I don't remember which is better
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Looks good. More or less equal to the latest 'discrete' version of LMK/Wiederhold amp, but faster.
Since I already built few of these, I would rather try something new, unless it's new LMK/Wiedehold style amp is much improved than these that I already built.
4 stage topology (not exactly Otala!) is something new I never tried, so maybe it's time...
But I'm going to spend more time on simulating it and trying different things with it first.
Another option I'm considering researching is this CFA Marantz offspring:
Apex A40 fundamental improvement. (Sandy)
Totally different animal.
Since I already built few of these, I would rather try something new, unless it's new LMK/Wiedehold style amp is much improved than these that I already built.
4 stage topology (not exactly Otala!) is something new I never tried, so maybe it's time...
But I'm going to spend more time on simulating it and trying different things with it first.
Another option I'm considering researching is this CFA Marantz offspring:
Apex A40 fundamental improvement. (Sandy)
Totally different animal.
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I would really prefer op-amp version too. But I had bad experience with fast op-amps, especially those that need extra compensation.
I built several amps with op-amps, and in most of them I could not even stop LT1056 from oscillating... (not much oscillating, but it's not acceptable).
I would prefer to use TLE2071, TLE 2081 which are around 50V/us fast, but
the final amp is still 15V/us. I don't know how to resolve this issue.
Each stage separately should be fast enough (op-amp, VAS, output), but put together that are still at 15V/us...
Or - if the amp is faster, than square waves won't behave properly... and fix them, you need to make it slower..
I built several amps with op-amps, and in most of them I could not even stop LT1056 from oscillating... (not much oscillating, but it's not acceptable).
I would prefer to use TLE2071, TLE 2081 which are around 50V/us fast, but
the final amp is still 15V/us. I don't know how to resolve this issue.
Each stage separately should be fast enough (op-amp, VAS, output), but put together that are still at 15V/us...
Or - if the amp is faster, than square waves won't behave properly... and fix them, you need to make it slower..
Symmetrical Wiederhold amp
It seems that secret to higher slew rate in this topology (LMK/Wiederhold) is in symmetry.
I see that symmetrical LMK (or is Wiederhold?) is able to do over 50V/us with all other parameters not worse than before.
Here is an example. Square waves have rise time ~1us for 50V swing.
That's even with relatively slow op-amp (LT1056).
With asymmetrical design, it was impossible (for me) to get good square waves handling, and speed, at the same time.
For some strange reason, this symmetrical designs reminds me of Blomley/Hartsuiker design..
It seems that secret to higher slew rate in this topology (LMK/Wiederhold) is in symmetry.
I see that symmetrical LMK (or is Wiederhold?) is able to do over 50V/us with all other parameters not worse than before.
Here is an example. Square waves have rise time ~1us for 50V swing.
That's even with relatively slow op-amp (LT1056).
With asymmetrical design, it was impossible (for me) to get good square waves handling, and speed, at the same time.
For some strange reason, this symmetrical designs reminds me of Blomley/Hartsuiker design..
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What you are simulating in last post, is not the same as mine.
When I tested your symmetrical designs from few weeks ago, I agree - they did not surpass LMK. That's why I didn't continued with them.
But I tried slightly different design yesterday.
Schematic I published yesterday night, simulates the same as LMK, at least for me. I don't see any problems with it. All the numbers/graphs are very close to LMK/Wiederhold.
When I tested your symmetrical designs from few weeks ago, I agree - they did not surpass LMK. That's why I didn't continued with them.
But I tried slightly different design yesterday.
Schematic I published yesterday night, simulates the same as LMK, at least for me. I don't see any problems with it. All the numbers/graphs are very close to LMK/Wiederhold.
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.
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.