Access VIRUS C SERIES User manual

1
TABLE OF CONTENTS
INTRODUCTION ................................................................................................................................. 3
A DETAILED INTRODUCTION FOR NOVICES....................................................................................... 5
Cable Connections........................................................................................................................... 5
Listening to the Factory sounds ........................................................................................................ 6
Listening to the Multi Programs........................................................................................................ 6
Your First Sound Program ................................................................................................................ 6
The Amplifier Envelope .................................................................................................................... 7
The First Filter ................................................................................................................................. 8
Filter Moulation ............................................................................................................................... 9
The Saturation Stage ...................................................................................................................... 11
The Second Filter........................................................................................................................... 11
The First Oscillator ........................................................................................................................ 14
The Second Oscillator.................................................................................................................... 15
The MIXER Section......................................................................................................................... 17
The LFOs....................................................................................................................................... 18
LFO 1 ............................................................................................................................................ 18
LFO 2 ............................................................................................................................................ 20
LFO 3 ............................................................................................................................................ 21
Volume and Panorama Position...................................................................................................... 21
Velocity ......................................................................................................................................... 22
Twin Mode .................................................................................................................................... 22
The Chorus/Flanger Effect............................................................................................................... 22
The Delay Effect............................................................................................................................. 23
More to Come ............................................................................................................................... 23
COMPREHENSIVE OVERVIEW............................................................................................................ 24
Operating Modes........................................................................................................................... 24
Operating Conventions .................................................................................................................. 25
Parameter Selection and Data Entry............................................................................................ 25
Knob Mode ............................................................................................................................... 25
Display of Numeric Parameter Values ........................................................................................ 26
Operating Modes....................................................................................................................... 28
Multi Single Mode................................................................................................................. 28
The Store Modes ....................................................................................................................... 28
Controller Assignments.............................................................................................................. 28
Edit Mode.................................................................................................................................. 29
THE PARAMETERS.............................................................................................................................. 30
Sound Parameters with a Dedicated Control Element...................................................................... 30
Master Volume.......................................................................................................................... 30
Definable 1/2............................................................................................................................. 30
Transpose.................................................................................................................................. 30
LFO 1........................................................................................................................................ 30
LFO 2........................................................................................................................................ 31
Oscillator 1 ............................................................................................................................... 32
Oscillator 2 ............................................................................................................................... 33
Mixer ........................................................................................................................................ 34
Filters........................................................................................................................................ 34
Filter Routing............................................................................................................................. 35
Amplifier ................................................................................................................................... 37
Sound Parameters in the Edit Menu (Single) ................................................................................... 38
Edit Mode.................................................................................................................................. 38
Output ...................................................................................................................................... 38

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Twin Mode................................................................................................................................ 39
Chorus...................................................................................................................................... 40
Delay ........................................................................................................................................ 41
Punch ....................................................................................................................................... 43
Oscillator 1 ............................................................................................................................... 43
Oscillator 2 ............................................................................................................................... 44
Oscillators Phase Init................................................................................................................. 44
Sub Oscillator ........................................................................................................................... 44
Noise ........................................................................................................................................ 45
Filters........................................................................................................................................ 45
LFO 1........................................................................................................................................ 46
LFO 2........................................................................................................................................ 47
LFO 3........................................................................................................................................ 48
Input......................................................................................................................................... 49
Sound Parameters in the CTRL Menu (Single) ................................................................................. 52
Part Enable................................................................................................................................ 52
Common................................................................................................................................... 52
Arpeggiator ............................................................................................................................... 54
Velocity..................................................................................................................................... 55
Assign 1-3 ................................................................................................................................. 57
Definable 1/2 ............................................................................................................................ 58
Global Parameters / System Parameters / MIDI Parameters............................................................. 60
MIDI Dump .............................................................................................................................. 60
MIDI......................................................................................................................................... 61
MIDI Control............................................................................................................................. 62
System...................................................................................................................................... 62
MULTI Parameters in the EDIT Menu ............................................................................................. 65
Single Select.............................................................................................................................. 65
Part Transpose........................................................................................................................... 65
Part Detune............................................................................................................................... 65
Part Volume .............................................................................................................................. 65
Part MIDI Panorama .................................................................................................................. 65
Output Select ............................................................................................................................ 66
Delay Multi ............................................................................................................................... 67
MULTI Parameters in the CTRL Menu............................................................................................. 69
Part Select................................................................................................................................. 69
Part Enable................................................................................................................................ 69
MIDI Channel............................................................................................................................ 69
Low Key .................................................................................................................................... 69
High Key ................................................................................................................................... 69
MIDI Volume Enable ................................................................................................................. 70
Hold Pedal Enable ..................................................................................................................... 70
Program Change Enable............................................................................................................. 70
Appendix ........................................................................................................................................... 71
Definable 1/2 Parameter List .......................................................................................................... 71
Assign 1-3 Source- and Destination Parameter List.......................................................................... 73
MIDI Controller Assignments......................................................................................................... 76
Poly Pressure Controller Assignments............................................................................................. 78
MIDI Implementation Chart ........................................................................................................... 80

