Kick 808 2
The patch tries to recreate the kind of 808 kick that gets made on fixed architecture monosynths, except it uses the sine wave from VCO-A instead of a self-oscillating filter.
To recreate the pitch bend you get from the envelope controlling the filter frequency, ENV-B modulates VCO-A FM. ENV-B simulates the batter head of a kick drum, providing the initial punch and attack of the sound.
ENV-A uses a longer envelope to control the VCA. This envelope simulates the resonant head of a kick drum, contributing to the decay and body of the sound.