I installed my sub and speaker amp a few weeks ago and have had no problems until now. I did mine myself and have done mates installs in the past.. ive got a fair idea. Since yesterday, ive got interference coming out of the sub. It sounds like someone tapping the top of a microphone to test it, but constantly. boom...boom...boom...boom for about 30 second then itll stop, a minute later itll repreat itself. It does it if im playing music or not, and regarless of what setting the decks on (radio aux cd) Anyone?

First thing to do would be check ALL the connections in your sound system, make sure none are loose / corroded (ie all speaker wiring, all power wiring, all rca's etc). and make sure your head unit and amp both have good earth connection points to the car. Sounds to me like its just a loose wire between the amp and the sub (i'm assuming the sub is in a box - take it out and make sure the connection between the sub and the terminals on the box aren't loose either). cheers Sam

yeah sounds like bad earth connection or loose connections on the wires to the sub

Do you have any filters on it?

As stated above sounds like loose speaker wire. Good luck mate.

A dodgey earth is to blame! thanks guys