3
INTRODUCTION
Dear Virus Owner,
Congratulation on your choice, the new Virus. You have purchased a cutting-edge synthesizer 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 - for instance
the Prophet 5 or Memorymoog to name just two popular examples of the species - in a previously
unparalleled level of quality and handling ease. We're not kidding, the Virus actual delivers the
authentic response of an analog synth via a digital signal processor chip, although the sound
shaping and voicing options out-perform those of it historical predecessors by a considerable
margin.
•The Virus offers a maximum of twelve voices. In Multi Mode, these can be allocated dynamically to
sixteen simultaneously available sounds.
•You have no less than two audio oscillators plus one suboscillator, a noise generator, two Multi
Mode filters, two envelopes, a stereo VCA, three LFOs and a saturation stage (SATURATOR) for
cascade filtering, tube and distortion effects.
•Two of the three oscillators produce 66 waveshapes, 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 and frequency modulation between
the audio oscillators 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 parallel within the voices via several options. When you
switch the filters in series, the saturation stage is embedded between the filters. Consequently, 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. And if for some reason these options are
insufficient for what you have in mind, the Virus features a well-engineered signal routing system
that allows you to patch the voices to the filters of other voices in parallel or in series for further
sound shaping.
•You can also process two external audio signals - either two independent mono signals or a
combination stereo signal - via the filters, VCAs of the voices and the Virus' internal effects in
virtually any manner you see fit.
•Four of the sixteen sounds in Multi Mode feature individual (!) chorus/flanging units. You also have
a delay at your disposal. It can be routed to all sixteen sounds via the internal FX loop. All effects
process stereo signals.
•The LFOs feature five waveshapes each, including a triangle with variable symmetry and infinitely
variable aperiodic oscillations for random variation of the controlled parameters. The LFOs are
capable of polyphonic as well as monophonic oscillation. In other words, if several voices are
active, the 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 cycle once
only, like an envelope.
•Sounds and effects are patched out via six audio outputs which of course can also be used to route
three stereo signals out.

VIRUS Owner’s Manual
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•And last but not least, you have all of these features without the major hassles inherent in vintage
analog synthesizers. Compared with its behemoth predecessors, the Virus is exceptionally compact,
light-weight and dependable. You never have to contend with lengthy warm-up periods and pitch
instability due to temperature changes. (You might even feel that the Virus is TOO small. Those
massive analog beasts certainly had a stunning visual effect, especially on stage. However, we will
guarantee that you will change your mind the first time you carry your Virus into a rehearsal room
and find that you are not even winded. The long-term benefits become apparent when your
chiropractor stops sending you Christmas cards.)
In additional to its killer sounds and tone, the Virus was designed to deliver ultimate handling and
control comfort. It is equipped with dedicated knobs and buttons for the crucial synthesizer functions,
the more unusual parameters are accessible via data entry procedures. We distinguished between these
two levels of expertise to enable you to create complex sounds while keeping the user interface as clear
and uncluttered as possible. If you enjoy devising complicated sound structures, you can set the Virus to
Expert Mode, where you will find a wide range of additional intriguing sound parameters. A novice might
find the vast number of options daunting, so we kept them separate from the standard operating mode.
In all modesty, we are especially proud of a feature 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 SEAMLESSLY. No more zipper noises! The Virus responds just as smoothly as analog
synthesizers did prior to the introduction of digital sound storage. Additionally, the four control feature
operating modes let you program a sensible as well as practical setup for the diverse live and sequencer-
based applications.
And users of contemporary software sequencers will appreciate the fact that the Virus sends all sound
shaping commands immediately in the form of MIDI Controller or Poly Pressure data (and of course
accepts all of the corresponding Controller and Sys-Ex messages). 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 musical 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

5
A DETAILED INTRODUCTION FOR NOVICES
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 basics 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 features 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 majority of less significant functions, accessible via menus, are discussed
here. You will find a detailed, comprehensive description of all functions 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 synthesis and MIDI control you might desire or need to
acquire. If you are keen to learn more about these subjects, you should consider becoming a regular
reader of one or several of the leading trade publications in your country. Your local musical instruments
dealer or more experienced 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 recommend 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 subsection 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
structure 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.
Connect the MIDI OUT of the desired MIDI send device (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 controls of all the
connected devices (Virus: MASTER VOLUME, located at the upper left hand of the control panel) are
dialed to the lowest possible setting. Switch the devices on in the following 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 finally the amplifier. Now while you are sending notes on
MIDI Channel 1 of the Virus, turn the master volumes 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.

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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 offer 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 Program Bank (A or B) as well as the number and name of the current
sound program. Now if you play notes you should be able to hear this sound and a ¼ 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 single programs of Bank A in sequence. (The VALUE pot is
inactive in this operating mode.) To hear the remaining 128 single programs stored on Bank B, use the
PARAMETER button to activate the other program bank.
Listening to the Multi Programs
The Virus not only has the capability of playing single programs, but also combinations consisting of
more than one sound (MULTI PROGRAMs) simultaneously (MIDI Multi Mode). To call up the
multiprograms, press the MULTI button and select these combination programs via the VALUE button.
The Virus features „only“ 128 multiprograms, 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 multiprograms, the sounds involved are allocated side-by-side (split) or on top of
one another (layered) on the keyboard. In other MULTI PROGRAMs, 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 should control 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 A127 - START -. Press any key on the connected keyboard. You should hear a
sound that, for lack of better description, 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
especially 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.

