**** ground loop...help!

[D-C 10+ year member]

Hi all. I'm having a tough time getting rid of some noise in the system. Seems like a ground loop, and it's pretty independant of engine RPM. If I plug in RCAs, that's when it happens- a little bit with the first amp, and a bunch more when I plug in the second amp. It goes away as soon as the amps are powered down.

The HU is grounded to the chassis in the front, the amps are grounded to the same spot near them in the chassis at the back. Both are ground down to metal. I also have an additional ground strap from the cab to the frame rail. This is all on a 2001 GMC pickup by the way. No other electrical system mods (big 3 etc.) have been done.

So anyway, I'm not sure what to try next; any ideas would be appreciated. I'm hoping I just missed something.

Thanks!

P.S. one thing I forgpt to mention- my rear factory speakers are still hooked up to the HU's stock amp/stock harness if that matters.

Click to read more...

 

[jrz126 10+ year member]

try grounding the HU and amps in the same spot.

 

[D-C 10+ year member]

ok, I'll give it a shot. I originally thought having such a long ground wouldn't be good.

Any other suggestions would be great too, I won't be working on it for a few days.

 

[ballstothewall 10+ year member]

ground loop isolator?

 

[phantom240 5,000+ posts]

ground loop isolator?

Thats what my money's on. if grounding your amp again doesnt help, try one of those... its worth a shot considering its designed to reduce ground loop noise.

 

[PRIVATEpastry 10+ year member]

Did you run your RCAs alongside your power wire? If so, just run the RCAs on the other side of the car.

RCAs near power wire sometimes generates feedback.

 

[D-C 10+ year member]

RCAs go down the center, power is along the right side...and speaker wiring along the left for the record.

 

[jrz126 10+ year member]

ooo...you have a pioneer.

I'll bet you need to reground your RCAs.

See this thread...http://www.caraudio.com/vb/showpost.php?p=1121098&postcount=39

There's a bunch of info in that thread as well. http://www.caraudio.com/vb/showthread.php?t=113520&page=3

Its a pretty common problem with the pioneers.

 

[D-C 10+ year member]

interesting. I will add grounding the RCAs to my to-do list. I wish I didn't have to do shit like that, but oh well heh. Thanks.

 

[D-C 10+ year member]

Ok, grounded the RCAs, no change. I will try a few more things and update.

 

[barryboy]

Recently resolved my sound system noise after a 2 year search! I took my alternator apart for the fourth time and noticed a small burnt field connection to a diode that evidently been sparking a little more over time eventually causing corrosion I could see.

I put in a new rebuilt alternator and it perfect now. No matter who I talked to at local shops, they wanted an arm and a leg to trouble shoot but most said it was the nature of vans etc. or wanted to sell me a noise filter. I rejected that notion as the system had been clean before. I hate the look that some of these "audio professionals" give you when they are asked to solve a problem rather than sell a massive system to a teenager spending dads money.

I look for a clean system as I am half deaf as well as half dead from the music and experience of the 60's and 70's. Unfortunately, my learning curve with auto stereo has been costly as I managed to screw up my Pioneer head unit by sending it to a certified repair person who "resoldered a few loose grounds on the circuit boards" without resolution. It never did play well after that experience so I bought an Alpine unit. I also rewired my van a number of times using different wiring configurations as well as trying to sheild all the wires under the dash that could be emitting noise. As I say, I have truly learned alot and hope to finish putting back all the dash parts and carpet etc to get my wife off my back! Good luck and appreciate your ears, you will need them for the long haul!

 

[D-C 10+ year member]

ok, problem resolved. It was the ****ing piece of shit Kenwood amp. I now have an old school soundstream in there- the sound is way better and the noise is gone. Im really psyched. Now I'm going to take the Kenwood apart, maybe I can fix it....

 

[helotaxi 5,000+ posts]

Good luck fixing it, you'll need it.