Presenting the May Queen from runoffgroove.com
This treble boost/overdrive screams harmonics !!!
The changes I made from the original:
Q1 - MPSA 18 for a 2N5088 - not much difference.
R3 & R4 - not critical (I use these because I have a lot in stock)
C2 - the treble was a bit too much for my taste - went from 470pF to 1nF
I've shown my voltage measurements (in blue) compared to ROG's measurements (in green). I adjusted the 10kΩ trimpot to get the same Q3 drain reading.
The original was designed as a one knobber - I added a treble cut circuit to the output of Q3. If you add this mod and want a bit more treble, then reduce C7 from 22nF to 10nF. If you don't want this mod then disregard P2, C7 and C8, connect C5 to the drain of Q3. The output is very hot. I have a Pevey backstage with the pre-amp on 2 and the pedal volume at about 10 o'clock and that is more than loud enough for home use. If it is too hot for your liking, add a 20kΩ - 30kΩ resistor between C5 and lug 3 of the volume pot.
The layout differs slightly from the schematic. The schematic C7 and C8 are layout C5 and C6. Schematic C5 is layout C7 (Sorry !!)
To remove the treble cut circuit, DO NOT cut a11 - c11. Remove C6 and C7 from the board. Make C5 100nF. Take the output from e14.