7
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 hearing, 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 five
pots labeled ATTACK, DECAY, SUSTAIN, TIME and RELEASE, respectively. 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 random position before you made any adjustments.
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.
NOTE:NOTE: Always keep in mind that for a programmable synthesizer the position of the control feature 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 value you
determine manually.
Now fiddle with the DECAY pot while you repeatedly 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 determines 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 minimum
levels at which the volume remains constant. This level in turn is controlled via the SUSTAIN pot.
Whenever the SUSTAIN level is set to maximum, the volume cannot drop during the DECAY phase; in
other words, in this situation the DECAY pot is ineffective.
NOTE:NOTE: The individual functions of a synthesizer are designed to interact; many functions are
dependent on other functions. In a number of cases this means that some functions are
subordinate to others, i.e. the effectiveness of a control feature is altered, modified or even
negated completely by other related functions.
The next phase of the amplifier envelope is determined by the SUSTAIN-TIME pot: If the pot is set to
the center position (12 o’clock) indicated by the mathematical infinity symbol, then the SUSTAIN level
remains constant through to the end of the note; if you turn it counter-clockwise to the left (towards

VIRUS Owner’s Manual
8
FALL), then the level drops off at an increasing rate towards the minimum level much in the manner you
just experienced with the DECAY pot; If you turn the pot clockwise to the right (towards RISE), the level
rises at an increasing rate to maximum and remains there until you release the key.
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
DECAY 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 increase to the maximum level. Once
the maximum level is achieved, DECAY determines the fall or rate of decrease to the SUSTAIN value,
which is infinitely variable between the minimum and maximum levels. The amplifier envelope may
remain at this value until the end of the note, fall towards the minimum level as determined 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. Consequently, the control pots labeled
ATTACK, DECAY, TIME and RELEASE control a speed or rate, where as SUSTAIN actually controls a level.
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, directly
above the section labeled AMPLIFIER. Rotate the pot to the left and right and note how the sound
becomes muddier and clearer in response to the direction in which you turn the pot. (To ensure this
effect and the following aural experiments are most pronounced, 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 suppresses, or in technical jargon, attenuates the higher
frequencies in a signal and allows the lower frequencies 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 frequencies to keep out.
The frequencies above the so-called cutoff or filter frequency are suppressed, those below it remain
unaffected.

9
Now locate the FILT 1 MODE switch which is also located in the FILTERS section. It enables you to
select a filter operating mode from the four available options:
•LP: the low pass filter we have just discussed.
•HP: the high pass filter which works in the opposite manner of the low pass filter: It suppresses the
lower frequencies in a signal and lets the higher frequencies pass.
•BP: the band pass filter which suppresses both ends of the tonal spectrum and allows only a
narrowly defined bandwidth of the original sound to pass.
•BS: The band stop filter, band reject filter or notch filter which works in the opposite manner of the
band pass filter. It allows all of the frequencies of a signal except for a narrow frequency band
around the cutoff to pass. The term „notch“ is fairly descriptive; you might say this filter chops a
notch out of the sound spectrum.
Now activate the different operating modes and rotate the CUTOFF pot to get a feel for the way each
filtering option works.
Along with the CUTOFF pot, the RESONANCE pot is the most important control feature of a filter. The
filter resonance increases the volume of the frequencies located near the cutoff frequencies and
suppresses the more remote frequencies. This sound shaping feature has a striking effect - especially
when used in conjunction with the low pass filter: it produces a nasal or honking type of tone which
increases as you turn the resonance up. Experiment by varying the RESONANCE setting in the different
operating modes in conjunction with different CUTOFF settings. You will find the effect that the
RESONANCE pot achieves is markedly different for the band stop filter in comparison to the effect it has
on the other filter types: as the resonance increases, the bandwidth of the notch decreases; in other
words more frequencies on both sides of the filter frequency are allowed to pass.
Filter Modulation
Of course we don’t want to require you to execute every sound modification manually by twiddling pots.
All kinds of sound modifications in the Virus can be executed automatically much in the way of your
previous experiments with the volume controls: 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 (turns it up or down) an imaginary volume pot.
Similar procedures are applicable to the filter frequencies. The FILTERS section features its own
envelope, the structure of which is identical to the amplifier envelope, located directly above the
amplifier envelope on the control feature panel. Much like the amplifier envelope, the filter envelope
automatically „rotates“ the CUTOFF pot.
However there is one significant difference between the two envelopes. With the amplifier envelope, you
are always dealing with an initial 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

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10
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 filter. 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 cutoff frequency; the further you turn the
pot 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 pot or was manipulated via other control options. In extreme cases where the filter is
already completely open, the filter frequency cannot be increased regardless of how high you set the
ENV AMOUNT.
Go ahead and spend some experimenting with different ENV AMOUNT, CUTOFF and RESONANCE
settings for the diverse filter operating modes. Also try varying the settings for the amplifier 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-instruments; some sound picked, plucked or snapped,
others sound bowed.
For your next experiment set the amplifier envelope 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 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 overtone
content, whereas the higher notes sound muddier and their volume decreases until the notes are
completely inaudible. You might already 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 ever higher, more portions of the signal rise above the cutoff frequency and subsequently are
suppressed 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 pot.
Please note that KEY FOLLOW is a so-called bipolar parameter: Its control range is not limited to the
positive end of the spectrum (0 to a maximum of 127). Bipolar controls effect negative values as well, in
this case from the negative maximum of -64 through 0 an on to the positive maximum of +63.
Consequently, if this pot is set to the center position (12 o’clock or 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 pot clockwise towards the positive control 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 pot counter-clockwise 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.
Now experiment as much as you like with different KEY FOLLOW settings and tune the settings via the
CUTOFF pot. And remember to bring all of the other parameters you have encountered thus far into
play.

