Purple Face V2 schematic! for those who asked...

[Steben]

Presence is counter-clockwise wired lin pot. As the treble fades, the overall volume is compensated.

[lenwood]

thanks Steben, I'll have to build one.
Do you have any sound clips of it?

[petemoore]

  Presence is counter-clockwise wired lin pot
  The place labeled presence has two pots shown. looks like a dual ganged there?
  I'm not sure I understand what it does, or more how it does 'As the treble fades, the overall volume is compensated'.
  Also I notice the absence of the 470 ohm - 1k resistor [between the 33k and the 100k on FF's].
  This is the first I've heard or seen of this circuit, does it have ample output?

[Steben]

Presence is counter-clockwise wired lin pot

True, it should be clockwise, right, for a presence . Maybe it's because I use these controls as compensation for too much treble, hence the "counter-clockwisiness" logic.

The place labeled presence has two pots shown. looks like a dual ganged there?
  I'm not sure I understand what it does, or more how it does 'As the treble fades, the overall volume is compensated'.

true, when the the first one rises, treble is cut off. The second one lowers, this way the overall volume gets bigger again. I noticed that with a treble cut on distortions (-3dB point much lower than 10kHz) the volume diminishes very fast. You'll always have to twiggle with both volume and presence, but a bit less now.

Also I notice the absence of the 470 ohm - 1k resistor [between the 33k and the 100k on FF's].
  This is the first I've heard or seen of this circuit, does it have ample output?

Do you mean the voltage divider at the output of a FF? I don't see a 470ohm resistor between 33k and 100k...
And yes, it has a large output (a couple of volts), but there is loss at the end (tone-volume). With the load on full, treble on and guitar volume control it acts a bit as a booster.

[Steben]

thanks Steben, I'll have to build one.
Do you have any sound clips of it?

noop... I even don't have the pedal. I sold them 

BTW: the silicon trannies should be low gain. ... don't forget!
BC107-108-109 "A", BC547-548-549 "A", 2N4125, some 2N2222's...

[Steben]

hehe... spicy...
200mV peak-to-peak 500Hz in Purple Face with (black) and without (red) 470pF treble cap (not as in schematic). 2N2222 as Q's, biased with 5K collector resistor.