First the PSU diagram form audio power amplifier
![2.PNG 2.PNG](https://www.electro-tech-online.com/data/attachments/76/76513-8ff7ee7cce76f6d4304b4efe84d655b0.jpg)
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?
![2.PNG 2.PNG](https://www.electro-tech-online.com/data/attachments/76/76513-8ff7ee7cce76f6d4304b4efe84d655b0.jpg)
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?