Access virus indigo ii Manuale Utente

CHAPTER 4
Introduction

the ring modulator. Be sure to check out what
the ring modulator does when you select a sine
wave for Oscillator 1 and 2.

Now we can go on and solve the mysteries of
the signal flow as determined by the FILTER
ROUTING operating mode SPLIT: Here Oscilla-
tor 1 and the SubOscillator are routed to Filter-
1, whereas Oscillator 2 and the Noise Generator
are routed to Filter-2. Although the sound
sources are split into two signal paths, you can
still control the volume levels of the different el-
ements as well as OSC VOL in the usual man-
ner.

 

When you first started this series of experi-
ments with sounds, we promised that many of
the functions the VIRUS can be “programmed”
so that they are executed automatically. You
have already learned how to control the volume
and cutoff frequencies of both filters as well as
the pitch and intensity of the frequency modula-
tion of Oscillator 2 via “preprogrammed” enve-
lopes. These options are great, but you have
already encountered a number of functions
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.

For our next experiment, you should recall ei-
ther the basic sound you have always started
with so far, or a version you have already edited
and saved. Look for the RATE control in the
LFOS/MOD section. To the left of this knob is
an LED, which should be flashing in time with
the LFO 1 (the currently selected LFO – see be-
low). Turn the RATE control and see the speed
of the LED changing. The buttons to the right of
the RATE knob are used for selecting LFO
waveforms.

The controls in the LFOS/MOD section only ap-
ply to the currently selected LFO (like in the OS-
CILLATORS section), and you can switch LFOs
using the SELECT button in the top lefthand
corner of this section. When LFO 3 is selected,
the LED to the right of the RATE control flashes
in time with LFO 3, otherwise it show the rate of
LFO 2

Start with the usual basic sound configuration
or chose a modified sound to suit your taste.
Locate the RATE pot in the LFO 1 section of  the
control panel. The RATE pot is equipped with
an LED that indicates the speed of the LFO as
well as its waveshape. Turn the RATE pot and
check out how the flash of the LED indicates
the change of pace as you rotate the pot.