[morzh]

A few uF cap will drop as much AC without dissipating. I just need to calculate 10V drop. This is if I only want to keep the filaments happy. Which is fine, the tubes themselves are 250V types.

Let's see.

I need to drop 10V at 150mA.

The current active impedance of filaments is 760 Ohms at 114V.
I need 847 Ohms to keep 150mA at 127V.
I need 374 Ohm of capacitive impedance.

So I need 7.1 uF cap (have Solen 6.8uF).

And the filaments are important as extra 10V makes it app. 1.4V extra per tube, and while for 19 and 35V ones it is small, for 12V tubes this is more than 11.5% rise or 25% rise in power dissipation. Nothing to sneeze at.


But.

Thing is, if I decided to get rid of the resistor after the diode (it does not affect the filaments, but does affect the tubes voltages, which would be OK), my voltage on the primary cap would be in excess of the 150V of the cap's rating. I don't want that.