Access VIRUS C SERIES User manual

ENGLISH VERSION
ACCESS VIRUS C SERIES
USER MANUAL OS5

©2002 Access Music GmbH, Germany.
VIRUS is a trademark of Access Music GmbH.
All other trademarks contained herein are the
property of their respective owners. All features
and specifications subject to change without
notice.
Written by Christoph Kemper, Uwe G. Hönig,
Wiland Samolak and Marc Schlaile.
Translation by Thomas Green and Howard
Scarr. Graphic Design and DTP by
Babylonwaves Media.
http://www.access-music.de
[email protected]

2 1
Content
IMPORTANT SAFETY REMARKS
PROLOGUE
INTRODUCTION
The Virus ............................................................. 14
The Amplifier Envelope ........................................ 17
The First Filter...................................................... 18
Filter Modulation .................................................. 19
The Saturation Stage ........................................... 21
The Second Filter................................................. 21
Filter Routing ....................................................... 24
The First Oscillator............................................... 25
The Second Oscillator .......................................... 27
The Third Oscillator.............................................. 29
The Mixer Section ................................................ 29
The LFOs ............................................................. 30
The MOD Section ................................................. 33
Soft Knob 1/2....................................................... 33
Volume and Panorama Position............................ 34
Velocity................................................................ 34
Unison Mode........................................................ 35
The Effects........................................................... 36
The Arpeggiator ................................................... 38
SoundDiver Virus ................................................. 38
More to Come ...................................................... 39
CONCEPT AND OPERATION
Operating Modes ................................................. 42
Master Clock and Midi-Clock ............................... 44
Handling...............................................................44
All about the memory ...........................................47
The Modulation Matrix and Soft Knobs..................48
Random Patch Generator......................................50
Categories............................................................52
The Effects Section...............................................52
Audio Inputs .........................................................53
Internal Audio Routing ..........................................54
Additional functions..............................................55
SYNTHESIS PARAMETERS
OSCILLATORS ...................................................... 58
Oscillator-1/2/3 (Panel).........................................58
Oscillator (Edit-Menu)...........................................59
FILTER ................................................................. 63
Filters (Panel) .......................................................63
Filter Envelope......................................................64
Filter-Edit-Menu ...................................................65
ENVELOPES ......................................................... 69
MIXER .................................................................. 70
LFO AND MODMATRIX ......................................... 71
LFO (Panel)...........................................................71
LFO (Edit Menu)....................................................73
ARPEGGIATOR EDIT.............................................. 80
THE INTERNAL EFFECTS ...................................... 82
Distortion (Panel)..................................................82
Chorus (Panel)......................................................83
Chorus (Edit Menu)...............................................83
Phaser (Panel) ......................................................84
Phaser (Edit Menu) ...............................................84
Delay / Reverb......................................................85
Delay / Reverb (Panel) ..........................................86
Delay / Reverb (Menu) ..........................................87
Vocoder................................................................92
Analog Boost ........................................................92
Equalizer ..............................................................92

