Jean,
Have you checked to see how much vibrations from the woofer make transmission through the rear baffle at various bass frequencies?
It just seems to me that the resonances and vibrations from the speaker cabinet would far exceed that from within the capacitors and this would be worth testing and I am sure a some simple test with Floyd Dark Side of the Moon would tell you this..LOL
For this reason would it not be better to completely de couple the crossover from the speaker cabinet?
Okay removing the crossover components from the interior of the bass enclosure is
acknowledged as better for "audio" but if you are critical of vibrations why attach the crossover panel to the speaker box and rear panel the largest panel most susceptable flex and to vibrations?
:dont-know .
Sorry if am am a pain in the arse.!
The Doctor
Ps Be careful of the fibreglass, it can make you very itchy in all the wrong places..Muhhahahah