Terrible Ground Loop! This one will stump the PRO's!

**audiophyle_247** · 11-02-2009, 11:20 AM

It will be alright. Just put a little more detail into your system planning.
Like planning all your grounding locations, the best place to run your wires in your particular vehicle (best place, not easiest place), and get ahold of a wiring schematic of your car.

The more components you have the greater the risk of introducing noise, thus the more thorough you need to be with the install.

**JuniorGeezer** · 11-09-2009, 05:42 PM

First I had separate grounds for CarPC and amp and I got processor noise and alternator whine.

Then I ran a ground wire from the amp to the CarPC and things got better, but not perfect.

Then I ran a fat ground wire from the battery to the amp and left the ground wire from the amp to the CarPC, now it's perfect.

Before I used the battery minus for ground, I used a seat bolt, which is a bad idea.

Wisdom: A bad ground can mess up things, even if everything is hooked up to it.

You should at least for testing purposes hook every damn thing directly to the battery minus. If that cures the ground loop, take it from there.

**pulsarsimon** · 11-10-2009, 04:07 AM

The JL has balanced RCA inputs, so there won't be a ground loop there.

checked the battery ground? - That's a likely candidate, as a bad (high resistance) ground can have similar symptoms to a ground loop in the audio circuits.

otherwise, maybe the JL is faulty. I have lots of JL 'Slash' amps and never a ground loop problem.

**JuniorGeezer** · 11-10-2009, 02:14 PM

Originally Posted by pulsarsimon

The JL has balanced RCA inputs, so there won't be a ground loop there.

How is this possible? A balanced input requires two conductors and a shield per channel and RCA has only one connector and a shield. And even if this thing had balanced inputs, if the source does not, there's no benefit to it.

I've read that amplifier's manual. It doesn't explain how balanced can be done with RCA either. Edit: Maybe they have the RCA shield floating as opposed to connected to ground. Is that it, anybody know?

**foko** · 11-10-2009, 08:00 PM

Originally Posted by JuniorGeezer

First I had separate grounds for CarPC and amp and I got processor noise and alternator whine.

Then I ran a ground wire from the amp to the CarPC and things got better, but not perfect.

Then I ran a fat ground wire from the battery to the amp and left the ground wire from the amp to the CarPC, now it's perfect.

Before I used the battery minus for ground, I used a seat bolt, which is a bad idea.

Wisdom: A bad ground can mess up things, even if everything is hooked up to it.

You should at least for testing purposes hook every damn thing directly to the battery minus. If that cures the ground loop, take it from there.

In my situation, that was nearly the first thing I did. ALL the components, including the headunit, grounded to the battery terminal still made noise. I finally was able to improve things by using the stock HU feeding the processors and amps. A replacement Nak HU did not help. Only using the stock HU worked. Sounded relatively bad, but no noise. The problem was somehow associated with the Nak HU's.

PS....JL slash amps have regular RCA inputs (at least mine did).... Not balanced.

Fabian

**pulsarsimon** · 11-12-2009, 06:53 AM

they are rca inputs, but the outer is not grounded. The ground is isolated from the inputs.

this way they can be used for hi-level (speaker) inputs as well.

A balanced signal does not need a shield, just two conductors.