Back Speaker Trouble

[TimG]

in my 1998 Grand Am GT, I installed some Pioneer 6x9's, and while I'm listening to any music, when the beat is a kind of low bass thump, somewere in the back of the car, it sounds like it's shakeing something. It sounds really bad, like something's loose, but I don't think anything is, my dad and I had the screws pretty tight. Anyone know how I can fix this problem? It's like right under the back window.

[birdhouse]

our car's = rattle machines... it's most likely not something you did in the install, but more or less something that's on the car rattling... look and feel around in the trunk when you have a bassy song on, you might be able to find the problem then