Contour Enthusiasts Group Archives Forums Modifications Audio what gauge wire do i need?

You sure about that math APT CSVT?

By your example, this "360watt" amp should be just fine with a 10 or 15 amp fuse on the power cable.

I am using 4 gauge and I am running around 500 watts.

I think for 1500 watts 8 gauge is not an option. What is the rated current draw of the amplifier that you are using. 4ga is not that expensive so I would not bother with anything else. Whole kits are available for $32.00 delivered!!!

I'm sure. According to my HP calculator, there are 4 of Ohm's laws.

V=IR
P=VI
P=(I^2)R
P=(V^2)/R

360w into 4ohms was an example. However, if this amp is capable of 1500w, probably bridged mono into 2ohms, then 27A max. But if Marshal is going to hook up 2x400w into 2 ohms, then 20A will be peak current draw.

What amp is this anyway, we may arguing over a Pyramid amp.....LOL. Anyway does Ohms Law take into account the amps inefficiency? and what voltage are you using for that constant? Also what resistence are you using or figuring? I have not done the math myself, but I have a 1000 watt Class D (real power, puts out 34V AC at 1 Ohm) It draws 123 amps peak! Yet is stays extremely cool (around 110-115 degrees F after 1 hour at full clip at full volume) so I know it is pretty efficient.

Ohm's laws are electricity fundementals. They work regardless of how the amp is rated. Regardless, 8GA should work, but I still recommend 4 for Marshal.

I'm not tying to start a pi..ing match with you here by any means. In fact I agree with your choice of the 4ga..
But, I'm sorry, even with a class D amp there is no way the POWER SUPPLY section is going to require only 20 amps of current at 14+ volts to produce an "honest 2x400".

BTW how much current would you say is on the speaker leads at that point?

4 guage!! Let the current get through!!!

At what load?

800w into 4 ohms is 14.14A.
800w into 2 ohms is 20A.

That's at the speaker terminals and only if the amp is acutally putting out 800w continuously. Most likely, the amp will not deliver 400Wx2 at say 20Hz, but maybe 50-60Hz.

If you want to know how much current you are actually putting to your driver with your class D amp, measure the voltage (AC) at the speaker terminal with a sine wave being played through it. Maybe 20Hz or 40Hz. (V^2)/R = current.

Ok, I took Math/calc etc. ( Seems like years back) Now my understanding of this after playing with numbers is that R is the resistence in the wire not the amps load impedence. Do this one 80 amps of current at 1 ohm, according to your interpretation you need 80V for it to be possible(80=80*1) I think we all know most true 800-1000 watt class AB amps will draw this amount. Now figure 14V with 80 amps R=.175 Ohms. So you going to say that in order for an amp to draw 80 amps it has to be at .175 Ohm! I think there is a more advanced law that has efficiency figured in. I haven't looked for it yet, most likely will be in my calculator as well (HP 48G)

Maybe I am wrong and dont remember math at all but something does not seem right.