At the introduction of a V-trigger signal from an external source, the SW911 Envelope Generator produces a single voltage contour whose time/voltage variation is determined by potentiometers T1, T2, T3, and a time constant sustaining level potentiometer (Esus). Closure of the trigger signal will direct the voltage contour to T3 (final decay) regardless of what stage (T1, T2 or E) was in current operation.



The 911 Envelope Generator completes one of the most important musical functions: That of producing a variable one-shot control voltage contour in time. This output is thus capable of controlling any voltage controlled module – most notably a Voltage Controlled Amplifier – resulting in the articulation of a single sound. Keyboard controllers initiate a trigger on every key, which is depressed in sequence specifically to fire the envelope generator. Ribbon Controllers, Sequential Controller Complements and Envelope Followers, all output trigger which initiate the action of this module as well.

Characteristic spectral sweeps associated with the articulation of a note by an acoustic instrument are simulated by utilizing the Envelope Generator to control the frequency cutoff of the 904A Low Pass Filter, or other associated modules. With considerable attenuation, the Envelope Generator can create tunable glissandi when controlling a signal oscillator.

Envelope Generators are used in association with the 911A Dual Trigger Delay to create multiple or combined DC voltage contour outputs.


Trigger Input : V Trigger
Output impedance : 10KΩ
Time Range on T1, T2, T3 : 2 milliseconds to 10 seconds
Peak DC Output on Esus : +5,5V  +/-10%

Power supply requirements : +12V@30 mA / -12V@15mA