11
The Saturation Stage
In the signal chain of the Virus, Filter 1 is followed by a saturation stage. It enables you to add overtones
to the filtered signal via distortion. Locate and press the button labeled SATURATION in the FILTERS
section. The display will read "SATURATION CURVE OFF", which means exactly what it says. With the
VALUE buttons or the VALUE pot, you can now select from a number of saturation/distortion curves.
Once you have selected a curve, the SATURATION button LED illuminates.
Regardless of what the display might indicate at any given time, this LED will always illuminate when you
have activated a saturation curve.
At this point we would like to mention the OSC VOL pot in the MIXER section. The portion of the
control range from the far left to the center position (12 o’clock) determines the volume of the filter
section’s input signal. The portion of the control range located to the right of the center position (12
o’clock) does not achieve any increase in volume; it simply intensifies the degree of saturation or
distortion. This effect is only achieved when you have activated a saturation curve.
Feel free to experiment with the diverse saturation curves and be sure to vary the OSC VOL settings.
Note how the different CUTOFF and RESONANCE settings influence the saturation curve.
The Second Filter
You probably noticed that by a adding a bit of saturation to the signal you can come up with a pretty
heavy, aggressive sound - especially with a low filter frequency level and high resonance. You’re
probably thinking these types of sounds could do with some more filtering. We had the same idea,
which is one of the reasons why we equipped the Virus with another filter per voice.
The technical design of this second filter is identical to the first, so we won’t discuss it in as much detail
as we did the first filter. However, there are few differences in how you handle the second filter: Only
two control features of the Virus are allocated exclusively to Filter 2: CUTOFF 2 and FILT 2 MODE. The
RESONANCE, ENV AMOUNT and KEY FOLLOW pots can be allocated to either of the two filters or both
simultaneously. Use the two SELECT buttons located at the far right of the FILTERS section to select the
desired operating mode. For instance, if you press the FILT 2 SELECT button, then the values you set via
the RESONANCE, ENV AMOUNT and KEY FOLLOW pots apply exclusively to Filter 2. The
corresponding parameters of Filter 1 remain unaffected. On the other hand, if you press both SELECT
buttons at the same time, the values that you dial in apply by the same measure to Filters 1 and 2.
In the sound program we are using for our experiments, the LEDs of both buttons are illuminated, so that
all adjustments to the given parameters affect both filters. However, you have yet to actually hear the
effect of Filter 2 on the signal because it is mixed out of the audible signal path of the Virus.
Before we get started with our next experiment, deactivate SATURATION, set the ENV AMOUNT of the
filter envelope to zero and set CUTOFF 2 to the center position (12 o’clock) so that Filter 2 always has
the same cutoff frequency as Filter 1 (we’ll explain CUTOFF 2 a bit later). Set CUTOFF to a medium or
middle value and turn the RESONANCE pot counter-clockwise to the far left to achieve a relatively
muddy sound. Now locate the FILTER BALANCE pot at the upper right hand of the control panel and
rotate it from the left to the right. You will note the sound becomes muddier as you turn the pot towards
the center position (12 o’clock) and that the sound is somewhat brighter at the far right of the control
range then at the far left.
The reason for this effect is that when you turn the FILTER BALANCE pot to the far left, only Filter 1 is
audible. When you rotate the pot to the right, Filter 2 is blended in so that it follows Filter 1 in the signal

