Modulating the decay envelope length with a clock divider creates alternating open and closed hi-hat patterns

In a modular hi-hat patch, the decay envelope controls how long the VCA stays open after each trigger, determining perceived hat length. By routing a CV signal (e.g., gates from a clock divider that outputs on every other beat) into the decay envelope’s time parameter, you can alternate between two decay lengths on successive triggers. Short decay = closed hat; long decay = open hat. This gives rhythmically varying articulation without needing two separate voices. Beyond open/closed variation, CV can modulate the HPF cutoff frequency or either oscillator’s pitch, introducing timbral variety across the pattern — useful for avoiding the static quality of machine-precision percussion.

Examples

Patch: trigger sequence → hat VCA + envelope. Clock divider (every other gate) → envelope time CV in. Result: short-decay (closed) and long-decay (open) hats alternating. Add VCA attenuverter to scale the CV depth.

Assessment

Implement alternating open/closed hats using a single FM hi-hat voice and a clock divider. Then add a second modulation: route a slow LFO to the HPF cutoff to evolve the timbre over 8 bars. Describe the musical effect.