An old buddy once said "man, I want a simple project to learn a little about VCAs, and would also love a distortion module." That buddy's name was Taylor, Taylor got their wish, and Taylor's VCA rules.
TVCA is a 2-input VCA built around the LM13700, taking advantage of its characteristic hyperbolic tangent transfer function to yield delicious distortion. The DIST slider is just an attenuator on the input of the VCA, with something close to unity gain at the bottom and "major crunchy squashing" at the top. The rest works as a standard VCA, with two separate inputs with their own associated attenuators.
IN: DC-coupled signal inputs with associated level controls.
CV: The VCA's CV input. 0V is closed, 5V is fully open.
DIST: Distortion amount.
INIT: Initial gain. An offset to the CV input or manual control of VCA gain.