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Speaker Wire Gauge

3574 Views 6 Replies 5 Participants Last post by  MikeBiker
Setting up home theater in a new building. Longest run is about 50 feet, but most runs are 25-40 feet. Running through blown-in foam insulation. Power is coming from an Onkyo HT-RC370 7.2 receiver with a separate power amp for additional speakers. Counting the subwoofer in the main room, there are 12 speakers in our array.

I was planning on using 14 gauge CL2 speaker wire, but my electrical engineer friend (whose judgment about these things tends to be good) says he thinks I need 12 gauge. The extra money doesn't bother me that much (difference of about $35 for a 500 foot roll). It's working with 12 gauge vs 14 gauge that has me reluctant to go bigger unless I think there's a real advantage to it. Any thoughts on what would make more sense?
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12 gauge wire has a resistance of 0.00187 ohms per foot. For 50ft, the total resistance would be 0.09 ohms. Driving an 8 ohm speaker, the wire would cause about a .17 db loss with 100 watts from the amp.

14 gauge wire is 0.00297 ohms per foot. The same 50ft wire would be 0.15 ohms. There would be about a 1/4 db loss due to the 14 gauge wire outputting 100 watts into an 8 ohm speaker.

Both are negligible losses and, to me, not worth the hassle of using the thicker wire.
Excellent! Thanks for the clarity. That's just what I needed.
Just to back up the suggestion, this source agrees for speakers at 4 ohms or more and distances of 40' or less based on a wire resistance of < 5% of the nominal speaker impedance.
Yeah, I don't even consider 12AWG unless it's a run over 50', high power, low impedance, or a combination.

14AWG is easier to work with, cheaper, and adequate for most situations. Even it is overkill for many applications (but I usually have a roll of it around).
I would use 12 gauge wire on the Subwoofer, The others won't matter so much. The extra Damping you get will give you a deeper tighter bass sound.
If it's a powered sub, there is almost no power being sent through the connection wire. A small shielded wire is more than adequate.
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