A MOSFET Crybaby experiment

[Transmogrifox]

Has anyone tried replacing the trannies in a crybaby/Vox/Bad Horsie type wah with MOSFETs?

I took a swing at it the other night on my Morley Bad Horsie--a mere 45 min. project.  I had to re-bias (of course) to get it into operating range.

It's definitely darker, more soft "woofy" sound, more noisey (as would be expected) and I think a little lower Q.

I haven't decided whether it's an improvement or not.  It's definitely different.

Anyway, for anyone who cares to give it a try:  take the 22 ohm resistor out of the emitter (source for MOSFET)--replace it with a jumper--then tune one or both of the bias resistors on Q1 until the collector voltage is somewhere around 4 or 5 volts.

[gez]

I once breadboarded the circuit using a 4007 chip for the whole thing; an inverter for the amp, one device to buffer it and another for the follower to provide the feedback.  The inverter made the circuit slightly simpler (think de-couple AC feedback and hopefully you'll understand what I mean).

I only had a crappy audio transformer so it didn't sound stellar, but it sounded exactly the same as the normal circuit with said transformer subbed in.  Should imagine it would be good with a proper inductor.  Surprisingly it was just as noisy as the original...

[Transmogrifox]

Sounds like it was an interesting experiment anyway.