Using Fuses On Amplifier To Work Out RMS?

[Migz]

So i've heard a few times that you can use the fuses on an amplifier to work out roughly how much power the amplifier could put out.

I,e an amplifier with 2x 25amp fuses, has a total fuse size of 50 amps, so the amp could put out around about 400w rms give or take.

But the thing i dont get is at what impedance is this? Is this 400w rms at 4ohms? Or at the lowest ohm the amplifier is capable of?

I've seen an amplifier with a total fuse rating of 120 that says it does 1000w rms at 4ohm, which would sound about right for that fuse rating, but then it says 1400w rms at 2ohm, 1800w rms at 1 ohm. Which doesnt fit in with the fuse rating, but then it might be something to do with the fact they are at different impedances. Could anyone shed any light on this?

[Guest]

So i've heard a few times that you can use the fuses on an amplifier to work out roughly how much power the amplifier could put out.

I,e an amplifier with 2x 25amp fuses, has a total fuse size of 50 amps, so the amp could put out around about 400w rms give or take.

But the thing i dont get is at what impedance is this? Is this 400w rms at 4ohms? Or at the lowest ohm the amplifier is capable of? it's at the lowest impedance the amp was designed to handle.

I've seen an amplifier with a total fuse rating of 120 that says it does 1000w rms at 4ohm, which would sound about right for that fuse rating, but then it says 1400w rms at 2ohm, 1800w rms at 1 ohm. Which doesnt fit in with the fuse rating, but then it might be something to do with the fact they are at different impedances. Could anyone shed any light on this? cause its a false power rating. shit audio companies do this

Edited May 20, 2012 by Kranny

[jdw46]

Ive heard that you can take the fuses add them up and multiply that by your voltage and get a rough estimate of the wattage but im not sure if it works

[Guest]

Ive heard that you can take the fuses add them up and multiply that by your voltage and get a rough estimate of the wattage but im not sure if it works

yes it does, but you have to factor in for efficiency too. cause if you just do the fuse number times voltage, thats at 100% efficiency. which no amp ever can produce (except the rf t15k but thats different). so the "general" numbers are 50% for class AB amps and 75% for class D amps. but technology is changing to make things more efficient.

[deathcards]

Ive heard that you can take the fuses add them up and multiply that by your voltage and get a rough estimate of the wattage but im not sure if it works

yes it does, but you have to factor in for efficiency too. cause if you just do the fuse number times voltage, thats at 100% efficiency. which no amp ever can produce (except the rf t15k but thats different). so the "general" numbers are 50% for class AB amps and 75% for class D amps. but technology is changing to make things more efficient.

class d for example the sd250.2 has about 95%

and my massive audio p1500.1 has 86% if i remember correctly

Edited May 20, 2012 by deathcards