Hi,
it would appear to be an earth fault of some kind, I connected the amp in the footwell directly to the battery earth and the buzzing stopped on the rear speakers, I don't understand this as isn't the Amp bolted onto the body and therefor earthed to the battery anyway?
Before I tried the simple stuff I tried the hard stuff first "as you do", anyway on stripping the amp down I found several dry joints on the amp chip itself and also the connector, so soldered them up with no difference, then did the old TV repair trick of squeezing the electrolyte capacitors gently one by one, there was one that changed the tone of the buzz to almost zero, it's a 2.2mf 50volt black coloured capacitor, I don't have one but will change this to see what happens.
Anyone got the circuit diagram for the Amp? That way I'll be able to see what this Cap does.
Edit Update: Changed the 2.2mf Capacitor and it lowered the buzz a little for sure but not the full fault.
I've just ran another earth from the 12volt cig lighter earth to the Amp, when this was just a touch test it stopped the buzz but now that it's soldered in place at both Amp & cig 12v earth the buzz is still there, this makes no sense? I can also take a wire from the body of the stereo CD and ground it on the seat runner and the buzz stops. My only conclusion is the suppression is being done through my body/fingers, we used to get a similar fault on TV's and VCR's.
I don't want to buy an amp yet as I still think this is an external earth or suppression problem, we'll see?
Any more suggestions?
Thanks