"Stab" control for a tube OD

[tomtom]

I really love the Stab control on my Fuzz Factory. Beside the oscillator fonction, I find it's a great way to add some dirt (or a looser kind of sound).
 I have a nice one tube distortion box that works fine but this kind of "voltage" control could bring some new (read better) sounds to it.

 I wonder if such a control works with tubes and how I may step down the 250v rail with a pot as simple as possible (without a variable regulated power supply).

 Any ideas ?

 Tom  :roll:

[Rodgre]

Doesn't "Stab" on the Fuzz Factory/Probe stand for "Stability"?

Roger