Access virus os2 Manuale Utente
VIRUS Owner’s Manual
18
The LFOs
When you first started this series of experiments 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 modulation of Oscillator 2 via „preprogrammed“ envelopes. 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 function or two you would like to be able to control periodically - independently of notes. Some
features that come to mind are traditional techniques 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 significantly 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.
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 modulation of Oscillator 2 via „preprogrammed“ envelopes. 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 function or two you would like to be able to control periodically - independently of notes. Some
features that come to mind are traditional techniques 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 significantly 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
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.
of the LED indicates the change of pace as you rotate the pot.
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 setting, you must access the AMOUNT button which works in
conjunction with five vertically arrayed LEDs labeled OSC 1, OSC 2, PW 1+2, RESO 1+2 and FILT
GAIN: Press the AMOUNT button repeatedly and observe how the LEDs flash in succession (the LEDs
OSC 1 and OSC 2 flash separately as well as in unison). The corresponding modulation targets appear in
the display, along with the modulation intensity values as determined by the VALUE pot and VALUE
buttons. (You can also scroll through the modulation targets via the PARAMETER button after you have
pressed the AMOUNT button once.) Once you have dialed in a value other than 0 for a modulation
target, the corresponding LED illuminates continually. This feature tells you at a glance that a modulation
is underway even when the display indicates some other type of operation.
program. In order to change this setting, you must access the AMOUNT button which works in
conjunction with five vertically arrayed LEDs labeled OSC 1, OSC 2, PW 1+2, RESO 1+2 and FILT
GAIN: Press the AMOUNT button repeatedly and observe how the LEDs flash in succession (the LEDs
OSC 1 and OSC 2 flash separately as well as in unison). The corresponding modulation targets appear in
the display, along with the modulation intensity values as determined by the VALUE pot and VALUE
buttons. (You can also scroll through the modulation targets via the PARAMETER button after you have
pressed the AMOUNT button once.) Once you have dialed in a value other than 0 for a modulation
target, the corresponding LED illuminates continually. This feature tells you at a glance that a modulation
is underway even when the display indicates some other type of operation.