Hi, just jumping into the conversation to bring my 2 cents worth of professional knowledge. Such general assertions like "microphone cable has a high capacitance because it is a twisted pair" or "50 ohms cable has a low capacitance because is it is done for HF", very often prove wrong. It entirely depends on manufacturing parameters that vary widely between types.
But then there is a way to actually know: all the cable types have a data sheet available on the manufacturer's site. Check the capacitance in pF/m (or pF/ft depending on the country you live in), multiply it by the length you plan to cut, and voila, you have the capacity of your cable. Contrary to a common belief, a balanced cable can very well have have a low capacitance.
To concur and expand on LPspinner's post, here's how interconnects are done in studios where your records / films / TV shows are made (I know because I've done it). OFC, silver or 24K gold wire are not even considered, because they add cost for no known benefits. All the pro cables just use copper, sometimes tinned for protection.
- Low capacitance, well shielded cable for the phono sections. It is difficult to get these two qualities at the same time, so the cable may be a little more expensive. Note that the shielding is also specified in the data sheet, so you don't have to guess. Note that phono-level interconnects are rare except in community radios, usually the preamplifier is integrated in the turntable. Well, vinyl is a thing of the past anyway, so why bother to mention it (just joking! But as far as radios are concerned, well... that's the sad truth
).
- Well shielded cable for the line level interconnects. Balanced is better, even for short runs, since it reduces ground-induced hum (not that grounding doesn't matter even then). Capacitances does not really matter, except maybe for very long runs but then the induced noise becomes a nuisance before the trebles loss, especially on unbalanced links. Note that the extra circuitry involved by balanced interconnects is considered less harmful than unbalanced ones - of course YMMV, but this is how things are seen in the broadcast circles.
- In digital: 75 ohms cable for SPDIF (any plain video type, 10 metres max length), and 110 ohms balanced cable for AES/EBU (not an ordinary balanced cable). A specific connector of the same impedance is not required, because its influence on the signal is so low.
- Gold contacts are liked because they don't get oxidized, which reduces problems and maintenance. Nickel is standard too.
...And that's how your records/films/shows are made. No exotic gadgets involved, just commonsense engineering and manufacturing quality. Widespread cable brands are Belden, Canare, or Gotham. And Neutrik or Switchcraft for the audio connectors (no hierarchy implied, no affiliation). Neutrik NY273 is well regarded as a high quality, low cost RCA connector; their insanely expensive model with a retractable ground contact is often used in mobile applications, just because it is reliable and does not cause a noise burst when inserted.
by timbloke » 30 Dec 2011 20:27 
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