Opamp based current dumping amp

[moschfet]

The simulation of this little amp looks quite good. It's an old circuit but the low effort with such good results, I won't hide from you 😉

 

[Grasso789]

This amplifier has positive output impedance, because feedback includes voltage occuring over 0.1 Ohms shunt resistor R20. This reduces clang of loudspeakers, as most electromagnetic drivers work best when being semi-voltage-current-driven. On the other hand it could cause some HF instability, because parallel capacitance of loudspeaker cable may reduce gain to unity.

 

[moschfet]

Yes, in this example, there is a mix of current and voltage feedback. But the amplifier works excellent with pure voltage feedback.
LT Spice simulate relatively good phase margin.

 

[tiefbassuebertr]

check out this URLs:
http://www.audiostereo.pl/g-schmidt-currenl-dumping-amplifier_86956.html
http://www.diyaudio.com/forums/solid-state/16350-current-dumping-amp.html

 

[moschfet]

check out this URLs:
G. Schmidt "Currenl dumping amplifier" - DIY - Audiostereo.pl
http://www.diyaudio.com/forums/solid-state/16350-current-dumping-amp.html

Interestingly, the same basic idea (opamp). However, when I applying the original CD circuit, I get worse results than in my simplified circuit. THD is higher and the phase margin is less.
Thus arises no misunderstanding. I am happy when an amp in reality reached 0.005% THD. The simulation is only for optimization.

Incidentally, the whole amplifier has only 17,5mA quiescent current.