Expanding acoustic foam in speakers

[Parky]

I have a pair of secondhand wharfedale 12.2 speakers I want to experiment. They are rather tatty so good for experimenting on. I am thing of using expanding acoustic foam to fill them up and the carve out place for the parts and the woofer port has anyone done anything like this before? If so do you have a brand or type of foam that the best to use?

 

[DVDdoug]

I'm not familiar with expanding acoustic foam. Is it porous like regular acoustic foam?

Regular expanding form is too dense and filling them will effectively reduce the internal volume and the bass will be fouled-up!

Filling the speaker with regular acoustic foam will probably also foul-up the bass by reducing the volume. You might try that first. And if you try it with one speaker you can A/B compare before/after.

Lining the internal surfaces (or stuffing) with something like fiberglass that can absorb internal reflected sound and that can help reduce some internal resonances. But you could be fixing a problem that doesn't exist. Or stuffing with fiberglass may also degrade overall performance. Usually, internal resonances are related to the internal dimensions and wavelength so they end-up in the midrange. If the resonances are above the woofer's operating range they won't be excited.

It also seems like an irreversible modification...

 

[Zek]

stuffing with fiberglass

Do not use fiberglass. Its fine particles can be inhaled, which is harmful to health.
It is better to use cotton acoustic felt.

 

[kemmler3D]

What @DVDdoug said. Any expanding foam I've seen (comes out as a thick liquid and hardens?) is not porous enough to use in a speaker as filling. If you just do a thin layer on the inside walls it might help with resonances, but beyond that, best case you just kill the bass.