OKKO Diablo + Voltage Doubler using switch

[teknoman2]

Thank you for the info's mate,
I ve never had the time to finish this project, probably cause it has those jfets....
Since now you verify that everything works well with these changes.
I should try to find some time to make a board of this one.

[bordonbert]

Good to hear someone else is interested in it, on first listening to my prototype it seems to be a really well set up box and deserves more exposure.  Far better than the "diode clipping" approach which is never done properly for a crunch pedal rather than all out fuzz.  The controls are great, useful range without being overdone.  The crunch is well tamed and very gradual and allows loads of feel to your playing.  All in all one of the best overdrives I've heard.  Mind you if you play death metal look elsewhere, this pedal is more suited to the classic blues/rock player than the thrasher.

I built my own into the standard Hammond 1590BB enclosure and I got a bit creative with the layout.  I put the 5 pots and their associated passive components, and the 9V socket onto one board which mounted independently.  Each separate stage came out to pads on the edge of the board.  Then PCB mounting input and output jack sockets, the voltage doubler circuit and 9V/18V switch, and each active stage went on a second board.  I then wired up the connections between them.  It meant a very easy mount and breakdown procedure.  It oscillated!  I've played around with moving a few of the components from board to board and cured this but the pedal is so good I'm going to start again and do it all on one board in a more conventional manner.

If you come up with a working PCB I would be interested to see it.  I should also say that I've built the Okko Boost stage as a separate clean pedal again with voltage doubling and that works really well too.  While I'm sure there are improvements to be made by trimming values, (not myths like capacitor and resistor types and swapping semiconductors), it's a very usable setup as is.  Once you correct the schematic error of course!