ACCESS VIRUS OS5 3
MAIN EDIT MENU
Common.............................................................. 96
Unison Mode........................................................ 99
Punch Intensity .................................................. 100
Envelope Sustain Time....................................... 100
Analog Inputs..................................................... 100
Follower (Envelope-Follower) ............................. 102
Ringmodulator ................................................... 102
Second Output/Surround.................................... 103
Velocity.............................................................. 104
Sound Category ................................................. 106
Soft Knob-1/2 .................................................... 106
MULTI MODE & SYSTEM SETUP
MULTI MODE PARAMETERS .............................. 110
SYSTEM ............................................................ 114
Keyboard ........................................................... 114
Input.................................................................. 116
MIDI................................................................... 117
System .............................................................. 121
THE KEYBOARD VERSIONS OF THE VIRUS
The VIRUS kc and the indigo ............................. 126
The Keyboard-Modes......................................... 128
THE VOCODER OF THE VIRUS
Vocoder ............................................................. 132
The parameters of the VIRUS Vocoder ................ 134
Notes about the vocoder: ................................... 137
THE VIRUS AND SEQUENCERS
Problems Related to Parameter Control ..............144
Arrangement Dump - The Sound in the Song......145
TIPS AND TRICKS
All abouts Inputs.................................................148
About the Delay/Reverb ......................................149
The Virus as an Effect Device .............................150
Envelope Follower ..............................................150
Oscillators ..........................................................151
Filters.................................................................153
Saturation for Added Grit and Dirt .......................153
LFOs ..................................................................154
Volume Control...................................................155
Assign and the Soft Knobs..................................156
Arpeggiator ........................................................156
How to modulate the Vocoder parameters ..........156
MIDI ...................................................................157
How to install Updates........................................158
APPENDIX
System Exclusive Data .......................................162
Parameter Descriptions ......................................166
Multi Dump Table...............................................178
Classes ..............................................................180
Mod Matrix Sources ..........................................182
Mod Matrix Destinations.....................................183
Soft Knob Destinations ......................................184
MIDI Implementation Chart .................................185
FCC Information (U.S.A) ......................................186
FCC Information (CANADA) .................................187
Other Standards (Rest of World)..........................187
Declaration of Conformity ...................................188
Garantie Bestimmung.........................................189
Warranty ............................................................190

4 1
INDEX
INDEX ................................................................ 192

Important Safety Remarks

6 2
Important Safety Remarks
Please read all notes carefully before you power
the device up. A few fundamental rules on han-
dling electrical devices follow.
SET-UP
• Operate and store the device in enclosed
rooms only.
• Never expose the device to a damp envi-
ronment.
• Never operate or store the device in ex-
tremely dusty or dirty environments.
• Assure that air can circulate freely on all
sides of the device, especially when you
mount it to a rack.
• Don’t set the device in the immediate vicini-
ty of heat sources such as radiators.
• Don’t expose the device to direct sunlight.
• Don’t expose the device to strong vibrations
and mechanical shocks.
CONNECTIONS
• Be sure to use exclusively the included
mains power supply adapter.
• Plug the device only into mains sockets that
are properly grounded in compliance with
statutory regulations.
• Never modify the included power cord. If its
plug does not fit the sockets you have availa-
ble, take it to a qualified electrician.
• Always pull the power plug out of the mains
socket when you won’t be using the device
for prolonged periods.
• Never touch the mains plug with wet hands.
• Always pull the actual plug, never the cord,
when you’re unplugging the device.
OPERATION
• Don’t set beverages or any other receptacle
containing liquids on the device.
• Make sure the device is placed on a solid
base. Set it on a stable tabletop or mount it to
a rack.
• Make sure that no foreign objects fall into or
somehow end up inside the device’s hous-
ing. In the event that this should occur, switch
the device off and pull the power plug. Then
get in touch with an authorized dealer.
• Used on its own and in conjunction with
amps, loudspeakers or headphones, this de-
vice is able to generate levels that can lead to
irreversible hearing damage. For this reason,
always operate it at a reasonable volume lev-
el.
MEMORY BATTERY CHANGE
The VIRUS stores its sound programs in a bat-
tery-buffered RAM. This battery (general type
designation: CR2032) should be replaced every
three to four years. The housing has to be
opened to change the battery, so take the de-
vice to a qualified service technician. Do your
part in protecting our environment and take it to
a shop that disposes of batteries properly.
Before you have the battery changed, save the
entire memory content of the RAM by loading it
to a sequencer via "Total Dump". Be advised
that RAM content is lost when the battery is
swapped (see "Midi Dump TX" on page 117).).
CARE
• Do not open the device, it is not equipped
with any user-serviceable parts. Repair and
maintenance may only be carried out by qual-
ified specialists.

ACCESS VIRUS OS5 7
• Use only a dry, soft cloth or brush to clean
the device.
• Do not use alcohol, solvents or similar
chemicals. These can damage the surface of
the housing.
FITNESS FOR PURPOSE
This device is designed exclusively to generate
low-frequency audio signals for sound engi-
neering-related purposes. Any other use is not
permitted and automatically invalidates the
warranty extended by Access Music Electronics
GmbH.

