Apex A40 fundamental improvement. (Sandy)

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https://reader016.staticloud.net/reader016/html5/20180801/55374de34a795936258b4cea/bg1.png

 

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https://forum.cxem.net/uploads/monthly_08_2010/post-69184-1281121566,11.jpg

 

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https://elektrotanya.com/PREVIEWS/63463243/23432455/egyeb/mark_levinson_33_output_sch.pdf_1.png

 

[SandyTodorov1]

These are examples of how amplifiers should not be made.

 

[petr_2009]

I agree with Todorov 100%, development is mediocre
here is her Bode diagram and loop gain plot
other parameters are not even interesting to watch

 

[minek123]

Sandy, did you actually build your amp?
Or do you have any updates on it?
Do you consider your latest published version as final, and worth to actually build?

 

[SandyTodorov1]

I didn't do it. I just wanted to show what can be achieved with a CFA amplifier.

 

[SandyTodorov1]

VFA amplifiers have many more advantages in audio.

And a comparison between CFA / VFA

 

[minek123]

error - "Указано е невалидно Прикачване"

invalid request, I guess?

So far I avoided CFAs, because usually they require DC servo...

 

[petr_2009]

Current feedback amplifiers have great potential. I also made my own version of a similar amplifier. In such amplifiers, the output impedance is close to ohmic and to stabilize the operation, a small inductance is enough, and often it is not needed at all.

 

[SandyTodorov1]

The only advantage of CFA is the high growth rate but only at high signal levels.

 

[SandyTodorov1]

Audio-P FET 1-1-3.4 V2.2

 

[minek123]

Alex, your CFA doesn't need DC servo? Output DC is stable?

 

[SandyTodorov1]

The complete scheme is this:

A simplified servo-free CFA was used for the simulations

 

[SandyTodorov1]

This is the scheme with which the simulation works
HV = V + 10V minimum
V can reach up to 70-80V with the transistors used.
HV 80-90V

 

[minek123]

What is the role of D7/D8 ?

 

[SandyTodorov1]

Very special!!
Audio P5.20 4om 400KHz
Without D7 / 8
Audio P5.20 4om 500KHz
With D7 / D8

 

[U130421]

With CFA, ground loop breaker causes inter channel crosstalk and it will with your circuit also.

 

[stanislav1957]

What is the role of D7/D8 ?

The effect of dynamic Zener capacitance is used . Bonus a small limit on the maximum current of the output transistors in short circuit mode
Используется эффект динамической емкости стабилитрона . Бонус небольшое ограничение максимального тока выходных транзисторов в режиме короткого замыкания

 

[minek123]

This trick with D7/D8 can be useful in any amp, or just in this specific situation?