3 audio questions, can 2 wire line carry a stereo signal ?

[fenix]

Have a side job to a surveillance installation job tomorrow afternoon, and am trying to troubleshoot a customers audio system: 2 stereo (I would presume) speakers and a bass woofer. Here's the setup

The problem with the sound is that there are intermittent scratchy sounds like a connection being broken occasionally (I played midi and wav files from the C:\windows). The sound is similar to an intermittent connection, but maybe a little softer. Which might be the case, please read on.
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It is a Boston system that was sold with a top of the line Gateway athlon(spare no expense on features) about 1 1/2 years ago. Even though the color coding is correct on the back of the sound card to the bass woofer, the connection on the bass woofer is an RCA female, which as far as I have ever experienced is always a 2 channel wire. The sound card is a Nvidia 32MB. The other end that is color coded to go into the sound card Line OUT, ends in a MONO mini plug. (The bass connection is from the bass speaker via a 9 pin mini din like plug, (3+4+2) to the one small speaker with the on/off and bass/treble knobs.)(The Boston system and setup manual came with the package and it's connected accordingly)

The customer's sound system never worked correctly since it was installed a few years ago by a tech contracting for Gateway, but having no audio wasn't a concern at the time for this user.

My first and primary question is this: is it possible for the 2 wire line, with an RCA on the woofer end and a 1 ring mini plug on the soundcard end, to carry a stereo signal ???? I always thought you needed 3 wire line to carry stereo signals, (L, R, ground) but this is a brand new system so I'm guessin' it's possible, need confirmation And that would make his sound card different(2nd question) from the norm, is this a new technology or just a manufacturer's mistake?
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Also, his sound card is very dusty/furbally, and maybe some contacts are being slightly shorted, gonna bring some air tomorrow and clean if off, maybe that's all it is, but need to know if there is such a stereo design as I'm speculating. 3rd question- -In this day in age would a vendor manufacture a mono audio system,

To repeat the problem:
The problem with the sound is that, on his computer, there are intermittent scratchy sounds like a connection being broken occasionally (I played midi and wav files from the C:\windows) The sound is similar, but a little softer, to an intermittent connection! Which might be the case.
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I took the system home to troubleshoot on a working soundcard, and it didn't play at all. sorry for the length of this question, but all these questions can be answered in a sentence or 2 if someone knows this info. As always, thx.

 

[mradmin]

Hi, It sounds as though you may have something incorrectly installed / configured (how's that for stating the obvious x-) !). As far as I know, 1) A 2-conductor cable (if the connector only has 2-conductors, the construction of the "wire" doesn't matter) can only carry a "mono" analog signal. An "RCA" connector is only 1 signal and ground, as you thought. 2) the Nvidia 32MB refers to an [AGP] graphics accelerator and not a sound card. 3) any of these types of systems that I've seen have a stereo sound card, so the "line-out jack" is for a 3-conductor (stereo) mini-plug. There are some surround or 3-D cards that have multiple speaker or line outs, you need the correct docs. While I don't know those exact speakers, the ones that I've dealt with use a stereo cable from "line out" of the sound card to an input on the main small speaker (the one with the controls) and then a "mono" cable to the sub. The multi-pin is probably power and controls, not audio. My guess is that the main audio cable is wrong (even if it matches Gateway's color code) and should be replaced with the typical stereo mini-plug type, but we should check the docs if possible. This could be causing the bad sound problem, too. Let us know what you find, good luck!

 

[fenix]

Everything went well, the hook up was correct, turns out that it was a digital sound system, that's why it wouldn't play at all on my analog sound card. It's a newer technology that uses a rca like jack with only two contacts. But there are still 3 wires, the shielding (ground ) is in parallel with one of the channels, the guy that told me this thinks it's the crown, not the pin. Anyway, learn something new everyday, huh?

The digital Boston system sounded amazing. I reinserted the SoundBlaster Live sound card and blew out chunks of furballs from it and the rest of the machine, and it worked great. Suspect that it wasn't seated correctly from 1 1/2 years ago when Gateway set it up.

I was a little sleepy when I said the Nvidia was the name of the sound card!!

Thx for your suggestions, fortunately my theories were correct so I got $250 bucks more than I did yesterday. 2nd half will be mounting the lens permenantly and pulling wires, after that install a client on his laptop (when he gets one) for remote viewing from Europe.

Cheers !