Revisiting some "old" ideas from 1970's - IPS, OPS

AX-Deluxe+NS

Square Wave Test.
Listening test & FFT test not yet.
 

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Last edited:
Looking at your sqwave plots:
I have to ask, do you see any extra information in terms of overshoot, or ringing as you step from 1kHz sqw to 100kHz sqw?

I can't see any thing extra.
The only thing you are achieving is pushing more power into the Output Zobel (making it hotter) and taking the output devices closer to cross conduction.

Just test at 1kHz, that gives you all the information you need to see. Expand the horizontal ten times if that facility is available on the digital scope. This will let you see ripple detail, if there is some overshoot/ringing.
 
Looking at your sqwave plots:
I have to ask, do you see any extra information in terms of overshoot, or ringing as you step from 1kHz sqw to 100kHz sqw?

I can't see any thing extra.
The only thing you are achieving is pushing more power into the Output Zobel (making it hotter) and taking the output devices closer to cross conduction.

Just test at 1kHz, that gives you all the information you need to see. Expand the horizontal ten times if that facility is available on the digital scope. This will let you see ripple detail, if there is some overshoot/ringing.
No,i can't see any overshoot not ringing even expanding the horizontal all the way.
 
I normally like to do 1KHz and 20KHz.
1KHz gives me a good overall view of the step response.
20KHz can be considered as a "close up" - you see the corners and vertical step curve's angle much better. If it's too "trapezoid" - the amp is relatively "slow".
Some 20Vpp swing is normally more than enough for "express assessment".
 
AX-Deluxe FFT Test.

AX-Deluxe FFT using 6R dummy load.
+/-50V
75.000uf/Rail
Idle=7mV/0.22R=31mA
R dummy=6R
 

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Hi Thimios, thank you for the spectrums - looking good.

I think overall distortion level may be even lower if you roughly double the bias - as I remember, my optimum value was 62.5mA of idle current per output pair.
It's interesting that distortion level is rather consistent throughout the bandwidth.

Cheers,
Valery