OK I was listening to my ipod in my 97 town car (using a cassette tape) and then the bass in the back speakers make a weird sound and then was just gone. The speakers are not blown, I can put all the sound into any one I want and they still work perfectly and when I crank up the treb you can here it in the front and rears but when I go to turn up the bass, it only comes through in the front two speakers and it isn't very good, with nothing in the rear 2. HELP ME. What happened? Blew a fuse, or maybe I blew the amp. I know I have one back there. Has this ever happened to anyone else? If there is an easy to diagnose this i would greatly appreciate the input.