What does the "Drain wire" on my RCA's do? I have Hufgen RCA's and they have a drain wire on each end. I suppose they are to be grounded but what exactly does this do?

I dont have much noise right now in my system (very small amount of whine but you cant hear it when you turn volume up past 5--- 0 being min and 20 being max)

Should I waste my time grounding them or just tape them off?
I just want to know what is their real purpose or are they just BS.

I know that if you dont ground the sheilding of the RCA 's then you may induce noise but then again all this RCA mumbo jumbo hoopla out to get your money is confusing me.

Are you talking about a third line that goes between your left and right RCA cables?

hmmm you might not understand what i mean by that.

OoO <--cross-section of cable, where the capital Os are your coax rca lines and the little o is the "drain wire"

If so, that's just a utility, a handy ground line if you should need it. (afaik)

If you should need it for what though? that is my question.

You can use it as a remote lead.

It is an easy way to keep a nice bundle when running the RCAs from the HU to the amps.

Using it as a drain would mean connecting it to the chassis of the HU and to the chassis of the amp/crossover/etc... This allows each component chassis to maintain the same voltage level(potential).

Whether that use is good for sound quality, I have no idea.

I have only heard of that wire being use as a remote turn on lead. I use it all of the time.

The only wires you have to run to the rear from the head unit is the RCA and Remote turn on lead (typically). Since they are all together, it just makes it easier to run to the rear.

there is a big sticker on it that says "DRAIN WIRE ONLY. DO NOT USE AS REMOTE WIRE"

The wire is no insulated and I believe it is the shielding of the RCA's that has been twisted into a wire

Yeah and definitely don't run power wires directly along with audio cables, that's a huuuuge source of bad noise.

Not insulated? zuh??

and as far as "if you should need it," I was purposely being ambiguous... I think I have some old "hi-fi" (yeah right) gear that has ground screws for the RCAs... maybe it's just for backwards compatibilty with old shat.

BTW reread your first post, you can probably get rid of that whine. Try a shorter/fatter ground cable, and try different ground points. Also make sure you've routed your cables carefully, try to perpendicularly cross power connections (and only do that if you really have to).

good good thanks everyone.

People use drain wires to reduce induced noise in their systems. They are used extensively in studio setups. Typically they are grounded at only one end and "drain" off any induced current. There is some debate over how to properly connect this wire to ground - some say source ground, others say both ends, others say that this is dependent on the frequency of the emi that you are trying to shield. I've got mine grounded at the source. Try it different ways and see what it does for you.

Thanks Noman for asking that question and everyone else for answering. I've always wondered what the third wire was for but never thought to ask. I love this board.