so i'm getting ready to sell my car, so i took out my 2 amps and my component set in the front and replaced it with alpine 5x7's to run off the h.u. I installed the right speaker, and it sounded great and loud, the left one, my friend installed and it came out very quiet, and I'm not quite sure what it could be. bad connection doesn't seem to be a problem, maybe out of phase?