+18v Charge Pump and JFET devices

[mikepurcell]

I built a Clark Gainster and I'm going to be using a charge pump to run it at +18v. It's just a basic 4558 distortion with some clipping in the feedback loop. I've also got an Xotic EP Booster in the same enclosure, I've got a 2N5457 and a 2N5088 in that one.

Is there a need to run the Xotic off the standard +9v rail? I haven't worked with JFET's that much and barely have a rudimentary understanding of how they function, I wasn't sure if the higher voltage would cause some unexpected behavior. I just checked it out on the bench and it sounds interesting, nothing obviously wrong with the tone but I'm not sure if it will cause problems down the road.

Thanks

[antonis]

Hi & Welcome..

A schematic of both distortion and booster circuits should be helpful..
(no problem with +18V power supply except for caps voltage rating and bias configuration..)

[mikepurcell]

The Gainster is all the same values, just not the mojo components.

Couldn't find a schematic with exact values I used on the EP Booster, so here's the vero layout.

[antonis]

Gainster should be fine..
(check for 50μF voltage rating - the one on Vref point (N))

For Xotic EP Booster, I think you'll need a 10k (or bigger) trimpot for Drain resistor and alter BJT bias configuration, both for 2N5088 different pinout and double supply voltage..

edit: You also might to modify 1M biasing 2N5088 Base resistor value, in case of significantly off-setting Emitter quiescent voltage..