Question about the 1' of "audio" cable

[giantslayer]

First off, I am completely replacing all the electronics on my Squier strat and shielding it.

I went to Radio Shack to get some "audio cable which has two insulated conductors inside a single shield," and the guy thought I was talking about speaker cable used for home audio systems. I saw no logical reason for this to be right, so I didn't get any. Then, later, I took apart my guitar and noticed that the wire going from the volume pot to the input jack has 4 layers (wire - tubing - wire - tubing).

Is that what he was talking about? In my ignorance, it seems as though I could get the job done with two strands of the thin wire I'm using for everything else. Is that the case? I could take the old wire and use that if need be.

[Runewalker]

Do you want this for the wires from the jack into the shielded cavity?

[wolf]

Truth be told (without sounding sacrilegious to the "quieting the beast" mentality), I do all of my wiring in the guitar cavity with thin, unshielded, solid (not stranded) wire. I know a lot of people would say that shielded cable should always be used in any audio work in which amplification is involved¹. However, because the runs are so short in the guitar cavity, it is not worth (to me anyway) the extra effort that would be involved with using shielded cable.

Basically, I'd say phone hookup wire is good enough to do the wiring.
Something like this
www.radioshack.com/product/index.jsp?productId=2036272&cp=&pg=9&origkw=wire&kw=wire&kwCatId=2032058&parentPage=search
will give you enough wire to work on a few dozen guitars.
(DON'T buy speaker wire. It's too thick to work with.)

¹(speaker wire is exempt from this rule because the signal is not being amplified).

[bam]

same as wolf. You can use any type of wire inside a shielded cavity as long as your wire has low inductance. (in other word, don't use power wires). if you ask why? because the cavity is shielded. putting a shielded wire inside a shielded cavity (MHO) is just a waste of time, effort, and money. Got the idea, right ?

[Runewalker]

bam said:

same as wolf. You can use any type of wire inside a shielded cavity as long as your wire has low inductance. (in other word, don't use power wires). if you ask why? because the cavity is shielded. putting a shielded wire inside a shielded cavity (MHO) is just a waste of time, effort, and money. Got the idea, right ?

I'm with Wolf and bam. That was why I asked where you planned on running the wire. Since in a strat shielding project the entire cavity is the shielded enclosure, shielded wire in the cavity is superflous. Some here then argue the merits of shielded cable on the short run to the jack. That's a belts and suspenders approach and could not hurt, but I've done it both ways and can't say I hear a difference. But maybe I am not senstive enough. Unk is more sensitive though and may 'feel' differently.

[giantslayer]

runewalker said:

Do you want this for the wires from the jack into the shielded cavity?

Yes. I'm also honestly not sure how to tell if a wire is shielded.

[sumgai]

giantslayer,

Hi, and to the forums!

Rune says that shielding the wire that runs out to the jack is a belt and suspenders thing, but in truth, there is no other shielding in that little "tunnel", so this would be the only protection against hum in that wire run. It is short, and under most conditions, it's not necessary. However, if you have the time, materials, and talent to install it, then there's no good reason not to do so. One thing I sure hate is taking the guitar back apart to do something that I could have done in the first place, and didn't because I was too lazy.


Yet another short lesson
Some definitions first.... A wire is single conductor of electricity. It can be either solid or made up of several smaller wires, which is then called 'stranded' wire.

A cable is a set of two or more wires, in any manner of construction.

A conductor needn't be a wire, per se, but is usually used to refer to the shielding element in a shielded cable.

A shielded cable is where one of the conductors is wrapped completely around any and all other conductors (wires). That shielding is, of course, capable of carrying current, so it becomes part of the signal path, or at least a connection to ground, if not directly in the signal path.

A shielded cable can have more than two conductors (one wire in the center, the other conductor being the shield). Two or more central wires can be found inside the shielding. If some of the wires are twisted together, they are called a 'twisted pair', and are usually color coded to match (often a stripe of the same color). If they aren't twisted, then they're just normal wires, nothing special about them.

Now, there are several types of shielded cable. The first ones came about for use in transmitting radio. This is also where the term "coax" came about (or co-ax). It stands for coaxial, which describes the two conductors running along on the same axis. Anway, that stuff is heavy duty, to say the least. For audio purposes, we need a much lighter degree of current-carrying capacity, so we get the small stuff. But the idea is the same, no matter what the size might be.

For speakers, there is only one valid reason to use any type of coax, and that would be for cosmetic purposes - to carry all the wiring in one round jacket. And at that, a speaker run must contain at least two center wires, the outer conductor should not ever carry any of the speaker signal. Why? Because it becomes a radiating antenna! Don't want that around the house, it might attract unwanted attention from the FCC or other busybodies.

But for low-level stuff like in our guitars, a single center conductor like you found is more than good enough. The outer shielding is carrying part of the signal, but the current is so low that there is no effective radiation.
</lesson>

HTH


sumgai

[ashcatlt]

Sumgai did a pretty good job of explaining, but in case your still confused here's a couple pictures that might help.

The first page of this document shows a cable with one conductor inside a single shield. This would represent your normal guitar cable or other typical mono (unbalanced) audio cable. It is also what I think you are describing having found inside your guitar.

Page 3 of this document shows a cable with 2 conductors inside a single shield. This type of cable is most often used for microphones, but also for balanced audio signals of other sorts. You might also find something like this in applications where stereo connections are necessary, like headphone cables.

I'm not sure why you need the 2 conductor shielded cable for inside a guitar, but I'm not going to argue. I can't think of any reason (aside from space constraints) that you couldn't get away with just using two single conductor shielded cables instead, if these are easier for you to find. Just connect the shield from each together.