What is the name of the tool?


Forgive my absence of knowledge, but what is the name of the tool that one uses to measure the wattage coming out of ones speakers. I called it a watt meter to my family and got something that measures the watts and current coming from the outlet to the powered device I was using instead, for Christmas.  
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Showing 2 responses by ieales

Meters are too slow unless they are instantaneous peak reading with decay, read voltage, not power, and only if you know the amp voltage capability at all frequencies.

Most meters come under the classification of jewelry and are installed for appearance ONLY.

In the studio, we had a wall of amps, all without meters. Many studios have amps in separate rooms due to fan noise and the ability to duct in copious cold air to keep them happy. In million dollar+ studios, if power amp meters were of any use we'd have purchased them.

If you want to really know, use an oscilloscope. You can purchase an Android phone/PC based unit for under $100 Loto USB Oscilloscope OSC482M for Both Android Phone/Tablet & Windows PC, 2 Channels, 50M S/s, 20MHz (Bandwidth), 8~13 bit Vertical Resolution: Amazon.com: Industrial & Scientific

You won't know what the power is as you don't know the speaker impedance at the frequency in question, but by using Peak Hold function you will know how close you are to clipping. If you see an flat top peaks, you are clipping and your tweeters are probably not long for this world.

One caveat of using a scope on both channels at the same time is they must have a common GND terminal. Most amps do, but some use bridged outputs and may be destroyed by commoning GND.
The Illuminated Power Output Watt Meter on the MC501 is peak responding, and indicates the true power output of the amplifier
No, they measure voltage. Power would only be correct for a pure resistance. Examine loudspeaker impedance curves. Some of the more egregious ones have a 10:1 impedance ratio.