Hi everyone. I'm new to the forum, hope someone can help. I have a thumping noise coming from the sub when the radio is on and the sound is on 0. I have replaced the rca cables and it still happens. The ground cable has been checked and is perfectly in place. The system was working perfectly for a long time and suddenly the problem started. Could it be the head unit? What else could it be? The system was working perfectly for a long time and suddenly the problem started. Could it be the head unit? What else could it be? Please help

 

Pioneer head unit?

 

Alpine head unit. I've narrowed it down to the rca connection to the amp. Could be one of 3 things. Either a short in the mids, going to try and ground the rcas or its my 2 month old amp. Only 2 of a 4 channels are currently working. Still a slight whining noise though.