ENGLISH VERSION

ACCESS VIRUS C SERIES

USER MANUAL OS5

2002 Access Music GmbH, Germany.

VIRUS is a trademark of Access Music GmbH.All other trademarks contained herein are theproperty of their respective owners. All featuresand specifications subject to change withoutnotice.

Written by Christoph Kemper, Uwe G. Hnig,Wiland Samolak and Marc Schlaile.

Translation by Thomas Green and HowardScarr. Graphic Design and DTP by Babylonwaves Media.

http://www.access-music.deinfo@access-music.de

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Content

IMPORTANT SAFETY REMARKS

PROLOGUE

INTRODUCTION

The Virus ............................................................. 14The Amplifier Envelope ........................................ 17The First Filter...................................................... 18Filter Modulation .................................................. 19The Saturation Stage ........................................... 21The Second Filter ................................................. 21Filter Routing ....................................................... 24The First Oscillator ............................................... 25The Second Oscillator .......................................... 27The Third Oscillator.............................................. 29The Mixer Section ................................................ 29The LFOs ............................................................. 30The MOD Section ................................................. 33Soft Knob 1/2....................................................... 33Volume and Panorama Position ............................ 34Velocity ................................................................ 34Unison Mode........................................................ 35The Effects........................................................... 36The Arpeggiator ................................................... 38SoundDiver Virus ................................................. 38More to Come ...................................................... 39

CONCEPT AND OPERATION

Operating Modes ................................................. 42Master Clock and Midi-Clock ............................... 44

Handling............................................................... 44All about the memory ...........................................47The Modulation Matrix and Soft Knobs..................48Random Patch Generator......................................50Categories ............................................................ 52The Effects Section...............................................52Audio Inputs ......................................................... 53Internal Audio Routing ..........................................54Additional functions ..............................................55

SYNTHESIS PARAMETERS

OSCILLATORS ......................................................58

Oscillator-1/2/3 (Panel).........................................58Oscillator (Edit-Menu) ...........................................59

FILTER ................................................................. 63

Filters (Panel) .......................................................63Filter Envelope......................................................64Filter-Edit-Menu ...................................................65

ENVELOPES ......................................................... 69MIXER .................................................................. 70LFO AND MODMATRIX .........................................71

LFO (Panel)........................................................... 71LFO (Edit Menu)....................................................73

ARPEGGIATOR EDIT..............................................80THE INTERNAL EFFECTS ......................................82

Distortion (Panel) ..................................................82Chorus (Panel) ......................................................83Chorus (Edit Menu) ...............................................83Phaser (Panel) ......................................................84Phaser (Edit Menu) ...............................................84Delay / Reverb......................................................85Delay / Reverb (Panel) ..........................................86Delay / Reverb (Menu) ..........................................87Vocoder................................................................ 92Analog Boost ........................................................92Equalizer .............................................................. 92

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MAIN EDIT MENU

Common.............................................................. 96Unison Mode........................................................ 99Punch Intensity .................................................. 100Envelope Sustain Time....................................... 100Analog Inputs..................................................... 100Follower (Envelope-Follower) ............................. 102Ringmodulator ................................................... 102Second Output/Surround.................................... 103Velocity .............................................................. 104Sound Category ................................................. 106Soft Knob-1/2 .................................................... 106

MULTI MODE & SYSTEM SETUP

MULTI MODE PARAMETERS .............................. 110SYSTEM ............................................................ 114

Keyboard ........................................................... 114Input .................................................................. 116MIDI................................................................... 117System .............................................................. 121

THE KEYBOARD VERSIONS OF THE VIRUS

The VIRUS kc and the indigo ............................. 126The Keyboard-Modes ......................................... 128

THE VOCODER OF THE VIRUS

Vocoder ............................................................. 132The parameters of the VIRUS Vocoder ................ 134Notes about the vocoder: ................................... 137

THE VIRUS AND SEQUENCERS

Problems Related to Parameter Control ..............144Arrangement Dump - The Sound in the Song......145