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12
chain. When you turn the FILTER BALANCE pot clockwise, Filter 1 is blended out of the signal chain until
at the far right position only Filter 2 is active and audible.
The term used to describe the efficiency of a filter is „slope.“ The unit of measurement is the so-called
filter pole: the more poles a filter has, the greater its slope. Each filter in the Virus normally features 2
poles. However in the FILTER ROUTING operating mode SER 6, Filter 1 operates with 4 poles, so the
signal patched through Filter 1 (FILTER BALANCE to the far left) is trimmed more drastically than when it
is routed through Filter 2 (FILTER BALANCE to the far right). When you set the FILTER BALANCE pot to
the center position (12 o’clock) - as we mentioned before - the two filters are routed in series, which
means they respond as if they were a single filter with 6 poles and consequently a great deal of slope.
This is why the input signal is trimmed substantially when you set the pot to this position.
Experiment with the diverse FILTER BALANCE positions to get a feel for the different degrees of slope.
Rotate the CUTOFF pot or activate the filter envelope (for both filters!) to hear the filters in action.
The CUTOFF 2 pot is a special feature: It controls the cutoff frequency of the second filter, but is
subordinate to the CUTOFF pot located above it. In other words, at the center position (12 o’clock) the
manually selected frequency of Filter 2 is identical to that of Filter 1. When you rotate the pot to the left
the cutoff frequency level of Filter 2 is increased relatively to Filter 1, when you turn to pot to the right
the cutoff frequency level is decreased relatively. Now when you adjust the CUTOFF pot, you adjust the
cutoff frequency of both filters by the same measure! This feature lets you determine a difference in
values in the filter frequencies (called an offset) via the CUTOFF2 pot which remains constant whenever
you adjust the CUTOFF pot.
Yet another experiment in which you can come up new filtering characteristics that are typical of the
Virus:
Set the FILTER BALANCE pot to the center position (12 o’clock) and CUTOFF 2 to the maximum level.
The FILTER ROUTING operating mode must remain SER 6. Set CUTOFF and RESONANCE to a middle
value and select a clearly audible SATURATION curve.
Now you can filter this complex signal produced by a combination of the saturation stage and the Filter 1
yet again. Rotate the CUTOFF 2 pot slowly towards the center position (12 o’clock). You can hear how
Filter 2 gradually modifies the distorted signal. You can set a RESONANCE value for Filter 2 if you press
the FILT 2 SELECT button and rotate the RESONANCE pot to the desired position. Set the CUTOFF 2
pot to a position to the right of the center position. This configuration can be described as a complex
non-linear filter set up where the cutoff frequency is controlled via the CUTOFF pot. You can dial in a
wide range of sound-shaping option via CUTOFF 2. Also try modifying the resonances of both filters as
well as the SATURATION curve to come up with different filtering characteristics.
Now experiment with the diverse filter modes and listen closely to the effect of the parameters
RESONANCE, ENV AMOUNT and KEY FOLLOW in conjunction with the SELECT button. Please also keep
in mind that the chances of choking a sound off are substantially greater when you are using both filters:
For instance, if the first filter is used as a low pass with a low cutoff frequency and the second as a high
pass with a high cutoff frequency, the Virus will not generate an audible signal when you set the FILTER
BALANCE pot to the center position (12 o’clock).

13
The final parameter we’ll discuss for the time being is FILTER ROUTING. This feature offers several filter
routing options which allow you to operate the filters in series, i.e. patch one after the other in the signal
chain, or in parallel, which means side by side in the signal chain:
SER 4 The filters are switched in series; with two poles each, both filters have the same slope for a
total of four filter poles.
SER 6 The filters are switched in series; Filter 1 has four poles, Filter 2 has two poles so the
overall slope is equivalent to six poles.
PAR 4 The filters are switched in parallel and feature two poles each.
SPLIT The filters are switched in parallel and feature two poles each. Additionally, they receive
independent input signal s (more on this later). The stereo position of the signals can also
be manipulated via the parameter TWIN MODE PAN SPREAD in the EDIT menu.
Regardless of which FILTER ROUTING option you chose, the SATURATION stage is always
post-Filter 1, i.e. after Filter in the signal chain.

VIRUS Owner’s Manual
14
The First Oscillator
To this point, we have turned our attention exclusively to sound-shaping functions and have always
started with the same basic material: a so-called sawtooth wave. This waveshape is especially well-suited
as a neutral starting point as it contains all of the so-called natural scale of overtones, which give the
filter plenty of quality material to work with.
The filters, with the exception of a notch filter or band stop (BS), trim the far reaches of the tonal
spectrum, so for instance a signal sounds muddier after it has been routed through a low pass filter. You
can well imagine that this type of sound modification is substantial but insufficient for shaping more
subtle differences in tone. For instance the tone of a trumpet differs significantly from that of a
saxophone even though no one would seriously claim that either of the instruments has a muddier tone
than the other.
What you need is a sound-shaping option for the portion of a signal that a filter allows to pass. And of
course you also need a tool for determining the pitch of a signal. In synthesizers, both of these tasks are
executed by oscillators. They oscillate at a variable pitch that can be modulated and they also generate
different waveshapes which give the filters a wider variety of material to work with.
The Virus is equipped with two main oscillators and a so-called suboscillator. We will first take a look at
Oscillator 1, which is the oscillator you have already heard in action during your experiments thus far.
Dial in the same basic sound that you started with at the very beginning. Now modify the amplifier
envelope so you are working with a less grating sound, but hold back on any other filter or saturation
modifications so you can hear the purest oscillator signal possible.
Locate the section labeled "1", it is bordered off in a separate area at the far left of the section labeled
OSCILLATORS. No check out the two pots labeled SHAPE and WAVE SEL/PW. These enable you
determine the waveshape and consequently the tonal spectrum of Oscillator 1.
In the sound program, SHAPE is preset to the center position (12 o’clock), which is equivalent to a
value of 64. On the pot, this position is identified via a graphic depiction of a sawtooth wave. You can
definitely see why this waveshape bears the name „sawtooth.“ Press and hold a key and slowly turn the
pot clockwise. You should be able to hear how the tone becomes increasingly more hollow-sounding.
You might say this effect thins the sound out, but in any case, the entire tonal spectrum is affected by an
equal measure, which is an audio result filters are unable to achieve.
The waveshape that is audible when you turn the SHAPE pot to the far right is a so-called pulse wave.
The graphical representation of this waveshape on the control panel gives you a good idea of its
appearance. It is unique because the duration of the negative pulse is equal to the duration of the
positive pulse: It has a so-called pulse width of 50%. The tone of a pulse wave is different to that of a
sawtooth wave because it does not contain all overtones in the natural overtone scale, only the odd-

