Calculate an amps efficiency

Hi all,

Is there a mathematical way to calculate an amps effciency

I thought its was input divided by ouput times 100Any ideas?

Later

Skold

2004 Honda Civic Ex 4Dr

Kenwood DDX-7015/W Nav

4 Fosgate T152C

Hifonics Brutus BX1500D

RE XXX 12 in a 4 Cube Snail Shell

input voltage times input current = input watts RMS output watts divided by input watts times 100 = efficiency 14.4 X 30 = 432 watts 300 / 425 = .694 X 100 = 69.4% efficiency While this is a VAST oversimplification, this is pretty close, and will get you an efficiency number approaching the real numbers...It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Thanks, then in theory my new Memphis 16-MC500D is 71.4% efficent and my

Not bad for a Class D amp

Thanks a bunch

2004 Honda Civic Ex 4Dr

Kenwood DDX-7015/W Nav

4 Fosgate T152C

Hifonics Brutus BX1500D

RE XXX 12 in a 4 Cube Snail Shell

My amp is 500 RMS. The manual says use a 40A fuse. 14.4x40 = 576 watts input 500/576 = .87x100 = 87% efficent??? In a class A/B amp?? Huh?? Paul

As I said, this is a GRAND OVERSIMPLIFICATION. This formula takes the power supply AND the outputs into consideration. If you have a very efficient power supply (and most switchers are) and a not so efficient output, they will average in this formula. If you get a number TOO much above around 60 to 66% for a class AB, then I would suspect your manufacturer may be stretching the truth a little bit as for the output power... that or they offer a better protection system by underrating the input fuse. I expect your amp COULD take probably around 50A without damage (DON'T DO IT! THIS IS SPECULATIVE) and the mfr just wanted to extra protect it with a smaller fuse than is necessary... Insofar as the digital amp, that sounds pretty close to the mark. In THEORY, digital amps can run as high as 95% efficient, but in PRACTICE, 70 to 80% is more like it...It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."