TIPS AND TRICKS

All abouts Inputs.................................................148About the Delay/Reverb ......................................149The Virus as an Effect Device .............................150Envelope Follower ..............................................150Oscillators .......................................................... 151Filters................................................................. 153Saturation for Added Grit and Dirt .......................153LFOs .................................................................. 154Volume Control ...................................................155Assign and the Soft Knobs ..................................156Arpeggiator ........................................................156How to modulate the Vocoder parameters ..........156MIDI ................................................................... 157How to install Updates ........................................158

APPENDIX

System Exclusive Data .......................................162Parameter Descriptions ......................................166Multi Dump Table ...............................................178Classes .............................................................. 180Mod Matrix Sources ..........................................182Mod Matrix Destinations .....................................183Soft Knob Destinations ......................................184MIDI Implementation Chart .................................185FCC Information (U.S.A) ......................................186FCC Information (CANADA) .................................187Other Standards (Rest of World)..........................187Declaration of Conformity ...................................188Garantie Bestimmung .........................................189Warranty ............................................................ 190

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INDEX

INDEX ................................................................ 192

Important Safety Remarks

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Important Safety Remarks

Please read all notes carefully before you powerthe device up. A few fundamental rules on han-dling electrical devices follow.

SET-UP

Operate and store the device in enclosedrooms only.

Never expose the device to a damp envi-ronment.

Never operate or store the device in ex-tremely dusty or dirty environments.

Assure that air can circulate freely on allsides of the device, especially when youmount it to a rack.

Dont set the device in the immediate vicini-ty of heat sources such as radiators.

Dont expose the device to direct sunlight.

Dont expose the device to strong vibrationsand mechanical shocks.

CONNECTIONS

Be sure to use exclusively the includedmains power supply adapter.

Plug the device only into mains sockets thatare properly grounded in compliance withstatutory regulations.

Never modify the included power cord. If itsplug does not fit the sockets you have availa-ble, take it to a qualified electrician.

Always pull the power plug out of the mainssocket when you wont be using the devicefor prolonged periods.

Never touch the mains plug with wet hands.

Always pull the actual plug, never the cord,when youre unplugging the device.

OPERATION

Dont set beverages or any other receptaclecontaining liquids on the device.

Make sure the device is placed on a solidbase. Set it on a stable tabletop or mount it toa rack.

Make sure that no foreign objects fall into orsomehow end up inside the devices hous-ing. In the event that this should occur, switchthe device off and pull the power plug. Thenget in touch with an authorized dealer.

Used on its own and in conjunction withamps, loudspeakers or headphones, this de-vice is able to generate levels that can lead toirreversible hearing damage. For this reason,always operate it at a reasonable volume lev-el.

MEMORY BATTERY CHANGE

The VIRUS stores its sound programs in a bat-tery-buffered RAM. This battery (general typedesignation: CR2032) should be replaced everythree to four years. The housing has to beopened to change the battery, so take the de-vice to a qualified service technician. Do yourpart in protecting our environment and take it toa shop that disposes of batteries properly.

Before you have the battery changed, save theentire memory content of the RAM by loading itto a sequencer via "Total Dump". Be advisedthat RAM content is lost when the battery isswapped (see "Midi Dump TX" on page 117).).

CARE

Do not open the device, it is not equippedwith any user-serviceable parts. Repair andmaintenance may only be carried out by qual-ified specialists.

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Use only a dry, soft cloth or brush to cleanthe device.

Do not use alcohol, solvents or similarchemicals. These can damage the surface ofthe housing.

FITNESS FOR PURPOSE

This device is designed exclusively to generatelow-frequency audio signals for sound engi-neering-related purposes. Any other use is notpermitted and automatically invalidates thewarranty extended by Access Music ElectronicsGmbH.

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Important Safety Remarks

Prologue

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CHAPTER 3

Prologue

Dear VIRUS Owner,

Congratulations on your choice, the new VI-RUS. You have purchased a cutting-edge syn-thesizer that comes fully loaded with severalrevolutionary features. Here are just a few of thehighlights:

The VIRUS delivers the sound characteristicsand tone of traditional analog synthesizers in apreviously unparalleled level of quality and han-dling ease. Were not kidding, the VIRUS actualdelivers the authentic response of an analogsynth via a digital signal processor chip, al-though the sound shaping and voicing optionsout-perform those of it historical predecessorsby a considerable margin.

