Foam or Butyl?

[pmsummer]

My EPI 100W speakers have developed cracks along the butyl surrounds. Shame on me, but I've patched them with silicon for now.

Should I replace them with butyl (from RS Sound), or go with foam? Hu at Human Speakers is ambivalent about the choice, so I thought I'd ask the combined Great Wisdom of this forum.

[Pete B]

Rubber surrounds are *much* heavier, and it will alter the in box resonance if you substitute the wrong type.

See section "Update for the ML-1C" on this page:

http://64.233.161.104/search?q=cache:xaW7A...er+repair&hl=en

Pete B.

>My EPI 100W speakers have developed cracks along the butyl

>surrounds. Shame on me, but I've patched them with silicon for

>now.

>

>Should I replace them with butyl (from RS Sound), or go with

>foam? Hu at Human Speakers is ambivalent about the choice, so

>I thought I'd ask the combined Great Wisdom of this forum.

[dynaco_dan]

>Rubber surrounds are *much* heavier, and it will alter the in

>box resonance if you substitute the wrong type.

>

>See section "Update for the ML-1C" on this page:

>

>http://64.233.161.104/search?q=cache:xaW7A...er+repair&hl=en

>

>Pete B.

>

>

>

>>My EPI 100W speakers have developed cracks along the butyl

>>surrounds. Shame on me, but I've patched them with silicon

>for

>>now.

>>

>>Should I replace them with butyl (from RS Sound), or go with

>>foam? Hu at Human Speakers is ambivalent about the choice,

>so

>>I thought I'd ask the combined Great Wisdom of this forum.

>

Hi there;

The Dynaco woofers have a very soft rubber surround.

I believe most, if not all European woofers use rubber rather than foam.

I bought 10" and 12" rubber/neoprene surrounds off ebay several years ago.

This is a slightly heavier feeling neoprene than the Dynaco.

When I asked if 11" (AR-3 + 3A) diameter were available I never received a reply.

I made several requests and no replies were forthcoming.

I never did see them on ebay again.

I was just at a high end stereo store a few hours ago and they had a subwoofer with a rubber surround but it looked real heavy.

I am sure it would alter the output some but can we hear the difference?

Good luck.

[pmsummer]

The consensus opinion across the net seems to be foam. Foam it shall be.

Being as I'll be replacing the caps and wiring (and terminals) at the same time, pinpointing where any sonic differences are between the rubber and the foam is going to be difficult.

BTW: The darn little things STILL sound good even with the patched surrounds!

Thanks for the input!

[Pete B]

Let me remind you that the lay consensus is often wrong, however one thing about speakers is that they usually work even when things are far from optimal. The link is the opinion of a pro, most on the boards are not, but hey do whatever you want.

>The consensus opinion across the net seems to be foam. Foam

>it shall be.

>

>Being as I'll be replacing the caps and wiring (and terminals)

>at the same time, pinpointing where any sonic differences are

>between the rubber and the foam is going to be difficult.

>

>BTW: The darn little things STILL sound good even with the

>patched surrounds!

>

>Thanks for the input!

[pmsummer]

>Let me remind you that the lay consensus is often wrong,

>however one thing about speakers is that they usually work

>even when things are far from optimal. The link is the

>opinion of a pro, most on the boards are not, but hey do

>whatever you want.

Lay concensus is not just often wrong, it's QUITE often wrong!

Considering Huw Powell and Winslow Bruhoe to both be pros, it was their ambivalence that threw me (EPI did after all switch from rubber to foam without any other changes early on).

However, Master Bruhoe has suggested late (on his website) that sticking with the butyl would now be his preference. So, I've decided to follow the Master's advice.

Call it a rubber match.

[Pete B]

>Considering Huw Powell and Winslow Bruhoe to both be pros, it

>was their ambivalence that threw me (EPI did after all switch

>from rubber to foam without any other changes early on).

Hi P.M. Summer,

You mention the switch and no other changes, are you sure? The cones might have looked the same but the one used with the rubber edge should have been lighter, unless they wanted lower moving mass when they switched.

It's intesting that most of my better speakers, really all of them have rubber edge drivers. Most are getting old and I've been looking into them as it seems the rubber becomes very stiff with age.

Anyway, I came across some notes where I weighed replacement foam and rubber edges for standard 10" woofers:

rubber 34.5 g

foam 5.8 g

There's a significant difference.

Pete B.

[pmsummer]

Pete,

>

>Anyway, I came across some notes where I weighed replacement

>foam and rubber edges for standard 10" woofers:

>rubber 34.5 g

>foam 5.8 g

>

>There's a significant difference.

>

>Pete B.

>

The non-chalance of Bruhoe and Powell was/is quite a surprise. The LATEST comment from Mr. Bruhoe was to stick with rubber. And so I have decided to do.

As for other changes when EPI switched from rubber to foam: I don't know. All I read was they changed "mid-stream", and that (combined with Bruhoe/Powell's relative indifference) made it seem a bit like the great "cable wars" of audio.

I'm putting off work on the 100s until after a thorough evaluation of some 150s I got last week. The surrounds (rubber) seem fine, but I'm going to Armorall them before I spend much time listening to them. If I decide they need surrounds as well, I'll do both pair at once.

After all... it IS a hobby. :-)