8 2
Important Safety Remarks

Prologue

10 CHAPTER 3
Prologue
Dear VIRUS Owner,
Congratulations on your choice, the new VI-
RUS. You have purchased a cutting-edge syn-
thesizer that comes fully loaded with several
revolutionary features. Here are just a few of the
highlights:
The VIRUS delivers the sound characteristics
and tone of traditional analog synthesizers in a
previously unparalleled level of quality and han-
dling ease. We’re not kidding, the VIRUS actual
delivers the authentic response of an analog
synth via a digital signal processor chip, al-
though the sound shaping and voicing options
out-perform those of it historical predecessors
by a considerable margin.
The VIRUS comes with up to 1024 slots for
storing SINGLE sounds. These are organized in
eight banks. The first two banks (A and B) are
located in the RAM, so you can overwrite them
with new sounds. The other six banks are
”hard-wired”, i.e. they’re programmed into the
FLASH ROM. To make use of the banks E-H
you need to install the second1024.mid file first
(“The 1024 sounds update” on page 158).
The VIRUS offers a maximum of 32 voices. In
Multi Mode, these are allocated dynamically to
sixteen simultaneously available sounds.
You have no less than three audio oscillators
plus one suboscillator, a noise generator, a ring
modulator, two Multi Mode filters, two enve-
lopes, a stereo VCA, three LFOs and a satura-
tion stage (SATURATOR) for cascade filtering,
tube and distortion effects.
The VIRUS offers a veritable arsenal of effects.
You have seven powerful sound-sculpting func-
tions, including chorus, phaser and distortion,
at your disposal, with each effect available sep-
arately for every sound. Thus, in 16-way MULTI
mode, the VIRUS offers over 98 effects, no
less!. Among them you also get a global reverb/
delay unit that lets you create high-quality re-
verb effects and rhythmic delay taps. Delay
time can be synced up to MIDI clock.
With the benefit of two external audio inputs,
the VIRUS may also serve as an FX device and
signal processor that you can use creatively to
come up with all kinds of effects. External sig-
nals can be processed with filter, gate and lo-fi
effects, routed to the VIRUS effects section and
serve as a modulation source for frequency and
ring modulation.
Beyond that, you can use internal or external
signals as sources for the VIRUS’ on-board
vocoder serve. The vocoder works with up to
32 filter bands and offers diverse manipulation
and modulation options.
The three main oscillators produce 66 wave-
shapes, three of which are dynamically mixable
so that spectral effects are possible within the
confines of a single oscillator. In conventional
synthesizers, this type of effect requires several
oscillators. Synchronization, frequency modula-
tion and ring modulation between the audio os-
cillators delivers additional complex spectral
effects that you can use for all kinds of sound
shaping purposes.
The filters can be switched in series or in paral-
lel within the voices via several options. When
you switch the filters in series, the saturation
stage is embedded between the filters. Conse-
quently, an overdriven filter resonance can be
re-filtered within the same voice! A maximum of
six filter poles (36 dB slope!) enables radical
tonal manipulations.
The LFOs feature 68 continuous variable wave-
shapes each, including a triangle with variable
symmetry and infinitely variable aperiodic oscil-
lations for random variation of the controlled
parameters. The LFOs are capable of poly-
phonic as well as monophonic oscillation. In
other words, if several voices are active, the

