I've been working on the interior and wanted to install the stereo system so I can button up the dash and side panels.

I have a Boss head unit, with Boss 4 channel amp. Kicker 5.25 speakers in back, with JBL 6.5 components up front.

When I place the key in accy, I get a faint buzz on the speakers, not too bad.
When I place the key in run, I get an annoying high pitched squeal.
When I start the car, it's not tolerable.

The battery is mounted in the frunk.

I've run seperate power and ground from the head unit to the battery.
I have a short run from amp to battery, direct.
I tried grounding the case of the amp because it's mounted on the plastic floor of the frunk.
I bought new Gearit RCA harnesses, no luck.

Not sure what else to look at or what to do.

Any audiophiles that can help???

thanx

Bob

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My Build

quote Originally posted by RCR: I've been working on the interior and wanted to install the stereo system so I can button up the dash and side panels. I have a Boss head unit, with Boss 4 channel amp. Kicker 5.25 speakers in back, with JBL 6.5 components up front. When I place the key in accy, I get a faint buzz on the speakers, not too bad. When I place the key in run, I get an annoying high pitched squeal. When I start the car, it's not tolerable. The battery is mounted in the frunk. I've run seperate power and ground from the head unit to the battery. I have a short run from amp to battery, direct. I tried grounding the case of the amp because it's mounted on the plastic floor of the frunk. I bought new Gearit RCA harnesses, no luck. Not sure what else to look at or what to do. Any audiophiles that can help??? thanx Bob

Sounds like a poor ground or line noise. Do you run your RCA / Speaker wire along your power and ground? Try and change your ground / if that doesnt work you can wrap your power and ground with foil to see if it goes away.

They also make some filters you can add in on the RCA's but its more of a band aid to the problem.

This may or may not be related... but years ago I started to get some kind of interference noise on my Fiero's radio that went up and down in frequency with the revs of the engine. (Found the thread Here.) Shortly thereafter, the alternator failed (stopped charging). Replaced the alternator... racket on the radio was gone.

It occurred to me that when I first hooked everything up, I had a bad connection at the battery that ultimately roached my first amp ( I'm running a replacement). Any chance the head unit was damaged, causing this noise issue?

Bob

PS thanx for the feedback, guys...

quote I've run separate power and ground from the head unit to the battery. I have a short run from amp to battery, direct. Any chance the head unit was damaged, causing this noise issue?

To me, test the head unit on the bench; if it is good, then make sure the speaker/amp lines are separated from any power source.

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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

When I tested my head unit, 5 channel amp, speakers and sub on the bench everything was great. When I put it in the car it had a feeback type sound. It ended up being a ground loop issue.

On my amp, I had a choice of line level or RCA inputs, and I used the line level as that is what my head unit had. The instructions said that the line level input connectors (3) were to be gounded at the same location as the amp ground so that is what I did. As I was troubleshooting the issue, I disconnected the line level input grounds and the noise stopped and everything worked great.

So I would check any additional grounds the instructions might have suggested, especially on the input to the amp, and start disconnecting them.

Prior to finding the ground issue, I went down the rabbit hole for signal conditioners, locations and routing of power wires vs. speaker wires, and none of that helped.