Crazy interference when using dual RCAs on 4ch amp..

[TheGr8Schlotzky]

Here's the setup:

1996 Camaro

Pioneer 7800MP deck

Stock Bose door speakers (real soon to go)

Rainbow 165 SL sail panel speakers

ED 11kv.2 in stealth box

Kicker KX350.4 powering sub (bridged) and sail panels

Here's the problem...

Well I upgraded my rear speakers, and while I was working on the stereo, I decided I would go ahead and wire up my sub the correct way..that is, using my pioneer 7800MP's subwoofer outputs. Before I was using the rear outputs of the deck (RCA) to the 4 channel amp in the back, which had a low pass for the sub and full range to the sails off those two RCAs. Now I ran another set of RCAs to the amp from the deck (sub out) and hooked them up to the respective input on the amp. I turned it on to make sure it sounded good before putting everything back together..works great, put it all together, and startup the car. Now the sails are humming somewhere around 2khz and the blinker can be heard through them, the headlights increase the pitch of the hum, the fog lights decrease the pitch, and the brake pedal clicks when it engages.

obviously there is some kind of interference, so I tore it all down, messed with connections, then rerouted the sub RCAs on the other side of the car, put it all together, same problem. Note that this is only with the car on.

Here's the deal: I plug either set of RCAs into 'amp 1' input on the amp, (ch1&2)[also 3&4 if there is no amp2 input detected] and everything works fine, no buzz, no hum, no interference. I plug the other set in to amp2, and the humming starts in again. Plug either set just into AMP2 input, and there is a LOUD rumbling/buzzing noise until I hook up amp1, and then the rumbling goes away and the humming noise quiets down a bit.

The only way to get rid of the hum is either turn the gain almost off on the amp2 (sail panels) or turn on the lowpass (obviously neither eliminates the problem)

So I ask, WTF is wrong?

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[Etac 10+ year member]

check the grounds of the amp and HU..

wish i could help you more, but im guessing you didnt have this problem when your using the rear deck outputs?

maybe it has something to do with the rca's position behind the HU? being bent or something. pushed up against the back, somehow messing up.. or similar