• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Rectifier tube arcing?

The secondary DCR + series resistor to anode, enough large for this load current. Increasing series resistor only makes a small difference of initial problem.

The initial charge pulse of empty C1 and C2 (via choke) about same order of magnitude (with these parameters). It's sum -if larger, than rectifier tube (depending on its condition) tolerate-, usually cause arcing.

In my practice both of them capacity much smaller (about half).
If you use larg/er/ capacitor in PSU than needful, the impulse response of PSU would deteriorates. This will be heard.

If you increase PSU impedance (larger series resistances), this also would be heard.
 
There's a short blue/violet lighting on the lower mica.
Anyway for starters I increased the series resistance of the anodes. Although I get absolutely no warning in psud2 I still get the arching at power on.
I my assumption that the tl783 regulator represents a low impedance correct?
At this point I will need to revise more thoroughly the psu design.
Can you confirm that once a rectifier tube arches it will have a tendency to arch even when used with the correct specifications?
 
Why not use switch between secondary CT and first capacitor negative?
If I use such tubes, which are requiring preheating or has slow heating, I use this switch.
There are no AC current on rectifier tube anodes until tubes (power tubes, or rectifier) not "glowing".