Feedback after installing new speakers

[TwizztedVizzion]

Hello everyone, I just did a complete overhaul on my stereo, I replaced everything but the amp, and headunit. I re-wired my amp with 4 awg wire from the battery, to a 30 amp fuse, to the amplifier.

I was running Infiniti reference series speakers, they blew recently so I upgraded to Kicker CS series speakers, to match the subwoofer, which is a Kicker CompR 12. The speakers get loud feedback when ever the engine is running, I seperated the RCA cables from the 12v cable incase that was causing alternator hum, I've regrounded the headunit from the factory ground to the firewall, to where the amplifier is grounded in my trunk, the wire is 8 awg, the feedback does not go away if I unhook the RCAs from the amp, it only goes away if I unhook the RCAs from the headunit itself, I'm not sure what else to try. Could it possibly be bad RCA cables? I don't see what they're getting feedback from when they aren't hooked to anything but the headunit.

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[keep_hope_alive Premium Member]

yes, noise can be from ungrounded RCA shields. this ground can be broken at the head unit, amp, or in the RCA.

 

[PSturmer 10+ year member]

^^^^ this would be my first guess. the easy fix is to just ground the RCA jacket. they also make ground loop isolators but those cost more than the first option.