Very intermintent high pitched distorted squeal/hissing noise from my speakers

[negative_camber 10+ year member]

Ok, I'm having problems with this very intermintent high pitched distorted squeal/hissing noise from my speakers. I know for sure I can hear it on my front speakers, but my rear speakers are much quieter so it's harder to tell. I have 3 amps (front, rear, sub).

What I know:

Older model JVC head unit, grounded through a Metra harness

very intermintent

only happens when the engine is running; does not change pitch when engine is revved

only happens after listening to music for a while... then goes away after a while

does not change when unhooking the rca

adjusting the amp gain does not affect the noise; the noise remains at the same volume

ground wire ran from cd player to amp ground does not help

grounding the rca's does not help

front speakers are ~3.4 to 3.5 ohms each when measured on the speaker wire at the amp

rear speakers are ~4.3 to 4.4 ohms each when measured on the speaker wire at the amp

the amps are are a board; amp chassis does not touch metal

will making hissing noise at no volume level or low volume

music will have a distorted/static noise during low volume when the hissing problem is happening

0 gauge power wire from the battery + to the back of the vehicle into a distribution block. 4 gauge from the distribution block to each of the 3 amps. 4 gauge ground from each amp to a bussbar. 0 gauge from the bussbar to the battery -

What else can I check? Any ideas on what the problem may be?

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[bald bull]

sounds like a grounding issue. try different grounding locations besides the battery, and keep the wires as short as possible. i had that same high pitched noise when my ground was too long.

 

[SethPhillips 5,000+ posts]

ground the outter part of ur rca's...