I simulated this amp, looks stable. Damir knows what he is doing.
I suspect pcb or component problem.
Thimios, can you measure the VAS idle current ?
I suspect pcb or component problem.
Thimios, can you measure the VAS idle current ?
Last edited:
Problem solved with Valery's suggestion.
Attachments
Last edited:
Cherry compensation is difficult. It is highly depend on capacitance input of output transistor. In Symasym amplifier, if output transistor change to 2SC5200 it become oscillated. Change the value of cherry compensation resolve the problem.
Damir, maybe you should try exicon latfet model of Ian Heglun in this forum. Maybe it need change the value of gate resistor and adjust the cherry compensation.
Damir, maybe you should try exicon latfet model of Ian Heglun in this forum. Maybe it need change the value of gate resistor and adjust the cherry compensation.
Damir CFA120W +/-50V FFT
+/-50V
bias=130mA
Last picture the sound card loop test for comparison.
+/-50V
bias=130mA
Last picture the sound card loop test for comparison.
Attachments
Last edited:
Too much for TO92 device. Try to set ca 4mA. ( 820R R14,R18) and go back to cherry comp. recheck bias.
I used exactly exicon latfet model of Ian Heglun in my simulation.
If not OITPC I will not support anymore.
Yes, VAS current should be between 3.5 and 4 mA. Decrease R14 and R18 to 560R and check.
You can try also without C8 and C11 (paralleled to VAS emitter resistor).
Last edited:
Here is simulated LG with C6 connected and with C6 not connected.
ULGF does not change but PM and GM drop dramatically.
It could be that Exicon latmosfet need higher value for gate stoppers, try 680R.
ULGF does not change but PM and GM drop dramatically.
It could be that Exicon latmosfet need higher value for gate stoppers, try 680R.
