Mark Hammer Muff Fuzz for Bass

[Chris S]

Hey all, I successfully modded a Mark Hammer Muff Fuzz for Bass.

Pretty simple...
2.2 uF input cap
0.47 uF output cap
47pf cap across the collector resistor of the 1st transistor
Also...
Added a switch to turn off and on Mark's add on (switching between fuzz and overdrive)
Wired the Fuzz to full and put in a 100k smooth control at the start of the circuit to dial in the fuzz
Added a switch to turn clipping diodes on and off.

Posting because the bass player in my band (who loves his bottom end) is using it by itself and not in parallel with a clean signal.

Original Mark Hammer Muff Fuzz: http://www.diystompboxes.com/smfforum/index.php?topic=77456.0

[antonis]

Added a switch to turn clipping diodes on and off.

Any Volume unbalance between switching positions..??

[Chris S]

Any Volume unbalance between switching positions..??

Yep, volume drop and more compressed signal when diodes are engaged. But worth it IMHO for the range of tones that it gives you.

[antonis]

I was about to suggest a resistor in series with off-diode switch placement to keep Volume at same level (more or less)..

[Mark Hammer]

Or, alternatively, use a 3-position toggle to insert a larger, smaller, or no resistance between the diodes and ground.

Another thing I will suggest, if your bass player likes the idea of a glitchy fuzz now and then, is to insert an additional 150-250k in series with the 100k feedback resistor from Q2 to Q1.  ZVex uses this twist in the Fuzzolo and Wooly Mammoth pedals.  It's not the sort of mod where one would notice tonal changes with an additional 10k, 50k, 100k, etc., but a 250k trimmer would be profitably used to identify a pleasing change in tone that one could then switch in and out.

I can also suggest sticking a small-value cap in parallel with that 100k feedback resistor to tame top end.  Try 100pf at first, and opt for either smaller or larger values from there.

Thanks for resurrecting this.  Its a very maleable circuit that EHX never really did enough with.  The early tradition of one-knob/one-switch led them to cut off a lot of decent designs at the knee.  It's our job to give those circuits "legs" again.

[antonis]

Or, alternatively, use a 3-position toggle to insert a larger, smaller, or no resistance between the diodes and ground.

Money saver...!!! 
(resistors are far cheaper than Schottkies, Zeners, LEDs & MosFets..)

[Mark Hammer]

I'm a regular cheerleader for 3-position toggles.  They provide enough variation that is easily reconstituted, unlike continuous controls that may have a hard-to-pin-down sweet spot.  And they do so without taking up very much real estate.