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I had a similar "issue" with fake 072s. https://forum.pedalpcb.com/threads/tl072-vs-tl072.12830/

Is the schematic similar to this one?

@Paul.Ruby - do you use a buffer between output of your AMT preamps and next pedal? Btw - O2 schematic omitts input buffer.

Vp 0.6–0.63V and Idss 0.5–0.52mA

Gain @ noon. Bat41 Bat46 Bat42 Bat48 Bat85 1N4148 Ge diode

Some oscilloscope shots from the O2 on a breadboard. Testing different diodes. Cyan trace - second stage output, yellow trace - third stage output. 1kHz sinewave, 200mv p-p Gain @ max. Bat41 Bat46 Bat42 Bat48 Bat85 1N4148 Ge diode

For me O2 is ok, but not amazing. Maybe because I connected it only to the audio interface instead of the power amplifier. I'll give it another chance in some time. Btw - I recommend Crunch channel of the AMT Bulava SS30. Schematic available here One comment about the diode in O2. Schematic...

Just tested O2 on a breadboard. Seems to be ok.

@Paul.Ruby - O2 schematic appeared today on freestompboxes

99% yes. Why?

1.4.3. Parts 1, 2 and 3 - different gain and MID settings. In each part MID at min, noon, max. Part 4 - hm.. I played with MID and PUSH pot. Probably... :) https://www.dropbox.com/scl/fi/kn1xcaboxl9wg2lz8qxhm/push5.wav?rlkey=6f1nk8x4jw4wcsoxwnuh6y47n&st=oi7o7srq&dl=0

Layout 1.3.2 is still on breadboard so I will soon convert it to 1.4.3 and upload a recording.

1.3.2. Maybe a little bit too much.. at least to me. Btw - I'll try to upload raw recording, without IR applied. Then everyone interested will be able to try their favorite IR.

I agree.

VCC is more or less supply voltage. That would be around 9V (voltage of the power supply minus voltage drop on a protection diode). Your 6.19V is drain voltage, not VCC. VCC is constant. Drain voltage changes with trimpot adjustment. Vp - it's a parameter of the transistor. You have to remove...

Can you measure Vp of the Q5 and Q6? With 9V supply, J201 with Vp between -0.6V and -0.8V, 1k source resistor and 50k trimpot, you should be able to adjust drain voltage from VCC value down to about 1V. You can try changing the trimmers to 100k. But, from my experience - here, you should be...

Not sure about previous setting but not in the middle of rotation. Rather something like 10-11 o'clock. Yes. 15-16 o'clock is the max I'd use with bridge pickup on the strat.

You didn't write anything about transistors.. did you use J201, what type (tht or smd). Are you sure Trim 1 and 2 are 50k and not a lower value. Are R14 and R22 1k and not a higher value.

So.. https://www.dropbox.com/scl/fi/bmjyutddaf9btjpgzq64d/push3.wav?rlkey=qspskiou4gmhfffq92riz9shy&st=bdgwym6a&dl=0 Settings for the above Strat (bridge pickup) -> breadboard -> audio interface -> 4x12 V30 Mesa IR. First three parts - 2N2905 as Q2, then another three parts with ASY34. Gain...

If you want to trace the O2 - it's available on Amazon, quite cheap (around 100$). Not sure about worldwide shipping.