Specifies how decay time is calculated. When true/on/1, indicates decay time is the time it would take to get from 0dBs to -oo, NOT the time to reach current sustain (as when false/off/0). Default is true.
In other words, under default behavior, the decay slope is fixed, and the lower
the sustain level of the envelope, the less time the decay stage will actually
take. Setting this to false will make the decay always happen during the entire
time period specified by ampeg_decay,
regardless of the current