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Dial in the basic sound program that you had at the very beginning; change the amplifier envelope
to suit your taste. In the sound program, the OSC BAL (Oscillator Balance) pot in the MIXER section
is preset to the far left. In order to hear Oscillator 2 in action, rotate the OSC BAL (Oscillator Bal-
ance) pot in the MIXER section to the right. Towards the center position (12 o’clock) you will hear
how the tone is modified and as you rotate the pot further to the right, how the intensity of this mod-
ification is reduced. This effect is known as the comb filtering effect. It occurs when two signals with
the same frequency but different phase lengths are mixed. Press the same key on your keyboard
several times with the OSC BAL set to the center position (12 o’clock). You should notice that each
note has a slightly different tone. The oscillators are the source of this effect. The oscillators of the
Virus oscillate freely, consequently every time you play a note, the phase constellation between the
two oscillators is different. For now, leave the OSC BAL POT at the center position (12 o’clock).
You are already familiar with Oscillator 1’s SHAPE and WAVE SEL/PW pots. These functions are
identical for Oscillator 2, so we won’t go into detail on them again.
Locate the pot labeled DETUNE and slowly rotate it to the right from the far left position (which is
preset in the sound program). You can hear the tone start to waver and as you turn the pot further to
the right, how this vibrato effect increases until Oscillator 2 sounds distinctly out of tune with
Oscillator 1. This wavering or vibrato-type effect has a popular traditional in synthesizers. It is used
to achieve chorus effects, create sounds reminiscent of stringed instruments/ string sections or
simply beef up the sound.
The SEMITONE pot enables you to transpose Oscillator 2 by plus/minus four octaves in semitone
steps while Oscillator 1 maintains the pitch. This feature is especially interesting when used in con-
junction with two other oscillator functions: synchronization and frequency modulation.
Locate and activate the SYNC button in the Oscillator 2 section (the LED must illuminate). The syn-
chronization function forces Oscillator 2 to restart its wave cycle at the same time as Oscillator 1
waveshape starts its cycle. The initial effect of this measure is that the wavering tone that resulted
from detuning and mixing the oscillator signals disappears.
The SYNC effect really becomes interesting when you transpose Oscillator 2 upwards in compari-
son to Oscillator 1 via the SEMITONE pot. What happens is that the wave cycle of Oscillator 2 is
interrupted as soon as Oscillator 1 starts its cycle. The pitch of the second oscillator no longer has
the expected effect, instead it generates special tones, in some cases for lack of a better descrip-
tion “screaming” type effects.
The other effect that benefits from manipulating the interval between the oscillators is frequency
modulation (FM). It generates new tonal spectra in which the signal of the first oscillator controls the
frequency of the second oscillator similar to the manner in which filters can be controlled via enve-
lopes. And here too you have a pot which allows you to control the intensity of: FM AMOUNT. Basi-
cally, this effect is similar to a vibrato, although here you’re dealing with an extremely fast vibrato
featuring a frequency within the range of human hearing. This signal is not actually audible as a
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