to clean the frame and the kevlar cone.


Then it was time for placing the new foam surrounds. For glueing I used a universal flexible transperent glue I found locally - brand JIP.
First fixed the surround to the kevlar and when it dried for 30 mins fixed it to the metal frame. Here the key thing was the free movement of the cone up and down - without any scraping or scratching.


Then was the reasembly and waiting overnight before connecting them to my system.
And what I can say is that after a few days playing - so that the foams got flexible (or at least that is how I felt it) - I can say that these small speakers have VERY, VERY good sound!


I hope this info will be helpful to someone...

 

[sax6]

Thx for sharing and good job on the refoam thing.

One smally thing is that, the poor things look uneasy, sitting on the cold floor.
Let your woodwork skills build them a simple 39 inches piedestal....

... 3 x thing... is too many

 

[AngelAT]

Thx for sharing and good job on the refoam thing.

One smally thing is that, the poor things look uneasy, sitting on the cold floor.
Let your woodwork skills build them a simple 39 inches piedestal....

... 3 x thing... is too many

sax6, thanks for the reply!
This last picture was taken halfway through my new setup fixing. Otherwise, you are right - they do not sit on the floor.

 

[AngelAT]

Well, was the replacement surround the same flexibility/dampening that the original did? If not, you just changed the physical parameters of the driver and more than likely changed the crossover point and sound.

I agree - you are right!
But then again, do you think that (at the market) you can find absolutely the same characteristics surrounds? Furthermore, the original ones I do not think are of great quality since they got hard/unflexible and lost their characteristics.
What I can say for sure is that the CM2s sound much better now than with the old unflexible surrounds.

 

[Ramseybella]

They originally had Rubber surrounds the way they look.

 

[Bynem]

The previous owner must have stored those CM2s very much in the wrong place. I have B&W speakers that are from the 1980s, and the rubber surrounds are fine (I believe my three pairs have all their original equipment, except for the set that I had recapped).

In the end, I am glad you could bring those kevlar woofers (and the CM2 overall) back to life.

 

[AngelAT]

Just an update!

After the comments here I have decided to correct the mistake. So I ordered rubber surrounds and replaced the foam ones.

Now the B&Ws are at my workbench.

 

[teebee]

How does the rubber sound vs the foam??

 

[teebee]

That gray rubber doesn’t last long... same for the early ’90s Boston Acoustics Lynnfield series and ADS CM MV and SAT series rubbers.

Foam surrounds are said to be sonically superior. I wonder how they would compare. I’d much rather have foam than dried out cracking rubber.

 

[AngelAT]

To be honest, I think the foam sounded a little better. But still cannot make a big difference. But rubber looks better because of the smaller inner lip.
The difference was more noticeable from the initial stiff ones and the foam for sure.