http://subdecay.com/effect/proteus-sample-hold-filter
I had the pleasure of demoing the very first Proteus. In fact, I still own the prototype. I loved it then and I love it even more now. The Proteus does envelope filter, cocked wah and sample and hold filter really well, all with analog circuitry. It's a ton of fun and I suggest you try one out if you're able. Or just take the punt!
This demo attempts to explain with dialogue most or all of the Proteus' functionality. A no-talk demo where I'm simply running through the functions and playing over a backing track can be viewed at https://youtu.be/2IxdRK_rwrI
Improvements / changes from the original Proteus:
•Switchable bandpass and lowpass filter.
•New design closer to the Maestro Filter Sample Hold.
•Can be powered at up to 18 volts for maximum headroom.
•Resonance knob added allows the filter to go from subtle to nasty greasy synthesizer grit.
Today's tools:
Guitar: 2016 Oakland Axe Factory (now Drinkwater Guitars: https://drinkwaterguitars.com) SS8.
Amp: Boogie Tri-Axis Clean Channel (model; Fractal Audio Axe-FX II XL+ running FW Q9b)
Extra effects: ZenDrive, reverb, delay - Axe-FX II
Cables: Goodwood Audio and Montreux
Power Supply: Strymon Zuma
Mic: Samson Airline77 (me)
Camera: Canon 60D (me) and Nikon D5100 (pedal)
Soundcard: Fractal Audio Systems Axe-FX II XL+
Computer: Apple iMac 27" i7 3.4 GHz 16 GB RAM
Software: Logic Pro X, Eventide Elevate Mastering Limiter, Apple Final Cut Pro X (video editing and Youtube compression).