Why would my amp do this?

i hooked my Orion 2500d back up to my subs today after getting it repaired and I'm getting a real high pitched squeal coming through my mids and highs. they run off of a completely different amp. I've heard it discussed before its some kind of alternator wine or something to that matter, its really squeaky and then when I give my truck gas that sound gets louder. it was very slightly noticable before I put my orion amp back in but barely. How could hooking up an amp that has nothing to do with mids and highs cause interference with my mids?!? both amps are mounted to wood, and then mounted to the fiberglass box. my mids and highs amp and my sub amp are on different sides of the back of the cab. it makes the same noise even when the truck isn't running and I just turn the key back to the "accessories position." Both amps are being fed and grounded with 4 awg through my capacitor. Then the cap is grounded with 1 awg to the frameany help greatly appreciated

its a "ground noise" as i have been told. i had a component set installed back in april and my 07' chevy does the same thing i havent figured it out why but i guess some newer vehicles do it.

your ground wire cant be more than eight inches long, dont ground your amp to the capacitor ground it to the cab some where close to the amp and make sure your rca's arent ran on the same side your power wire is on, one of those helpful hints should fix it

You can also get a filter for your RCA's that will take alot of it out. I had it bad at first also, then I hooked up a filter I got from a local shop. I think it was made by PAC10 or something like that. Now I have no noise at all.

my rca's come from the front and my power wires come from the back because my entire system runs on a 2nd battery that I have underneath the bed. But my remote turn on wire runs with my rcas could this be a problem?

thacru78, did you get those filters at a local audio shop?

thanks for all of the fast responses

That would be a ground loop isolater. If it is still doing it when the truck is off, try taking a jumper wire from a good bare metal ground to the ground on the RCA(the skirt part not the center pin). Also, get an ohm meter and measure resistance between your negative post on the battery and where your amps are grounded. You don't want hardly any resistance between these points. Also, make sure your grounds are clean and making good contact.

I have fought stranger noise problems before.

Are you using line level inputs to the amps only? if so then....

To help find where the noise is comming from you can try:

1. Unplug all your RCA's from your head unit. If the noise is still there then you know it's not the head unit.
2. Unplug all your rca's (one amp at a time) from the amps. If the noise is still there, then it's not from your line level inputs, or the RCA cables. It is from the amps themselves.

If this is the case, then either one of the amps is generating the noise, or it is the power, ground setup.

You can remove the power from each amp one at a time to find it.

If you can live with reducing the gain on the offending amp this can help some too.

Hope this helps!

Read this document.

It can help alot.

https://resources.myeporia.com/company_38/tech%20note%201002.pdf

thanks guys for the flood of quick responses. I now have enough information to keep my busy for hours this weekend...

cruz lo, love the document, it's basically "system noises for dummies"

Yeah I found them at a hole in the wall stereo shop.

Here they are.

http://cgi.ebay.com/PAC-SNI-1-SNI1-Ground-Loop-Isolator-RCA-Noise-Filter_W0QQitemZ170123384348QQihZ007QQcategoryZ50552QQrdZ1QQcmdZViewItem