Hi,

I've just installed a Sony Cd head unit, and Sony 4-way amp driving two 7 x
10's on channels 1 and 2 and a sub which is bridged across 3 and 4.

The head just drives 2 100mm units in the dash

Systems sounds great on both CD and Radio but when I switch on the engine I
get a high pitched interference which varies in pitch according to revs,
regardless of the source (CD or Radio).

My question is what causes this interference and how can I kill it ?

TJ