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View Full Version : How Can You Tell When It's Time to Re-Foam???



toddalin
09-12-2005, 07:11 PM
I have a pair of L112s with the original surrounds. They appear as new, but I would bet that if they are touched, they would disintegrate.

My Roger Sound Labs (L112 copies) also have foam (and are much newer than my JBLs) and I found they needed a re-foam when I cranked them one day a couple years ago and the surrounds blew out. When I touched them, the foam disintegrated under my touch.

My four Cerwin Vega surround speakers also have foams that concern me as they have been in place over 10 years.

Is there a nondistructive way to evaluate the condition of the foams?

edgewound
09-12-2005, 07:34 PM
I have a pair of L112s with the original surrounds. They appear as new, but I would bet that if they are touched, they would disintegrate.

My Roger Sound Labs (L112 copies) also have foam (and are much newer than my JBLs) and I found they needed a re-foam when I cranked them one day a couple years ago and the surrounds blew out. When I touched them, the foam disintegrated under my touch.

My four Cerwin Vega surround speakers also have foams that concern me as they have been in place over 10 years.

Is there a nondistructive way to evaluate the condition of the foams?

There's really no non-destructive way to check the foam surround other than looking at it closely. The usual clue most people get that it needs to be
replaced is when the woofers start to rattle upon low frequency program, they remove the grill....and "EEEEKKKKKK...My speeeeeekers are blown!!!"...But here, we're not like most people, are we? We check our speakers like a good service station attendant checks under the hood. Remember those guys?...Oops showing age here. I good indicator of rotten foam surrounds is to rub it with slight pressure or better yet...give it a little pinch. If a chunk of foam comes out...it's time to re-do. A big warning here...DON'T PLAY THE SPEAKER WITH A ROTTED OUT SURROUND OR YOU RISK DAMAGE TO THE VOICE COIL. This becomes especially apparent due to the slowly disappearing supply of some JBL Factory recone kits. And as some members have found out lately some are becoming ridiculously expensive.

Hope that helps.