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VIRUS Owner’s Manual
20
You may have gathered that the LFOs of the Virus are polyphonic: If several notes are played
simultaneously, these are controlled by dedicated LFOs, each with a slightly varied rate. This effect livens
up the sound of chords, especially when they are sustained. To enhance this effect, activate the LFO 1
KEY FOLLOW 
button.
This function enables you to control the rate of the LFOs via the pitch, or more accurately, via the MIDI
note number, so that higher notes generate faster LFO rates. As result, when you press and hold several
notes you will hear all kinds of substantially different periodic fluctuations.
Finally, the LFO can also be used as an envelope. The control feature for this effect is the ENV MODE
button. When you press this button, two things occur: For one, the LFO no longer initiates its cycles
periodically, but only once at and in sync with the start of a note, and for the other, the active range of
the LFO is switched from bipolar (in both directions from the zero position) to unipolar (from zero in
one direction only). Please note that this applies to the modulation target but not the modulation
intensity. Here you can still determine a value in the entire bipolar range.
This effect is especially prominent when used in conjunction with the sawtooth wave, which enables a
fade-out type of effect (when you dial in a positive AMOUNT value) or a volume-swell type of effect
(negative AMOUNT) for the available modulation targets. Dial in the desired speed via the RATE pot.
You can also use S&H and S&G in ENV MODE to come up with some attractive results: S&H generates a
single random value at the start of a note (in this case, the RATE pot has no effect); S&G works in the
same manner although in this case the RATE value is crucial. It determines the amount of time it takes to
glide from the previous to the new random value.
LFO 2
The design of the second LFO is essentially the same as the first, so we’ll spare you the repetition of
details. The only two differences are immediately apparent when you look at the control panel: SHAPE 1
and 2 are available as a joint modulation target; the FM intensity, filter frequencies and the Panorama
position can be manipulated individually. And instead of the KEY FOLLOW function of LFO 1, here you
have an option entitled KEY TRIGGER. It works like this:
When you press the KEY TRIGGER button, the wave cycle of LFO 2 is started anew with the same phase
length at start of each note. This effect is similar to ENV MODE, except that the LFO continues to
oscillate when the note is initiated. By the way, ENV MODE is available regardless of whether you chose
to activate the KEY TRIGGER or not.