Any ideas on where to start with diagnosing electrical noise?

My problem right now is a damn annoying whine when my engine is off. All I've done is removed my alpine CD changer and installed the Riocar using all the same wiring. The alpine had noise when the engine was on, but not when it was off.

I read through the FAQ on installation and didn't get any ideas.

I also tried regrounding the rio with no luck.

There were three documents linked in the FAQ that should help you diagnose noise. Have you gone through every single one of the steps in each of those documents? Did you try following the flowchard at Crutchfield?

When I installed my EMPEG, it had all kinds of noise. Even my cell phone was going through it... I had to get triple shielded rca cables. They were 70 dollars a piece, but all the noise is gone.

I'm gonna try some things tomorrow that I read from crutchfield... I'm just wondering what are the most likely causes of noise when the engine is off... all the documents merge ground loop noise and alternator noise together.

Is it possible that the noise is coming from my power leads? or is that just for alternator noise?

Tomorrow I'm gonna try regrounding the unit, adjusting amp settings, checking amp power connections, and... I dunno, any more tips?

all the documents merge ground loop noise and alternator noise together.

Right. Because 99 percent of the time, those two things are exactly the same. If you have a ground loop somewhere, then you will also get alternator whine.

Is it possible that the noise is coming from my power leads? or is that just for alternator noise?

I think you're misunderstanding the nature of a ground loop. Electrical wiring is not like a water hose. It's not unidirectional, so it's not like you have a "contaminated water supply".

Ground loops happen when some of the electrical energy ends up getting routed through the audio cables. Then every single electrical device on the entire system (car alternator, player hard disks, player CPU, cell phone circuitry, spark plugs firing, brake light turning on, air conditioner fan, everything) can be heard through the speakers.

Your job is to make sure the electricity flows exactly where it's supposed to, and no where else. This means you have to convince the electricity that the better route is through the proper power wires.

Alright, this is starting to make some sense now

One way to do it, which is a PITA, but may end up being shorter - is to hotwire the whole Empeg up. Run your power and ground leads staright to the battery. Droop your cables over the seats to the amps, etc. At this point you should have NO alternator whine. Now, hook these items one by one back up to the way you have them now, and something should suddenly make it come back.

I generally rewire all my cars from scratch. The only time I had alternator whine was with a bad ground... I had a CD player grounded to a vary large piece of metal, and assumed that was good enough. It turned out the metal was a structural part of the dashboard, and was actually isolated from the frame of the car by some large plastic bumpers (to keep noise and vibration down). Anyhow, that piece of metal I grounded too was not actually a "ground". Instead the CD player grounded itself through the RCA cables to the amp!

Good luck -

Sometimes you can wire it up that way (straight to the battery, all wires in open air, etc.) and still get noise. Depends on the situation and the components. Usually it only happens when you've got multiple components besides just a player and an amp. For instance, if you have multiple amps and/or some electronic crossover separates.

I'm going to reground it... I have a feeling it's in a bad place... but now I have another problem... this isn't working out for me.

Oh well, I'll make a new post