ACCESS VIRUS OS5 11
LFOs can run independently or in sync. A
number of keyboard trigger options enable you
start LFO waveshapes with variable phase
lengths at the beginning of a note and/or to cy-
cle once only, like an envelope.
Next to the numerous ”hard-wired” or fixed
modulation configurations, you can assign
three modulation sources to up to nine different
modulation destinations via the Modulation Ma-
trix. For your modulation sources, you have
LFOs, velocity, the pitch bender, aftertouch, the
modulation wheel, numerous MIDI controllers
and other sources to chose from. For your
modulation destinations, you can select any
sound parameter of the VIRUS that is condu-
cive to being remote controlled.
Up to 16 arpeggiators are available in MULTI
mode. These give you countless options for
creating arpeggios, which can also be synced
up to MIDI clock.
Sounds and effects are patched out via six au-
dio outputs which of course can also be used to
route three stereo signals out.
In additional to its killer sounds and tone, the
VIRUS was designed to deliver ultimate han-
dling and control comfort. It is equipped with
dedicated knobs and buttons for the crucial
synthesizer functions, further parameters are
accessible via data entry procedures. We distin-
guished between these two levels of expertise
to enable you to create complex sounds while
keeping the user interface as clear and unclut-
tered as possible.
In all modesty, we are especially proud of a fea-
ture we developed called Adaptive Parameter
Smoothing. For the first time in the history of
synthesizers equipped with memories, you can
manipulate a knob or control feature without an
audible step or increment. In other words, the
sound does not change abruptly but SEAM-
LESSLY. No more zipper noises! The VIRUS re-
sponds just as smoothly as analog synthesizers
did prior to the introduction of digital sound
storage
And users of contemporary software sequenc-
ers will appreciate the fact that the VIRUS
sends all sound shaping commands immedi-
ately in the form of MIDI Controller or Poly Pres-
sure data (and of course accepts all of the
corresponding Controller and SysEx messag-
es). This feature lets you dynamically control the
VIRUS and all its functions via computer.
Although far from complete, the features listed
above give you some indication that you now
own an exceptionally versatile, high-quality mu-
sical instrument that will give you plenty of joy
for years to come. We certainly hope you can
fully exploit the enormous potential of this fine
instrument.
Have fun and enjoy!
Your VIRUS Development Team
By the way: a rack mounting kit is optionally
available for the Virus C. Feel free to get in
touch with your local authorized dealer for more
info.
Many thanks to:
Ben Crosland, Maik Fliege, Thomas Green, Axel
Hartmann, Uwe G. Hönig, Jörg Hüttner, Timo
Kaluza, Oliver Käser, Andrea Mason, Thorsten
Matuschowski, Jörg Meißner, Paul Nagel, Kai
Niggemann, Rob Papen, Matt Picone, Wieland
Samolak, Daniela Sauerbier, Howard Scarr,
Hans-Jörg Scheffler, Shehryar Lasi, Jenny Si-
mon, Matt Skags, Joeri Vankeirsbilck, Jay
Vaughan, Jens Wegerhoff and Daniel Wewer.

12 CHAPTER 3
Prologue

Introduction

14 CHAPTER 4
Introduction
 THE VIRUS
This section provides deliberate, step-by-step
guidelines on operating and handling the VIRUS
for those of you who are new to the world of
synthesizers and MIDI. The following covers ba-
sics such as how to connect the VIRUS to an
AC power supply, your MIDI system and your
audio system. Then we will guide you through a
series of experiments designed to demonstrate
the different functional groups, their control fea-
tures and the tasks they execute.
After you have finished reading this section, you
will be able to handle virtually all of the sound
generating and sound shaping functions of the
VIRUS. All of these are described in context,
along with their control features. Even the ma-
jority of less significant functions, accessible via
menus, are discussed here. You will find a de-
tailed, comprehensive description of all func-
tions of your new synthesizer in the section
following this introduction.
Please keep in mind that within confines of this
introduction, we are unable to impart all of the
knowledge and skills in acoustics, sound syn-
thesis and MIDI control you might desire or
need to acquire. If you are keen to learn more
about these subjects, you should consider be-
coming a regular reader of one or several of the
leading trade publications in your country. Your
local musical instruments dealer or more expe-
rienced musicians will be able to recommend
the best magazines to you. And of course there
is a wide range of books available on these
subjects.
If you decide to read this section, we recom-
mend you read it in its entirety from the start -
rather than begin with a subsection that is of
particular interest to you. A fitting metaphor for
the basics discussed in this section might be a
house where each bit of information in a sub-
section is a brick that builds on a preceding
brick and interlocks with those next to it. You
want your knowledge base to be a sound struc-
ture so you won’t run into problems when you
find one of the “bricks” is missing.
CABLE CONNECTIONS
Before you connect the VIRUS to an AC outlet
and the rest of your equipment, ensure that all
of the devices are switched OFF. If your VIRUS
does not have a build-in keyboard, then con-
nect the MIDI OUT of the desired MIDI send de-
vice (keyboard, computer, hardware sequencer,
etc.) with the MIDI IN of the VIRUS.
Connect the audio outputs of the VIRUS with
the signal inputs of your audio system. In order
to receive a signal, as a minimum you must
connect the output OUT 1 R/MONO. However,
we recommend you also connect the output
OUT 1 L so you are able to enjoy the stereo
sounds of the VIRUS.
Once you have established the desired cable
connections, make sure the main volume con-
trols of all the connected devices (VIRUS: MAS-
TER VOLUME, located at the upper left hand of
the control panel) are dialed to the lowest pos-
sible setting. Switch the devices on in the fol-
lowing sequence: the MIDI send device
(computer, master keyboard, etc.) first, then the
sound generators (VIRUS and the other signal
sources), followed by the mixing console and fi-
nally the amplifier.
Now while you are sending notes on MIDI
Channel 1 of the VIRUS, turn the master vol-
umes of the connected devices up in the same
order that you switched the devices on. Be sure
to keep on eye on the signal level indicators of
your mixing console.

