Hi Mark,
it`s a Dual 1M pot between PI and the 1,5k grid resistors with 0,1uF caps in front and behind.

 
I think the Overtone has plenty of PAB;for most people it is too much.
Maybe a matter of the pickups and speakers?

HI Jack,
besides a Overtone Special I also have a ALLEN OLD FLAME from the first
made.
How to improve the Master Volume?
The sound is only full with the Master at 10;

I have a TC Electronic Nova Reverb in the effect line;it works fine even without
any help of a Dumbleator or Kleinulator.

I tried both the Nova Delay and the Nova Reverb which I kept.Both work fine
without a Klein or Dumbleator. You have to calibrate the input of the Nova
to aviod distortion.

Hi,
I use a t.c.electronic Nova Delay in the effect loop;it works fine.I had too some
problems with other effects.

  Nice sound clip SPM ,
what tubes do You use in Your Overtone Special?