Stereo Help (ground loops)

I have tried everything to get rid of the the annoying alternator humming in my speakers. I have tried different RCA cables, different speaker wire, different crossovers, different grounds for all three amps, the same ground for all three amps, power straight from the battery to the deck, different ground for the deck, running the RCA's and power cables on opposite sides of the car, unplugging the antenna. I think it might just be the deck, any thoughts or help.:runaround:

is it a pioneer headunit?

Yes, it is a Pioneer Premier DEH-P500UB.

pioneers are so notorious for rca noise. here's a simple fix, not a complete one but it does make it better.

http://www.icixsound.com/vb/showthread.php?t=40067

interesting fix, but technically the signal ground is NOT chassis ground. I guess if you have blown the ground from hot-swapping the RCA's, chassis grounding the RCA's is better than no gnd at all.

So i switched out the deck to a clarion DXZ675USB, same problem. It is not the RCA's, the speaker wire or harness, the crossovers, the ground. It shouldn't be that i am drawing to much power form the alternator, i am only running about 300 watts RMS. It is also all hooked up to a capacitor, I don't think that has anything to do with it, but all three amps are hooked up to it. Any more ideas or suggestions?

I forgot to add that you hear just about all electronic noise in the speakers. Signal lights to changed songs on the deck.:banghead:

how are you grounding the cd player ? If you are using the ground from the wiring chassis .... DON'T. Ground the cd player to something metal behind the dash.

Neither the power to the deck or the ground go through the wiring harness, the power is to the battery and the ground is in the back of the dash.

interesting, because what you are describing is usually the result of a poor ground.

Let's try a more scientic method to try and determine where the noise is coming from. Make shorting plugs for all the RCA inputs you have to the amps, unplug all the RCA's and anp put the shorting plugs in. A shorting plug is just a male RCA end where the two posts are pushed together and soldered if possible - it shorts the RCA input to signal gnd on the amp. Leave everything else connected like it was and start the car. If the noise is still there, it is one or more of the amps, if it's gone then it's further upstream. What other components (other than speakers) do you have in the system and where are they installed. Is the crossover active (before the amps) or passive (between the amp and the speakers) ?

It is a passive crossover, could it be the ground for the battery to the chassis.

Well i have triple checked all my grounds and everything else. I was listening to my engine and it sounds like the alternator was working very hard. I think i might be drawing to much current from the alternator.

What kind of car is it?

Its a 2000 Pontiac Grand am, 3.4L.

you need to start at the amps and work your way back thru the chain .... just wildly jumping from one thing to the next will typically take a lot more time. I assume with that number of amps you have, that you are using the crossover in the headunit or the ones built into the amp. Does the alternator whine come thru all of the mid/tweet speaker groups or just one (some of them) ?

I can only assume you are drawing quite a bit of power, You will need three ground wires for the CAR. Battery to engine, battery to chassis, and chassis to engine. Many people do the big 3, whigh is replacing those wires with bigger ones (or just adding a bigger one on top of them) plus a bigger power wire from the alternator to the battery.

What amps are you running and how much power do they have ?

The alternator whine comes through all of the speakers except the subs. I am running a Clarion APX4240 for my front/rear speakers with 240RMS or 600max, a Rockford Fosgate 2.6 amp for the subs with 120RMS or 150max and a Sony amp for the overhead pioneer tuneup speakers with 15RMS or 20max. All of this is hooked up to a Stinger 1 farad capacitor.

Actually the Clarion APX4240 is 240RMS or 400Max

if it's coming thru all of the mid/tweet speakers, then it's not going to be a passive crossover unless maybe you have all of them mounted right next to each other. With the stereo off, unplug the 4 RCA's going to the clarion amp - then turn on the car and the stereo and see if the noise is still there.

I unplugged the RCA's and the noise went away, so i installed a ground loop isolator and the noise is 100% gone. Thanks for all of the help.

kind of a bandaid fix, but if you are happy with it then everything is cool.