VG2 is a Dual Passive Vactrol Gate. No power needed! Each Vactrol Gate has 1 CV Input (gate, envelope, LFO, etc.), 1 Audio Input and 1 Audio Output. The CV Input hits the Vactrol LED, allowing audio to pass through. In addition, there is a simple Low Pass Filter applied to the Audio Input with an Amount (Cutoff) knob. As this is a passive circuit, it will not give you full cutoff control, but it does allow the taming of harsh waveshapes. The LPF is simply the same concept as a guitar's "tone" control. Also, there is an LED at the CV Input for quick visual reference and LED light action!
As this is a passive circuit, it is advisable to use a Buffered Multiple before the Audio Input to maintain amplitude.