grat81

Just installed aftermarket head unit / EQ / RF punch power 4chan amp in my '08 GSR and I have serious ground loop from hell (alternator whine).

New Kenwood head unit and Clarion half-din EQ draw power from the factory power line and are grounded (together) under one of the bolts holding head unit bracket in place (bare steel, no paint). I tested continuity between the ground location and the battery ground in rear with a voltmeter - checked out fine.

I have a 4-ch Punch Power RF amp mounted in the rear. I grounded the amp to the battery ground location (under the same bolt). NOT a good place to ground, apparently. Huge alternator whine when engine started. Amp was disconnected. Still getting a hint of alternator whine even when the amp has no power / no signal, so that means something is up with the speaker wiring or RCAs as well.

Speaker wire and RCAs are running down the left side of the vehicle. I ran the speaker wires from the Punch Power amp to the factory locations under the seat where the factory RF amp was located (cut wires off harnesses, connected to new wire). I will probably rip out all of this and replace all wire with fresh new wire running directly to each speaker, even if it isn't as clean as using factory wiring.

For those of you who mounted amps in the rear, where did you find a good ground location? Did you make your own? Is there a usable bolt back there that is good for ground?

Pretty frustrated. Ground loops are a nightmare.

deanob

iTrader: (2)

Easy ground location without drilling is remove the trim on the B pillar between front and rear passenger side, the seatbelt retractor mount bolt is a M5 brass bolt. Right there is a sweet spot and tons of room to run it through the trim.

Veronica

iTrader: (2)

No, the battery ground is the best ground for the amp.

1. Try disconnecting the rca inputs (or did you use speaker/line level inputs?) and see if it still whines.
If it stopped - get a shielded RCA cable set. Then try an RCA 'noise eliminator' at the amp. Lastly, run the rca out of the radio directly to the amp (bypass the eq). Try using a headphone-to-two-rca adapter and use your iWhutever as a source to see if it whines....

If did not stop the whining - try a noise filter on the power input to the amp.

jakeleclair2000

agreed, battery is best place for amp ground. just make sure to ground at the chassis ground, not the battery post. you can try an alternate input source but if you still have whine at that point your amps input section could be going bad (amplifiers can appear to function normally and output audio a with ****ed up input section). But i would hesitate to use a "ground loop isolater" or "power conditioner" for your problem. You'll get much better end results with a proper fix, instead of a bandaid.