Unlike traditional synthesizers that use time-based ADSR (Attack, Decay, Sustain, Release) envelopes, the Smart Grid One uses phase-driven AHD (Attack, Hold, Decay) envelopes (AHD in private/src/AHD.hpp).
The progression of the envelope is not tied to absolute wall-clock time but rather to the phase of the Theory of Time clock. This has profound implications for how the envelopes behave:
While the envelope is driven by phase, the user interface and parameter system configure the Attack and Decay stages in terms of absolute time (e.g., milliseconds or seconds).
To reconcile this, the system calculates the required phase increments for the Attack and Decay stages based on the current, unmodulated speed of the clock. This means that if you set an Attack time of 500ms, it will take 500ms at the current tempo. If you then modulate the tempo (e.g., with an LFO), the 500ms Attack will stretch or compress, but the base setting remains constant relative to the unmodulated clock.
The Hold (H) stage is handled differently. It is not set in absolute time but is instead relative to the specific time loops affecting the voice.
The length of the Hold stage is derived directly from the voice’s gate length, which is determined by the Multi-Phasor Gate using the voice’s clock loop and any read loops from its lens. This ensures that the sustain portion of the note perfectly matches the rhythmic subdivision assigned to that voice, creating tight, interlocking sequences.