Dual battery ground

[Mal Gal]

I am looking for some information on stereo/battery ground. We hear alternator noise in the speakers when the stereo is low and motor is idling. I read several threads on grounding....but still could not quite understand information. We have dual batteries, and the ground cable runs from battery to battery. Is this my problem? if not, where would the stereo ground be? One thread said to have everything grounded to one battery??? Please help, I am not very "battery/stereo" smart!

Thanks for any help!

Mal Gal

[shawndoggy]

All of the stereo equipment (headunit, amps, equalizer, etc) should be grounded to one common point, which should be the negative battery post on the battery that you use to power your stereo system.

[Awest]

Also please keep all RCA cables away from power cables if possible. If you must cross a power cable do it at 90 degrees. Check all RCA connections to your amp as well. Simple things that are often overlooked. Especially loose wires.

[Mal Gal]

Also please keep all RCA cables away from power cables if possible. If you must cross a power cable do it at 90 degrees. Check all RCA connections to your amp as well. Simple things that are often overlooked. Especially loose wires.

DUH? to me! Sorry, but what does an RCA look like? What is the difference between RCA and power cables?

Thanks,

Mal Gal

[Awest]

DUH? to me! Sorry, but what does an RCA look like? What is the difference between RCA and power cables?

Thanks,

Mal Gal

RCA cables look like this photo

The stereo installer should have run RCA cables from your Head Unit (stereo) to the amp. Actually there should be one more thing in between the amp and cables. Ground Loop isolators. These are $25 items from Radio Shack that eliminate engine noise. Attached is a photo of a typical unit. Power cables should be Red coming off the amp and it should run directly to your second battery if you have one.

[Mal Gal]

RCA cables look like this photo

The stereo installer should have run RCA cables from your Head Unit (stereo) to the amp. Actually there should be one more thing in between the amp and cables. Ground Loop isolators. These are $25 items from Radio Shack that eliminate engine noise. Attached is a photo of a typical unit. Power cables should be Red coming off the amp and it should run directly to your second battery if you have one.

Thanks a lot! The pictures and directions make it look easy enough. After reading your explanation, I am missing the ground loop isolator. Looks like I am headed for Radio Shack in the morning.

Thanks again,

Mal Gal

[shawndoggy]

You don't NEED a ground loop isolator. IMHO they are a crutch to mask a bad install. Pros do not use them. If you do your install right you won't need one at all. Skip it unless you have problems, and troubleshooting those problems proves fruitless. Ground loop isolators are filters. They are meant to filter out "bad" sounds but they are dumb and can't tell bad from good. Net effect is that they can make your system not sound as good as it could.

[Mal Gal]

You don't NEED a ground loop isolator. IMHO they are a crutch to mask a bad install. Pros do not use them. If you do your install right you won't need one at all. Skip it unless you have problems, and troubleshooting those problems proves fruitless. Ground loop isolators are filters. They are meant to filter out "bad" sounds but they are dumb and can't tell bad from good. Net effect is that they can make your system not sound as good as it could.

What do you suggest? Where do I start? It is very difficult to see if it is fixed as there is only a problem when the motor is on.

Thanks for your help

Mal Gal

[Ndawg12]

Please don't take offense, I only mean to help, but if you didn't know the difference between rca's and a power wire, then you may want to buy a case of beer for a good friend that is more familiar with these systems and have them assist you. There could be a number of possible reasons for your issue.

[Awest]

I agree with the beer method personally. I also have to disagree with the ground loop isolator comment. It was the only solution left for me after paying a "professional" installer to track down the problem to no avail. The cheap ones will limit your frequency range to a degree but for most people they would never know the difference. If you end up buying one Xitel makes an excellent one that will work better than the Radio Shack one albeit at 4 times the price. If after you get your power, ground and RCA cables worked out you still have a hum just try it as a cheap temporary solution. Lots of people use them. If it doesn't work return it.

In the end for me the only thing that eliminated my alternator hum was to get rid of my original amp and replace it with an Alpine. Now I don't need the isolator. Go figure.

Good luck. As you can see from all the threads on this site it is a common problem.

BTW why is this not in the stereo section of the forum?