Why would you put closed cell foam in the woofer compartment?
Because I was advised to do so by an engineer at Kef Audio UK. So I have used a thin layer of it (4mm) inside the woofer compartments. Here is what I understood from the conversation that I had with him…
Bass waves are absorbed by ‘Open Cell Foam’ (which is a bad thing!). Instead you should use ‘Closed Cell Foam’ which does not absorb bass waves, but instead redirects them. However, even though a thin layer of Closed Cell Foam does slightly reduce the space/volume inside the cabinet, it does still have some ability to absorb/muffle any stray midrange information coming out of the rear side of the woofer.
SClark please give me your opinion.