alternater whine

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Jan 25, 2005 | 02:06 AM

RomerB2

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From: Bixby, OK

alternater whine

For a while I have had installed Digital Audio speakers in my doors and back panels of my Bronco II. Today I decided I would take my 4 channel amp, that I have running my 2 subs (bridged) and push my satelites to see what it sounds like. Well whenever I did this I had horrible alternator whine and I check all connections, grounds and live wires, and traced everything to make sure nothing was running parallel, and I don't have any power lines next to my RCA cables or any that run perpendicular to them so my problem is not that. I looked behind the HU just to make sure that not even the RCA's or power just to the HU crossed. Where is this noise entering? Should I just put in a noise filter and hope that sounds better? Also, when I turn up the gain on the amp, the noise gets louder..

I'm not really a newbie at this, and I have installed a lot of stereos for friends and whatnot but this has gotten on my nerves.

Jan 25, 2005 | 10:48 AM

rangerxlt02

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From: Zimmerman, MN

I'd check ground. Make sure it's clean, and free of paint where it makes contact. Also, are you grounding the amp to solid metal, or a bracket somewhere? If you can, ground directly to the body.

You may also want to increase the size of ground wire (in case you're running a light gauge).

Jan 25, 2005 | 11:39 AM

Smaug

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From: Appling, GA

If that doesn't work, ground your HU and amp at the same point.

Jan 25, 2005 | 08:38 PM

RomerB2

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From: Bixby, OK

I have it grounded to the frame through 4 guage wiring. Rust free connection. Today I went out and drove to school and the whine was there, but a lot quieter.

Jan 26, 2005 | 03:06 PM

Tad1299

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From: Fort Worth

First trouble shoot how the noise is getting into your system. Does it come from the head unit? Does the noise continue when you unplug your RCA's at the head unit? Does it continue when you unplug the RCA's at the AMP? Depending on where the whine is introduced, will depend on how you go about fixing it. One other troubleshooting techinque is to take a wire and ground it to the chassis, then touch it to the shield (outside of the RCA) being careful not to touch the center pin of the RCA, then does the Noise go away, or is it worse?
Good luck.

Jan 27, 2005 | 12:43 AM

RomerB2

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From: Bixby, OK

The noise doesn't exist whenever the amp is turned off, and also doesn't exist whenever the RCA is unplugged from the amp, so I'm thinking it's being introduced from the HU, so in that case, I'll pull it out Saturday and do some clean house back there and zip tie speakers and seperate power lines from RCA's just in case they have gotten tangled together since I last seperated things.

Jan 27, 2005 | 04:27 PM

morcutt

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From: Sugar Hill, GA

Good suggestions from Tad1299. I'd only add a couple of other things to consider when you're looking at all that lovels wiring this weekend:
1) The gain setting (if there is one) may be too high on your amp. If the gains are set too high (typically above unity or 0db), then they will amplify noise with signal and produce the results you've described.
2) You could have a ground loop problem. A friendly stereo shop would let you try one (since they sell for $20 or so) inine between your amp and head unit to isolate the signal ground.

Before you go down those paths though, checking the wiring as you suggested is an excellent way to start as it is where many problems occur and it gives you a methodical way of troubleshooting (from the fron to the back).

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Jan 27, 2005 | 10:34 PM

RomerB2

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From: Bixby, OK

Thanks for the link, and information. Saturday I will try to find the problem and get it straightened out. I know it's not due to the gain being turned up or frequency being to high either. It's there with bass boost and without so I'm going to straighten wires behind the HU out and see if that does it for me, and if not, I might re-wire things. Thanks again.

Jan 28, 2005 | 08:44 AM

#10

kontai69

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From: Highland, TX

Quote:

Originally Posted by RomerB2

I have it grounded to the frame through 4 guage wiring. Rust free connection.

If all else fails, you might try grounding to the chassis (or cab in the case of a truck) and not the frame of the truck. From what I understand, grounding an amp, HU, etc. to the chassis uses the entire metal of the chassis as a "mega-sized wire" to carry the ground current back to the alternator and negative battery terminal. The current from the chassis "jumps" to alternator via a firewall-to-engine wire. The current "jumps" from the chassis to the (-) battery terminal via another wire. A truck's frame is usually isolated from the chassis (or cab) by rubber. By grounding to the frame, the current may not adequately get back to the alternator and battery, resulting in a poor ground which will cause the alt whine. I'm not an electrical system expert, so anyone correct me if I'm wrong in my assessment.
Upgrading the firewall-to-engine wire and chassis-to-neg terminal wire may also help...
http://forum.sounddomain.com/ubb/ult...c;f=5;t=007801

Jan 28, 2005 | 10:18 AM

#11

jsutton

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From: Northeast LA

RomerB2 you may just be able to go to radio shack and get a piece of braided ground strap and screw that to the back of the HU where the support bracket is supposed to screw into. hook the other end to some metal under the dash somewhere. This worked in a dodge shadow that i had a few years ago, when the HU was grounded with only the small ground wire it whined but, after i hooked the braided strap up the whine went away. just my 2 cents. hope you get it figured out.

jason

Jan 28, 2005 | 03:53 PM

#12

RomerB2

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From: Bixby, OK

Quote:

Originally Posted by kontai69

The ground doesn't go to the alternator does it? I thought it went to the block of the engine where the ground is created, then to the frame and from there to the (-) battery terminal.

Jan 28, 2005 | 04:11 PM

#13

jsutton

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From: Northeast LA

The negative side of the battery is connected to the engine block and the engine block is connected to the cab of the truck by a braided wire. the engine is insulated from the frame because of the rubber in the motor mounts and the cab is insulated from the frame because of the rubber cab mounts. So doing like i said to do with a braided strap is the same as what kontai69 said to do and creates a chassis ground. to the cab of the truck which goes back to the block then back to the negative side of the battery. if you want you can run a wire all the way back up to the battery and hook it straight to the negative post and see if that gets rid of the problem if it does then you know your not getting a good ground.

jason

Feb 2, 2005 | 03:37 PM

#14

RomerB2

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From: Bixby, OK

For a simple fix, I went out and bought a sound filter.. ended up being a waste of money, didn't fix a thing. So I'm going to try all sorts of things today, and find out where this is coming from. Thanks for all the help.