Unusual amp from 1987

[stanislav1957]

I tried with these capacitors, they were making it even worse...

inductor in there? Not a resistor?

On the MF-025 2-5 Ohm resistor, wind 10 turns with a wire with a diameter of 0.1-0.2 mm and there will be the required inductance or this coil
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[stanislav1957]

Total Harmonic Distortion: 0.000000%(0.000092%)

FFT also looks slightly better

>The gain is too high .We need to reduce it.

Now it works perfect even with my original gain (4k resistor in the input).

Wonder what slew rate will be. Will check later today..

This is not the limit in the model.Look at my forum, link in PM.Last post.

 

[minek123]

Thanks Maxim. Saw it.
Slew rate looks very high on your square waves screenshot.
I'll be checking your forum, very interesting.
Was simming your Ezi10 amp few days ago..

This new amp definitely looks like next build candidate.
I would do it with Exicon latfets (double die, just one pair is enough), just like in the sim..
And it doesn't need DC servo..

 

[minek123]

R11/R10 on your schematic (Zener resistors) - should they be lower in value?
All these extra transistors are drawing extra current.
In mine they needed to be 1k7 to leave enough current for Zeners.

 

[stanislav1957]

12 volt zeners

 

[stanislav1957]

Thanks Maxim. Saw it.

Was simming your Ezi10 amp few days ago..
.

I didn't understand about this amplifier

 

[minek123]

I see your coil has polarity ('+' and '-') ??

 

[minek123]

I didn't understand about this amplifier

I was sim-ing amp from your forum 't20-topic' "Re: Наш ответ оплеухе"

 

[stanislav1957]

I see your coil has polarity ('+' and '-') ??

No, this microcap is acting on its own.There is no polarity there

 

[stanislav1957]

I see your coil has polarity ('+' and '-') ??

I was sim-ing amp from your forum 't20-topic' "Re: Наш ответ оплеухе"

Monster is better.I also finished off the discretes based on this topic.The neophyte is called

 

[minek123]

Interesting thing - with higher gain (4k resistor) your amp shows lower Thd (0.0)
than with lower gain (5k6 resistor).

 

[stanislav1957]

Interesting thing - with higher gain (4k resistor) your amp shows lower Thd (0.0)
than with lower gain (5k6 resistor).

Check the settings in LTS spice, the analysis time, and so on.The accuracy of the analysis depends heavily on these details

 

[stanislav1957]

I'll show you a modified discrete version with a servo on the ideology of this topic. A fairly modest gain without OOS.Total 115dB at 20 kHz

 

[minek123]

I'll play more with the sim, and slowly design a board for it (op-amp version, not the discrete one with the servo)..

 

[stanislav1957]

I'll play more with the sim, and slowly design a board for it (op-amp version, not the discrete one with the servo)..

Just an example of an amplifier with a large loop gain.

 

[minek123]

I was thinking to design pcb that would fit for any output topology (bjt, hexfet, latfet),
but latfets have different pinout, so this would be an issue...

 

[stanislav1957]

The main thing is to start

 

[minek123]

Can't get square waves to simulate correctly.... Oscillating. I was trying to modify all obvious elements, to no luck...

 

[stanislav1957]

Lay out the model with the analysis settings
Will update LTS spice

 

[minek123]

I experimented more, and I'm getting better square waves (but still not acceptable yet) with bigger values of C11 (from your latest schematic from your forum)
(C7 in my sim).
My sim is up to date with your latest version.

One thing that worries me - square waves are very sensitive to the value of C11.
Very small changes in the capacitor value, trigger big changes in oscillations.
With a few pico farads difference, even pcb tracks can affect the results....

How is this behavior called? "Marginally stable" ?