The VIRUS comes with up to 1024 slots forstoring SINGLE sounds. These are organized ineight banks. The first two banks (A and B) arelocated in the RAM, so you can overwrite themwith new sounds. The other six banks arehard-wired, i.e. theyre programmed into theFLASH ROM. To make use of the banks E-Hyou need to install the second1024.mid file first(The 1024 sounds update on page 158).

The VIRUS offers a maximum of 32 voices. InMulti Mode, these are allocated dynamically tosixteen simultaneously available sounds.

You have no less than three audio oscillatorsplus one suboscillator, a noise generator, a ringmodulator, two Multi Mode filters, two enve-lopes, a stereo VCA, three LFOs and a satura-tion stage (SATURATOR) for cascade filtering,tube and distortion effects.

The VIRUS offers a veritable arsenal of effects.You have seven powerful sound-sculpting func-tions, including chorus, phaser and distortion,at your disposal, with each effect available sep-arately for every sound. Thus, in 16-way MULTImode, the VIRUS offers over 98 effects, noless!. Among them you also get a global reverb/

delay unit that lets you create high-quality re-verb effects and rhythmic delay taps. Delaytime can be synced up to MIDI clock.

With the benefit of two external audio inputs,the VIRUS may also serve as an FX device andsignal processor that you can use creatively tocome up with all kinds of effects. External sig-nals can be processed with filter, gate and lo-fieffects, routed to the VIRUS effects section andserve as a modulation source for frequency andring modulation.

Beyond that, you can use internal or externalsignals as sources for the VIRUS on-boardvocoder serve. The vocoder works with up to32 filter bands and offers diverse manipulationand modulation options.

The three main oscillators produce 66 wave-shapes, three of which are dynamically mixableso that spectral effects are possible within theconfines of a single oscillator. In conventionalsynthesizers, this type of effect requires severaloscillators. Synchronization, frequency modula-tion and ring modulation between the audio os-cillators delivers additional complex spectraleffects that you can use for all kinds of soundshaping purposes.

The filters can be switched in series or in paral-lel within the voices via several options. Whenyou switch the filters in series, the saturationstage is embedded between the filters. Conse-quently, an overdriven filter resonance can bere-filtered within the same voice! A maximum ofsix filter poles (36 dB slope!) enables radicaltonal manipulations.

The LFOs feature 68 continuous variable wave-shapes each, including a triangle with variablesymmetry and infinitely variable aperiodic oscil-lations for random variation of the controlledparameters. The LFOs are capable of poly-phonic as well as monophonic oscillation. Inother words, if several voices are active, the

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LFOs can run independently or in sync. Anumber of keyboard trigger options enable youstart LFO waveshapes with variable phaselengths at the beginning of a note and/or to cy-cle once only, like an envelope.

Next to the numerous hard-wired or fixedmodulation configurations, you can assignthree modulation sources to up to nine differentmodulation destinations via the Modulation Ma-trix. For your modulation sources, you haveLFOs, velocity, the pitch bender, aftertouch, themodulation wheel, numerous MIDI controllersand other sources to chose from. For yourmodulation destinations, you can select anysound parameter of the VIRUS that is condu-cive to being remote controlled.

Up to 16 arpeggiators are available in MULTImode. These give you countless options forcreating arpeggios, which can also be syncedup to MIDI clock.

Sounds and effects are patched out via six au-dio outputs which of course can also be used toroute three stereo signals out.

In additional to its killer sounds and tone, theVIRUS was designed to deliver ultimate han-dling and control comfort. It is equipped withdedicated knobs and buttons for the crucialsynthesizer functions, further parameters areaccessible via data entry procedures. We distin-guished between these two levels of expertiseto enable you to create complex sounds whilekeeping the user interface as clear and unclut-tered as possible.

In all modesty, we are especially proud of a fea-ture we developed called Adaptive ParameterSmoothing. For the first time in the history ofsynthesizers equipped with memories, you canmanipulate a knob or control feature without anaudible step or increment. In other words, thesound does not change abruptly but SEAM-LESSLY. No more zipper noises! The VIRUS re-

sponds just as smoothly as analog synthesizersdid prior to the introduction of digital soundstorage

And users of contemporary software sequenc-ers will appreciate the fact that the VIRUSsends all sound shaping commands immedi-ately in the form of MIDI Controller or Poly Pres-sure data (and of course accepts all of thecorresponding Controller and SysEx messag-es). This feature lets you dynamically control theVIRUS and all its functions via computer.

Although far from complete, the features listedabove give you some indication that you nowown an exceptionally versatile, high-quality mu-sical instrument that will give you plenty of joyfor years to come. We certainly hope you canfully exploit the enormous potential of this fineinstrument.

Have fun and enjoy!Your VIRUS Development Team

By the way: a rack mounting kit is optionallyavailable for the Virus C. Feel free to get intouch with your local authorized dealer for moreinfo.

Many thanks to:Ben Crosland, Maik Fliege, Thomas Green, AxelHartmann, Uwe G. Hnig, Jrg Httner, TimoKaluza, Oliver Kser, Andrea Mason, ThorstenMatuschowski, Jrg Meiner, Paul Nagel, KaiNiggemann, Rob Papen, Matt Picone, WielandSamolak, Daniela Sauerbier, Howard Scarr,Hans-Jrg Scheffler, Shehryar Lasi, Jenny Si-mon, Matt Skags, Joeri Vankeirsbilck, JayVaughan, Jens Wegerhoff and Daniel Wewer.

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CHAPTER 3

Prologue

Introduction

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CHAPTER 4

Introduction

THE VIRUS

This section provides deliberate, step-by-stepguidelines on operating and handling the VIRUSfor those of you who are new to the world ofsynthesizers and MIDI. The following covers ba-sics such as how to connect the VIRUS to anAC power supply, your MIDI system and youraudio system. Then we will guide you through aseries of experiments designed to demonstratethe different functional groups, their control fea-tures and the tasks they execute.

After you have finished reading this section, youwill be able to handle virtually all of the soundgenerating and sound shaping functions of theVIRUS. All of these are described in context,along with their control features. Even the ma-jority of less significant functions, accessible viamenus, are discussed here. You will find a de-tailed, comprehensive description of all func-tions of your new synthesizer in the sectionfollowing this introduction.

Please keep in mind that within confines of thisintroduction, we are unable to impart all of theknowledge and skills in acoustics, sound syn-thesis and MIDI control you might desire orneed to acquire. If you are keen to learn moreabout these subjects, you should consider be-coming a regular reader of one or several of theleading trade publications in your country. Yourlocal musical instruments dealer or more expe-rienced musicians will be able to recommendthe best magazines to you. And of course thereis a wide range of books available on thesesubjects.

If you decide to read this section, we recom-mend you read it in its entirety from the start -rather than begin with a subsection that is ofparticular interest to you. A fitting metaphor forthe basics discussed in this section might be ahouse where each bit of information in a sub-

section is a brick that builds on a precedingbrick and interlocks with those next to it. Youwant your knowledge base to be a sound struc-ture so you wont run into problems when youfind one of the bricks is missing.

CABLE CONNECTIONS

Before you connect the VIRUS to an AC outletand the rest of your equipment, ensure that allof the devices are switched OFF. If your VIRUSdoes not have a build-in keyboard, then con-nect the MIDI OUT of the desired MIDI send de-vice (keyboard, computer, hardware sequencer,etc.) with the MIDI IN of the VIRUS.

Connect the audio outputs of the VIRUS withthe signal inputs of your audio system. In orderto receive a signal, as a minimum you mustconnect the output OUT 1 R/MONO. However,we recommend you also connect the outputOUT 1 L so you are able to enjoy the stereosounds of the VIRUS.

Once you have established the desired cableconnections, make sure the main volume con-trols of all the connected devices (VIRUS: MAS-TER VOLUME, located at the upper left hand ofthe control panel) are dialed to the lowest pos-sible setting. Switch the devices on in the fol-lowing sequence: the MIDI send device(computer, master keyboard, etc.) first, then thesound generators (VIRUS and the other signalsources), followed by the mixing console and fi-nally the amplifier.

Now while you are sending notes on MIDIChannel 1 of the VIRUS, turn the master vol-umes of the connected devices up in the sameorder that you switched the devices on. Be sureto keep on eye on the signal level indicators ofyour mixing console.

