Here is the explanation stolen directly from the post in the SunVox forum (where also a link to the instrument is.
SloBo - a synth made purely with SunVox modules, no samples involved. It's my personal study case of synthesizing a raw approximation of bowed instruments and learning about the articulation techniques of cellos, violins & Co. It's called SloBo because as of now it allows only relatively slow bowing articulation. Future versions or derivations might include other playing styles (need to dig deeper into the topic).
Important note: The patches below were not tested with any traditional MIDI keyboard. They were designed for Linnstrument in first place. They expect ModWheel and Aftertouch action for successful expression.
ModWheel - sets the vibrato speed, from rather slow to faster, both set by ear to sound as human as possible
Aftertouch - tries to imitate harder bowing
While playing a single voice, you should avoid playing legato otherwise it will sound too synthetic while 'gliding' between notes, so always lift one finger before pushing another note. But this prevents faster playing.
Ideally you would play the 4 voices patch, each voice on it's own channel (1-4). This will give you smoother overlaps between notes and will sound more natural.
All resources about cello/violin synthesis I've studied so far are having one thing in common, they all state that the key is the playing technique. And it seems to be true. Sometimes these patches can sound pretty acceptable, other times, when screwing the technique, they simply sound too artificial. Anyway, SunVox is so much fun! Thank you Alex for the latest update which opens the MPE world!