I have uploaded a soundfile comparig the sound of a standard
VCA and the vactrol-powered Low Pass Gate at:

http://www.buzzclick-music.com/LPG_VCA_compare.mpg

The patch is as follows:

Identical ramp wave into a VCA and Low Pass Gate. A Doepfer
A-150 switch. Both are driven by the same envelope generator.

Here's what you're gonna hear:

Eight beats with standard VCA, switched then to eight with the
Low Pass Gate - done with three times at different speeds.

Hear the diff!

enjoy (or not)