ACCESS VIRUS OS5 15
The Virus
MASTER VOLUME
Controls the overall volume of the VIRUS. This
control determines the volume of the signal pair
piped through Output 1 before it is converted
into an analog signal. This means that under
normal circumstances, you should turn Master
Volume all they way up because you of course
want the VIRUS to deliver the most dynamic
signal possible.
LISTENING TO THE FACTORY
SOUNDS
The program memory of the VIRUS was loaded
with sound programs (SINGLE PROGRAMs)
and sound combinations (MULTI PROGRAMs)
before it left the factory. To hear the SINGLE
PROGRAMs (and gain an initial impression of
the possibilities your new instrument has to of-
fer in terms of sounds), first make sure your
MIDI source is sending on MIDI Channel 1.
Press the SINGLE button. A number, a letter,
number and name appear in the display. These
indicate the the MIDI Channel, the current Pro-
gram Bank (A to D or A to H) as well as the
number and name of the current sound pro-
gram.

Now if you play notes you should be able to
hear this sound and a
≤ note (the round dot at
the end of the note staff is solid black) should
appear in the display every time you press a key
and release a key. If you do not hear a sound
but you see a half note (blank note head) check
to see if you are sending on the wrong MIDI
Channel.
Press the VALUE button to call up the 128 sin-
gle programs of Bank A in sequence. (The VAL-
UE pot is inactive in this operating mode.) In
order to hear the sound programs in banks B, C
and so on, simply use the PARAMETER/BANK
buttons to step from one program bank to an-
other.
You’ll find that some sound programs are la-
beled with the abbreviations ”INP” or ”VOC”.
These use the external audio input as a signal
source for the filter section (INP) or vocoder
(VOC). This means that you won’t hear anything
until you route an audio signal into the external
audio inputs.

Tip: You can trigger a note on the Virus by
pressing both the EDIT and SYNC buttons in
the OSCILLATORS section at the same time –
this is the AUDITION function, which is espe-
cially useful for auditioning sounds when there
is no keyboard connected to the Virus.
Call up each of the 128 programs in Bank A in
turn. You can do this either with the VALUE
keys (which simply increment/decrement the
program number), or by holding down the MUL-
TI key and scrolling through programs with the
VALUE knob. To try out all the other sounds in
banks B to H, simply switch banks with the PA-
RAMETER/BANK buttons.
SOFT KNOB 1
SOFT KNOB 1
SINGLE
SINGLE
MULTI
MULTI
UNDO
UNDO
-+
STORE
STORE
MULTISINGLE
MULTISINGLE

