A sample-and-hold random voltage source injects controlled randomness into pitch, amplitude or timing

The Buchla Model 165 Dual Random Voltage Source outputs two uncorrelated random voltages, each of which changes only when a trigger pulse arrives and is held steady between triggers — a stepped, sample-and-hold random source rather than a continuous one (unlike white noise). Its purpose is to randomize musical parameters: patched to a VCO’s frequency input it randomizes pitch; to a VCA’s control input, loudness; to a pulse generator’s rate, timing. Because it is quantised in time by the trigger, chance is applied per-event, giving generative/aleatoric variation while the composer keeps control of when and where randomness enters.

Examples

Model 165: ‘Produces two uncorrelated, random output voltages, each of which is changed by applying a trigger pulse. Used to randomize frequency, amplitude, and time.‘

Assessment

Explain how a stepped (sample-and-hold) random source differs from white noise, and give two parameters you would patch it to for controlled variation.