Problem with audio-cables/soldering

i bought sum cables (dual-lines) and want to solder stereo jacks, but then i found out that a phone jack got three points to solder although there are only two cable-lines leavin the jack - i would like to know how to solder that.
The project is: We got a flat share here and i wanted to connect all computers (that got stereo jacks) with a switch (4 connectors per channel) and connect the switch with a pair of boxes in our kitchen so that we can chose the line in from the switch and not have to pump up the volume in our rooms to listen to our music while being in our kitchen; so there's 3 computers[stereo jack out] -> [4 line cable-ins]switch->[4 line cable outs] -> [not defined in; eventually stereo jack outs->stereo jack in-active-]boxes and i got this dual-lined cable (solid twisted copper; 100meters-spin), a pack of each kind of stereo jack plugs. What do i do to get sound?

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orksecurity7 years ago
There are two kinds of phone jack: Tip/Sleeve, and Tip/Ring/Sleeve. If you want stereo out, you do need a Tip/Ring/Sleeve connector. In this use, Tip generally provides the left channel, Ring provides the right channel, and Sleeve is the common signal-ground for both channels.

When wiring that, a stereo cable often uses the cable's shield for the common, the Black-insulated inner wire for the left channel, and the Red-insulated inner wire for the right channel. Mnemonic: Red-Ring-Right.

(And if you're working with sound boards, which use the same connector for a slightly different purpose, it's Red-Ring-Return.)

Beyond that, what you seem to want is routing switches (I went lazy and just bought a selector box from Radio Shlock )... and, if you want local control of volume, amps at each set of speakers with their own volume control. And wire, of course.

Hope that provides what you need.
If you're trying to wire a four-conductor cable to this: Both ground conductors go to the sleeve; signal from one pair goes to tip, signal from the other goes to ring.

Also, just to make the terminology clear (and provide a bit of background on why these are called "phone" connectors):
https://secure.wikimedia.org/wikipedia/en/wiki/TRS_connector
+1 and...Oh cripes, just tell him. Because they were invented to support the emerging telephone industry and were used by operators (human beings) to switch the lines between calls, back in the days when you didn't dial the phone, you picked it up and asked Edna the operator to connect you Mr Garvey's grocery store. They're (the connectors) an example of technology reuse or tech transmogrification, (alliright, word use is a bit of a stretch) if you like, from the telephone industry to the the audio industry. They were a convenient plug, just as the RS232 db9 grew from the DB25 and 37 and then was reborn as the micro USB...

It was a good primary design for pluggable connections.

Ork is right about the switch box...'taint lazy, 'tis common sense. There are obvious limits to DIY. One need not make one's own gasoline to complete a gasoline-engine powered go-cart project, if you catch my drift.

Having said that, you might consider adding audio grade buffers into said switch box and shield it. Sounds like you may be about to run into a classic problem most normal people don't understand, ie, impedance of shared loads. That is, one cannot simply parallel ad infinitum off a single source. one instead uses a high input impedance buffer that branches out to multiple drivers to clone the "data" to multiple loads.
Luziviech (author)  seandogue7 years ago
i dunno, if i understand it right what youre tellin me bout the existence/importance of so-called grade buffers, but i don't want to compbine signals, but connect several lines to one pair of boxes - and the "switch" i'm talkin bout seems to be the same as ork's "connector box": i bought that switch-thing and it's a box with four switches, one for each signal - the only difference between my plan and it's purpose: it got four line-outs and one line-in and i thought, it probably works as junction plate and i can use it in the other direction (hope so).
So you have one glass of water and you need four glasses of water for four people so you just get a switch box and then you have four glasses of water magic huh. Magic doesn't exist.

Audio grade buffer means the amplifiers used to buffer the signal for distribution to multiple recipients are "audio" quality. Audio amplification, buffering, etc requires a certain level of quality. to duplicate the waveform from the single source that's meant to drive a single load that's being asked to drive four loads.

The reason to have buffers is to provide enough drive current to allow four people to share one source properly., so you don't burn out the source or otherwise damage it so the quality of its output becomes permanently compromised. Sort of common sense. There is no free lunch.

You may get this thing working just by using a simple branch, but don't be surprised when your source magically stops working one day.
Luziviech (author)  seandogue7 years ago
get what you mean, but i don't want to use one source and four pair of boxes, but four sources and one pair of boxes: me&my room-mates linked to the chilly kitchen. I guess the same way i rather magically burn out the pair of boxes in the kitchen, if i overlay all sources (the same way as the irreversible black widow's poison effects on brains) - right ?
...and for the wires, i guess, i'll just buy me sum new shielded-ones this time and consider my actual wires as inappropriate - damn, i thought i could skirt that and use the 100m-coil of thick copper non-shielded box wires.

Btw: A source can't magically stop workin, if magic doesn't exist, but maybe there's a way to explain it by the Schroedinger's cat theory.
(I was more concerned with making sure he knew what "tip", "ring", and "sleeve" were, and didn't feel like redrawing/crossposting an illustration. The history came along as a free bonus, and I wouldn't have mentioned it except that I keep getting complaints about "phone" being too easy to confuse with "phono", which is the other electronic signal connector commonly seen in home audio equipment.)
Luziviech (author)  orksecurity7 years ago
umm, after checkin that wiki-link and seein the pics, i understood. So, i want to use those stereo TRS and this box that got four jacks for each signal. Sure, i could use two pairs of cables for each TRS. And i know what is what bout left/right/ground inside a TRS, but what i wonder about is the simple earphones: they seem to consist of only two cables - left and right - never found a shield there. Where's the ground there? The wire i want to use got no shield. Ant the TRS are quite tight, so i'd like to not try to stuff in three of the cables, if possible. (?)
I understand.
seandogue7 years ago
Stereo cables are usually four wire cables, two shielded pairs in a single casing.