Sapèl

Sapèl is a Eurorack module that produces random control voltages from analog thermal noise. Its main section has two identical clusters of four sample-and-hold circuits, so eight random values are generated at once. In each cluster, three circuits give stepped voltages (two quantized, one unquantized) and one integrating circuit gives a smoothly fluctuating voltage.

Each cluster has its own internal clock. That clock can be replaced by an external one, overridden temporarily by an external signal or the manual button, and its rate can be modulated externally. Every cluster has a clock output that mirrors the input clock and a random clock output, which can be set to pass fewer or more pulses than the main clock. The quantized circuits output either octaves or 12-EDO semitones, with a range set by a knob from 1 to 6. A probability distribution control shifts the generated values toward low, mid or high levels and can be routed to each generator independently.

A second section provides four analog noise outputs: blue, white, pink and red. All outputs are control or audio signals taken from the module's own noise sources.