spelltwister

Spelltwister is a dual function generator with a large palette of modulation algorithms. It has three modes: ENV (slow, single-cycle), LFO (slow, free-running), and VCO (fast, free-running). Each side of the module is a waveformer, which generates a signal controlled by three knobs. The basic structure of this signal is that of an AD envelope, so the signal first rises to it's maximum value (in a variable time and curvature), then falls back to it's minimum value (in a variable time and curvature).

The three knobs are Time, Shape, and Ratio. Time controls the overall time for one cycle of the waveform, so also functions as pitch in VCO mode. Ratio controls the ratio between the time spent on the first stage versus the second stage (so ratio set fully CCW would mean that all time is spent falling, which would form a downwards saw wave). Lastly, Shape controls the curvature of the rising and falling, from exponential to logarithmic. With Shape in it's center position, the slope is linear, but turning it below 12 o'clock makes the rising and falling more exponential, while turning it the other way makes it more logarithmic.