I just had some Focal's, Alpine PDX5, and Alpine CDA117 installed and I'm getting the infamous alternator whine.

First off, yes the power lead and the RCA's have a decent amount of space in between them. The head unit's ground shares the same ground as the amp (which is located under the passenger seat) and is located right under the passenger floor trim and has been cleaned/sanded.

When I adjust the gain higher, it gets worse; when I adjust the gain lower, it remains audible, albeit quieter. When I disconnect the RCA's from the amp, it still whines. When I disconnect the wiring harness from the amp, it still whines.

One more tidbit. I noticed they ran the red power lead, from the amp, to a terminal under the hood. I assume this is a remote positive terminal considering the battery is in the trunk? Would rerouting the power directly to the trunk make any difference?

Thanks in advance for any help!

 

 

Whine is now fixed! Switched headunits shared ground from the amp to a bolt behind the dash and moved the speaker/remote wire away from the power cable.

 

why did you run your power wire to the engine compartment? it's easier to get it at the battery in the trunk...

 

That's a great question....for the installer (which wasn't me). I think that they didn't know how to remove the back seats to gain access to the main. Who knows. It's the last time I have an audio system installed by someone else.