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Basic Grounding/Engine Whine
Basic Grounding/Engine Whine
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Old 7th May 2004, 12:56 PM   #1
Dfere is offline Dfere  United States
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Default Basic Grounding/Engine Whine

Hi, I have a sound system I am upgrading/repairing and finding many issues, one of which is whine/noise. I have read all the great posts here and other places on it and want to troubleshoot, but had a few questions.

First- A common ground ("star ground" etc)makes sense, but this requires running a long ground cable back from the amp to where I will be grounding the car stereo- doesn't this create a resistance difference in itself?

Second-Can this be eliminated by running all stereo grounds together before tapping the chassis for a ground?- or does this cause some sort of problem itself? I was thinking about varying lengths of individual ground to the main stereo ground wire to reduce differential if this was a problem.

Any help here would be appreciated- will give free tax advice in exchange....

BTW Crutchfield has some awesome advice on grounding issues- including interaction with other grounding- such as headlights, etc.......
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Old 7th May 2004, 07:50 PM   #2
maylar is offline maylar  United States
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This is one of those things that varies with each vehicle, and also by opinion. Everyone has a different idea of what works best.

The most common engine whine problem comes from ground loops... source and amp being at different ground potentials, and tied together with RCA cables. How you fix that depends on where the potential difference comes from.

Sometimes simply relocating the ground wire for either the source or amp does it. Sometimes running common (star) grounds to one point works. Sometimes the only solution is a ground isolator unit between source and amp.

In my case, the HU is grounded through its chassis to the dash. No matter where I attach the harness ground wire, it won't matter. The amp is grounded to the body in the trunk. The amp also does not have isolated (differential) inputs. It's a recipe for alternator whine.

I could isolate the HU with plastic mountings and screws. Or I could maybe run the amp ground wire all the way up to the dash. Both options are a pain. Maybe a different amp with isolated inputs might help. Ground isolators were a cheaper solution.

Some people also claim that crossing power and RCA cables can induce alternator whine. If that's the case, no ground scheme will make a difference. Some also claim that changing RCA cables has fixed noises. Each install is different.

Alternator whine sucks. Even with isolators, I still get a little.
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Old 8th May 2004, 04:15 AM   #3
pk386 is offline pk386  United States
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One quick Solution that works for me is leave both grounds connected as they are and run a small (20ga) wire from the ground of the HU to the ground of the amp.

If this doen't work you'll just have to experiment untill you fix it. Every car is different.

Also running the power wires and RCA's down the same side of the car is a bad thing.

it's the little things that cause this so look for all of those first. It shouldn't take more than a day of trying different things to fix it,
Let us know how it turns out
"I haven't failed. I've just found 10,000 ways that don't work." Thomas Edison
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Old 8th May 2004, 05:07 AM   #4
KMW is offline KMW  Canada
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I find that tightening the ground connection on my batt helps with whine, so while can be caused by anything related to grounding.


PS: when I rewire my deck, i'm gunna try that deck->amp w/20ga idea.
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