Access virus os4 Manuale Utente

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ACCESS VIRUS OS4
25
Filter Modulation
FILTER MODULATION
Of course we don’t want to require 
you to execute every sound modifi-
cation manually by twiddling pots. 
All kinds of sound modifications in 
the Virus can be executed auto-
matically much in the way of your 
previous experiments with the vol-
ume controls: The amplifier enve-
lope can be described as a variable 
curve which, depending on the 
type and duration of attack, hold 
and release data, automatically 
influences (turns it up or down) an 
imaginary volume pot.
Similar procedures are applicable 
to the filter frequencies. The FIL-
TERS
 section features its own enve-
lope, the structure of  which is 
identical to the amplifier envelope, 
located directly above the ampli-
fier envelope on the control fea-
ture panel. Much like the amplifier 
envelope, the filter envelope auto-
matically “rotates” the CUTOFF 
pot.
However there is one significant 
difference between the two enve-
lopes. With the amplifier envelope, 
you are always dealing with an ini-
tial volume level of 0 because of 
course you want absolute silence 
prior to the beginning of a note. 
After the RELEASE phase,  it is again 
highly desirable that your box is 
silent. With the filter envelope, the 
situation is somewhat different: It 
always starts at the CUTOFF value 
that you determined manually.  
And it is definitely not always 
desirable that the filter frequency 
is brought to the maximum level.
Consequently, you need a tool that 
limits the effective range of the fil-
ter. This is why we equipped the 
Virus with a control labeled ENV 
AMOUNT
 (short for Envelope 
Amount). When the pot is turned 
counter-clockwise to the far left, 
the filter has no effect on the cut-
off frequency; the further you turn 
the pot to the right, the greater 
the effect the filter envelope has 
on the filter frequency. The maxi-
mum level of the envelope may lie 
outside the audible range when 
the filter has already been partially 
opened via the CUTOFF pot or was 
manipulated via other control 
options. In extreme cases where 
the filter is already completely