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CHAPTER 
21
The Vocoder of the VIRUS
Center Frequency (Knob: CUTOFF
Default: 64 (middle)) The central 
frequency of the bandpass filters 
in the modulator- and carrier bank. 
Using a high Q (filter quality 
parameter, which is controlled 
using KEYFOLLOW) you can adjust 
the central frequency of the spec-
trum you edit.
Frequency Spread (Knob: KEYFOL-
LOW, Default: +63 (right)) The 
spread of the filter bands used by 
the modulator and carrier bank. 
This parameter can adjust both 
banks together or separately. The 
mode depends on the setting of 
the filter select buttons. FILT1 is 
assigned to the carrier, FILT2 con-
trols the modulator. With maxi-
mum KEYFOLLOW (+63) the filters 
cover the whole frequency spec-
trum. Reducing the KEYFOLLOW 
results in narrower spread, 
whereby just a part of the fre-
quency spectrum is covered. CUT-
OFF
 1+2 define the centre 
frequency. Linking FILT1 and FILT2 
results in identical frequencies for 
the modulator and the carrier. If 
only the spread of the carrier bank 
is being reduced, the analysed 
spectrum is being rendered on a 
part of the carrier signal. If you 
reduce the spread of the modula-
tor bank (FILT2), just a part of the 
modulator signal is analysed but 
applied on the whole carrier signal. 
This leads to an increased spread 
of the spectrum. If one of the two 
KEYFOLLOW parameters has a neg-
ative amount, the modulator spec-
trum is applied on the carrier 
spectrum in a mirror symmetrical 
way. This causes a very interesting 
change in the bands. The modula-
tor’s treble frequencies control the 
carrier’s bass frequencies and vice 
versa, for instance a human voice 
still has the sound of the human 
voice but it would be virtually 
impossible to understand any-
thing. We want to encourage you 
to experiment with mirror sym-
metrical sounds using this func-
tion. It is definitely worth a try!