The Amplifier Envelope - Access VIRUS CLASSIC User Manual

The Amplifier Envelope
Long-term exposure to this sound will definitely grate on your nerves, so let's get started with
changing it into a signal you might enjoy hearing, beginning with the volume characteristics. Locate
the section labeled AMPLIFIER at the bottom right of the control feature panel of the Virus. Here you
can see five pots labeled ATTACK, DECAY, SUSTAIN, TIME and RELEASE, respectively.
These controls will help you to dial in volume characteristics called an amplifier envelope and put an
end to the nerve-racking drone that may remind you of one of those cheesy organs that you hear in
'60s B-movie sound tracks.
Rotate the ATTACK pot while you repeatedly engage a key to hear the note. The further you turn the
pot up, the longer it takes for the sound to achieve maximum volume after the start of the note. So
you can say ATTACK controls the initial volume swell of the sound.
Presumably the ATTACK pot was set to a random position before you made any adjustments. Nev-
ertheless the volume automatically increased to the maximum level before you started rotating the
pot. The reason for this is that an ATTACK value of 0 is saved in the sound program - START - and
this value remains valid until you determine a new value by adjusting the position of the pot, even if
you turn it ever so slightly.
Take a look at the display of the Virus to gain an impression of the difference between these two
values. It shows two numeric values when you dial a pot: at the left you can see the value stored in
the sound program and at the right, the numeric equivalent to the value determined by the current
position of the pot.
Always keep in mind that for a programmable synthesizer the position of the control feature
or pot does not necessarily indicate the actual value of the given function. The reason for this
is that when you first activate a sound program, it will reflect the programmed value. You
have to adjust the control feature before the programmed value is superseded by the value
you determine manually.
Now fiddle with the DECAY pot while you repeatedly press a key to activate a note. Hold the key
down for good while. You will notice that the volume, once it reaches maximum level at the end of
the ATTACK phase, drops until it reaches a minimum level. The DECAY pot determines the speed,
or in synthesizer jargon, the rate at which the volume decreases.
However, the DECAY level does not always drop to the minimum level; you can determine a random
value between the maximum and minimum levels at which the volume remains constant. This level
in turn is controlled via the SUSTAIN pot.
Whenever the SUSTAIN level is set to maximum, the volume cannot drop during the DECAY phase;
in other words, in this situation the DECAY pot is ineffective.
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