I was thinking about hardwiring the aux in connectors on my sled to a phono jack mounted in my car, but I can't seem to find an appropriate schematic anywhere. I realize that the RatShack could probably sell me a cable that will do that without me needing to deal with it, but I'd rather get a mountable jack, and that won't be possible with their cable (of course, it now occurs to me that I could get such a cable and cut it open, but I've already typed this much now).

Can anyone point me to such a schematic? It should be quite simple, I imagine. I just don't know how to go from the separate to a shared ground.

In all probability, the 'separate' grounds of the RCA jacks are actually common in the empeg anyway, so joining them (or only using one) should not be problem - but you should probably get pca or altman to confirm this first. If they are not, then you could probably connect them to a common point using a resistor (1k should be fine), and using that common point as a shared ground.

Right.

Outer sleeve = RCA grounds (common).

Tip and Ring = Left and right positive.

Don't know which is which for the tip and ring, though. Anyone?

Also, you might want to have a defeatable chassis ground on the sleeve to compensate for different ground loop issues depending on what device is plugged into the jack.

So that would be one resistor for each separate ground, or join the separate grounds and put a resistor between that common point and the common?

I can figure out left and right by trial and error if I can't find it elsewhere. (Thanks, though.) But I actually had another project where I wanted to do this where I couldn't join the grounds or I'd get this weird crossover between the channels. And now that I'm doing it again, I might as well figure out what I did wrong the first time.

Edit: Supposedly, tip is left and ring is right. I suppose that works out well with Right == Red == Ring.

The first ---- but Tony has confirmed that you can just join them together and not worry about any resistors.

Well, I'm only assuming that they're joined. I don't see why they wouldn't be. But I could be wrong.

But it wouldn't be wrong to do it that way just to be safe, right? Especially considering that a pair of resistors costs next to nothing.