noise in my car speakers

I installed an Audiobahn amp which feeds a set of Pioneer 6 1/2 (TS-A1765--180W max) in the front and a set of Pioneer 6x9 (TS-A6975--220W max) in the back. They are wire to the amp via 12 gague wire. Each channel of the amp puts out 75 W. Ever since I installed the amp I now have a hissing in the speakers. It can really be heard when there is no music playing. The hissing gets worse when the engine is started. When the engine is reved up the hissing also gets louder. What is the deal? Will a filter fix this? All of my RCA cables are jacketed. Is there too much power for the speakers? Please help.
 

tool49

Member
2003-04-29 7:33 am
Montreal
Nope, not (never) too much power to the speakers.

I've installed/repaired quite a few amps and all the noise issues I've seen were related to two different problems.

1) Bad grounding; Make sure the ground runs from the amp to the closest chassis bolt you can find. It has to be short. It has to make GOOD contact (i.e. no paint on the chassis or the bolt where the hookup is made).

2) Bad signal cable routing; The power cable and the signal cables, should not, if possible, be run too closely to one another. The noise from the power cables can be picked up by the signal wires and then be amplified which is what probably what you are experiencing. I usually run the power wires by the passenger doors linings (usually not too crowded with cables) and the signal cables from the head unit to the amp in the middle deck (between the driver and passernger seats) keeping as much distance as possible from them to the high power cables in the car.

Other problems are also seen with head units putting out to little voltage on the line outs making you crank the gain in the amps too high. Sometimes this makes the noise pickup problems seem worse than they really are.

A quick way to tell if your problem is related to the first or second problem is to unplug your signal cables from the amp. If the hissing goes away than the problem is not grounding; it has to do with your signal. If you still have hissing with no signal connected, check your amp grounding or the amps itself for faults.

If you disconnect your signal cables from the head unit and the hissing remains, it is definitely problem 2. If it goes away, it can be a faulty head unit also.

Hope this helps you!
Sébastien