# speaker wire for 1503???

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

1. ### Greg P Stunt Coordinator

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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.

Thanks

2. ### Anthony_Gomez Guest

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

3. ### Greg Monfort Supporting Actor

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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

Where:

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

Example:

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.

GM