Yack fuzz

[Gus]

Look for a thread at the other forum for a Yack fuzz.
If the trace is correct it uses a pinch control bias(controls the base current) for the first transistor look at the date it was made.

That looks like a fun fuzz to build.

EDIT I ran some sims of the circuit for DC operating points. The bias appears to be stable even changing from 2n2222s to 2N5089s
The fuzz control adjusts the gain.

[Gus]

Sims like a fun circuit
R10 bias control R4 + R10, 470 to 5.47K
things to try remove C1 and/or C2
remove or adjust C7 value
adjust C5, C6, C4, C3 etc.
change R8 gain control volume pot try 50k to 1meg

[patrick398]

Assuming it's the same pedal/circuit it does sound really nice:
https://soundcloud.com/effector_sound_library/yack-yf-2-fuzz-box

I never know which forum people are referring to when they say 'the other place'....FSB? or ILF?

EDIT: just found the thread on FSB, duly noted

[Rob Strand]

The bias appears to be stable even changing from 2n2222s to 2N5089s

Due to the emitter resistors for sure.

That circuit would be more stable than the fuzz-face even with germaniums.    Interesting the Japanese got off the germanium band-wagon early on.  In fact from the 250p's it looks like it could have started off with germaniums  but was changed to silicon and the caps were added to match germaniums.   (all speculation)

[Gus]

This type circuit is a good beginner project. It can be built with two or three knobs. Gain, Volume and add a Bias control

As Rob posted the emitter resistor values help with stable bias. So no selection of transistors needed past maybe a min hfe, beta.

What I posted is not exactly what was posted at FSB. Q2 emitter resistor is a 4.7k fixed. 47k for a 50K, 220pf for 250pf etc things that are easy to find and some other changes.

I added some biasing fun with a fixed 470 and 5K control for  Q2s fixed resistor.
Input, output and other caps can be changed for what you like.

The sim with a fixed 4.7K Q2 emitter still looked to have a stable bias even with up to a 1meg gain control.

How soon before PCBs and petals by "effect designers"?