I just finished installing my system a few weeks ago, and I have a persistent electrical noise that is present at lower volumes, or when the music is off and the amp on.
My setup is as follows: 2001 VW Jetta GLX Audiobahn A8002T (class a/b 800w RMS @ 4ohm mono) 4 gauge power running from battery to trunk approx 14 feet 60A fused near battery terminal. 4 gauge ground ~3ft running to a luggage tie down bolt (unpainted, looks to be connected to chassis).
The amp input is run from the factory 250W auxiliary amp (pre-amp, which is still a high-level input from the factory deck) directly to the amp's speaker level input.
The voltage at the amp under the heaviest loads is about 12.5V, but stays above 13V under moderate load. The system hits hard as hell, so power or ground may not be a problem?
I'd love to run low-level inputs, but my deck doesn't have any, and before I go out buying a bunch of stuff, I'd like to know what usually causes these electrical noises..
Could it be a result of the speaker-level inputs, or ground location? What is most common for electrical interference? Any help is appreciated.
Did you run the speaker level inputs alongside the power wire? You may have the gains set too high on the amp (I had to turn the gains down a little below optimum on my wife's Xterra to get the engine noise to go away). I never use any existing bolts for my grounds (I always drill a separate hole through the floor and use a bolt with lock washer for my ground).
The speaker level input is run from the factory mid/high amp, which is nowhere near the 4 ga power wire going to the subwoofer amp. It is in somewhat close proximity to the sub amp's ground wire (a foot or so away). The speaker level input on the sub amp requires it's own ground which I routed to the tailight mount (should be contacting bare chassis no problem).
I'll try a different ground for the amp itself, but I don't believe that to be a problem, because the voltage measured at the amp is right on par, anywhere from 12.x - 14.x depending on load.