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The Virus

MASTER VOLUME

Controls the overall volume of the VIRUS. Thiscontrol determines the volume of the signal pairpiped through Output 1 before it is convertedinto an analog signal. This means that undernormal circumstances, you should turn MasterVolume all they way up because you of coursewant the VIRUS to deliver the most dynamicsignal possible.

LISTENING TO THE FACTORY SOUNDS

The program memory of the VIRUS was loadedwith sound programs (SINGLE PROGRAMs)and sound combinations (MULTI PROGRAMs)before it left the factory. To hear the SINGLEPROGRAMs (and gain an initial impression ofthe possibilities your new instrument has to of-fer in terms of sounds), first make sure yourMIDI source is sending on MIDI Channel 1.

Press the SINGLE button. A number, a letter,number and name appear in the display. Theseindicate the the MIDI Channel, the current Pro-gram Bank (A to D or A to H) as well as thenumber and name of the current sound pro-gram.

Now if you play notes you should be able tohear this sound and a

note (the round dot atthe end of the note staff is solid black) shouldappear in the display every time you press a keyand release a key. If you do not hear a soundbut you see a half note (blank note head) checkto see if you are sending on the wrong MIDIChannel.

Press the VALUE button to call up the 128 sin-gle programs of Bank A in sequence. (The VAL-UE pot is inactive in this operating mode.) Inorder to hear the sound programs in banks B, C

and so on, simply use the PARAMETER/BANKbuttons to step from one program bank to an-other.

Youll find that some sound programs are la-beled with the abbreviations INP or VOC.These use the external audio input as a signalsource for the filter section (INP) or vocoder(VOC). This means that you wont hear anythinguntil you route an audio signal into the externalaudio inputs.

Tip: You can trigger a note on the Virus bypressing both the EDIT and SYNC buttons inthe OSCILLATORS section at the same time this is the AUDITION function, which is espe-cially useful for auditioning sounds when thereis no keyboard connected to the Virus.

Call up each of the 128 programs in Bank A inturn. You can do this either with the VALUEkeys (which simply increment/decrement theprogram number), or by holding down the MUL-TI key and scrolling through programs with theVALUE knob. To try out all the other sounds inbanks B to H, simply switch banks with the PA-RAMETER/BANK buttons.

SOFT KNOB 1SOFT KNOB 1SINGLESINGLEMULTIMULTI

UNDOUNDO

- +

STORESTORE

MULTISINGLEMULTISINGLE

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CHAPTER 4

Introduction

SOUND CATEGORIES

To help you find the type of SINGLE sound youare looking for more quickly, the Virus operatingsystem lets you define so-called categoriesand save this information together with each ofyour SINGLE sounds.

Available categories are:

Off, Lead, Bass, Pad, Decay, Pluck, Acid, Clas-sic, Arpeggiator, Effects, Drums, Percussion, In-put , Vocoder, Favour i te1 , Favour i te2 ,Favourite3

Each SINGLE sound can belong to two cate-gories at the same time. Of course the catego-ries of all the presets in Banks C to H are fixed,but for sounds in the RAM Banks (A and B) theycan be defined and saved together with theprogram.

To search for sounds in a specific category (inSINGLE or MULTI-SINGLE mode):

Press and hold the SINGLE button. This causesthe currently selected category to appear in thedisplay, and it can be changed by stepping upor down with the Parameter buttons. Havingfound the category you want, do not release theSINGLE button and scroll through the soundsusing the Value buttons. Release the SINGLEbutton when you have found what you are loo-king for. SINGLE sounds which do not belongto the currently selected category are simplyskipped over.

LISTENING TO THE MULTI PRO-GRAMS

The VIRUS not only has the capability of playingSINGLE PROGAMs, but also combinationsconsisting of more than one sound simultane-ously (MIDI Multi Mode). To call up the MULTIPROGRAMs, press the MULTI button and se-

lect these combination programs via the VALUEbutton. The VIRUS features only 128 MULTIPROGRAMs, so you dont have to switch backand forth between banks they way you just didwhile activating single programs.

