schade feedback in push pull

[thiagomogi]

Hello guys.

is it possible to implement feedback schade in the push pull output stage?
if so, is there a golden rule?

Regards

Thiago

 

[AKSA]

Yes, Thiago, have a good look at the Baby Huey amp in the tube forum.
EL84 Amp - Baby Huey
It has Schade feedback with PP, requiring two separate feedback networks but dimensioned identically.
It's an extremely good circuit, developed by Yves from Alsace and Ian from South Australia, a friend of mine. This can relatively be adapted to bipolars too.

Ciao,

HD

 

[thiagomogi]

Thank you, Hugh.
I saw Schade in some tubes, including the PP, but I did not see anyone talking about using mosfet PP.
Anyway, I'm going to study the subject.

thank you my friend.

Thiago

 

[Nelson Pass]

I had occasion to play with Mosfet push-pull Schades. The basic topology
looked like this:

 

[thiagomogi]

Thanks Papa.
was exactly what I was looking for.

Thiago

 

[Zen Mod]

well known on forum ,even if silly me can't remember whom to credit for

 

[Pascal Nguyen]

well known on forum ,even if silly me can't remember whom to credit for

Nice curvature, perhaps my mind is still influencing by the Red Sparrow.

 

[Zen Mod]

Papa is having same one , in his files

(as little birdie told me )

 

[Pascal Nguyen]

Zeus Positive Feedback

My attempt for a positive feedback amp, can switch in and out by disconnecting the loop, it gives a nice effect like a “presence” plus “ loudness” switches.

 

[eLarson]

I had occasion to play with Mosfet push-pull Schades. The basic topology
looked like this:

Is that basically Zen version 5? (Or am I remembering wrong?)

 

[thiagomogi]

As incredible as it sounds, it was exactly the circuit I'm looking at right now.
It seems to be the easiest way to get started

 

[thiagomogi]

Am I forgetting something?

 

[Zen Mod]

most probably not

you chose 18K (instead of 10K shown in previously attached pic) , based on which criteria ?

overal THD or THD spectra ?

 

[thiagomogi]

Hey Zen Mod, thanks for the comment.
It was another initial test and I was looking at the gain, but now using 10k and 1k with 15v + 15v and additional stage of gain, I got good THD results.
Output Current 1.7A
7.1 volts AC output at 0.13% at 8 ohms.
What do you think?

thank you

 

[woody]

Will those 10k or 18k resistors allow enough current to drive the gate capacitence
at higher frequencies.

 

[juma]

Am I forgetting something?

Zen v.5 sch. - R2 is the feedback element and you don't have it...

 

[thiagomogi]

Hey Juma, I thought to Schade that we do not need any more Feedback

 

[juma]

Hey Juma, I thought to Schade that we do not need any more Feedback

Schade is (a form of) fedback.

 

[thiagomogi]

if we have Schade, do we still need the R2 of Zen V5?

 

[Nelson Pass]

Is that basically Zen version 5? (Or am I remembering wrong?)

Oh yeah, now I remember it...