Hi guys,

I've been trying to rin myself aof a horrible ground loop problem.

amp and head unit grounded to differnt points ( but some potential )

If i connect 1 pair of rcas between amp and head unit all is fine and happy. But as soon as i add the second pair it starts getting alternator whine in the signal.

I currently have a line isolation transformer hanging off the rear rca's and it removes the whine completely, but i would prefer to remove that unit.

Any ideas ?

What happens if you only plug in the rear RCAs partially, so that the center pin has contact at the amp, but not the shield? If that works without whine, there are RCAs with the shield/ground only connected at one end.

/Michael

I had a similar problem, where running the fronts and rears to the same amplifier caused a ground loop, but running them to two different amplifiers did not cause a ground loop.

Very interesting!

Are you using the exact same type/length of cable for both runs? If not, try doing that and see if it solves the problem.

Another thing to try. If the amp has pass-through connectors, try passing the rears from the fronts at the amp, with only one pair from the player. You will lose the ability to fade from the head unit, but you will get all four speakers working and then you can adjust the fade by fiddling with the amp gains. If you don't have pass-throughs, try Y-adapters. These various options are illustrated here.

Of course, make sure to go through the ground-loop troubleshooting documents linked in the FAQ.