15
numbered tones, i.e. the first (the root note that determines the pitch), third, fifth, and so forth. By
turning the SHAPE pot from the sawtooth control range towards the pulse control range, you are actually
dialing every other overtone out of the mix, which explains why the sound becomes thinner.
You can continue modifying the sound by reducing the symmetrical width of the pulse wave. In the
Virus, you can execute this sound-shaping measure via the WAVE SEL/PW (PW = pulse width) pot,
PROVIDED THE SHAPE POT IS SET TO A POSITION IN THE RIGHT HALF OF ITS CONTROL RANGE
(LATER THAN 12 O’CLOCK). Rotate the WAVE SEL/PW pot slowly from the left to the right and leave the
SHAPE pot at the far right position. You can hear how the treble content of the sound increases while the
sound becomes ever thinner. At the far right position, the signal is no longer audible because the pulse
width is equivalent to 0% and consequently the wave no longer oscillates.
Starting at the center position (12 o’clock) indicated by the sawtooth, turn the SHAPE pot counter-
clockwise towards the left. You can hear how the overtones are increasingly mixed out of the signal until
you can only hear the root note. This sound is produced by a so-called sine wave, one of 64 other
waveshapes that you have at your disposal for sound generation purposes. These waveshapes can also
be activated via WAVE SEL/PW (WAVE SEL: Wave Select), PROVIDED THE SHAPE POT IS SET TO A
POSITION IN THE LEFT HALF OF ITS CONTROL RANGE (EARLIER THAN 12 O’CLOCK). Regardless of
the current SHAPE setting, you can also select a wave in the EDIT menu under OSCILLATOR 1 WAVE.
Go ahead and check out the different waveshapes. The second of the 64 waves is a triangle wave, the
remainder of the waveshapes are each a unique tonal blend. After you have familiarized yourself with
this raw material, experiment with the parameters of the FILTERS and AMPLIFIER sections you have dealt
with thus far (don’t forget about SATURATION and the corresponding function of the OSC VOL pot), to
get a feel for how the diverse waveshapes respond to filtering, saturation and amplifier modifications.
The Second Oscillator
As we mentioned previously, in addition to the other sound sources, the Virus is equipped with a second
oscillator. Judging from the amount of control features on this oscillator’s section of the control panel,
you have probably already gathered that it has more sound-shaping options than Oscillator 1.
Dial in the basic sound program that you had at the very beginning; change the amplifier envelope to
suit your taste. In the sound program, the OSC BAL (Oscillator Balance) pot in the MIXER section is
preset to the far left. In order to hear Oscillator 2 in action, rotate the OSC BAL (Oscillator Balance) pot
in the MIXER section to the right. Towards the center position (12 o’clock) you will hear how the tone is
modified and as you rotate the pot further to the right, how the intensity of this modification is reduced.
This effect is known as the comb filtering effect. It occurs when two signals with the same frequency but
different phase lengths are mixed. Press the same key on your keyboard several times with the OSC BAL
set to the center position (12 o’clock). You should notice that each note has a slightly different tone. The

VIRUS Owner’s Manual
16
oscillators are the source of this effect. The oscillators of the Virus oscillate freely, consequently every
time you play a note, the phase constellation between the two oscillators is different. For now, leave the
OSC BAL POT at the center position (12 o’clock).
You are already familiar with Oscillator 1’s SHAPE and WAVE SEL/PW pots. These functions are
identical for Oscillator 2, so we won’t go into detail on them again.
Locate the pot labeled DETUNE and slowly rotate it to the right from the far left position (which is
preset in the sound program). You can hear the tone start to waver and as you turn the pot further to the
right, how this vibrato effect increases until Oscillator 2 sounds distinctly out of tune with Oscillator 1.
This wavering or vibrato-type effect has a popular traditional in synthesizers. It is used to achieve chorus
effects, create sounds reminiscent of stringed instruments/ string sections or simply beef up the sound.
The SEMITONE pot enables you to transpose Oscillator 2 by plus/minus four octaves in semitone steps
while Oscillator 1 maintains the pitch. This feature is especially interesting when used in conjunction
with two other oscillator functions: synchronization and frequency modulation.
Locate and activate the SYNC button in the OSCILLATOR 2 section (the LED must illuminate). The
synchronization function forces Oscillator 2 to restart its wave cycle at the same time as Oscillator 1
waveshape starts its cycle. The initial effect of this measure is that the wavering tone that resulted from
detuning and mixing the oscillator signals disappears.
The SYNC effect really becomes interesting when you transpose Oscillator 2 upwards in comparison to
Oscillator 1 via the SEMITONE pot. What happens is that the wave cycle of Oscillator 2 is interrupted as
soon as Oscillator 1 starts its cycle. The pitch of the second oscillator no longer has the expected effect,
instead it generates special tones, in some cases for lack of a better description „screaming“ type effects.
The other effect that benefits from manipulating the interval between the oscillators is frequency
modulation (FM). It generates new tonal spectra in which the signal of the first oscillator controls the
frequency of the second oscillator similar to the manner in which filters can be controlled via envelopes.
And here too you have a pot which allows you to control the intensity of: FM AMOUNT. In contrast to
an envelope, which consists of a single slow continual process initiated at the start of a note, the
controlled oscillator fluctuates periodically and in an audible frequency range. Consequently you are
unable to hear the individual pulses of the modulation; instead you hear a radical change in tone.
In the Virus you have the option of combining the two functions called oscillator synchronization (SYNC)
and frequency modulation (FM AMOUNT, to generate new harmonic spectra. Switch SYNC on and
experiment with the FM AMOUNT. Also try out different SEMITONE settings and the diverse waveshapes
of Oscillator.
The function FILT ENV MOD lets you use the filter envelope to control the frequency of OSCILLATOR 2
and the FM intensity. Here you can switch back and forth between the parameters FM AMOUNT and
OSC 2 PITCH by repeatedly pressing the FILT ENV MOD button. The currently valid value appears in
the display of the Virus.
Each of the two parameters has a bi-directional value range of -64 to +63. Enter the desired values via
the VALUE pot or VALUE buttons. As soon as you have determined a value other than 0 for one of the
two parameters, the LED of the FILT ENV MOD button will illuminate to indicate a modulation is
underway here.

