First the PSU diagram form audio power amplifier
The upper part (A1 and A3) is used to power front end (65V).
The lower part (A5, A7) is used to power the output stage (55V).
I would like to know what's the purpose of this circuit D911/D913; C909/C911; R901/R903?
Maybe they are here to make sure that power-up and power down voltages change in the same rate for the front end and the output stage?
The upper part (A1 and A3) is used to power front end (65V).
The lower part (A5, A7) is used to power the output stage (55V).
I would like to know what's the purpose of this circuit D911/D913; C909/C911; R901/R903?
Maybe they are here to make sure that power-up and power down voltages change in the same rate for the front end and the output stage?