Hey just got the hartman envelope filter (AWESOME birthday present) a few days ago and have had some time to tweak the knobs a bit. This thing is awesome!
I've tried a few envelope filters to get an idea on what to expect and here is my opinion on it:
Envelope filters are (like most pedals) instruments in themselves. They require practice and discipline and you get better at them the longer you play with them. It gets tricky when you have a pre-conceived expectation for what the pedal should sound like. My knowledge of jerry's mutron sound made me incredibly picky when it came to which envelope filter i wanted to invest in. I wanted to sound just like him. I tried the q-tron mini, the q-tron plus, the AF-9, and even a bass envelope filter, and each of these pedals did a great job at what they did...but for me they either got one tone right but not the other or came kinda close... Its also important to note that jerry's tone came from the envelope filter partly, but was primarily his style/attack/sensitivity/guitar/pickups/amp/equalizer settings/volume..all of which can effect (no pun intended) the pedal's sound.
With all that in mind..the hartman is the closest thing i can hear to mimicking the sounds of the mutron, when I play it.
In the next few days i plan on trying to make a demo video for all of ya... there isn't much out there for the pedal as far as demos go..