17
The MIXER Section
You have already come across two parameters of the MIXER section: OSC BAL determines the mix ratio
between Oscillators 1 and 2; in the left half of its control range, OSC VOL determines the master
volume of the oscillator mix. In the right half of the control range from the center position to the far
right, OSC VOL increases the saturation intensity when a SATURATION curve has been activated.
Now we’ll take a closer look at the final control element, the SUB OSC pot: It controls the volume of
the third oscillator, the so-called SubOscillator, which always operates an octave below Oscillator 1. The
SubOscillator is mixed to the Oscillator 1 and 2 master mix signal as determined by the OSC BAL pot.
The master volume of the composite mix is controlled by the OSC VOL pot. The only other parameter
available for the SubOscillator is accessible via the EDIT menu where you have the option of selecting a
triangle or pulse waveshape (SUB OSCILLATOR WAVE SQUARE/TRIANGLE).
The final voice-internal signal source of the Virus has no visible control features on the control panel: the
Noise Generator. It has no dedicated sound parameters, only the option of determining its volume
(NOISE VOLUME in the EDIT menu). Please keep in mind that the level of the Noise Generator is not
subject to the master volume controlled by the OSC VOL pot. In other words, it is audible even when
OSC VOL is set to 0.
Now we can go on and solve the mysteries of the signal flow as determined by the FILTER ROUTING
operating mode SPLIT: Here Oscillator 1 and the SubOscillator are routed to Filter 1, whereas
Oscillator 2 and the Noise Generator are routed to Filter 2. Although the sound sources are split into two
signal paths, you can still control the volume levels of the different elements as well as OSC VOL in the
usual manner.

VIRUS Owner’s Manual
18
The LFOs
When you first started this series of experiments with sounds, we promised that many of the functions
the Virus can be „programmed“ so that they are executed automatically. You have already learned how
to control the volume and cutoff frequencies of both filters as well as the pitch and intensity of the
frequency modulation of Oscillator 2 via „preprogrammed“ envelopes. These options are great, but you
have already encountered a number of functions where it would be a helpful if you could also program
them to be executed automatically. And of course envelopes are great modulation sources, but you have
to play a note every time you want to initiate an envelope. During your experiments you probably came
across a function or two you would like to be able to control periodically - independently of notes. Some
features that come to mind are traditional techniques such as vibrato (periodic pitch control) and
tremolo (periodic volume control). Another option you might like to have at your disposal is random
parameter control.
In the Virus, both of these tasks are executed by a so-called LFO (low frequency oscillator) that oscillates
at frequencies below the audible range. An LFO is similar to the oscillators you have encountered thus
far, but it oscillates significantly slower so that its output signal is too low for human hearing. So what
good are they if you can’t hear them? LFOs are used in much the same manner as envelopes, with the
major difference that the are repeated indefinitely.
LFO 1
Start with the usual basic sound configuration or chose a modified sound to suit your taste. Locate the
RATE pot in the LFO 1 section of the control panel. The RATE pot is equipped with an LED that
indicates the speed of the LFO as well as its waveshape. Turn the RATE pot and check out how the flash
of the LED indicates the change of pace as you rotate the pot.
Currently you are unable to hear the effect of the LFO as its modulation intensity is set to 0 in the sound
program. In order to change this setting, you must access the AMOUNT button which works in
conjunction with five vertically arrayed LEDs labeled OSC 1, OSC 2, PW 1+2, RESO 1+2 and FILT
GAIN: Press the AMOUNT button repeatedly and observe how the LEDs flash in succession (the LEDs
OSC 1 and OSC 2 flash separately as well as in unison). The corresponding modulation targets appear in
the display, along with the modulation intensity values as determined by the VALUE pot and VALUE
buttons. (You can also scroll through the modulation targets via the PARAMETER button after you have
pressed the AMOUNT button once.) Once you have dialed in a value other than 0 for a modulation
target, the corresponding LED illuminates continually. This feature tells you at a glance that a modulation
is underway even when the display indicates some other type of operation.

