help me make this fuzz gate

[alange5]

I'm building a fuzz based on some unverified Wolf Computer schematics with some nods to the Fuzz Factory (apparently a very similar circuit).

Here's a crudely drawn schematic:


Not pictured:
-1K resistor in series between Gate and Q2 collector
-Gate has since been changed to 10K, Sag has been changed to 5K

The gate control only really gates when the resistance is very low - approaching the 1K resistor on Q2's collector.  The very last notch of the turn gives me the splatty velcro fuzz sound I'm looking for.  The rest of the turn doesn't make much of an audible difference.

I experimented with the Q3 collector resistor, and found that higher values greatly increase the gating effect, but greatly diminish the oscillation and octave effect produced by the sag control.  10K seems to be the magic number, producing the most usable octaves and oscillation when the sag is introduced.

I'm looking for a happy medium.  I have the sag control on a switch to introduce oscillation on-the-fly.  I'd like to be able to dial in a gated fuzz, and still get some weird glitchy effects when the sag is switched on.

Any suggestions?

[amz-fx]

The 2N5088 might have too much gain for this application.

Try a 2N3904 for Q1 and low gain transistors for Q2 and Q3, such as the 2N2369A or PN2484. I think that Small Bear has some low gain transistors.

Best regards, Jack

[Mark Hammer]

I'll put in a vote for playing with the value of the 100k resistance between Q3 and Q2.  The stated value is appropriate to achieving smooth sustaining fuzz.  Higher resistance values will start to produce a sort of "micro-glitch" that yields a different fuzz tone without compromising sustain, and even higher values produce a choked sound.  If 100k is the default, I'd start with a 250k pot wired as a variable resistance in series with 100k.

In tandem with the Sag control, you can seriously degrade all sustain.  I installed a trio of 3-position toggles on my build of Jack's Mos-Face  FF derivative.  One toggle varies the input cap value.  A second provides for 2 sag-resistance values and no sag.  And a 3rd provides for stock feedback resistance and two higher values.  Some truly sick possibilities, in addition to very normal sounding beefy fuzz.