Current Calculation for Audio Amplifer

[mike poon]

I have one Bryston Amplifer designed for 4 ohm and 8 ohm load. I need to find out what is the output current if I replace the load with 1.5 ohm load. Amplifier rated at 900W at 4ohm and 600W at 8ohm.

Can someone please enlighten me?

 

[Nigel Goodwin]

I have one Bryston Amplifer designed for 4 ohm and 8 ohm load. I need to find out what is the output current if I replace the load with 1.5 ohm load. Amplifier rated at 900W at 4ohm and 600W at 8ohm.

Can someone please enlighten me?

If the amplifier is rated at 4 ohms, then you can't feed a 1.5 ohm load from it, you would destroy the amplifier - or (if lucky) the protection circuits 'might' protect it. As the amp derates so massively from 8 ohm to 4 ohm (4 ohm should be double 8 ohm, 1200W), you don't have a chance at 1.5 ohm.

The calculations are simple enough though, W=IxIxR or W=VxV/R and V=IxR. Use the second formula to work out the voltage at 8 ohms, then the third one to work out the current using the voltage you just calculated and the load (1.5 ohms).

But DON'T actually do it, the amplifier won't stand it!.

 

[audioguru]

Only 1.5 ohms is pretty darn close to a dead short, isn't it?

 

[bogz]

right. your amp prob has some sort of output current 'limit'. (so you dont fry it). Never good to rely on that, though