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

Well we can backcalculate from that:

1720341500581.png


I assumed it did not have PFC due to the big 50Hz transformer, but it has above 0.7 at some points and varies until 0.85 at full load so this has the behavior of passive PFC.

Also strangely enough I'm not seeing the class G-ness of this amp because efficiency at 1/8 and 1/3 is pretty ahem compared to full, where's the region of high efficiency that people keep pointing on the graphs.
Edit: Oh
1720342454544.png


Edit2: Ok I did the same for GX5 because I just had to see the G-ness
1720342659711.png
 
Last edited:
DonH56 said:
For comparison, Buckeye Amps stereo 350 W/ch (8 ohms) amp (Hypex NC502MP based) uses 0.5 W at idle and is specified as 92% efficient at full power.
Click to expand...

0.5W is standby (soft off), not idle.
 
wwenze said:
Well we can backcalculate from that:

View attachment 379509

I assumed it did not have PFC due to the big 50Hz transformer, but it has above 0.7 at some points and varies until 0.85 at full load so this has the behavior of passive PFC.

Also strangely enough I'm not seeing the class G-ness of this amp because efficiency at 1/8 and 1/3 is pretty ahem compared to full, where's the region of high efficiency that people keep pointing on the graphs.
Edit: Oh
View attachment 379514

Edit2: Ok I did the same for GX5 because I just had to see the G-ness
View attachment 379517
Click to expand...
I missed QSC had PFC, not something I looked for. My original idea was a quick calculation, should have known better than try that here.

I earlier mentioned that QSC does not make it clear class of operation; you have to dig into various documents for each amplifier series, and not all amps in the series have the same class. Lower-power amps are often AB, higher-power H or D.

restorer-john said:
0.5W is standby (soft off), not idle.
Click to expand...
Figures.

I think I've screwed up enough for one thread, out.
 
PF = power factor
PFC = power factor correction

QSC uses PFC to correct a low PF.
 
I don’t much care about efficiency as a percentage at low power outputs. If I’m putting a watt into the speakers, I don’t care idf the amp is consuming 10 watts or 1.1. And efficiency will always be zero at idle.

I do note idle power consumption. B&K claimed my amp idles at 60 watts. That’s a significant amount of heat for no output—enough to need significant heatsinks. But not heatsinks larger than at rated power.

The efficiency of Class D matters for heatsink and cooling design, it seems to me, which isn’t much of a thing at idle. Cooling sufficient for rated power will be abundant for idling, it seems to me. My Buckeye, if it is indeed producing 300 wpc, is creating about 50 watts of heat from the devices (plus power supply). It’s creating less than that at idle.

Percentages are statistics that can be really misleading.

Rick “just tell me how many watts are being radiated as heat” Denney
 
rdenney said:
I don’t much care about efficiency as a percentage at low power outputs. If I’m putting a watt into the speakers, I don’t care idf the amp is consuming 10 watts or 1.1. And efficiency will always be zero at idle.

I do note idle power consumption. B&K claimed my amp idles at 60 watts. That’s a significant amount of heat for no output—enough to need significant heatsinks. But not heatsinks larger than at rated power.

The efficiency of Class D matters for heatsink and cooling design, it seems to me, which isn’t much of a thing at idle. Cooling sufficient for rated power will be abundant for idling, it seems to me. My Buckeye, if it is indeed producing 300 wpc, is creating about 50 watts of heat from the devices (plus power supply). It’s creating less than that at idle.

Percentages are statistics that can be really misleading.

Rick “just tell me how many watts are being radiated as heat” Denney
Click to expand...
I keep requesting mains wattage draw c/w current metering too so we can see what is occurring with this gear. I had it at one electronics lab I owned and it was so nice to operate when it is all prewired with meters and one just plugs in and also have a variac to it if required but for @amirm's purposes a variac is not required.
 
Doodski said:
I keep requesting mains wattage draw c/w current metering too so we can see what is occurring with this gear. I had it at one electronics lab I owned and it was so nice to operate when it is all prewired with meters and one just plugs in and also have a variac to it if required but for @amirm's purposes a variac is not required.
Click to expand...
Wattmeters are $10 on Amazon.
 
Doodski said:
There is a little more to it than a Watt meter. It needs voltage metering and current or watts. I prefer current and then we can make our own Watts calc.
Click to expand...
The ready made ones are recording. It would be useful to know the energy consumption over a week or month of actual use.
 
Petrushka said:
The ready made ones are recording. It would be useful to know the energy consumption over a week or month of actual use.
Click to expand...
The week or month is a difficult metering because the unit needs to be operated and used for that period otherwise it sits there quiescent. To get Amirm to meter the voltage and current will be a hurdle... LoL.
 
Doodski said:
The week or month is a difficult metering because the unit needs to be operated and used for that period otherwise it sits there quiescent. To get Amirm to meter the voltage and current will be a hurdle... LoL.
Click to expand...
But that’s the point. Annual energy consumption.
 
Petrushka said:
But that’s the point. Annual energy consumption.
Click to expand...
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.
 
Doodski said:
There is a little more to it than a Watt meter. It needs voltage metering and current or watts. I prefer current and then we can make our own Watts calc.
Click to expand...
Not unless you know the current/voltage waveform and phase relationship you can't.
 
@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.




 
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