ok, i have a mtx 500d amp and a 12" alpine type r sub and i can not get it set up right. I have installed many systems but i have allways used rca's. I have the stock bose system and i tried to tap into the sub signal and it didn't work, then i tapped into the rear driver speaker and it didn't do **** either. I then tapped into the pass rear speaker and i finally got a signal, but only with one wire(i'm not sure if its pos or neg.) when i try to conect the other one the sub goes crazy. It works but to get any sound i have the gain and the bass boost turned all the way up, and then after a few min. the sub will start to kinda buzz so i unhooked it. What is going on????

 

any ideas?