Relax/ Push Mastotron

[JonnyAngle]

I play active basses, but want to try a Woolley Mammoth. I was checking out the Mastotron layout and it looks like the relax/push knob is just a 100k pot with a 100r resistor.  Can I just throw that pot and resistor in a box with jacks and call it good?  It looks like it doesn't need a power source or anything. Or did I miss something completely?

[nocentelli]

Woolly mammoth/mastodon is a fuzzface. Some people like a series resistance before the input to soften the distortion, and is known as a Smooth pot in some schematics - it can also somewhat reduce some of the negative effects of having a buffer in front of a fuzzface.A series resistance pot on its own is unlikely to do much for your sound that you can't do with the onboard volume and tone pots.

[induction]

Nocentelli might be right, but I've had great results improving the sound of fuzz faces fed by buffers by putting inline resistance between the two. Much different results than turning down the volume or fuzz controls. But I've never added tone controls to my fuzz faces, so I can't comment about that.

In any case, it's easy to try. Just as you said, put a 100k pot wired as a variable resistor in front of the pedal. No power source required. I'd suggest doing it on a breadboard before you sacrifice a box to it, in case it doesn't do what you want it to.

[Mark Hammer]

One of the quirks in the Wooly Mammoth that I've played with and rather like is the variable resistance between the emitter of Q2 and base of Q1; what ZVex calls the "Pinch" control.  As you might expect, it interacts with the resistance to ground of the Gain/Wool pot, but it does so in interesting ways.  As that E-to-B resistance decreases, the fuzz is smoother and less aggressive.  Once increased past a certain threshold, the unit becomes glitchy and somewhat gated.

Given your input signal from a bass with active circuitry is likely (though not necessarily) going to be high-amplitude, you might want to consider inserting a smidgen if series resistance with the gain-setting emitter leg to ground, and tailoring back the E-to-B resistance, with a trimmer.