I have a basic ground loop in my audio system now. Whenever the engine is on the noise is also there. It is the alternator whine problem, and I know it.

I am trying to figure out how to defeat this problem though. And the idea that I have come up with is to increase the guage of wire connecting the battery to the car chasis. I have a theory that the audio system is requiring a lot of power, but it can't get back to the negative battery terminal. This is due to the fact that the negative wire between the battery and the car is a skinny one. And when the resistance getting back to the battery is too high, the power will look to get out of the system through my speakers and components.

What do you guys think? I plan on doing this simple upgrade tomorrow to test my theory. The only question I have is how will this effect the life of the battery?

This is a fairly common upgrade that people do when they're installing a big system. I'm not sure how much help it will be to fix a ground loop, however it can't hurt to try. The FAQ has a large section how to go about troubleshooting a ground loop which is required reading if you havn't found it already.

Matthew

One thing you should know: once the car is running, the battery is NOT supplying any power. Rather it is now a load on the alternator just like the stereo system. Increasing the size of the negative power cable to the battery is unlikely to help.

I still have a ground loop in my system to work out... but just a thought...

If, and this has not happened yet, I had a system installed that would require a larger ground wire than what is coming off the negative battery post, and the negative battery post was the point I had grounded the components to, would increasing the size of the ground wire from the negative post to the chassis possibly help then?

After further investigation, I have found that the existing negative wire is about an 8 gauge wire. So it is bigger than I had thought. Now my question is whether I should try and wire the ground of the amp directly to the negative battery terminal? I have 2 spots in the car that are getting grounded, the amp and the head units. I think that this is causing some issues, and if I can get rid of the amp ground spot it won't be a problem anymore.

Well, I searched on the Internet and found this page.

http://www.eatel.net/~amptech/elecdisc/battgrnd.htm

It anwsers a few of the questions I had.

Hey, that's a good link. I was aware of the site, but hadn't read that particular sub-page. Interesting. Think I'll add that to the FAQ entry.

My great experiment went down today. And 98% of the alternator sound is gone. Now what worked and what didn't are another story. I basically did every improvement to the ground system before testing it. I sanded some more of the coating from the metal where the amp ground makes contact. Now it is bare metal against the gold-plated ground connector. This probably helped a lot. Next I connected the RCA cables ground center wire to the ground behind the head unit. Then I connected the empeg's sled ground screw to ground.

Under the hood, I replaced the negative battery terminal with one of those big gold-plated plugs. I did it for 3 reasons. 1, my threads were stripped on the old one and I was worried about it falling out. 2, it now looks like the other positive side. and 3, I can easily connect another cable to the chassis ground. So I did run this experiment to see if the second 8-gauge cable would make a difference. And I say it is about 90% gone without it and 98% gone with it connected.

And, if anybody has any idea where that other 2% noise is coming from, I'd like to hear it. I am taking a crazy guess here and saying the empeg head unit's ground wire back to the car is too small. I am grounding 2 head units, a line-level to speaker-level box, 2 RCA cables that are connected to the amp, and the empeg sled. This wire used to just ground the AM/FM head unit. The thing is that it sounds like a mix betwen the empeg hard drive noise and the alternator. It is present when the engine is turned off, but the accessories are on. Plus it wasn't there prior to all of these current improvements.

Sounds like a new dedicated ground for the empeg would be a good idea to try.
Who knows where the stock ground wire actually ends up, or what other equipment it shares with...

/Michael