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[ Volume ] - Output Level.

[ Drive ] - Input fuzz level.

[ Low ] - Boost/cut frequencies. 0dB at noon.

[ Mid ] - Boost/cut frequencies. 0dB at noon.

[ High ] - Boost/cut frequencies. 0dB at noon.

​PCB Level Controls

[ True/Buff ] - True bypass or buffered bypass.


[Dip Switches]

  • Pre clipping gain (Low/High)

  • Clipping style (Hard/Softer)

  • EQ Overload (On/Off)

  • Low EQ frequency  (250Hz/500Hz)

  • Mid EQ low frequency (260Hz/350Hz)

  • High EQ frequency (2.3kHz/4.6kHz)

Fine tune your tone with sixty-four possible combinations of fuzz in one pedal.

  • Jeff (JFET + Muff = Jeff) is a Big Muff in spirit, and spirit alone. It's in no way a clone, nor does it chase after the original tone in a Big Muff. Not one component carries over from the original and the entire circuit has been completely re-engineered from the ground up. This is our interpretation on what a "New Muff" could be while still respecting the paradigm of the original.

  • Replacing the original common emitter pre-clipping amplification stage is a higher gain solid state push-pull stage with switchable high and low gain.

  • Replacing every clipping stage is a JFET booster/clipper. Combining JFETs with traditional silicon feedback diodes found in the original big muff provides a familiar, yet different style of fuzz. Clipping stages can be switched to a much softer style for a warmer tone if so desired.

  • Replacing the original passive, 1-knob  tone control is an active and discreet gyrator based 3 knob EQ with customizable cut/boost frequencies for all 3 bands.

  • Buffered send/return jack between EQ and final boost/clipping stage for added flexibility. Run other pedals "inside" Jeff without loading issues, reverse the order of the internal stages, split the pedal "in 2" etc etc....

  • Switchable -15dB pad (post send/return, pre EQ) to prevent EQ overdrive in full boost situations. Or turn this switch off to allow the full signal to saturate the EQ stage for even more drive and fuzz. The choice is yours!


if out of stock, please feel free to contact us regarding availability.

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