Adding soft clipping and second harmonic to class AB guitar power stage

[Blujay]

Adding soft current limit to feedback (Q10) rounds the clipping. Current limiting one side will add second harmonics. Output capacitor required to block DC from Asymmetry

 

[Osvaldo de Banfield]

IMO C4 looks too small. I would use 220uF there. And ideally R28 and R29 paralleled ougth to be conparable to R12 for current balance at both bases of differential pair.

 

[Blujay]

OK

Yes -- break frequency 159Hz -- you are right

Thanks for balancing diff pair suggestion

 

[jjasniew]

Wondering if that could be part of an output short circuit protection scheme, where one side simply clamps some in normal operation?

 

[Blujay]

For sure

I have added current limit on both sides before and have different thresholds so still get second harmonic. It survives short-current through the two power transistors with shorted output

 

[Blujay]

In case above only one side is needed to protect from shorted output