no current mirror, current mirror, cascoded current mirror, bjt or jfet VAS?

[maxpou]

And now at 100Khz

 

[peufeu]

Tiny bit of overshoot but otherwise looks good.
And the sound ?

Anyway, inserting a 100R in the output is always a smart move, just in case you get a short at the output (easy with RCAs), to avoid smoking the JFETs... it will also protect against oscillations.

If you use it to drive headphones (but the JFETs seem a bit wimpy for that) you must add a resistor since headphone jacks short for a brief time on connection.

 

[maxpou]

Hi Peufeu,
i don't know how it sound because i take all mesurement on my breadboard. thank you Maxpou

 

[aparatusonitus]

Hi maxpou,

Pulse response looks good, no ringing at all, try some small compensation capacitor over local feedback resistors to take care of overshoot.

 

[Onvinyl]

Hi Maxou,
You could as well try without the output followers. The overshoot will most probably vanish, the stability (into capacitive loads) is amazing. I would probe the output while it is connected to the following amp and check the sound both with complimentary output follower and without.
Nice work, keep it going!
Rüdiger

 

[maxpou]

Hi Guys,
here the pic without the output stage with 3.9K//300pf. thank you! Maxpou

 

[Onvinyl]

At what freq?

Rüdiger

Edit:
if it's 10kHz, it's not good. I have a very simple version of this with 170/74 in the front and BC550/BC560 as VAS, set for 6dB of gain, and the square is fine up to several tens of khz!

 

[maxpou]

Hi Rüdiger,
sorry i forgot the frequency: 100Khz. Thank you! Maxpou

 

[Onvinyl]

Hi Maxpou,
you could swap the bases of Q14 and Q18 to the corresponding FET drains. increases (ol-) gain and decreases distortion.
Rüdiger

 

[padamiecki]

...

Hi Maxpou,
in my opinion
please f*** 2nd, 3rd, 4th harmonics
but beware of this 15kHz peak!
Better use OLG,
true

 

[maxpou]

Hi Maxpou,
you could swap the bases of Q14 and Q18 to the corresponding FET drains. increases (ol-) gain and decreases distortion.
Rüdiger

Hi Rüdiger,
i use the schematic in post #5 not the schematic in post 7.

Hi Maxpou,
in my opinion
please f*** 2nd, 3rd, 4th harmonics
but beware of this 15kHz peak!
Better use OLG,
true

Hi padamiecki,
i don't understand your all message, but yes i will test OLG with local feedback later.

Thank you! Maxpou

 

[maxpou]

Hi Guys,
what's the best solution for my VAS cascode? use zener or replace it by resistance as show on the schematic. My original schematic is show at post #5. Thank you! Maxpou