speaker wire for 1503???

Discussion in 'Archived Threads 2001-2004' started by Greg P, Jan 24, 2002.

  1. Greg P

    Greg P Stunt Coordinator

    Jan 7, 2001
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    What type of internal and external speaker wire do I need for this guy? I heard in another post that I need a low gauge or special type that can handle the 1000+ watts I will probobly feed it.

  2. I am using 12awg with no problems at all. ..just zip cord. Nothing special.
  3. Greg Monfort

    Greg Monfort Supporting Actor

    May 30, 2000
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    Assuming you don't want the wire to act as a resistor to either flatten a

    rising response or better match the impedance of a tube amp, then the size

    is determined by how much voltage drop you consider acceptable.

    Using the driver's Pe, Re (or total Pe, Re if multiple drivers are used),

    then with the formula:

    I = sqrt P(Pe) / R(Re)

    you can calculate ~ max current draw capability. If this number is >the

    amp's rating, then you may clip it on loud passages.

    To determine wire size required:

    Circular Mils (CM) = (2*L*I*10.8)/VD


    L = length of wire in ft

    I = max current of circuit

    VD = voltage drop

    Some rounded off CM values based on a single solid core:

    32ga = 64

    30ga = 100

    28ga = 159

    26ga = 320

    24ga = 404

    22ga = 640

    20ga = 1024

    18ga = 1624

    16ga = 2580

    14ga = 4109

    12ga = 6529

    10ga = 10384

    8ga = 16512


    Pe or short term peak rating = 400W

    Re = 3.4ohms

    wire run (one way) = 20ft

    VD = 1V (this is considered the max acceptable, I usually use 0.3-0.5V)

    Sqrt 400/3.4 = 10.846A

    (2 x 20 x 10.846 x 10.8)/1 = 4685.472CM, or 12ga.

    As you can see, small wire/long distances can eat up amp headroom.

    Conversely, if the amp is near/on the speaker, acceptable wire size becomes

    tiny (or Vd vanishingly low if a large gauge is used).

    At what point downsizing the wire becomes audible is of course dependent on

    the individual and his system/room.


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