alternator whine, 88 vette
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=33940
Printed Date: July 12, 2025 at 8:18 AM
Topic: alternator whine, 88 vette
Posted By: mxxmikexx
Subject: alternator whine, 88 vette
Date Posted: June 15, 2004 at 4:31 PM
just got done installing a mtx 4 channel amp <new in box> in a 1988 vette. pioneer din & 1/2 source unit. ran 8 ga. power and ground to battery. everything is fine until i plug in the factory antenna to the back of the pioneer, then i get alt. whine, unplug the antenna and noise goes away, any suggestions?. this is a new one to me, ive never had this problem with alt whine going away when i unplug the antenna. and also, the head unit is grounded to the amp ground point, i did not use the fact. ground for the source unit
Replies:
Posted By: DYohn
Date Posted: June 15, 2004 at 4:33 PM
This is an antenna grounding issue. Your antenna mount to the car body is not providing a ground. You'll need to ground it. ------------- Support the12volt.com
Posted By: Ravendarat
Date Posted: June 15, 2004 at 5:06 PM
Um, did you say that you ran the ground to the battery? If you did, then I have to point out that amp grounds should not be longer than 3 feet. If the ground is running all the way to the front, then try grounding the amp to a piece of bare metal, preferably double metal, but it must be scrapped clean of paint. See if that helps
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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer
Posted By: kgerry
Date Posted: June 15, 2004 at 5:53 PM
it's a little tougher on those vehicles as the chassis is mostly fibreglass.... sometimes going right to the battery is the only way to get a good ground potential... i remember working on them when they were new cars and seem to remember encountering loads of ground issues.....
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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer
Owner/Installer
Classic Car Audio
since 1979
Posted By: mxxmikexx
Date Posted: June 15, 2004 at 6:28 PM
thats why i ran the ground to the battery, because of the fiberglass body issue. im going to try using a different antenna and see what happens. ive only worked on a handful of vettes and every one was a pain in the ass
Posted By: Ravendarat
Date Posted: June 15, 2004 at 6:38 PM
I totally forgot about the boddies being complete fiberglass. I understand why you went to the battery know. Have you tried using a "bandaid" on the RCA's. I mean a noise filter on the rca lines. Plug the filter in right after the deck and see if tha works. I dont like using them but it may be just what you need.
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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer
Posted By: customsuburb
Date Posted: June 15, 2004 at 7:02 PM
Could he just ground the antenna to the battery?
Posted By: DYohn
Date Posted: June 15, 2004 at 8:22 PM
customsuburb wrote:
Could he just ground the antenna to the battery?
Yep. Or to any ground bus connection. ------------- Support the12volt.com
Posted By: mxxmikexx
Date Posted: June 16, 2004 at 11:04 AM
one crutial point i forgot to mention is that the deck the guy had in there was an old school din and a half pioneer with no preouts, so i had to feed hi level from the deck into the amp, which normally wouldnt be a big deal because ive done it before with these mtx amps and never had a problem, but in this vette ive got nothing but problems, so im thinking about temporaly hooking up an alpine deck ive got sitting here with 5 volt preouts and using rcas to the amp and then see what happens. there might be a problem with the pioneer deck, who knows?.....
Posted By: forbidden
Date Posted: June 16, 2004 at 1:19 PM
My bet is that it is the ground plane in the Pioneer cd player. I would still run a new ground from the base of the antenna to the battery and also look at a new ground from the cd player to the battery as well.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: sparkie
Date Posted: June 16, 2004 at 10:46 PM
The best ground in any vehicle is not the battery in terms of audio, but the vehicle's chassis or frame. The biggest piece of metal that the negative side of the battery is connected to has the highest zer voltage potential or best ground. The older Corvettes were notorious for noise problems. Your antenna whether it is a power antenna or a fixed mast antenna should have a ground strap running from it the the frame rail below it. Make sure it is in good shape and not corodded. A good test for a poor ground on the antenna is to run your engine and listen to a distant AM station. If you get a buzzing noise and hear clicks or pops when you apply the brakes you have a bad ground on the antenna. Try also checking the ground from the battery to the frame. The problem is likely due to a difference in ground between the system and the antenna. This is known as a ground loop and is the major reason for noise problems. Use a meter and measure the resistance to ground between the outer antenna contact at the radio and a known good ground. Have everything turned off when checking this. You should get a reading of less than 1/5 ohms. If you don't repair the antenna's ground or replace the antenna or it's lead cable to the radio.
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sparky
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