14 or 12 guage wire

Discussion in 'Home Theater Projects' started by brandon*b, Aug 12, 2003.

  1. brandon*b

    brandon*b Extra

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    For my rear surrounds, is 14 guage wire too light for approximately 30' run? Or would you suggest 12?
     
  2. Vincent_S

    Vincent_S Second Unit

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    Use 12 gauge if you can. The longer the run the thicker the wire. 14 gauge will work fine but go with the 12 if you can.[​IMG]
     
  3. Chu Gai

    Chu Gai Lead Actor

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    The short answer that probably works for 99% of all cases, is to just use 12 gauge. In your particular case, you can buy a 100 foot spool and realize some cost savings. A prudent approach is to cut off a few more feet than you actually need. This will allow you flexibility in repositioning as well as leeway should you need to remake the connector. Beats splicing.

    The long answer is as follows and uses a reasonable rule of thumb. This 'rule' or guide is that your total loop resistance of your speaker wire should be less than 5% of your speaker's minimum impedance. The rationale for this is to avoid situations where the speaker wire resistance affects the frequency response of your speakers as well keeping power loss from your receiver or amp to a trivial level. Before you go out and start trying to find out what your speaker's minimum impedance is, just assume it's 2 ohms so 5% of that is 0.1 ohms.

    Let's look at the loop resistance of some common gauges of copper and remembering that we must double the values given below because speaker wire is a loop. The first number is the gauge, the second is the resistance in ohms/foot.

    4 .000292
    6 .000465
    8 .000739
    10 .00118
    12 .00187
    14 .00297
    16 .00473
    18 .00751
    20 .0119
    22 .0190
    24 .0302
    26 .0480
    28 .0764

    Now let's go back to your question, which is what gauge to use for a 30 foot length? Well given what's been said, the total loop resistance for 30 feet should be 0.1 ohms or less. Therefore 0.1 ohms/30 feet = 0.0033 ohms/foot.

    The loop resistance of 14 gauge is 0.0059 ohms/foot
    The loop resistance of 12 gauge is 0.0037 ohms/foot
    The loop resistance of 10 gauge is 0.0024 ohms/foot

    12 gauge is pretty damned close to our target number. Now you see why people almost automatically respond with 'just get 12 gauge' when asked what size to get.
     
  4. brandon*b

    brandon*b Extra

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    Thanks Chu, you definitly answered that one for me!
     
  5. Sean Romo

    Sean Romo Agent

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    Where is a good place to get 12 gauge spool for reasonable price? I could get 100'.

    And...would it hurt to use 12 gauge for short runs?
     
  6. Chu Gai

    Chu Gai Lead Actor

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    Lowes, Home Depot, Partsexpress.com, knukonceptz.com (they've got a sharp looking one...blue), etc. No it doesn't hurt.
     
  7. Sean Romo

    Sean Romo Agent

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    Thanks
     
  8. NicholasTS

    NicholasTS Stunt Coordinator

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    when does the law of diminishing returns come in to play here? When is the guage just getting too big?
     
  9. Chu Gai

    Chu Gai Lead Actor

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    by too big are you saying the wire gets too thick or are you saying when does it get too thin?
    in any event, maybe this link (http://home.earthlink.net/~rogerr7/wire.htm) will answer some questions. take a look at the very brief examination that Stereo Review did back in the 80's. Now granted certain things didn't take place such as listener training but perhaps all that means is they need to move up a couple of gauges. Also not too long ago, Tom Nousaine was challenged by the president of Transparent basically stating that he, the president, could easily distinguish his speaker wire in a test. A few months later Nousaine and a couple of people drove up to the guy's house where basically he renegged. Draw your own conclusions.
     
  10. NicholasTS

    NicholasTS Stunt Coordinator

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    smaller guage, larger diameter. Thanks for that link! It was very interesting.
     

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