There have been many thoughts shared on interconnects and speaker cable elsewhere in this forum and in other forums. A lot of debate occurs regarding the advantages of different means to overcome various problems, most of which are minor in the large scheme of things. I think the main point for speaker cables, beyond safety, reliability and proper installation ("Will these things short out?") is resistance. To a much lessor degree come considerations of capacitance, inductance, skin effect, oxidation, etc. But back to resistance ...
If you can glean useful information from wire resistance and gauge tables, I would pick a wire or combination of wires that allow 0.2-ohms or less round-trip for 8-ohm loads, and 0.1-ohms or less round-trip for 4-ohm loads.
See:
http://www.epanorama.net/documents/wiring/wire_resistance.html The 0.2 and 0.1 numbers are my preference and not entirely arbitrary. I did a graph showing a calculation of watts delivered for various wire resistances and speaker loads. I also did calculations of the reduction in amplifier damping (the amplifier’s ability to maintain control over the motion of the loudspeaker’s voice coil) based on the introduction of resistance between the voice coil and the amplifier. The lines of the graph fell off sharply (bad news, in my opinion) if one went much beyond twice the numbers I just recommended.
Loudspeakers near the amplifier pose a smaller problem because the cable round-trip length is not very long.
Slightly off topic, and discussed elsewhere: the passive crossovers found in most loudspeaker systems introduce some non-linear impedance between the voice coil and the amplifier. While the problems introduced by passive crossovers may outweigh most speaker cable issues (why some gunslingers advocate active crossovers prior to bi- or tri- amplification), having a low resistance connection between amplifier and crossover will help the crossover ‘behave’ in the best manner possible for most crossover networks.
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A quick way to use one of the tables presented at the link I posted above:
A table almost halfway down is labeled, “Copper wire resistance table.” Just below the table, the first sentence reads, “These Ohms / Distance figures are for a round trip circuit.”
Looking at the 14-gauge section and rounding off, we can see that a 190-foot cable length between supply and load would introduce about 1 ohm of resistance. So, in order to maintain 0.1-ohms or less using 14-gauge wire, the cable length between supply and load should be 19 feet or less. 16-guage limits the 0.1-ohm length to 12 feet and 12-gauge extends the 0.1-ohm length to 30 feet.
Because most people are more concerned with the best power and control for their main and center speakers, locating the amplifier(s) near the front of the viewing area works out. Having longer cable runs to the side and rear surround speakers means either running parallel cables, heavier gauge cables or accepting just a little less ‘control’ of the surrounds.
I recently helped a friend install a moderate system in their home. I found a reasonably good deal on a 250-foot roll of 12-gauge speaker wire at a large home improvement franchise store.
[This message has been edited by bestbang4thebuck (edited June 03, 2004).]