16 CHAPTER 4
Introduction
SOUND CATEGORIES
To help you find the type of SINGLE sound you
are looking for more quickly, the Virus operating
system lets you define so-called „categories“
and save this information together with each of
your SINGLE sounds.
Available categories are:
Off, Lead, Bass, Pad, Decay, Pluck, Acid, Clas-
sic, Arpeggiator, Effects, Drums, Percussion, In-
put, Vocoder, Favourite1, Favourite2,
Favourite3
Each SINGLE sound can „belong“ to two cate-
gories at the same time. Of course the catego-
ries of all the presets in Banks C to H are fixed,
but for sounds in the RAM Banks (A and B) they
can be defined and saved together with the
program.
To search for sounds in a specific category (in
SINGLE or MULTI-SINGLE mode):
Press and hold the SINGLE button. This causes
the currently selected category to appear in the
display, and it can be changed by stepping up
or down with the Parameter buttons. Having
found the category you want, do not release the
SINGLE button and scroll through the sounds
using the Value buttons. Release the SINGLE
button when you have found what you are loo-
king for. SINGLE sounds which do not belong
to the currently selected category are simply
skipped over.
LISTENING TO THE MULTI PRO-
GRAMS
The VIRUS not only has the capability of playing
SINGLE PROGAMs, but also combinations
consisting of more than one sound simultane-
ously (MIDI Multi Mode). To call up the MULTI
PROGRAMs, press the MULTI button and se-
lect these combination programs via the VALUE
button. The VIRUS features “only” 128 MULTI
PROGRAMs, so you don’t have to switch back
and forth between banks they way you just did
while activating single programs.
The majority of available MULTI PROGRAMs
contain sound combinations that are controlled
via a single MIDI channel. In these MULTI PRO-
GRAMs, the sounds involved are allocated
side-by-side (split) or on top of one another
(layered) on the keyboard. In other MULTI PRO-
GRAMs, the sounds are divided up over several
MIDI channels to make it easier to work with a
sequencer. If you activate a MULTI PROGRAM
and hear a single sound only, then you can con-
trol this MULTI PROGRAM via several channels.
YOUR FIRST SOUND PROGRAM
If you have never created or changed a sound
on a synthesizer, we now have the pleasure of
introducing you to this fascinating process.
Select the single program “C127 - START -”.
Press any key on the connected keyboard. You
should hear a sound that, for lack of better de-
scription, is a bit harsh or biting, but above all
completely static. It should start immediately
after you press a key and sustain indefinitely for
as long as you hold the key down. As soon as
you release the key, the sound should end
abruptly. This sound is not designed to be es-
pecially pleasant; it is intended to be as neutral
as possible to give you a basis from which you
can begin creating or shaping your own sound.

ACCESS VIRUS OS5 17
The Amplifier Envelope
 THE AMPLIFIER ENVELOPE
Long-term exposure to this sound will definitely
grate on your nerves, so let’s get started with
changing it into a signal you might enjoy hear-
ing, beginning with the volume characteristics.
Locate the section labeled AMPLIFIER at the
bottom right of the control feature panel of the
VIRUS. Here you can see four pots labeled AT-
TACK, DECAY, SUSTAIN and RELEASE, re-
spectively.
These controls will help you to dial in volume
characteristics called an amplifier envelope and
put an end to the nerve-racking drone that may
remind you of one of those cheesy organs that
you hear in ‘60s B-movie sound tracks.
Rotate the ATTACK pot while you repeatedly
engage a key to hear the note. The further you
turn the pot up, the longer it takes for the sound
to achieve maximum volume after the start of
the note. So you can say ATTACK controls the
initial volume swell of the sound.
Presumably the ATTACK pot was set to a ran-
dom position before you made any adjust-
ments. Nevertheless the volume automatically
increased to the maximum level before you
started rotating the pot. The reason for this is
that an ATTACK value of 0 is saved in the sound
program - START - and this value remains valid
until you determine a new value by adjusting
the position of the pot, even if you turn it ever
so slightly.
Take a look at the display of the VIRUS to gain
an impression of the difference between these
two values. It shows two numeric values when
you dial a pot: at the left you can see the value
stored in the sound program and at the right,
the numeric equivalent to the value determined
by the current position of the pot.