19
Here are the definitions for the modulation targets:
OSC 1 refers to the frequency of oscillator 1
OSC 2 refers to the frequency of oscillator 2
PW 1+2 means that the pulse widths of both oscillators are controlled in unison
RESO 1+2 refers to the resonances of both filters. Please keep in mind that although each set of
these parameters is assigned a common modulation intensity, you can still dial in
different sound-shaping settings manually. In other words, the audible result of a joint
modulation varies according to the values you have determined for the other
parameters.
FILT GAIN This term refers to the input level of the first filter (and of course the subsequent
saturation level) - although WITHOUT THE LEVEL COMPENSATION CONTROLLED VIA
OSC VOL. Here you can actually modulate a parameter that is not manually accessible.
The effect of a FILT GAIN modulation is a periodic change in the saturation level which
is linked to a corresponding tremolo (periodic change in volume). If the signal is not
saturated in any manner, then the only audible result is a tremolo effect.
Modulate the five parameters separately and in combinations with different intensities. Try to anticipate
the sound you will come up when you modulate the first oscillator, the second oscillator or both
oscillators at once and see if the results match your expectations. If you can fairly reliably predict the
outcome of your sound-shaping effort, this should you have a handle on the information discussed thus
far and can use it to create specific sounds you have in mind.
During the course of your experiments, it is entirely possible that you have generated modulations that
have no effect whatsoever on the sound, for instance if you modulate the frequency of Oscillator 2
although it is dialed out of the oscillator mix. When you run into this type of problem, check out the
signal routing, see if any configurations conflict with each other and memorize the situation, problem
and solution. If you make a habit out of this, you won’t panic when you run into similar situations;
instead you’ll keep your cool, analyze the unexpected sound and fix the mix.
You are currently using a triangle as the LFO waveshape. You shouldn’t have any problem associating the
periodic up and down fluctuation of the target parameter with this waveshape. Now activate the other
available waveshapes for LFO 1 and try to picture the respective waveshape and associate it with the
results of the modulation.
The second waveshape is a descending sawtooth wave. You can convert it into to an ascending sawtooth
by simply dialing in the requisite negative modulation intensities (AMOUNT).
Two waveshapes require an in-depth explanation: S&H (Sample and Hold) is a structured random
modulation. Here random modulation values are generated. The value is held until the next beat
impulse, then it abruptly jumps to a new random value.
S&G (Sample and Glide) is a continual random modulation. Here the random values glide seamlessly
into one another, the rate of which is determined by random modulation of the RATE value.
Continued your experiments with different LFO waveshapes. Note that after a while you no longer
consciously hear minimal modulation intensities - depending on the waveshape and modulation target
(e.g. S&G +1 on OSC 1 or 2). However they do pep up the sound of lend it a certain vitality. The key to
many great sounds are these types of minimal modulations.

VIRUS Owner’s Manual
20
You may have gathered that the LFOs of the Virus are polyphonic: If several notes are played
simultaneously, these are controlled by dedicated LFOs, each with a slightly varied rate. This effect livens
up the sound of chords, especially when they are sustained. To enhance this effect, activate the LFO 1
KEY FOLLOW button.
This function enables you to control the rate of the LFOs via the pitch, or more accurately, via the MIDI
note number, so that higher notes generate faster LFO rates. As result, when you press and hold several
notes you will hear all kinds of substantially different periodic fluctuations.
Finally, the LFO can also be used as an envelope. The control feature for this effect is the ENV MODE
button. When you press this button, two things occur: For one, the LFO no longer initiates its cycles
periodically, but only once at and in sync with the start of a note, and for the other, the active range of
the LFO is switched from bipolar (in both directions from the zero position) to unipolar (from zero in
one direction only). Please note that this applies to the modulation target but not the modulation
intensity. Here you can still determine a value in the entire bipolar range.
This effect is especially prominent when used in conjunction with the sawtooth wave, which enables a
fade-out type of effect (when you dial in a positive AMOUNT value) or a volume-swell type of effect
(negative AMOUNT) for the available modulation targets. Dial in the desired speed via the RATE pot.
You can also use S&H and S&G in ENV MODE to come up with some attractive results: S&H generates a
single random value at the start of a note (in this case, the RATE pot has no effect); S&G works in the
same manner although in this case the RATE value is crucial. It determines the amount of time it takes to
glide from the previous to the new random value.
LFO 2
The design of the second LFO is essentially the same as the first, so we’ll spare you the repetition of
details. The only two differences are immediately apparent when you look at the control panel: SHAPE 1
and 2 are available as a joint modulation target; the FM intensity, filter frequencies and the Panorama
position can be manipulated individually. And instead of the KEY FOLLOW function of LFO 1, here you
have an option entitled KEY TRIGGER. It works like this:
When you press the KEY TRIGGER button, the wave cycle of LFO 2 is started anew with the same phase
length at start of each note. This effect is similar to ENV MODE, except that the LFO continues to
oscillate when the note is initiated. By the way, ENV MODE is available regardless of whether you chose
to activate the KEY TRIGGER or not.