I agree, The fibreglass theory only works on a Ported enclosure as far as I know, and even if it did work in sealed, it would not be audible enough to the raw human ear!! Now if this was a ported, I noticed it almost right away, so with sealed, Ima say ditch the glass Idea..save your money and buy something a little more worth your while!

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I've seen many things in my time, but to achieve any of them is a different story!