Always keep in mind that for a programma-
ble synthesizer the position of the control fea-
ture or pot does not necessarily indicate the
actual value of the given function. The reason
for this is that when you first activate a sound
program, it will reflect the programmed value.
You have to adjust the control feature before
the programmed value is superseded by the val-
ue you determine manually.
Now fiddle with the DECAY pot while you re-
peatedly press a key to activate a note. Hold
the key down for good while. You will notice
that the volume, once it reaches maximum level
at the end of the ATTACK phase, drops until it
reaches a minimum level. The DECAY pot de-
termines the speed, or in synthesizer jargon, the
rate at which the volume decreases.
However, the DECAY level does not always
drop to the minimum level; you can determine a
random value between the maximum and mini-
mum levels at which the volume remains con-
stant. This level in turn is controlled via the
SUSTAIN pot.
Whenever the SUSTAIN level is set to maxi-
mum, the volume cannot drop during the DE-
CAY phase; in other words, in this situation the
DECAY pot is ineffective.

The individual functions of a synthesizer are
designed to interact; many functions are depen-
dent on other functions. In a number of cases
this means that some functions are subordinate
ATTACK
ATTACK
DECAY
DECAY
SUSTAIN
SUSTAIN
RELEASE
RELEASE
0
6
12
12
0
6
12
12
0
6
12
12
0
6
12
12
AMPLIFIER
AMPLIFIER

18 CHAPTER 4
Introduction
to others, i.e. the effectiveness of a control fea-
ture is altered, modified or even negated com-
pletely by other related functions.
The final pot, RELEASE, determines the speed
or rate at which the volume decreases when
you release the key: At low values the sound
ends relatively abruptly, at high values, the
sound fades out more gradually and softly. The
length of the RELEASE phase also depends on
which level the amplifier curve is at when you
release the key: The lower the level, the shorter
the RELEASE phase. If you dialed in a brief DE-
CAY or SUSTAIN-TIME phase and it ended
while you held the key down then of course
there will not be an audible RELEASE phase.
The amplifier envelope can be described as a
variable curve which, depending on the type
and duration of attack, hold and release data,
automatically influences an imaginary volume
pot (turns it up or down). At the beginning of the
note, ATTACK controls the rise or rate of in-
crease to the maximum level. Once the maxi-
mum level is achieved, DECAY determines the
fall or rate of decrease to the SUSTAIN value,
which is infinitely variable between the mini-
mum and maximum levels. The amplifier enve-
lope may remain at this value until the end of
the note, fall towards the minimum level as de-
termined by the variable TIME value, or even
rise again towards the maximum level. After the
end of the note, RELEASE controls the fall or
rate of decrease to the minimum level. Conse-
quently, the control pots labeled ATTACK, DE-
CAY, TIME and RELEASE control a speed or
rate, where as SUSTAIN actually controls a lev-
el.
 THE FIRST FILTER
Now we will take a look at a component of a
synthesizer that is generally regarded as the
most important functional 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.
Locate the Cutoff pot (not to be confused with
Cutoff 2!) in the section labeled FILTERS, direct-
ly above the section labeled AMPLIFIER. Rotate
the pot to the left and right and note how the
sound becomes muddier and clearer in re-
sponse to the direction in which you turn the
pot. (To ensure this effect and the following au-
ral experiments are most pronounced, adjust
the amplifier envelope so that the VIRUS gener-
ates a constant level while you hold a key
down).
This is how a low pass filter works: it suppress-
es, or in technical jargon, attenuates the higher
frequencies in a signal and allows the lower fre-
quencies through. Think of the Cutoff pot as a
bouncer and the VIRUS as your pub. You can
tell it which frequencies to let in and which fre-
quencies to keep out. The frequencies above
the so-called cutoff or filter frequency are sup-
pressed, those below it remain unaffected.
-100%
-100%
0
100%
100%
6
-
0
6
1
1+2
1+2
2
FILTER BALANCE
FILTER BALANCE
CUTOFF
CUTOFF
RESONANCE
RESONANCE
ENV AMOUNT
ENV AMOUNT
CUTOFF 2
CUTOFF 2
SELECT
SELECT
MODE
MODE
FILT 1
FILT 1
FILT 2
FILT 2
EDIT
EDIT
BP
BP
BS
BS
HP
HP
LP
LP
FILT 2
FILT 2
FILT 1
FILT 1
0
6
12
12
0
6
12
12
FILTERS
FILTERS