The First Filter - Access Virus Rack User Manual

22 CHAPTER 4
Introduction

THE FIRST FILTER

Now we will take a look at a component
of a synthesizer that is generally
regarded as the most important func-
tional unit as it enables drastic sound
shaping measures: the filter - or in the
case of the Virus, the two filters.
But first we will concentrate on just one
of the two filters.
Use the UP or DOWN buttons to activate
the filter section FILT. The second enco-
der knob in this row is labeled CUTOFF
(not to be confused with CUTOFF 2!).
Rotate the encoder to the left and right
and note how the sound becomes mud-
dier and clearer in response to the direc-
tion in which you turn the encoder. (To
ensure this effect and the following
aural experiments are most pro-
nounced, adjust the amplifier envelope
so that the Virus generates a constant
level while you hold a key down).
This is how a low pass filter works: it sup-
presses, or in technical jargon, attenu-
ates the higher frequencies in a signal
and allows the lower frequencies
through. Think of the CUTOFF encoder
as a bouncer and the Virus as your pub.
You can tell it which frequencies to let in
and which frequencies to keep out. The
frequencies above the so-called cutoff or
filter frequency are suppressed, those
below it remain unaffected.