Content - Access Virus Rack XL User Manual

22
CHAPTER 5
Introduction
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 ef-
fective range of the fi lter. This is why we
equipped the Virus with a control labeled ENV
AMOUNT (short for Envelope Amount). This en-
coder is positoned in the Filter section. When
the encoder is turned counter-clockwise to the
far left, the filter has no effect on the cutoff fre-
quency; the further you turn the encoder to the
right, the greater the effect the filter envelope
has on the filter frequency. The maximum level
of the envelope may lie outside the audible
range when the filter has already been partially
opened via the CUTOFF encoder or was manip-
ulated via other control options. In extreme cas-
es where the filter is already completely open,
the filter frequency cannot be increased regard-
less of how high you set the ENV AMOUNT.
Go ahead and spend some experimenting with
different ENV AMOUNT, CUTOFF and RESO-
NANCE settings for the diverse filter operating
modes. Also try varying the settings for the am-
plifier envelope. You will find that with just these
few parameters you are able to come up with a
vast amount of sound settings. If you are
among the many musicians who are associative
listeners, you might say many of the settings
produce sounds reminiscent of stringed-instru-
m e n t s ; s o m e s o u n d p i c k e d , p l u c k e d o r
snapped, others sound bowed.
For your next experiment set the amplifier enve-
lope so that you hear a constant level when you
press and hold a note. Now deactivate the filter
envelope by setting the ENV AMOUNT to 0. Set
Filter-1Filter-1 to low pass mode and decrease
the filter frequency until you just barely hear a
muddy signal when you play notes in the mid-
range.
Now play a few higher and lower notes. You will
find that the lower notes have a greater over-
tone content, whereas the higher notes sound
muddier and their volume decreases until the
notes are completely inaudible. You might al-
ready suspect what this is all about: As the
notes are transposed ever lower, more portions
of the signal fall below the cutoff frequency,
whereas with the notes that are transposed ev-
er higher, more portions of the signal rise above
the cutoff frequency and subsequently are sup-
pressed until the root note and the last audible
portion of the signal is silenced.
To avoid this effect - or if desirable, to amplify it
- you have the option of influencing the cutoff
frequency via the pitch of the note, i.e. the note
number. The degree of influence is determined
by the KEY FOLLOW parameter. You'll find this
parameter in the filter section using the PA-
RAMETER buttons just like you did in FILTER 1
mode earlier on.
Please note that KEY FOLLOW is a so-called
bipolar parameter: Its control range is not limit-
ed to the positive end of the spectrum (0 to a
maximum of 127). Bipolar controls effect nega-
tive values as well, in this case from the nega-
tive maximum of -64 through 0 an on to the
positive maximum of +63. Consequently, if this
value is set to the center position (0) the pitch of
the notes corresponding to the keys on your
keyboard has no effect on the cutoff frequency.
If on the other hand you turn the KEY FOLLOW
parameter clockwise towards the positive con-
trol range, you will find that the filter opens up
increasingly as the pitch increases with higher
notes. At lower notes, the filter closes down
again. If you turn the encoder counter-clock-
wise towards the negative control range, the
KEY FOLLOW effect is reversed. With the Virus,
you will encounter this feature - intensity control
via a bipolar parameter - again in conjunction
with other modulation sources and targets.