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Originally Posted by poo /img/forum/go_quote.gif
I thought of this - but considered that even if I do use separate cables, they will pretty much run so close together that they may as well be one. Perhaps I should use something like well shielded speaker cable - RCA one end and 1/4" at the other?
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Many misconceptions here, let's start at the beginning........
Properly shielded stereo cables, with the shield connected at one end only, have such little interchannel interaction that it's not an issue.
Here is a well regarded audio signal cable for a single channel signal:
One would normally connect the "clear" conductor to the tip on a 1/4" plug, the blue to the sleeve, and make sure the shield didn't connect to anything on that end. On the other end, the clear would be connected to the center signal pin on the RCA, with the blue AND shield connected to the outer ground. The shield then effectively funnels all interference to ground at the amplifier end only.
If you wished to make it a truly "single" cable, this "star quad" construction is often used for stereo mini-to-RCA pair cables:
This photo sort of hides one of the blue conductors......there are two clear, two blue, four total. One clear conductor is connected to the tip of the mini, the other clear to the ring, and the two blues are attached to the sleeve. On the other end, you have to split out the spirally wound conductors, then connect one clear and one blue to each RCA as noted above. The big question in that case is where to connect the shield....and it usually ends up being at the mini end, because it is harder to split the shield on the other side.
In your case, which requires pairs of plugs on both ends, this is not necessarily the easiest or neatest thing to build.
Look at how closely the two stereo signal conductors are to each other--they very nearly touch, with no shield between them. Interference/crosstalk follows an inverse square relationship with respect to distance. In starquad, the signal conductors are maybe 1 mm apart. Placing the signal conductors in separate runs only 5 mm apart cuts crosstalk to 1/25 of what it would be in star quad. And that's without shielding, which reduces the effect even further.
But by "single cable", do you mean something like this--two independent channels physically connected together, but separately shielded?
Using cable such as this you would just make it up like the first cable shown above. It's simply for ease of handling that the two sides are connected in the middle, like speaker "zip" cord.
Many of the stereo pair cables with molded ends are made this way; some less expensive versions use a pair of small coaxially constructed cables, with just one conductor in the middle as the signal, and the shield serving as the ground side of the audio connection (connected to the RCA ground on both sides rather than just one.)
I'm drawing a complete blank by what you are referring to as "well-shielded speaker cable"........most speaker cables are just two-conductor, unshielded designs.
Quote:
Originally Posted by poo /img/forum/go_quote.gif
Just making sure... but what I assume I need is left and right 1/4" plugs running from the card (bottom one in this http://www.dolphinmusic.co.uk/shop_i...5741203c66.jpg pic) which connects to amp at the other end via left and right RCA plugs... correct?
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Correct, you need a plug like this on the card end:
