Access Virus Classic User Manual
English
German
Copyright 2004 Access Music GmbH. All rights reserved.
Virus Classic user manual in English and German.
This manual, as well as the software and hardware described in it, is furnished under license and may be used
or copied only in accordance with the terms of such license. The content of this manual is furnished for informational use only, is subject to change without notice
and should not construed as a commitment by Access
Music GmbH. Access Music GmbH assumes no responsibility or liability for any errors or inaccuracies that may
appear in this book.
Except as permitted by such license, no part of this publication may be reproduced, stored in a retrieval system,
or transmitted in any form or by any means, electronic,
mechanical, recording, or otherwise without the prior
written permission of Access Music GmbH.
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.
Visit our website here: www.access-music.de
Table of contents
> PROLOGUE !9
Important Safety Remarks 12
> INTRODUCTION 15
The Amplifier Envelope 18
The First Filter 20
Filter Modulation 21
The Saturation Stage 23
The Second Filter 24
Filter Routing 26
The First Oscillator 28
The Second Oscillator 29
The Mixer Section 31
The LFOs 32
LFO 1 33
LFO 2 35
Volume and Panorama Position 36
Velocity 37
Unison Mode 37
The Chorus/Flanger Effect 38
The Delay Effect 39
More to Come 40
> CONCEPT AND OPERATION 41
Operating Modes 41
The Multi-Single Mode 42
Edit Buffers 43
> HANDLING 45
Parameter Selection and Data Entry 45
Knob Modes 47
Display of values 48
> ALL ABOUT THE MEMORY 49
Store 49
Compare 50
Store To Flash 51
> ABOUT TIME ... 53
Master Clock and Midi-Clock 53
The Mod Matrix and Soft Knob 54
The Virus’ Soft Knobs 55
> THE EFFECTS SECTION 57
Audio Inputs 57
Osc Volume and Input 59
Input Level Indicator 59
> INTERNAL AUDIO ROUTING 61
Aux Buses 61
The Audio Outputs 62
> ADDITIONAL FUNCTIONS 63
Panic Function 63
Audition function 63
Reset Function 64
VIRUS CLASSIC MANUAL 5
Table of Contents
> THE PARAMETERS 65
Front Panel Parameters 65
LFO 1 – Panel 66
LFO 1 – Edit Menu 67
LFO 2 - Panel 69
LFO 2 Edit Menu 70
LFO 3 Edit Menu 70
Oscillator 1- Front Panel 72
Oscillator 2 – Front Panel 73
Oscillator 1 Edit Menu 74
Oscillator-2 Edit Menu 74
Oscillator-3 Edit Menu 76
SubOscillator Edit Menu 77
Osc Mixer Edit-Menu 77
Mixer 78
Filters – Front Panel 80
Filter Edit Menu 84
Amplifier 87
Main Edit Menu (Common) 88
Key Mode 89
Unison Mode 92
Assign 93
Velocity 94
> WITHIN THE CONFIG-MENU 97
Common 97
Arpeggiator 98
Soft Knob 1/2 100
Soft Knob Modes 101
Multi Mode Parameters 102
> THE EFFECTS MENU 107
Input 107
Input Mode 108
Input Select 109
Envelope Follower 110
Ring Modulator 111
Vocoder 112
Distortion 112
Analog Boost 113
Phaser 114
Chorus 115
Delay And Reverb 116
Delay Specific Parameters 119
Reverb Specific Parameters 121
> GLOBAL AND SYSTEM PARAMETERS 125
System 130
Random Patch Generator 133
Categories 134
> PURE TUNING 137
Pure tuning the Virus 137
Theory 139
> THE VOCODER OF THE VIRUS 141
The Parameters Of The Vocoder 143
Notes About The Vocoder 146
> THE VIRUS AND SEQUENCERS 149
Parameter Control via MIDI 149
Organisational Information 149
Handling MIDI Parameter Control 151
Adaptive Parameter Smoothing 151
Parameter Control Insides 153
DUMP: The Sound in the Song 154
> TIPS AND TRICKS 157
All About Inputs 158
About The Delay/Reverb 159
The Virus as an Effect Device 160
Envelope Follower 160
Oscillators 161
Filters 163
Saturation - Adding Grit and Dirt 164
LFOs 165
Arpeggiator 167
MIDI 168
OS Update Installation 169
Support 172
6
> APPENDIX 351
System Exclusive Data 351
Parameters Description 358
Multi Dump Table 369
Classes 371
Mod Matrix Sources 374
Mod Matrix Destinations 374
Soft Knob Knobs Destinations 375
MIDI Implementation Chart 376
Oscillator and LFO waveforms 378
Block Diagram 381
> LEGAL STUFF 383
FCC Information (U.S.A) 383
FCC Information (CANADA) 384
Other Standards (Rest of World) 384
Declaration of Conformity 385
> GARANTIE BESTIMMUNG 387
> WARRANTY 389
VIRUS CLASSIC MANUAL 7
Table of contents
8
Prologue
Dear Virus Classic Owner,
Congratulations on your choice, the new Virus Classic. 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 Classic
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 comes with 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 two banks are ”hard-wired”, i.e. they’re programmed into the FLASH
ROM.
The Virus offers a maximum of 24 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 envelopes, a stereo VCA, three LFOs and a saturation
stage (SATURATOR) for cascade filtering, tube and distortion effects.
The Virus Classic offers a veritable arsenal of effects. You have seven powerful sound-sculpting
functions, including chorus, phaser and distortion, at your disposal, with each effect available
separately for every sound. Thus, in 16-way MULTI mode, the Virus offers 80 effects, no less!.
You also get a global reverb/delay unit that lets you create high-quality reverb effects and rhythmic delay taps. Delay time can be synced up to MIDI clock.
VIRUS CLASSIC MANUAL 9
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 signals 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 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, frequency modulation and ring 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.
The LFOs feature 68 continuous variable 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.
Next to the numerous ”hard-wired” or fixed modulation configurations, you can assign three modulation sources to up to six different modulation destinations via the Modulation Matrix. 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 Classic that is conducive 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 audio 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 handling 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 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.
10
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
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 SysEx 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
VIRUS CLASSIC MANUAL 11
Important Safety Remarks
A few fundamental rules on handling electrical devices follow. Please read all notes carefully before
you power the device up.
SET-UP
> Operate and store the device in enclosed rooms only.
> Never expose the device to a damp environment.
> Never operate or store the device in extremely 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 vicinity 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 available, 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 pro-
longed 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
o a rack.
12
> Make sure that no foreign objects fall into or somehow end up inside the device’s housing.
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 device is able
to generate levels that can lead to irreversible hearing damage. For this reason, always operate it
at a reasonable volume level.
MEMORY BATTERY CHANGE
The Virus Classic stores its sound programs in a battery-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 device 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 125).
CARE
> Do not open the device, it is not equipped with any user-serviceable parts. Repair and mainte-
nance may only be carried out by qualified specialists.
> 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 engineeringrelated purposes. Any other use is not permitted and automatically invalidates the warranty
extended by Access Music Electronics GmbH.
VIRUS CLASSIC MANUAL 13
14
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
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.
VIRUS CLASSIC MANUAL 15
Introduction
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 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.
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 to D) 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
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.) In order to hear the sound programs in banks B, C and D, simply
use the PARAMETER/BANK buttons to step from one program bank to another.
You’ll find that some sound programs are labeled 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.
16
≤
LISTENING TO THE MULTI PROGRAMS
The Virus not only has the capability of playing SINGLE PROGAMs, but also combinations consisting of more than one sound simultaneously (MIDI Multi Mode). To call up the MULTI PROGRAMs,
press the MULTI button and select 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 PROGRAMs, 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 can 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.
VIRUS CLASSIC MANUAL 17
Introduction
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.
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.
18
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 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 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 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 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.
VIRUS CLASSIC MANUAL 19
Introduction
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.
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:
Mode Description
LOW PASS (LP)
HIGH PASS (HP)
BAND PASS (BP)
BAND STOP (BS)
Now activate the different operating modes and rotate the CUTOFF pot to get a feel for the way
each filtering option works.
20
the low pass filter we have just discussed.
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.
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.
The band stop filter, band reject filter or notch filter which works in the
opposite manner of the bandpass 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.
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 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 par-
VIRUS CLASSIC MANUAL 21
Introduction
tially 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-1Filter-1 to low pass mode and decrease the filter frequency until you just barely hear a muddy
signal when you play notes in the mid-range.
Now play a few higher and lower notes. You will find that the lower notes have a greater 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.
22
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 EDIT in the FILTERS
section.
MENU
DISPLAY
FILTER EDIT > SATURATION > CURVE
01111111111111111112
1 SATURATION
Curve Off≤
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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. Next to the distortion curves, the SATURATION stage offers further DSP effects such as the
shaper, rectifier and filter. These are explained in detail in the section on the SATURATION stage.
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. The intensity of
the remaining available DSP effects is also controlled via the OSC VOL knob.
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.
VIRUS CLASSIC MANUAL 23
Introduction
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 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.
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
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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).
VIRUS CLASSIC MANUAL 25
Introduction
Filter Routing
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
Regardless of which FILTER ROUTING option you chose, the SATURATION stage is always post-Filter-1, i.e. after Filter in the signal chain.:
Mode Description
SER-4
SER-6
PAR-4
SPLIT
The filters are switched in series; with two poles each (12dB/Okt.), both filters have the same slope for a total of four filter poles (24dB/Okt.).
The filters are switched in series; Filter-1 has four poles (24dB/Okt.), Filter-2
has two poles (12dB/Okt.) so the overall slope is equivalent to six poles
(36dB/Okt.).
The filters are switched in parallel and feature two poles each (12dB/Okt.).
The filters are switched in parallel and feature two poles each (12dB/Okt.).
Additionally, they receive independent input signals (more on this later).
Each of the two oscillators routes its signal into one of the two filters whose
signals can be spread in the panorama via a parameter called UNISON Pan
Spread.
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Her is the filter routings capabilities of the Virus.
VIRUS CLASSIC MANUAL 27
Introduction
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 wellsuited 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 hollowsounding. 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
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odd-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 counterclockwise 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.
VIRUS CLASSIC MANUAL 29
Introduction
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 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. Basically, this effect is similar to a vibrato, although here you’re dealing with an extremely fast vibrato
featuring a frequency within the range of human hearing. This signal is not actually audible as a
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