RCA to Headphone jack Question

[Judg3]

Hey guys,
Called radioshack and they wanted 6.99$ for a Headphone jack to RCA converter (headphone jack on one end, RCA jacks on the other).

I have a bunch of old RCA cables. So I bought a blank headphone jack instead. I love building my own anyway hehe.


Erm, ok, anyway, for the question.

Headphone jack has a place for Ground, Left side + and right side +. Each RCA jack contains it's own ground cable (surrounding the postive cable).

Question is: Do I need to attach BOTH ground cables to the headphone jack, or would only 1 be sufficient?

Your overall thoughts on this would be great

[smb]

I think you need to attach both, since both channels are grounded individually.

[eGoCeNTRoNiX]

What smb said.. BUT!... If my knowledge of this (which is limited) is correct, if you want to do it right, you'll need to isolate the wires that you use for ground on each channel so they can't touch each other.. Otherwise they may cause some interference.. I could be wrong, but I think I tried to do this once, and that was a problem.. GL either way.... eGo

[FlyingPenguin]

No, you don't have to isolate the grounds. The grounds get tied together (Sound Engineer here in a former life).

[eGoCeNTRoNiX]

Like I said, I could be wrong, and I was.. eGo

[Judg3]

Ah ok, so ground both sides, got ya. I didn't want to wire it all up, only to not have it work and having to buy another jack. Cause then my 3$ savings turns into a actually costing me an extra 1$ for the new jack hehe. (Jacks are 3.99/each, cable is 6.99)

THANKS GUYS!

[FlyingPenguin]

Actually Ego, what you're probably thinking about is a cable with transformer isolation.

If you connect two audio devices, and they don't share the same power source, you may get a ground loop hum. That's because some voltage if flowing between the two devices via the ground (shield) in the audio cable (it's a voltage differential).

With home stereo equipment the solution is simple - plug both devices into the same wall outlet (note to people with a band - always try to plug ALL your sound gear into ONE outlet if possible - it avoids ground loops).

However, sometimes this isn't practical (like if you want to run a cable from your computer to the living room TV). In this case you want to buy a special cable from Radio Shack that has an isolation transformer in it (in the sound and viseo business they're called Isos or Hum-Buckers). This is a transfomer that allows the audio signal to pass through without a common ground.

You can also get a ground loop hum over a composite video cable (it'll look like a fat, translucent black horizontal bar scrolling up or down over the image). They make hum buckers for video also, although it's not something you find at Radio Shack.

I used to design and maintain sound systems for horse and dog tracks. Ground loop isolation was always a problem in long cable runs (for example between the sound room and the TV control room). I'd have racks of Iso transformers to deal with that.

[Judg3]

Well, it has to be the ulgiest most bastardized cable I've ever used, but it works great - thanks guys.

I learned a lesson to, don't use real high quality RCA cables to make this stupid converter, the wires where to damn thick hehe. Had to use some electrical tape to make sure everything was seperated.