C12 pattern switch resistors each 50k, not 400k.

[ln76d]

So has anyone figured out why it is better at 50K than a higher value?
A hint look closer at a U47

I don't know is it "better",  at least these units i seen had 50k.

maybe a bit off topic, but there is something mysterious for me in the c12 schematic...
could someone tell me what is the exact role of the two diodes VB24-101 at the end of the heater rail (between c3 and 50ohm adj. ) ?
an attempt of regulation ?
are they really needed ?
i don't think so but i can't understand why they put such a current leakage here ...
a simple resistor could do the same, even nothing at all works anyway...
why diodes?
any opinions ?

It was some sort of regulation, but to be honest, not worth even considering - definately N12 PSU design is better, with OD603 and OA126/6 - if we of course talking about original PSU designs from AKG.