Disintegrated speaker foam surrounds

[Michael Weiss]

Share your suggestions or experiences here. Thanks.

[Ken Dryden]

I had that problem with a set that were around 18 years

old, I trashed them and bought new speakers, as the

technology had improved over time.

[Kevin Bresnahan]

There's a place about 10 minutes from my work in Stoneham, MA called New England Speaker. They came highly recommended. I brought in two woofers and by the next day, I was listening to my old Boston Acoustics A-100s like they were new. I had forgotten how good the bass was.

I believe they charge $45 per woofer. Not cheap, but when they're done, you have new speakers.

I watched them do my speakers. I imagine there are two keys to doing it right. First, you have to make sure you apply the adhesive and set the foam suuround with the cone "locked" in the "out" position. If you don't, the woofer excursion will be limited. They use curved pieces of plastic in between the voice coil and the magnet. They next most important thing is that when you "lock" the woofer in place, if must be as near to centered as possible or it will bind up and not work right. I actually had to get one of my woofers re-aligned after I got it back because there was a slight buzz in one of them. They say it wouldn't have happened if I had waited a couple of days before using it, so mail order repairs shouldn't have this problem.

Kevin

[Son-of-a-Weizen]

I had my 4 Advent Large(s) (purchased in '79) re-foamed in '98 or so. All those years of Black Flag, Blue Oyster Cult, Suicidal Tendencies and the Angry Samoans put a major hurt on them. Kevin's $45 a pop sounds about right.

[Stefan Wood]

...... in addition to the Captain and Tenille collection you keep boasting about, that alone can rot foam, wiring, and the faux wood panelling of the speakers!

[Son-of-a-Weizen]

Don't knock the Cap'n.......you can never have too much of the Cap'n around. Are the re-mastered editions out in Japan? I need 'em all w/obis!

[Michael Weiss]

Mine are Snells from 1988. I bought a foam surround replacement kit online for $19 figuring that's all I have to lose if I screw it up since the original surrounds are disintegrated anyway. If that doesn't work I guess I'll have to buy new drivers from Snell.

[Daniel A]

To switch the surrounds properly you would need some special equipment. You could possibly get OK results without them, but it takes some practise. A pro would probably use a multimeter and a tone generator to test the element. A Kevin said, it's a difficult task to center the cone properly.

Here's a guide, unfortunately in Swedish, but maybe the pictures may be of some help:

http://carlssonplanet.com/forum/viewtopic.php?t=1459

[Claude]

If you do a Google search on "refoam", you can find a lot of information and offers on that subject.

Refoaming speakers generally changes the (bass) sound slightly, as the replacement material is not identical in it's physical properties to the original foam.

[Kevin Bresnahan]

I watched the guy fix my speakers so I could see that alignment would be a "gotcha".

First thing they do is remove the old foam surround material. They used a razor blade, but it didn't look to be very sharp. Removing it from the paper cone looked like an acquired expertise. The guy carefully shaved off the old foam until it looked like he had it down to paper. I imagine the better you get it cleaned, the easier it is to glue the new surround.

Next they removed the center dust cap. They were pretty cavalier about it, simply sliding an old razor blade under an edge and popping it off. I imagine they use a dull razor blade to avoid cutting the paper cone. FWIW, it turns out that the reason they are cavalier about it is that they simply replace it with a new one if they damage it.

After the dust cap is removed, they take these plastic sleeves that look like a cut-up drinking cup. These pieces are slightly curved to the approx radius of the inside of the woofer. They slide several of these down into the opening. Each piece looked to be about 1 inch in width. They stuck 4 or 5 of them in them while carefully checking that the cone was still centered in the voicecoil. You have to use enough material to "bind up" the cone. Once you have it "frozen", pull the cone up until it sticks out of the basket about at the maximum throw.

With the woofer at this extended position, the you can glue in the new surround. From the looks of it, more goopy glue is better and don't skimp or you'll leave air holes. I suppose air holes are less important on a ported speaker, but mine were acoustic suspension so air holes would kill the sound. I think the guy at New England Speaker went a little overboard with the glue as there is a lot of it showing near the surround but since the speakers sound great, it really shouldn't bother me.

After gluing the surround, wait at least a day to take out the shims. When you take out the shims, the woofer cone will try to pull back in as far as the foam will allow. This tension is what makes the cone "float" in the voice coil. It should be able to freely go in & out in the voice coil. If it doesn't, your alignment is off. I don't know how they fix this... it must be a "trick of the trade".

Glue the dust caps back on when you're satisfied that the cone is freely moving and after that glue dries, you should be good as new.

Kevin

Edited April 20, 2006 by Kevin Bresnahan

[Kevin Bresnahan]

I almost forgot...

When they removed the old foam surround, they had to cut off the thick cardboard that went around the outer edge of the speaker (on the metal). When they were done, they put a new cardboard piece on top of the edge of the foam surround. I hope the kit you got in has this cardboard piece as it looked to be near impossible to get the old one off without damaging it.

Kevin

[porcy62]

I would't try it by myself on expensive loudspeakers.

[Daniel A]

After the dust cap is removed, they take these plastic sleeves that look like a cut-up drinking cup. These pieces are slightly curved to the approx radius of the inside of the woofer. They slide several of these down into the opening. Each piece looked to be about 1 inch in width. They stuck 4 or 5 of them in them while carefully checking that the cone was still centered in the voicecoil. You have to use enough material to "bind up" the cone. Once you have it "frozen", pull the cone up until it sticks out of the basket about at the maximum throw.

With the woofer at this extended position, the you can glue in the new surround.

Another way to do this is to apply a small current to the speaker element, for example from a 1.5 V battery, which makes the cone to rise. The power from a small battery will not harm the magnet.ö

[Michael Weiss]

Ugh...

I've found illustrated instructions online which more or less match the above posts. Thanks for the suggestions. Nothing left to do but get my hands in there...

[Kevin Bresnahan]

This was the tricky part:

As I said, the place I went to used plastic shims, not paper, although the plastic was very thin. The trick appears to be making sure you get the paper/plastic material as far down into the voice coil as you can to make sure it's well centered for the whole length of the coil. If you only shim it at the lip, it could tip at the back and it won't work.

[tatifan]

There's a place about 10 minutes from my work in Stoneham, MA called New England Speaker. They came highly recommended. I brought in two woofers and by the next day, I was listening to my old Boston Acoustics A-100s like they were new. I had forgotten how good the bass was.

I believe they charge $45 per woofer. Not cheap, but when they're done, you have new speakers.

Kevin

That's funny, same happened to me with those exact speakers a few years ago! Boston Acoustics themselves actually had replacements, and shipped them out for pretty cheap. Still running strong today in my 2nd system!

[Allan Songer]

I had that problem with a set that were around 18 years

old, I trashed them and bought new speakers, as the

technology had improved over time.

BITE YOUR TOUNGE!!!

(My speakers are over 40 years old--no foam on THOSE woofers!)

[Kevin Bresnahan]

(My speakers are over 40 years old--no foam on THOSE woofers!)

Shellac on cloth? Have you checked that it's not all cracked? That material isn't immune to age. You may find yourself switching over to foam some day.