Let's stop calling Class D amplifiers "efficient" when they are not.

[Doodski]

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]

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.

Amazon.com

 

[Doodski]

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.

Amazon.com

View attachment 380617

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.

 

[mhardy6647]

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.

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!

 

[DonH56]

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

 

[Doodski]

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

Excellent review literature material @DonH56.

 

[wwenze]

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.

 

[Tell]

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.

 

[Doodski]

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...

www.audiosciencereview.com

 

[ElJaimito]

There's a lot of reasons that smart plugs can sometimes melt or explode when they are used with high amperage or high wattage devices in your home.

I suspect user idiocy to be a major contributory factor...

 

[Doodski]

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]

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.

No 2 doesn't work because that will be speaker dependent.

 

[Doodski]

No 2 doesn't work because that will be speaker dependent.

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.

 

[Doodski]

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.

The best route is to use a load resister(s) and sine waves. Do it the same way each time.

 

[wwenze]

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.

Rewrite 2. as Watts used producing 5W then. Or actually at 70dB it would be more like 0.2W

I decided to arbitrarily use 5W instead of any other arbitrary number since that is the number that is already being arbitrarily used (SINAD @ 5W)

Actually why doesn't Audio Precision put a simulated speaker load inside the box, or is that a paid upgrade
Or even a input power / I / V sensor upgrade but I predict it would cost $30,000

 

[DonH56]

Actually why doesn't Audio Precision put a simulated speaker load inside the box, or is that a paid upgrade
Or even a input power / I / V sensor upgrade but I predict it would cost $30,000

The benchmark speaker load for a long time has been the PowerCube, around $30k last I checked (few years ago). https://www.audiograph.se/stand-alone/ You can (could, I have not looked recently) buy it stand-alone or as part of an AP test system.

 

[mhardy6647]

Hmmm... maybe "we" need a "Green Audio" website.
I am not being 100% facetious.
Maybe 87% facetious -- but not 100%.



Mrs. H & I are listening to a Rumours via a single-ended direct heated triode amplifier on DIY loudspeakers with Altec drivers and 100-plus dB sensitivity (1 watt @ 1 meter) as I type this.



ca. 6 kW worth of photovoltaics on the roof and a high-efficiency inverter Mitsubishi heat pump keeping us comfortable, so I don't feel too guilty...

 

[Doodski]

Hmmm... maybe "we" need a "Green Audio" website.
I am not being 100% facetious.
Maybe 87% facetious -- but not 100%.



Listening to a Rumours via a single-ended direct heated triode amplifier on DIY loudspeakers with Altec drivers and 100-plus dB sensitivity (1 watt @ 1 meter) as I type this.

I think it's prime time for 1 or all of these measures like efficiency, Watts, power factor and maybe mains volts metering of all tested gear. People are energy efficiency conscious these days.

 

[wwenze]

Hmmm... maybe "we" need a "Green Audio" website.

SilentPCReview died, so we couldn't even sustain a Green Computer website

 

[Doodski]

SilentPCReview died, so we couldn't even sustain a Green Computer website

Maybe but ASR can add the power, power factor and efficiency figures to it's measurement repertoire. I suspect that will draw in a lot of interested people that otherwise might not come here to ASR.