Originally Posted by Clockwork

RB, I used a thick foam like this https://www.selfadhesive.co.uk/scapa...th-7-mtrs.html (as I knew it would compress, but even a thinner one would still be fine I guess depending on its density).

I put 3 pieces (cut 0.5" strips the width of the tape) between screw holes around the perimeter of the mid-bass speaker hole (used 9 pieces in total) and then put the mid-bass speaker back in and any vibrations from the speaker are now lost in the foam.