We’ve seen all sorts of Mu-Tron III variations throughout the past year. Some early models that don’t have a DC jack, some late models that didn’t have an option for batteries, some bare circuit boards in need of rehousing. These pedals really do sound amazing although their large footprint and heavy casing can be annoying for gigging musicians. My personal favorite mods so far:
1. Install a charge pump so the pedal can operate off of a single 9V battery.
2. Remove the Gain knob and install a Filter Sensitivity knob. The Gain knob adjusts the volume of the pedal both while on and when bypassed which can be a nightmare for keeping a consistent volume throughout your signal chain. Bypassing the Gain knob would set the volume to unity gain; Installing a sensitivity knob would adjust how wide the filter opens without changing the overall volume of the effect.
More info on our Mu-Tron mods can be found on the main site.