The Pinche Cabron - an AS3046D Superfuzz

[jubal81]

I went over to Smallbear's site and noticed a new IC he's stocking on the front page. It's the AS3046D, which is 5 BJT, NPN transistors, with two of them a matched, differential pair. Since reading Chuck's transistor matching thread the other day, I've had the Superfuzz on the brain, since I've always been curious and have never built one.

So when I saw that chip, my brain:

So, I've whipped up this so far:

 

[Chuck D. Bones]

Is it me, or is that the world's tiniest schematic?

 

[jubal81]

Lol. I didn't realize you can't click to blow those up.
Updated the layout a bit, too.

 

[jubal81]

I'm interested in the classic version, but just to spitball:
I could use one of the NPNs on the chip as a bootstrapped 'cornish' input buffer. Replace the phase splitter with a dual opamp. Add another dual opamp after the Ge diode clippers for a proper tone stack and makeup gain.

 

[cooder]

Pretty clever stuff you're cooking up there....! Whoop whoop. Interested to see and hear how this pans out.

 

[perfboarder]

Cornish Chip for everyone

 

[Chuck D. Bones]

If you've got opamps, why go to the trouble of building a Cornish buffer?

Have you played a pedal that uses a differential pair for octave generation? I played around a bit with that configuration when I was building & modding the Apple Fritter. You can bias it so both transistors are off or both are on a little bit. Either way, there is a dead-band where no signal gets thru. Alternatively, you can deliberately unbalance the biasing so that as the signal decays, the octave drops out. In all cases, you get a gating effect, so make sure you like that part of it before spending too much time developing a circuit around that particular functional block. I prefer the diode octave-up, like the Squidward, Foxx Tone Machine, etc., but that's just my personal preference.

 

[jubal81]

If you've got opamps, why go to the trouble of building a Cornish buffer?

Have you played a pedal that uses a differential pair for octave generation? I played around a bit with that configuration when I was building & modding the Apple Fritter. You can bias it so both transistors are off or both are on a little bit. Either way, there is a dead-band where no signal gets thru. Alternatively, you can deliberately unbalance the biasing so that as the signal decays, the octave drops out. In all cases, you get a gating effect, so make sure you like that part of it before spending too much time developing a circuit around that particular functional block. I prefer the diode octave-up, like the Squidward, Foxx Tone Machine, etc., but that's just my personal preference.

A year or two ago, I had a Muff type thing on the breadboard with that diode octave up on a sidechain and blended back in with a mixer at the output. If I remember, it actually worked pretty well.