Help with Line Noise, Ground Loop?

I've got some engine whirring from my front speakers, and subtle bass rumble from my sub.

There is one set of RCAs from my headunit, that then go into a Coustic Crossover. Then a pair of RCAs, one to the amp that runs my front speakers and another to the amp that run my sub.

I connected the Remote Turn on for the EQ to one of my amps remote turn on's, which already has a remote turn on from the headunit. Meaning that there are two remote turn ons being worked off of one if that may have anything to do with it.

Grounds are of proper guage and are mounted to screws under the rear seats. There is a bit of galvinization on the frame where the grounds are located, could this be a problem?

The RCAs are about 1-2 feet from the power line going to my trunk, but do cross paths with the 0/1 Guage power line until my trunk where the distributor is located. This distributor is also located next to one of my amps.

I know there are a few things that I need to look at to find out what might be causing the line noise, just need a refresh on what they are. I am going to try different grounding locations today, and see if that helps the situation any. Any tips would be appreciated.

Also, I have the gains on the amps and cross over dialed down as well.

Thanks,
Derek

Replies (1)

Swez on 07/26/2003 08:32:25
"Grounds are of proper guage and are mounted to screws under the rear seats. There is a bit of galvinization on the frame where the grounds are located, could this be a problem?"

Yes, if you have a poor ground to amps, crossover network and HU, this is often the cause of noise. You have to get to bare metal for a quality ground and seat bolts are usually painted and will rust over time as well.

May I suggest that you make a new grounding site to bare metal and ground all amps and co-processors there. Then grounding the HU to floor pan is generally a much better way then a harness ground. Again... a bare metal ground is needed.

Finally, keeping your RCA signal lines away from the main power feed is a good idea. Also, if your Coustic has a line driver function, good to use that to preamp the RCA signal voltage and turn the amp gains as close to 4.0 volt setting as possible to reduce noise, but still maintain adequate amp power to your syste.

Good luck and let us know how you make out OK?

Swez