Leo, there is a LOT more to consider than any one "spec" when talking about a long run of speaker cable. Here are some of the factors that i would take into consideration:
wire gauge: should be as heavy as possible to minimize series resistance. This also helps maintain amplifier damping and control over the speaker drivers and minimizes signal loss.
impedance: cables with a high reactance level ( capacitive or inductive ) should be avoided. These effects would become compounded due to the long run. As such, one should look for a cable that has relatively neutral characteristics and is of a low impedance / low reactance design. A long run of "zip cord" or "monster" style cable would result in increased high frequency and upper midrange roll off due to added inductance. A long run of high capacitance cable ( like Goertz, Chris VH's CAT 5 design and possibly even Kimber 8xx designs if long enough ) could produce amp stability problems.
susceptability to interference: any long run of wire becomes a "long wire antenna" whether we like it or not. As such, you need to look for a design that takes this into account and tries to minimize it. Using wires arranged in a braided pattern, twisted pair, star-quad, something that makes use of a shield, etc... would be my suggestion. Keep in mind the above mentioned caution about "radical" designs though.
flexibility: since you'll be making quite a few bends in order to route this, you'll need cable that is relatively easy to manipulate and is not "brittle". In my opinion, this would call for stranded rather than solid wire even though i typically prefer solid for best sonics.
cost: obviously, nobody wants to pay more than they have to although some are more willing than others : )
With all of that in mind, try looking at www.partsexpress.com for these part numbers:
100-756 ( 4 x 16 gauge )
100-768 ( 4 x 14 gauge )
100-728 ( 4 x 16 gauge )
The first two make use of slightly higher grade copper and jacket materials. The second is a slightly cheaper version but still fully useable. I figured that i would pass them both on as others might be interested and have various budgets. All are 100 foot spools and are very reasonably priced. They also come in 500 and 1000 foot spools if you get really carried away : )
These can be wired in what is called a "star-quad" pattern. In English, this would be referred to as "criss-crossed" or "kitty corner". This lowers inductance for wider bandwidth and more linear frequency response, reduces their susceptability to RFI and EMI and effectively doubles their gauge for lower series resistance. Since you are using 4 smaller gauges to make up what is effectively two larger gauge cables, flexibility isn't a problem either. The 4 x 16's would be the same as a 13 gauge pair of wires and the 4 x 14 would be the same as an 11 gauge pair of wires.
Hope this helps. I know that they might not have the fanciest materials or "hi-fi" brands, but they should work quite well for your situation. This is especially true since they are merely surrounds. Sean
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