Volts x Amps = Watts?

[lilmaniac2 5,000+ posts]

I did use a true RMS meter, it is an Ideal 61-766. And yes, I assumed that the most accurate readings would be under real-world conditions...installed in the vehicle with the subwoofer hooked up. I could tell that there was a fair amount of clipping during the test...does this express itself as a voltage higher reading? Would I want to take the measurements at the onset of clipping? Thanks for all of the input so far.

clipping f's things up...

You did it correctly, but if you had it on peak hold and it was clipping your getting garbage readings.

The apparent power argument always comes up when people test amps like this. My argument always is, until they show me a better way of doing it with the tools readily availible, it will do.

 

[Ed Lester 10+ year member]

I did use a true RMS meter, it is an Ideal 61-766. And yes, I assumed that the most accurate readings would be under real-world conditions...installed in the vehicle with the subwoofer hooked up. I could tell that there was a fair amount of clipping during the test...does this express itself as a voltage higher reading? Would I want to take the measurements at the onset of clipping? Thanks for all of the input so far.

clippling can add voltage but in audio it is not all too desirable. Sometimes a clipped reading is also referred to as peak wattage as the clipped portion is given off as heat and not usable.

A more true reading will be taken from a clean signal.

If you have an O scope you can see at what volume and gain settings will give you your top clean voltage.

 

[Lakota 5,000+ posts]

Uh oh, got to bust out the AC power triangle.

 

[Haunz 10+ year member]

The apparent power argument always comes up when people test amps like this. My argument always is, until they show me a better way of doing it with the tools readily availible, it will do.

You either need to measure the inductance and capacitance of the load so you can account for the power factor and the true impedance of the sub at your test freqency.... Or you can buy these funny little things called non-inductive resistors to use as a load.... TRY THAT !

FYI there are a few programs available on the net for free you can use to measure THD which is even better then using a scope IMHO....