how to measure amps output

[bonesninja 5,000+ posts]

can someone explain in detail to me how to measure an amps wattage output with a multi-meter including what settings to put the meter on when i doing it.

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[boister77 10+ year member]

you can find out how many watts your amps produces with a certain load by using the calculation, P=(V^2)/R where V is the voltage ouput from you amp and R is the ohm rating of your sub. you can find the voltage, V, by using your dmm. you have to set you dmm to read ac voltage. set it to range that is relative to the stated output of your amp at the ohm rating being used by using this equation (P*R)^(1/2)=V. you then play a test tone and measure the output voltage of your amp. be sure you have you speakers disconnected first. for the test tones, use a 50Hz for a lows amp and a 1kHz for a highs amp. after you find your voltage, plug it into the first equation and the will give you the output of your amp. sorry if i didn't explain it well.

 

[n2audio 5,000+ posts]

However, since you don't know the impedance of the speakers at any given frequency the voltage you measure really means nothing.

 

[Scarenius 10+ year member]

To sum that one up:

You need: Multimeter, pink noise (same thing as test tone)

unplug your subs, put the multimeter in the place of one or both if bridged. Set multimeter to volts AC

To check what your amp can do when you give it hell, give it hell playing pink noise. Write down the number it gives. We'll call it A.

To check what it does normally, set the volume to what you normally listen to and play pink noise. Write down the number it gives. We'll call it B.

C is the impedance of your subs.

A^2/C = your amp's max RMS output

B^2/C = your amp's dd RMS output

Again, this isn't exact, but hey, it beats not knowing at all.

 

[jellyfish420 10+ year member]

get an o-scope //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[JimJ 5,000+ posts]

x2.

 

[maylar 10+ year member]

However, since you don't know the impedance of the speakers at any given frequency the voltage you measure really means nothing.

I wouldn't say it's meaningless... most full range speakers are within 10% of rated nominal impedance at 1000 Hz and subs at 50 Hz.