Access Virus Rack XL User Manual page 19

Rotate the ATTACK encoder while you repea-
tedly engage a key to hear the note. The further
you turn the encoder 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.
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 encoder: 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 encoder.
Now fiddle with the DECAY encoder 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 encoder
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 mini-
mum levels at which the volume remains con-
stant. This level in turn is controlled via the
SUSTAIN encoder.
Whenever the SUSTAIN level is set to maxi-
mum, the volume cannot drop during the DE-
CAY phase; in other words, in this situation the
DECAY encoder is ineffective.
í
The individual functions of a synthesizer are
designed to interact; many functions are de-
pendent on other functions. In a number of ca-
ses this means that some functions are
subordinate to others, i.e. the effectiveness of a
control feature is altered, modified or even ne-
gated completely by other related functions.
The final encoder, RELEASE, determines the
speed or rate at which the volume decreases
when you release the key: At low values the
sound ends relatively abruptly, at high values,
the sound fades out more gradually and softly.
The length of the RELEASE phase also de-
pends on which level the amplifier curve is at
when you release the key: The lower the level,
the shorter the RELEASE phase. If you dialed in
a brief DECAY or SUSTAIN-TIME phase and it
ended while you held the key down then of
course there will not be an audible RELEASE
phase.
The next phase of the amplifier envelope is de-
termined by the SUSTAIN-TIME encoder: If the
encoder is set to the center position, then the
SUSTAIN level remains constant through to the
end of the note.
If you turn it counter-clockwise to the left, then
the level drops off at an increasing rate towards
the minimum level much in the manner you just
experienced with the DECAY encoder; If you
turn the encoder clockwise to the right, the level
rises at an increasing rate to maximum and
remains there until you release the key.
T he amplifier envelope can be described as a
variable curve which, depending on the type
and duration of attack, hold and release data,
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ACCESS VIRUS RACK XL OS5
The Amplifier Envelope
19