Well... If we can get a quiescent metering and a fully loaded metering we can determine a lot about the gear. Then we can compare them to each other and see what is what. Class D to class A/AB would be a interesting comparison.
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Let's stop calling Class D amplifiers "efficient" when they are not.
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Not unless you know the current/voltage waveform and phase relationship you can't.
Ahhh righto... How about a digital wattage meter with simultaneously displayed voltage and current?
@antcollinet how about any of these multi function LED/LCD display meters. I am thinking of fabricating a dedicated AC amps, AC volts and AC power (W) metering box with 2 AC outlets and a AC power cord for supply. Then I will gift it to @amirm.
That'll do it.
Thank you. I built one of these for myself decades ago without the power meter and it was so handy to have sitting there just needing to be plugged into and it's always ready to go.
mhardy6647
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Do youse guyses have something against the lowly Kill-a-Watt?
I am not saying that their calibration is NIST-traceable, but they're certainly easy to use.
ahem -- I've got one. 
I am not saying that their calibration is NIST-traceable, but they're certainly easy to use.
ahem -- I've got one.
I simply had no idea that a KIll-a-Watt meters for voltage and current as well as Watts. My bad...LoL... We have it sorted out that a Kill-a-Watt is the best, simplest, most cost effective readily available solution that's ready out of the box.Do youse guyses have something against the lowly Kill-a-Watt?
I am not saying that their calibration is NIST-traceable, but they're certainly easy to use.
ahem -- I've got one.
View attachment 380617
mhardy6647
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I don't like to lose.
ahem -- I'm kidding... mostly!
I do think it is a handy little gizmo for the $. The thingy you linked to is nifty, too. We live in an amazing time vis-a-vis the availability of nifty little modules to add features we want to stuff we're fiddlin' with -- often at bargain basement prices!
I think the debate is whether the measurement accurately reports watts vs. VA or something else. That is what ticked off @wwenze about my initial try; without knowing the phase angles of voltage and current, or the power factor (PF), you cannot know the true average watts.
W = VA * PF where W = watts, VA = volts time amperes (rms), and PF = power factor (usually less than 1; 1 for DC or purely resistive circuits, 0 for purely reactive circuits).
This found after a quick search; there are many others: https://www.electronicdesign.com/ma...the-difference-between-watts-and-volt-amperes
W = VA * PF where W = watts, VA = volts time amperes (rms), and PF = power factor (usually less than 1; 1 for DC or purely resistive circuits, 0 for purely reactive circuits).
This found after a quick search; there are many others: https://www.electronicdesign.com/ma...the-difference-between-watts-and-volt-amperes
Excellent review literature material @DonH56.
Most watt meters are accurate at reading watts. Only the more expensive ones will show the current due to display limitations.
For the calculation of efficiency, we only need to use watts.
Reactive power is energy sent to the load and then sent back to the source after a while (or, at a different phase for periodic signal). Something to think about with speaker loads.
For the calculation of efficiency, we only need to use watts.
Reactive power is energy sent to the load and then sent back to the source after a while (or, at a different phase for periodic signal). Something to think about with speaker loads.
Tell
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Would like to see @amirm test the efficiency of amplifiers at different wattage when reviewing them. Maybe not as a standard thing, but at least for a while to get some idea how they generally behave. I mean for example if it's less efficient to run a say 500w amp instead of a 50w if you only listen at low volumes.
That is what this thread is about. Metering for power, efficiency calcs, voltage and current.>
Fabrication of box containing AC power meter, AC volts meter and AC amps meter with AC outlet and power cord.
Howdy Doods. In effort to encourage @amirm to meter out the voltage, current and power when metering AC powered gear I propose me fabricating a nice sized test jig box with the following features and capabilities. - AC digital power meter. - AC digital voltmeter. - AC digital Amp meter. - 1 or...
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I suspect user idiocy to be a major contributory factor...
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Actually, no.
If the review included:
1. Watts used while idle (awake waiting for audio).
2. Watts used producing 70dB music.
3. Watts used after idle 10 minutes and energy savings are active (if any).
That would be fantastic.
What I find is amps offer a WIDE variety of energy efficiency while idle even among Class D. In fact, some multi-channel A/B amps offer superior energy characteristics to some multi-channel Class D builds.
The best practice is to turn the amp off when not in use. But even then some designs will use 2x - 8x as much power as others while playing music at the same SPL.
I drOOL for a Amps, Watts and Volts metering at clipping but that is a destructive test sometimes and we don't want that. A real life useful measure is what we need. Just like you stated.
Emlin
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No 2 doesn't work because that will be speaker dependent.
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Actually, it does work.
The test would simply use the same speaker each time for the test.
It gives a baseline of what to expect. With a speaker efficiency of 88dB and higher it's very likely Watts used while idle and at 70dB will be exactly the same or within 1W difference.
All tests will require sine wave sources to ensure a steady state for the the devices digital power, volts and current metering to get solid measures that do not have a delta change like music will.
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