On Monday, June 9, 2014 7:21:13 AM UTC-7, dave wrote:

I have some AR4x that appear to
have the original surrounds from ca 1968. All foam not created
equal. Refoaming is not difficult.
Are yours really foam? I have some AR-2ax's from the early 1907s, and the surrounds appear to be rubberized cloth (which should make a better seal than foam). They have survived over 30 years of California smog with no obvious degradation. I do not remember seeing foam on any of the old AR speakers (AR 1-4) I have seen at the swap meets.

" wrote:
On Monday, June 9, 2014 7:21:13 AM UTC-7, dave wrote:

I have some AR4x that appear to
have the original surrounds from ca 1968. All foam not created
equal. Refoaming is not difficult.
Are yours really foam? I have some AR-2ax's from the early 1907s, and
the surrounds appear to be rubberized cloth (which should make a better
seal than foam). They have survived over 30 years of California smog
with no obvious degradation. I do not remember seeing foam on any of the
old AR speakers (AR 1-4) I have seen at the swap meets.

Its not foam or rubber. It's treated cloth. Some kind of substance. I've
seen the treatment seep down, but the stuff might be different on different
drivers.

Greg

On 06/11/2014 11:36 AM, wrote:
On Monday, June 9, 2014 7:21:13 AM UTC-7, dave wrote:

I have some AR4x that appear to
have the original surrounds from ca 1968. All foam not created
equal. Refoaming is not difficult.
Are yours really foam? I have some AR-2ax's from the early 1907s, and the surrounds appear to be rubberized cloth (which should make a better seal than foam). They have survived over 30 years of California smog with no obvious degradation. I do not remember seeing foam on any of the old AR speakers (AR 1-4) I have seen at the swap meets.


I've had a bunch with cloth surrounds too. I have a pair of AR2 in the
middle of a refinishing project. These are AR4x which were "mass
produced" by Cambridge standards. They have been on a shelf on my patio
for at least 10 years as the tweets (HF drivers) are smoked; the rubber
surrounds are still alive and well. I am 30 miles North of UCLA. The air
here is not the cleanest. Houston (Petro Metro) will eat your surrounds
faster than anywhere.

On Wednesday, June 11, 2014 8:49:22 PM UTC-7, GS wrote:

Its not foam or rubber. It's treated cloth. Some kind of substance.
I've seen the treatment seep down, but the stuff might be different
on different drivers.

Greg
On reflection, I would guess that the cloth is impregnated with silicone rubber. I do not remember any of it oozing down; however, my sample size is small. Still, foam does not make sense for acoustic suspension woofers.

Foam does not make sense for acoustic suspension woofers.

If it were porous, it wouldn't make sense for any woofer. But it isn't
particularly porous.

On 06/13/2014 05:19 PM, William Sommerwerck wrote:
Foam does not make sense for acoustic suspension woofers.

If it were porous, it wouldn't make sense for any woofer. But it isn't
particularly porous.

Two major divisions in foam, closed cell, open cell. Open cell is what
we use for microphones pop filters, closed cell for gasketing, etc.

"dave" wrote in message
m...
On 06/13/2014 05:19 PM, William Sommerwerck wrote:

Foam does not make sense for acoustic suspension woofers.

If it were porous, it wouldn't make sense for any woofer.
But it isn't particularly porous.

Two major divisions in foam, closed cell, open cell. Open cell is what we
use for microphones pop filters, closed cell for gasketing, etc.

Thanks for the clarification.