[sdiy] MIDI Velocity on analog synths

[MTG]

I'm thinking of adding velocity as a CV parameter to the Pro One and I'm 
wondering how this is typically done on other synths or MID-CV 
converters since I have neither. I imagine when an Note-On arrives you 
apply the velocity value (voltage) to VCF Cutoff or Resonance or 
whatever, but have you noticed if the Note-Off or Note-On with velocity 
of zero then zeroes the velocity CV?  Or just leave the voltage where it 
is until the next Note-On?

If you have any experience with this let me know...

GB