Sziklai power amplifier

[maouna]

How can i see the phase and gain margins using multisim ?the expression i use for open loop gain is vout/(v(+) - v(-)) but which expression i use for the loop gain?

[maouna]

I made the amplifier and listened to it at full power .it sounds nice.there was no matter of instability ,no strange overheating.

But all these have to be confirmed by an oscilloscope which i dont have.


If anyone wants to build it ,please use the pcb below that Alex mm sent me.

previous pcbs had something missing and Alex mm corrected it.

this is the correct one.

transistors that i used were: 2sd669a-2sb649a instead of bd139-bd140
2sc5200-2sa1943 for output
bc546-bc556 for input
2n5551 as the small tranistor before the VAS (PINS REVERSED TO BC546)



my best regards to Alex mm who designed the pcb ,and to all of you that helped me with the schematic .

[maouna]

these are some updated values of the same schematic.what do you think?