Access Virus Rack XL User Manual page 31

where it would be a helpful if you could also
program them to be executed automatically.
And of course envelopes are great modulation
sources, but you have to play a note every time
you want to initiate an envelope. During your
experiments you probably came across a func-
tion or two you would like to be able to control
periodically - independently of notes. Some
features that come to mind are traditional tech-
niques such as vibrato (periodic pitch control)
and tremolo (periodic volume control). Another
option you might like to have at your disposal is
random parameter control.
In the Virus, both of these tasks are executed
by a so-called LFO (low frequency oscillator)
that oscillates at frequencies below the audible
range. An LFO is similar to the oscillators you
have encountered thus far, but it oscillates sig-
nificantly slower so that its output signal is too
low for human hearing. So what good are they if
you can't hear them? LFOs are used in much
the same manner as envelopes, with the major
difference that the are repeated indefinitely.
LFO 1
Start with the usual basic sound configuration
or chose a modified sound to suit your taste.
Locate the RATE encoder in the LFO 1 section
of the control panel. The VIRUS is equipped
with an LED that indicates the speed of the LFO
as well as its waveshape. Turn the RATE encod-
er and check out how the flash of the LED indi-
cates the change of pace as you rotate the
encoder.
Currently you are unable to hear the effect of
the LFO as its modulation intensity is set to 0 in
the sound program. In order to change this set-
ting, you must access the five parameters
called LFO AMOUNT button which works with
the modulation destinations Oscillator1,
Oscillator2, PulseWidth1+2, Resonance1+2 und
FilterGain:
THE MODULATION TARGETS
- OSCILLATOR1 refers to the frequency of
oscillator 1
- OSCILLATOR2 refers to the frequency of
oscillator 2
- PULSEWIDTH1+2 m e a n s t h a t t h e p u l s e
widths of both oscillators are controlled in
unison
- RESONANCE1+2 refers to the resonances
of both filters. Please keep in mind that al-
though each set of these parameters is as-
signed a common modulation intensity, you
can still dial in different sound-shaping set-
tings manually. In other words, the audible re-
sult of a joint modulation varies according to
the values you have determined for the other
parameters.
- FILTERGAIN This term refers to the input
level of the first filter (and of course the sub-
sequent saturation level) - although WITH-
O U T T H E L E V E L
CONTROLLED VIA OSC VOL. Here you can
actually modulate a parameter that is not
manually accessible. The effect of a FiltGain
modulation is a periodic change in the satura-
tion level which is linked to a corresponding
tremolo (periodic change in volume). If the
signal is not saturated in any manner, then the
only audible result is a tremolo effect.
Modulate the five parameters separately and in
combinations with different intensities. Try to
anticipate the sound you will come up with
when you modulate the first oscillator, the sec-
ond oscillator or both oscillators at once and
see if the results match your expectations. If
you can fairly reliably predict the outcome of
your sound-shaping efforts, you should have a
handle on the information discussed thus far
and can use your knowledge to create specific
sounds you have in mind.
PDF VERSION - RESTRICTIONS APPLY
ACCESS VIRUS RACK XL OS5
The LFOs
C O M P E N S AT I O N
31