[korg]
[ms50 title]

[owners manual]

3. The modules and their functions  ^

(4) ENVELOPE GENERATOR (EG) 1

[eg1 module]
- envelope generator 1


[one] ATTACK TIME
This knob controls how fast the envelope signal voltage rises from zero to its peak value when a trigger signal arrives.
[two] DECAY TIME
Controls the time it takes for the envelope signal to fall from its peak value (at the end of the attack time) to the sustain level.
[three] SUSTAIN LEVEL
Determines the voltage level at which the envelope signal stays after the decay time; it remains at this voltage for as long as the trigger signal is still on.
[four] RELEASE TIME
This knob controls how fast the envelope signal voltage falls from the sustain level back to zero, after the trigger signal turns off.
[five] TRIGGER INPUT
This input jack is for the trigger signal that starts and stops the EG operation. When the voltage drops from +2.5V (or higher) to 0V (GND), or there is a change from an open condition to earth (GND), EG operation begins. When the voltage returns to +2.5V (or higher), or an open condition, EG operation ends.
[six] [seven] [eight] ENVELOPE OUTPUT
These outputs can be used for different purposes. Output (6) [ms50 env1] is usually connected to the VCA and is used for volume control. (7) [ms50 env2] is usually connected to the VCF FcM input for the expand effect in which timbre varies in proportion to volume. (8) [ms50 env3] provides an inverted output signal for the opposite expand effect.

[role of the eg]
- the role of the envelope generator

In the figure above we turn again to our watergate model, this time in an attempt to explain how the envelope generator works. Here we have a secret agent who can see a light bulb that turns on when a key is played (and turns off when the key is released.) The light is the trigger signal, and the agent is the EG. What the agent does when he sees the light depends on the instructions he has received beforehand. You tell the EG what to do by setting the attack, decay, sustain and release knobs (ADSR).

Usually the agent's big stick is connected to the VCA, although it may also be connected to the VCF. As the agent raises and lowers his stick, more or less water will pass through. This corresponds to the VCA's effect on volume. When connected to the VCF, raising and lowering the stick will produce corresponding changes in timbre. This is called the expand effect, and is produced by using the EG envelope signal to modulate the VCF cut-off frequency (FcM).

To repeat: the trigger (from the keyboard, etc.) tells the EG to generate an envelope signal (ADSR) which controls the VCA's effect on volume and can also control the VCF's effect on timbre.

Besides the conventional trigger signal that continues until the release time, there is also a "multiple trigger" which just tells the EG when to start generating an envelope signal, but does not tell it when to stop. In this case, the rest of the envelope signal timing is determined automatically.


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