I recently installed a sub woofer to my stock sound system. I put in a capacitor and a alpine v12 amp. Now i am getting a hum from the sub. I first had the speaker wires on the same side as the power cable to the amp. So yesterday i put them on the other side of the car. I still had this annoying hum so i went to radio shack and got a ground loop isolator. When i put this in i had no sound out of the sub. Anyone have any ideas.