Unusual amp from 1987

[stanislav1957]

What is R2 in your schematic? connected between (+) and (-) of op-amp?
Also, if you want to test symmetrical schemas - do not use inverted input with (-) grounded.
This approach is messing up square waves.
Non-inverting approach gives much better results - at least for square waves and speed. I compared them.

You ignore common-mode interference. .In a non-inverting switch-on, the interference level may be high

 

[minek123]

Output stage shouldn't matter.
What is SR for square waves of your schematic?

 

[stanislav1957]

high frequency of the meander generator in the model.Not 20 kHz, but much higher.
In the model, it makes no sense to look at 20kHz.It is necessary to take the frequency higher and look at both the meander and the difference signal.
150khz
Meandr 20khz attach

 

[minek123]

To evaluate SR, I was looking at square waves at 1kHz, with amplitude of 50V.
If that looks bad - no need to look further...

 

[stanislav1957]

The microcap MS does not take into account the rate of voltage rise.Although, maybe I just don't know all the features of the simulator.

 

[minek123]

>You ignore common-mode interference

R9/C5 in your schematic? If I add it to mine, distortions increase a lot (increased 5 times)

 

[stanislav1957]

Fixed MS file . The output square wave is good.There is a small problem at the summation point.

 

[minek123]

C5/C11 at 1n5 were tuned to that value to smooth square waves.
At 50Vpp, there were kinks.
Otherwise, they don't affect anything else, as far as I can see..
720pF works OK?


If not for tuning for square wave response, C5/C11 were not needed...

Square waves with small amplitude are easy to handle, but if you go over 30Vpp, there are kinks in there....
That's why C5/C11 C7/C6 have these values....

Higher values of C6/C7 are slowing down rise time.

 

[stanislav1957]

1500pf . Overexcitation. It will whistle in the iron. That's why I changed this chain a bit initially, to remove the probability of exciting factors .
Difference signal look at the meander. The voltage at the input of opamp +in minus the voltage at the input of opamp -in

 

[tiefbassuebertr]

Fixed MS file . The output square wave is good.There is a small problem at the summation point.

This circuit reminds me of the P170 from musical fidelity - go to
post #66+67 under
Musical Fidelity P170 Power Amp
and post #22+76 under
Musical Fidelity P170 Power Amp

 

[stanislav1957]

This circuit reminds me of the P170 from musical fidelity - go to
post #66+67 under
Musical Fidelity P170 Power Amp
and post #22+76 under
Musical Fidelity P170 Power Amp

Рядом не стояло.
Similar, but from a different Opera.We have 80dB of loop gain at 20kHz and cascodes

 

[minek123]

Рядом не стояло => Nowhere near

 

[stanislav1957]

Рядом не стояло => Nowhere near

I am a little grumbled at one of the native language
The difference is visible without binoculars .

 

[minek123]

Maxim, so you think this symmetrical design is promising?
To me it looks good. As far as I can tell with my limited skills, it is no worse
than original LMK and Wiederhold I built, and it will be significantly faster.

BTW, I'm building 2N3055 version of Wiederlhold77 quasi with 25V rails and 2 pairs of output transistors.
Want to see how it's going to sound when compared with builds with
modern transistors. My guess is I won't hear any difference

 

[stanislav1957]

LMC and Sukhov are superliners in contrast to this.The sound of another

 

[stanislav1957]

A little bit dispersed this option . Distortion decreased,but still too much of them. C7/C6 10pF, 75pf in parallel with the resistor330 from the opamp output. And as always, I didn't forget about the protective diodes.

 

[stanislav1957]

A little bit dispersed this option . Distortion decreased,but still too much of them. C7/C6 10pF, 75pf in parallel with the resistor330 from the opamp output. And as always, I didn't forget about the protective diodes.

 

[stanislav1957]

LT1056 place in the integrator . It is better to use LF357 / LF356.
replaced with LF357 and another matter

 

[OldDIY]

Maxim, so you think this symmetrical design is promising?
To me it looks good. As far as I can tell with my limited skills, it is no worse
than original LMK and Wiederhold I built, and it will be significantly faster.

BTW, I'm building 2N3055 version of Wiederlhold77 quasi with 25V rails and 2 pairs of output transistors.
Want to see how it's going to sound when compared with builds with
modern transistors. My guess is I won't hear any difference

PCBWay
Чёрный холодильник" - Share Project
"Чёрный холодильник" - Share Project - PCBWay

 

[OldDIY]