Foam degradation

So assuming I don’t look at new speakers I need new foams to cover the drivers and appreciate there are a few sources.

Until a recent DBL thread I’d never considered the damping foam in the SBLs - if the external foam is disintegrating how about the internal foam, and I have no idea which boxes it’s in?

The internal foam has to be there for a reason, could that be a cause for my recent system fatigue and how on earth do you evaluate without removing mid/bass drivers or middle section and then having to redo the gasket etc?

I’d always considered speakers to be pretty much maintenance free unless you managed to blow one of the drivers (been there done that with the tweeters) but clearly not.

I have some old Heybrook HB1s and the ‘rubber’ surround for the mid/bass drivers have perished - I see there are repair kits available, may be worth a dabble with those.

In addition, what causes it? If it’s UV light related hopefully internal foam would be more durable, and equally if the gaskets are intact any atmospheric cause should be limited too?

I have several products from the 90’s to early noughties with plastic/rubbery covers which have become very sticky or tacky - USB hubs, Psion organiser, fancy computer mice etc - manufacturing issue or something atmospheric where I live?

Plastics disintegrate. Cheap ones do it faster and the softening agent seeps out, causing this terrible stickiness (and the remaining poly-carbonates in he plastic becomes brittle - there is a reason for the agent to be there in the first place). UV is a big factor, most plastics types have a time-to-live in UV light. Foams also start to get brittle over time, some more, some less. Again, evaporation of components like softening agent is a factor, but being away from UV helps. In the end, I suppose each kind of foam and plastic behaves differently, and if you don’t know the exact chemical makeup you can only hope or check by opening up, if possible. I had TDL speakers once, and the transmission line openings where covered with bricks made from a foam-like substance (but more air than substance). After 20 years or so, they looked still fine, but when I touched them the bricks disintegrated into basically a black powder. However, the foam stuff inside, which lined the speaker chambers and the transmission line, still felt ok.

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Plus yeah, the foam inside the speakers has a purpose :slight_smile: namely to turn the acoustic energy inside the speaker (coming from the membranes’ back sides) into heat. If the foam disintegrated or the foam’s structure and behavior changed considerably over the years, there must be an effect of that, probably not a good one.

There’s long haired wool (someone here will give you the genus of animal from which it came) in the lower box. I don’t know what is in the middle box or the top box, if anything. But again, someone will.

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The first pair of Naim speakers I had were pretty much the first domestic ones they made - serial number 2, with Mordaunt-Short mid/bass and Goodmans tweeters. There were foam panels inside the cabinet. At some point the foam deliquesced - it was really wet and horrible. I imagine that foam plastics have improved since then…

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