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I am looking to run some speaker cable through my unfinished basement. I will need 35 ft long cables for a couple of Technics SB-A10 speakers. What gauge of cable will I need? How is the gauge calculated? How much noise should I expect with a 35 ft long cable?

Impedance: 8 ohm

Input power: 200 W

Crossover frequency: 3000 Hz–6000 Hz

Output sound pressure level: 91 dB/W (at/a 1 m)

Woofer cone type: 25 cm (10")

Midrange cone type, ferrofluid: 10 cm (4")

Tweeter, cone type, ferrofluid: 5.5 cm (2 - 1/8")

Dimensions (W x H x D): 360 x 733 x 265
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2 Answers 2

up vote 20 down vote accepted

The most important aspect of speaker wire is resistance. There is a ton of junk-science and stupid audiophile marketing claims that will try to confuse you and make you spend absurd amounts of money, but don't be fooled.

Wikipedia actually has a good write-up on it:

Resistance is by far the most important specification of speaker wire. Low-resistance speaker wire allows more of the amplifier's power to energize the loudspeaker's voice coil. The shorter the cable and the greater the conductor's cross-sectional area, the lower its resistance. Depending on the hearing ability of the listener, this resistance begins to have an audible effect when the resistance exceeds 5% of the speaker's impedance.

They also have a chart: for 35' at 8Ω, you're good with 18 or 16AWG.


All you need is basic stranded cable. Don't pay extra for fancy brands, or "oxygen-free" or "hand woven by the dalai lama" or whatever (unless you have the money to burn and really way to, I guess) as there's really no difference -- you can use lamp cord, if you want.

In proper tests, the best audiophiles can't tell the difference between $500/ft "top of the line" speaker wire and coat hangers -- and if you can, James Randi will give you $1 million (sorry, a bit OT from your question, but people that believe in this nonsense really piss me off).


For in-wall applications, you should get wire rated for in-walls - which basically boils down to fumes that the wire gives off in a fire. There's a good article on Understanding In-wall Speaker, Video and Audio Cable Ratings on Audioholics. In short, in a 1-2 family dwelling, any cable with the following ratings is suitable for in-wall: CM, CMP, CMR, CMG, CL2*, CL3*.

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+ several million if I could - especially for "you can use lamp cord, if you want". Actually lamp cord is probably better than some speaker cables as it has a greater cross section and therefore lower resistance. –  ChrisF Jun 21 '11 at 7:59
    
Great advise, 16/2 SPT lamp cord works great. Expensive speaker cable is a joke, over-rated, just part of the snob factor. I have been using 16/2 zip cord on a Denon 70watt RMS analog amp with four Boston A100's for years. Works great. –  shirlock homes Jun 21 '11 at 9:59
    
If resistance is so important, wouldn't using solid wire be better than stranded? –  Tester101 Jun 21 '11 at 12:04
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solid wire isn't good in situations where you need flexibility or where the cable is periodically moved (e.g. when the speaker isn't built-in or you need to get to the back of the amplifier). But for the in-wall portions of the install, solid wire would be good. –  BMitch Jun 21 '11 at 12:35
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+1 for the good summery and answer for the specific size in this case. I would add that you should use wire that is rated for in-wall use. It should not be hard to find, monoprice or crutchfield should have plenty of options. –  auujay Jun 21 '11 at 16:13
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Crutchfield has a somewhat informative article: http://www.crutchfield.com/S-nBs26ogHK9Y/learn/learningcenter/home/speakers_wire.html

    Distance from speaker to amplifier  Gauge
    Less than 80 feet           16
    80 to 200 feet              14
    More than 200 feet          12

So you're fine with 16ga.

Remember that your total run from speaker to amplifier includes the leads from the amp to the wall at one end, and from the wall to the speaker at the other end. Still, with a 35' behind-the-wall run, you're still fine with 16ga.

That said, you could easily upsize to 14ga, as it's not very expensive. Lamp cord is great. Hardware stores often sell cheap speaker wire, too. Either works fine.

At the ends of the run, terminate in 5-way-binding posts:

While you're at it, pull an ethernet cable. Pulling an extra wire is only slightly more work, and you can use ethernet for a lot of different signals.

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Why run one ethernet when you can do two at twice the price! :) Seriously, one for networking, one for phone wiring, and they can use the same modular plates as the connectors in the above pic. –  BMitch Jun 21 '11 at 15:59
    
I'm also running 2 ethernet cables, and a coax cable :) –  Kevin Jun 21 '11 at 16:09
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@Kevin: when I wired my house, I pulled 3 ethernet + coax, so very similar to you. However, two coax is good for satellite HD signals. What about security cameras, audio/video, home automation? What if one of the wires you pull is damaged? Decide what you want, then double it. :-) –  Jay Bazuzi Jun 22 '11 at 2:22
    
Every house I buy, I end up running conduits and generally 2 ethernet cables as standard, with a string left in situ for whatever else I want to add. For some rooms I also add speaker cables, and/or telephone cables. I have no idea why builders don't put these in as standard - it has to be easier/cheaper at build time than as an afterthought. –  Rory Alsop Jun 24 '11 at 8:24
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