Moog Music Voyager Old School - Manual (Page 19)

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Voyager OS User’s Manual - The Components
Page 21
Voyager OS User’s Manual - The Components
D. The Envelopes Section
Musical sounds have a start, middle and an end. For example, a plucked string sound starts with an initial
burst of energy and then slowly fades out until it is silent. In synthesis terms, this progression is called an
envelope – a shape that defi nes the changes that occur in a sound over time. An envelope can defi ne any
aspect of change in a sound – volume, timbre, or pitch. The circuits that create envelope control signals in
synthesizers are called Envelope Generators (EGs).
When triggered, EG’s produce a time-varying control voltage that has a
specifi c start, middle and end profi le. The four parameters that defi ne
this profi le are Attack, Decay, Sustain and Release, sometimes abbrevi-
ated as ADSR.
Attack determines the character of the onset of the sound. The EG’s
ATTACK knob controls this parameter by adjusting the time it takes
for the envelope to go from zero to full value (in other words, the
fade-in time). The DECAY control adjusts the second stage in the
envelope’s evolution by determining the time that it takes for the signal
to drop from the full level to the level set by the SUSTAIN control.
The envelope will remain at the Sustain level as long as an envelope
gate signal is present (i.e. a key is held down). When the gate signal is
released, the RELEASE control determines the time it takes for the en-
velope to transition from the Sustain level to zero (refer to the ADSR
Envelope Signal fi gure below).
The Voyager has two identical EG circuits; one EG is dedicated to the
fi lter (to control the cutoff frequency), and one is EG dedicated to
the amplifi er (to control the volume). Both EG’s can also be used as
a modulation sources or modulation control through the Modulation
Busses..
Additional CV Connections
Filter:
The FILTER jack allows you to connect an external CV or expression pedal to control the fi lter cutoff
frequency. Both fi lters are effected by this connection, regardless of the fi lter mode setting. The effective
input range is -5 to +5 V, where a positive CV will add to the fi lter cutoff dial setting, and a negative CV will
subtract from the setting. Note that if an expression pedal is plugged into this jack, the cutoff can only be
made to increase from the cutoff dial setting since the pedal connection supplies only a positive voltage.