Audio Systems: car stereo, ground loop isolator, sony xplode

Question
I have a pioneer head unit i think it's a 3600 series owners manuel is in car,2 360 watt pioneer 6x9's,factory fronts,2 10 inch sony xplode 1100watt peak,amps -- 1 80watt(6x9's),1 330 watt,1 400 watt (Rears) both sub amps have built in crossovers. 4 gauge power wire to junction box 8 gage running to amps.I have very bad distortion in all speakers hooked up to amps. the distorton is so bad it drounds out music if volume is too low.if volume is at 00 i still fell bass because of distotion. Amps are grounded directly to frame I drilled a hole in the tunk and ran wire through to frame. Thr distortion is from head unit because it is still there with engine and accesories off,distortion is not realative to the idle of the car either. RCA jacks are opposite side as power cables rca's are fosgate cables. any suggestions would be appreciated. car is 1994 chevy caprice box in trunk head unit is only 2 mo. old

Answer
Hello Erik,
I would first disconnect everything from the head unit and if the head unit has speaker level outputs try connecting a speaker and see how it sounds. Also if you are using the factory power wires from the car wiring harness this could be part of the problem. With most factory wires they are too small of diameter to supply enought current to power up a high powered stereo correctly. The battery/memory wire should be ran directly to the battery. I also run a heavy gauge wire to the battery that is switched on from the ignition with a heavy duty relay. You may also want to install one or two stiffening capacitors to pick up the slack in the power line from music peaks. Also try this, with the radio playing disconnect one RCA cable at a time to locate which cable may be causing feedback by way of a groung loop. Whichever cable is causing the noise this is where you need to install a ground loop isolator. I also have noticed that your speakers are under rated for the output power of your amps, your speakers should be rated(power handling)at least at the rms output of the amps.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net