The PO of my 1967 Fastback had cut the trap door for speakers. It was not a professional install. Judging from the number of mounting holes, there had probably been at least three different sets of speakers mounted at various times. I installed a new set of 6x9 speakers and the grilles covered all of the holes from the front, but from the trunk the large speaker holes and the old mounting holes looked bad.
I made a couple of cover plates out of 1/4" garolite (the stuff circuit boards are made) to hide the holes. The garolite is very dense and should not resonate. I also filled the gaps in the hollow parts of the door that were opened up by the speaker hole with epoxy so they would be buzz free too.
I made a couple of cover plates out of 1/4" garolite (the stuff circuit boards are made) to hide the holes. The garolite is very dense and should not resonate. I also filled the gaps in the hollow parts of the door that were opened up by the speaker hole with epoxy so they would be buzz free too.