200W MOSFET CFA amp

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#1,143
The test at full 200W power on 8 ohm. This only 2.7 times more than the simulation showed, not bad for simulation and then some people do not take the simulation seriously enough.
 

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  • full rated power into 8. 20KHz. .002% THD.jpg
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#1,144
THD+N or 2nd harmonic only with hum filter bandwidth 80khz averaged or rms?
Simulation results depends on good transistor models. I'm lucky we have so much good models - thanks to all who contributed so good models to us!

BR, Toni
 
#1,145
astx said:
THD+N or 2nd harmonic only with hum filter bandwidth 80khz averaged or rms?
Simulation results depends on good transistor models. I'm lucky we have so much good models - thanks to all who contributed so good models to us!

BR, Toni
Click to expand...

Yes Toni we have to thank those who contributed with so good models.
Regarding measurement I don't know, it's not my measurement (I wish it is with so good tools what I don't have).
 
#1,151
astx said:
RNMarsh's measurements? Maybe he can bring some light into "darkness"?😉
I'm owner of a panasonic/levear vp7723d which has different measurement options.
Click to expand...


Hi. The 7723 wont go low enough. I used to have one. The test shown is THD only. 2H and 3H only --- nothing seen of higher harmonics. Average... not rms. 8 ohm load.

The EC works amazingly well at all levels and loads and freq. Works extremely well with CFA characteristics.


THx-RNMarsh
 
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#1,152
My vp7723d can measure below 0.0005% THD+N @ 20khz. Just using the sweet spot of the oscillator output and the balanced input range. Always included is noise which is of course also important to get a feeling of the overall performance. It is nice to be able to measure a specific harmonic with the vp7722.

With the vp7723d residual output displayed on a spectrum analyzer you can see in detail all harmonics and noise distribution.

Merry christmas to all diy'ers!

BR, Toni
 
#1,153
Most of the time and especially at normal listening output levels, the THD will be well below .001% and often below .0005%. So, you are marginal....... I use 3 instruments ... as the need gets lower and lower in THD/Harmonics.... VP7722, Audio Precision 2277 and the ShibaSoku 725D.

With the 725D and an FFT on its monitor output, -160dBv can be read accurately.

THx-RNMarsh
 
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#1,154
Really impressive measurement tools! Are you meaning AP 2722?
Wow: -160dbV are 0.028 µV Really? 🙁

Could you measure the 1W, 50, 100 and 200W@8R performance again using the THD+N function of your VP7722 with 80 kHz bandwidth filter activated. No 400Hz filter active. Using 2x60 - 2x62V stabilized power supply?
Just as reference because our measurement results are different. My results can be found by the link in post #1 of this thread.

Thx in advance, Toni
 
#1,155
Yes, AP2722. And -160 with 725D and QA401 on monitor.

some time in the not-too-far future,. but cannot now. I am not in Bangkok any more.... was there for 2 months but In California now. No amp here.

a very small portion of my T&M gear --->


DSC01717.JPG

FFT-THD.jpg

DSC01699.JPG

DSC01698.JPG



THx-RNMarsh
 
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#1,156
RNMarsh said:
Most of the time and especially at normal listening output levels, the THD will be well below .001% and often below .0005%. So, you are marginal....... I use 3 instruments ... as the need gets lower and lower in THD/Harmonics.... VP7722, Audio Precision 2277 and the ShibaSoku 725D.

With the 725D and an FFT on its monitor output, -160dBv can be read accurately.
Click to expand...

This leads to a question. How can-we explain the differences we can feel in our listening experiences, between two different amps with close performances like those ?
 
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