I've been pulling all the misc. wiring out, and rewiring the stereo properly, and came across this leading to the +12v switched on the stereo. It looks to me to be some sort of capacitor, so I figure it might do some good to leave it in. What do you guys think?

 

Probably a noise filter...

 

ground loop isolator = noise filter

They are used on cars with high performance ignition, or shitty stock wiring (where wiring runs absolutely everywhere in the car for no apparent reason [ground *loop*])Basicaly its either a mess of wire, or a certain system component (often times high-performance ignition will cause ground loopp) that causes resistance in the wiring. This resistance creates a hum when amplified through the stereo. Insanely annoying. I've never had a problem with my FC, but the stereo isn't using stock wiring either...

 

is that a xfrmr i see on the left?

 

That is a power supply noise filter, not a ground loop filter.

It is a simple coil and cap, to stop all upper and lower AC on the line.

 

*DOH*

Hey mark, are GLI the one's with RCA jacks then?

 

Yep... generally RCA type connection at each end, sometimes also a extra ground wire (depending on brand).

 

Cool, so it's to provide constant power. I did without it to try and save on clutter, and it isn't required anymore. I went with a direct line running from the battery and a relay to control it. Works like a charm, and now I don't have a billion wires all over the place.