noise with key in accessory?

Hello, I am looking for some answers on trying to remove some ridiculous noise from my system in my El Camino. This is a clicking type squeal or whining noise.  I have tried running temporary grounds to the head unit directly to the chassis, and I also ran a ground over the car from the head unit directly to the negative post of the battery.  The noise is present when key is in accessory, and ignition on, with or without engine running.  I am using a bunch of old school equipment I have had for years, but never had issues before in my other vehicles...

My components and system are as follows:  Alpine 7998 head unit, Alpine ERA-G320 processor, Orion 250 HCCA 1st gener, Orion 225 HCCA 1st gen.  The 250 is running a pair of Boston Pro 6.5 components and a pair of Boston Pro 5.25 components in stereo.  My 225 is running 4 JL Audio 10w3D4's in parallel to achieve a .25 Ohm load.  I am using the old school 400 bdg module to bridge the amp. 

  I am using 4 ga. power cable from positve post down passenger side of vehicle to a distribution block and a 3 way fuse block.  I have added a 2nd battery which is run in parallel to the 1st battery with 4 gauge cables.  Each amp is grounded in the rear with 8 gauge cable that is no longer than 3 foot long. 

When I unplug the RCA cables from the head unit, the noise goes away.  I assume the noise then is from the head unit ?

Any help is great...Thanks

Ok, the main reason for this type of noise is your equipment operating at different voltages.

Take a voltmeter and (with the car running) read the exact reference voltage at the battery. Write it down.

Now take voltage reading at every component in your system: radio, amp, eq, processor.

All the readings should be exactly the same as battery reading. If any are different, then thats where your problem is.

Tip: upgrade the ground wire that goes from your battery to the chassis. Use minimum 4ga wire

Yes, the noise comes from every speaker.  I tried grounding the small black wire from each amp, and the noise gets louder. 

I will check battery voltage to make sure the car is fully charged.  Again, this isn't much of a daily driver, so I guess I should start there.  I really haven't even gotten to the point of looking for the noise with car running yet, because I am blown away by this nuisance with just key on. 

Any additional help would be great.  Thanks

I know that this is not a common problem with Alpine decks, but at least perform the test at the top of the following page.

http://bcae1.com/images/rca/temporaryrcashieldrepair.html

Very good.  I will test for continuity tonite.   In the meantime, I am not real familiar with line drivers and ground loop isolators.  Will either of these or both fix almost all noises ?  Is this something for me to look at adding?  I'd prefer to fix without, but I guess I will have to do what I gotta do.

Thought I'd add one more bit of info....When playing the stereo loud, and when bass or drums hit, My volt gauge flickers and drops, there isn't much of lights dimming, but they do a tad...I added the 2nd battery thinking my 2 HCCA's were wanting more and more..

perhaps this is related to the crappy noise?

Best answer. Ensure that the HU and amps are also properly grounded with clean metal connections to the vehicle frame. You may have something funky engaged on the El Camino that is different than your previous one, electric fuel pump or fan etc that is unexpectedly generating noise with ACC is on. If after proper grounding you still have the whiny growl and your gains are set where they should be, consider installing noise filters.

Not related.

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