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I've noticed that the foam inside the rear cover on my 2420 compression drivers has deteriorated and becme a little sticky and doesn't "bounce back". How important is the quality of these foam inserts in terms of affecting sound quality? Should I replace these? With what? Altec uses a 1/4" thick felt pad, while JBL seems to always use plastic foam.
Thanks,
Tom
Hi Tom
Well can't answer but I have the same concern with 2425's. Same question?? Giskard? You out there?
Rob:)
I have opened quite a few vintage JBL compression drivers and have seen a variety of foams and the older ones used felt. I am not sure if it makes much difference what you use. Replacement foam is available from JBL for the 2441 I would guess it is still available for the others as well.
I had the same problem on the 375's,175's-I ordered new ones from jbl for $6.00 ea,they only had 1 size so I had to cut the pad downto size to fit the 175,
if anyone needs part # I have it around here somewhere with a picture of the replacement
jbwolf,
A part number would be great!
Thabks,
Toml
HI Tom,
I'm taking the number/description from the packing list---
model#60398 PAD,DAMPENER,POLYESTER,GR $6.70
I've also taken a picture of the part,I keep extra's on hand because of the work I do,this part will have to be cut down to fit your model driver,JBL no longer sells the dampener for older models but it can be cut down to fit the original,I use the old tar-cardboard part as a templet(less all the foam that came off) . I have seen this condition many times before on older drivers and if the foam get on the diaphragm it hell to get it off,but it can be done,but with vintage equipment why take a chance,I feel that the new replacement diaphragms just dont match the older original parts sound quality.
I just scraped the old, sticky foam out of the cover of one of my 2420s, cut a new pad out of 3/8" foam following a template I made and placed in on top of the old backing. When I replaced the cover on to the driver housing I felt it compress and resist going all the way down to close the gap. I was afraid to push too hard as it my touch the back of the domed diaphragm and deform it.
Any experience with this? Any informed suggestions?
Thanks,
Tom