[Vlad95]

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.


Uh, the calculations are a bit long.
If we limit ourselves to Ohm's law, then to damp 10 V at 150 mA, we need add resistance of 66 ohms and a power of 1.5 watts.