Hey y'all. Found this thread via Google search and figured I'd post up my situation and see if anyone has helpful advice.
Problem Description: Soft background hiss/whine when engine is running that is noticeably louder than the normal amp hiss (which goes away when I turn the gain down). It is not a high-pitched whine that goes up and down as I rev the engine. More like the sound of a low-rpm motor running at the same RPM regardless of the engine RPM. There is a slight variation with engine speed but its not the screeching whine I've heard before in other cars.
Install notes: Pioneer AVH-5600BHS HU, Infinity 474a amp, Infinity reference speakers front and rear. Knukoncepts Basik RCA cables. Klarity 14 gauge speaker wires. 4 gauge battery lead, 4 gauge ground to clean, scraped attachment to body. RCA cables run up opposite site of car from power.
What I've Tried: Unplugging RCA from the amp stops the problem. So does puling the RCAs from the HU. Interestingly, only 3 of the four RCA cables (and therefore speakers) is exhibiting the noise. I can pull the front 2 channels and one of the rears, have pure sound coming from the remaining speaker without background noise. As I plug in the remaining leads, they will each have the background noise.
No effect/improvement: Isolating the amp from its mount. Swapping RCAs to different channels. Running separate RCAs directly between HU and amp
Made problem worse: Grounding the amp body. Grounding body of HU with separate lead. Wrapping wire around RCAs on back of HU and grounding to the HU body (per the first post on this thread). Each of these made the ticking noise noticeably worse.
Not sure what to do next. What is puzzling me is that one of the channels is NOT having the noise, yet is wired exactly like everything else. FWIW, that channel doesn't exhibit the noise regardless of which cable I use, so the problem follows that signal channel, not the RCA...
Any suggestions short of using a pair of GLIs? (by the way is there such a thing as a "good quality" (or better quality) GLI, or are they all bad in terms of attenuating signal and flattening dynamic response?