I was playing around with my Mutron III the other night and comparing it with a Q-tron+. I've had both these pedals for a while and am very familiar with them, but last night I had an observation about what makes the Mutron so unique, even compared to the Q-Tron.
I've been through most of the other EF's out there (though not the proton). The first thing that I always notice when trying them out is the speed of the attack and decay of the envelope. The Mutron is pretty distinctive in that respect. Most are much faster and snappier, which makes it harder to get the very vocal Jerry-type sounds. In that respect, I found the Q-Tron+ to have the closest sounding envelope to the Mutron (it even has a slow response option which is very unique).
But there's another unique aspect to the Mutron that I always been aware of but never put my finger on it - the dynamic range at which it has a musical response. I can set up the Q-Tron to sound virtually identical to the Mutron for a certain range of the guitar and/or playing dynamics. At those settings, the Mutron can play pretty much anywhere on the neck and sound good. However, if the Q-tron goes outside a certain range it will stop working well - if you play too hard it will clip the input and sound very harsh, and if you play too soft it won't trigger the filter.
So, for example, if you set the Q-Tron up to match the Mutron in the middle register of the guitar, it gets hard to trigger notes properly when playing up high on the neck, and when playing down low on the neck you have to play extremely light to avoid clipping. The Mutron, however, can cover the entire range of the guitar without needing extreme dynamics.
I'm curious if anyone knows from an electrical or design perspective what accounts for that, and whether it's something that can be modded on current production pedals.