8 Gauge Speaker Cable


Hey. I recently moved to a new house and just finished ripping out a closet to make my audio room bigger. :-) I want to run my rear speaker cable through the ceiling and behind the wall I haven't put up yet.

1) Is this a good idea? There is nothing up there now except some plumbing. The outlet power lines are 6-8 feet from where I'm running the speaker wire.

2) Extrapolating from www.alphacore.com, in order to run 150 Watts 35 feet, I should use 8 gauge wire or larger. Does 8 gauge mean per terminal (+ or -), both terminals, the outer cover, or something altogether different?

3) Considering the cost of 8 gauge cable and that I only use the rear speakers 2-4 hours a week I'm considering using car audio grade wire and soldering the spades on myself. I used a blue/silver wire twisted into clear tubing in my car. It's $1.50 a foot on eBay. Anyone have experience with this? Good idea or am I missing something? Do I even need the braided wire or can I go with cheaper 8 gauge that isn't twisted?

Thanks!
leoturetsky
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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According to Bomarc's formula I need 4 gauge wire to my Thiel SCSs (3 Ohm minimum resistance x 35-40 feet). Of course the only reasonably priced wire of this size is the auto grade power wire Hiwaves mentions. While that itself doesn't bother me in the least I am worried that it doesn't protect against EMI/RF well. I guess I could "criss-cross" it along the entire run and hold it in that position with electrical tape. Sean, how many lengths of the wire you recommend would I need to join together to get 4 gauge? Thanks everyone!
Leo: That chart is pretty conservative. Especially if it's your surrounds that require the length, and you don't use them much, you can get away with smaller wire. 8 AWG is almost certainly sufficient, and Sean's pseudo-11-gauge might even do the trick. Maybe you can try a few things out, since you're not talking about huge outlays here.
Sean's mostly on target here. I didn't mean to ignore factors other than resistance, but to provide a simple guide that was more meaningful than the one Leo had been using. Capacitance can be a factor in longer runs of ANY cable, though I'd tend to worry about resistance first and foremost. Interference is situation-specific (and less common than usually imagined, IMO). We'll agree to disagree about the sonic superiority of solid wire. But his specific product recommmendations are good ones, at zipcord prices. (But, of course, I think all cables should be sold at zipcord prices.)
After monitoring this rather long open forum on speaker cable runs, would some one please write and assure me that this is not for the rear channels of a Bose AcoustiMass System? Thanks so much