Measuring Output

zingo

What is the easiest way that ya'll have found to measure the wattage coming out of components? I have a receiver that I want to test, plus an amplifier that I don't have any numbers on and would like to know before I hook it up to anything. Thanks for any help!

Refefer

A simple multimeter has always done the trick for me.

As for testing, I'd drive the amplifier and reciver slowly using a crummy pair of speakers until you hear some distortion. Turn it down until you can't hear it anymore and measure it at the amplifier. That should do the trick.

bikezappa

Yes you need a volt meter and you need to know the approximate impedance of the speakers.

Watts=Current times Volts or W=IV
Also ohms law states that
Volts= Current times Impedance
or
V=IR
or
I=V/R
Substitute I with V/R in the equation for Watts and get
W=(V times V)/R or W=Vsquared/R

For example at the loudness sound you can stand the voltage across the speakers is say 10 volts from your multimeter and you have 8 ohm speakers. Substitute these numbers to calculate the output power of your amp.

W=(10x10)/8=12.5 watts from your amplifier.

The amazing thing is that most people will not be able to stay in the room with 30 volts to 8 ohm speakers.

W=(30X30)/8=112 watts

Remember this is average watts, not peak watts.

Have a blast.

Peter

zingo

So what am I doing wrong...
I measured the output of my receiver at 8mv and my speakers present a 4 ohm load, which with voltage squared divided by resistance equals 1.6

bikezappa

Sounds like you have the wrong scale on the voltmeter. Try measuring the voltage on a 9V or 1 1/2volt battery.

zingo

Well, I played a 99Hz tone on my Denon DRA-335R and got 2 volts, which gives me about 1 watt when I have the receiver turned up about 2/3rds of the way and playing through a pair of R15s (which my multimeter measures at 4 ohms). Don't get me wrong, that 99Hz tones in uncomfortably loud, but only 1 watt! I also measured a battery and it gave me 1.5 volts so it is calibrated correctly (and yes I did change the meter back over to AC after measuring the battery).

ben62670

zingo wrote:

Well, I played a 99Hz tone on my Denon DRA-335R and got 2 volts, which gives me about 1 watt when I have the receiver turned up about 2/3rds of the way and playing through a pair of R15s (which my multimeter measures at 4 ohms). Don't get me wrong, that 99Hz tones in uncomfortably loud, but only 1 watt! I also measured a battery and it gave me 1.5 volts so it is calibrated correctly (and yes I did change the meter back over to AC after measuring the battery).

If you have a DBL meter, and turn the test tone to the same volume most speakers are around 1 watt at one meter will give you 90 Dbl. 90 Dbl is pretty loud especially with a test tone.

Ben