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Recently I posted my take on bazz-fussifying the Escobedo Push-Me-Pull-You. I've been so pleased with this little octave fuzz I thought it was worth playing with even more.

The PMPY is divided into two sections: A simple gain stage, followed by the push-pull circuit that cancels out the fundamental to give the octave. So, I got thinking, what happens if we add a second stage of fundamental cancellation? Well, it sounds pretty interesting, that's what.

So, building on my last circuit, I added a second bazz-fussified push-pull stage to the circuit. In the last circuit I'd put a pot on the base of the PNP to adjust the amount of octave in the circuit, this time I just opted for switches. I also added a simple LPF after the initial gain stage to see if a less complex sound going into the push-pull section would allow clearer octaves.

The resulting circuit is as follows:
Transistor choice isn't super important, I built mine with an MPSA13 for Q1 and 2n3904/6 pairs for the rest.

The sound of this circuit is super interesting to me. It has a strange, almost envelope-filter-like attack. The first stage seems to provide a lot of 'mwha' to the sound, whereas the second more of a "chyeow". The harmonics evolve over the course of a held note in a way that reminds me of FM synthesis.

I built it on vero and recorded a demo here:

For those who want to give it a try, here is my vero:

Interesting sounds out of it, synthesiserish. I like it. Did you do any hfe matching on the differential pairs? I'm curious what the hfe values are. Please continue experimenting with this circuit, I think you're really on to something unique here.

Thanks. The note on the original PMPY said something about "matched pairs need not apply", which I took to heart and have built the previous circuit with any number of random PNP/NPN pairs. For this one I just grabbed 2n390x units out of the bag and sounds amazing, but I am curious now what a closer match vs. a gross mismatch sounds like. Hoping I get a transistor tester for Christmas, so I can check hfe the easy way.

Really love how It sounds! Some great inspiration can come from this one for rippin solos. In case you have a bass, maybe you tried playing It through? Im curious how It would sound. There was a chopped down version of the oc2 that was added a pmpy octave Up, here in fstboxes, adding this one instead, could be the mothership of everything that is funky. Congrats on your ideas development!

I have tried it on bass, though I haven't recorded a demo. It does the same kind of synthy envelopes. I have mixed feelings about it on bass, as the envelope feels cumbersome and sluggish, and takes the punch out of the bass. But it's an interesting sound nevertheless.

I was contemplating adding the suboctave circuit from the davisson shocktave in parallel with the upper octave network and putting a blend pot at the end. That might be the next evolution of this circuit.

I think it's fine as is, maybe add some buffers to it,and increase the volume control to 50k or 100k so it has some enormous volume boost available. You could also combine the switch into one with a dpdt on/on/on type to simplify it a little bit, or change them to drive/balance controls or combination there of. Making them controls may add additional tone shaping possibilities to this circuit.

FWIW, I did just finish doing a build of this fuzz with the suboctave generator from the Shocktave tacked on. Sounds pretty cool, here's a demo: