P10 - SINE / MULTI, MW strength and HUM noise /understanding question)

The P10 is loaded at 80% under MULTI. Switching to SINE shoots load to 93%. Why is that ?
If I reduce the MW strength from 6 to 1 under MULTI the load moves from 80% to 87%. Why is that ?
In the first case the yellow indicators pops up (as expected) and in both case a audible hum appears

i thought MULTI would increase the load, but rather it seems to reduce it.

many thanks

Welcome Calabrache! I’m not qualified to answer that question but I’ll be looking forward to the answer. Maybe James can handle that one for you! Again welcome!

There can be some various inefficiencies going on here but a delta of 13% and even 7% does seem high. The fact that you’re running this big of a load definitely has something to do with it. I’m going to ask the team and see what they’re thinking is.


Ok, thanks look forward

here is more data (if helpful)
PS10, europe, 220V

Starting set up MULTI, MW strength 6, 227v out, config distorsion
940W - 5,44A - 82% load

switch from MULTI to SINE
1030W - 6,32A - 96% then comes the HUM quite audible if no music (not good)

then play with MW strength
MWS set to 1 then 1023W - 6,32A - 95%
MWS set to 4 then 1021W - 6,28A - 95%
MWS set to 6 then 1021W - 6,28A - 95%

If i raise the output V to 230 or 235, the load increases (normal)

hope this helps


Here is the explnation:

  • Mulitwave “fattens” the sine wave coming from the wall.
  • Voltage out of Powerplant is same in RMS for Sine and Mulitwave.
  • As Multiwave is “fatter” the peak voltage of multiwave will be lower.
  • The peak is largely what drives components, and power supply caps use the peak for charging.
  • So using multiwave will “starve” your equipment of peak voltage and lower the power they consume.
  • Hence you see lower power output with multwave on than on sine wave.

I think this implementation is wrong and go against the idea of multiwave. A more correct way to do it would be to maintain peak when turning on multiwave. I could see people being nervous though wiht voltage RMS which is what is displayed going up. The workaround is to increase output voltage when using multiwave so that you get same peak as for sinewave. This should be around 7% for full multiwave.

More about this here.

Any meter reading of RMS does calculation assuming you have a sine wav, so will give incorrect reading if you don’t which multi wave isn’t, unless you have spent 1000s in a high bandwidth analyser

Actually the Powerplant is capable enough to measure RMS properly.

This may be true, sorry I was thinking you were using a multimeter, but I bet it does it by a known stored value rather than using a very expensive A2D and measuring the waveform shape.