Shielded wire question

[horrorbiz]

I've read a lot of threads that recommend using shielded wire for long runs, like the output jack. I understand doing this for the hot side of the output jack but is it necessary to use it for the ground side run?
I would think that, for the ground of the output jack to the volume pot case, shielded wire wouldn't matter because it isn't in the path of the sound.
Am I thinking of this wrong?

[sumgai]

Aug 9, 2009 12:45:16 GMT -5 horrorbiz said:

I've read a lot of threads that recommend using shielded wire for long runs, like the output jack. I understand doing this for the hot side of the output jack but is it necessary to use it for the ground side run?
I would think that, for the ground of the output jack to the volume pot case, shielded wire wouldn't matter because it isn't in the path of the sound.
Am I thinking of this wrong?

Well, wrong is a state of mind, and of course, that depends on how you define "wrong".

In a nutshell, the shielding portion of a "shielded cable" is going from the jack's ground contact terminal to the back of the pot, so you are using shielded cable to make both connections, not just the hot side. Indeed, the very purpose of the shielded cable is to carry any hum-type noises to the ground contact, thus keeping them out of the hot lead, so our goal has been fulfilled.

Another little 'gotcha' is that one tends to get caught up in the trap of "ground", which is incorrect - it's not a ground at all, though following the circuit to it's farthest ends might reveal a single point of contact with a real Earth-type grounding connection. The point here is, it takes a whole circuit path to complete a circuit, and when you are looking at only the 'hot' side, you are actually naming it "hot" in reference to the other side of the circuit, which is not ground, but instead is called, "signal return".

Make note of that term, you'll find that it becomes much easier to dope out what's happening in a circuit if you think in terms of "the signal goes over there, and returns back here", instead of simple "hot" and "ground" nomenclature. Once you've got that concept, then it's real easy to figure out what someone is talking about when they're using the layman's terminology.

HTH



sumgai