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.

 

With a cap. in parallel with the amp you shouldn't have a hum from the power side. The cap should discharge into the line and resolve it. It sounds like you have a bad ground. Either the deck, the RCA cables shielding, and/ or the amp.

 

Does the noise change with engine rpm? With the engine off is the noise still present? If so, try relocating the ground. You said speaker wire was moved, are you runing speaker level inputs into the amp?

Maybe you just have the noise floor set top high (gains too high).

Dh

 

Im having the exact same problem, going to try moving the ground tomorrow.

BTW, I'm BAAAAAAAAAAACK. haha.

 

Okay moved the ground around a bit...same problem. I ordered a new head unit saturday, it MIGHT get here today, then i'll let you know if anything changes with getting a bit of a cleaner source. Here's hoping.