The majority of available MULTI PROGRAMscontain sound combinations that are controlledvia a single MIDI channel. In these MULTI PRO-GRAMs, the sounds involved are allocatedside-by-side (split) or on top of one another(layered) on the keyboard. In other MULTI PRO-GRAMs, the sounds are divided up over severalMIDI channels to make it easier to work with asequencer. If you activate a MULTI PROGRAMand hear a single sound only, then you can con-trol this MULTI PROGRAM via several channels.

YOUR FIRST SOUND PROGRAM

If you have never created or changed a soundon a synthesizer, we now have the pleasure ofintroducing you to this fascinating process.

Select the single program C127 - START -.Press any key on the connected keyboard. Youshould hear a sound that, for lack of better de-scription, is a bit harsh or biting, but above allcompletely static. It should start immediatelyafter you press a key and sustain indefinitely foras long as you hold the key down. As soon asyou release the key, the sound should endabruptly. This sound is not designed to be es-pecially pleasant; it is intended to be as neutralas possible to give you a basis from which youcan begin creating or shaping your own sound.

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The Amplifier Envelope

THE AMPLIFIER ENVELOPE

Long-term exposure to this sound will definitelygrate on your nerves, so lets get started withchanging it into a signal you might enjoy hear-ing, beginning with the volume characteristics.Locate the section labeled AMPLIFIER at thebottom right of the control feature panel of theVIRUS. Here you can see four pots labeled AT-TACK, DECAY, SUSTAIN and RELEASE, re-spectively.

These controls will help you to dial in volumecharacteristics called an amplifier envelope andput an end to the nerve-racking drone that mayremind you of one of those cheesy organs thatyou hear in 60s B-movie sound tracks.

Rotate the ATTACK pot while you repeatedly

engage a key to hear the note. The further youturn the pot up, the longer it takes for the soundto achieve maximum volume after the start ofthe note. So you can say ATTACK controls theinitial volume swell of the sound.

Presumably the ATTACK pot was set to a ran-dom position before you made any adjust-ments. Nevertheless the volume automaticallyincreased to the maximum level before youstarted rotating the pot. The reason for this isthat an ATTACK value of 0 is saved in the soundprogram - START - and this value remains validuntil you determine a new value by adjustingthe position of the pot, even if you turn it everso slightly.

Take a look at the display of the VIRUS to gainan impression of the difference between thesetwo values. It shows two numeric values whenyou dial a pot: at the left you can see the valuestored in the sound program and at the right,the numeric equivalent to the value determinedby the current position of the pot.

Always keep in mind that for a programma-ble synthesizer the position of the control fea-ture or pot does not necessarily indicate theactual value of the given function. The reasonfor this is that when you first activate a soundprogram, it will reflect the programmed value.You have to adjust the control feature beforethe programmed value is superseded by the val-ue you determine manually.

Now fiddle with the DECAY pot while you re-peatedly press a key to activate a note. Holdthe key down for good while. You will noticethat the volume, once it reaches maximum levelat the end of the ATTACK phase, drops until itreaches a minimum level. The DECAY pot de-termines the speed, or in synthesizer jargon, therate at which the volume decreases.

However, the DECAY level does not alwaysdrop to the minimum level; you can determine arandom value between the maximum and mini-mum levels at which the volume remains con-stant. This level in turn is controlled via theSUSTAIN pot.

Whenever the SUSTAIN level is set to maxi-mum, the volume cannot drop during the DE-CAY phase; in other words, in this situation theDECAY pot is ineffective.

The individual functions of a synthesizer aredesigned to interact; many functions are depen-dent on other functions. In a number of casesthis means that some functions are subordinate

ATTACKATTACK DECAYDECAY SUSTAINSUSTAIN RELEASERELEASE

0

6

12120

6

12120

6

12120

6

1212

AMPLIFIERAMPLIFIER

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CHAPTER 4

Introduction

to others, i.e. the effectiveness of a control fea-ture is altered, modified or even negated com-pletely by other related functions.

The final pot, RELEASE, determines the speedor rate at which the volume decreases whenyou release the key: At low values the soundends relatively abruptly, at high values, thesound fades out more gradually and softly. Thelength of the RELEASE phase also depends onwhich level the amplifier curve is at when yourelease the key: The lower the level, the shorterthe RELEASE phase. If you dialed in a brief DE-CAY or SUSTAIN-TIME phase and it endedwhile you held the key down then of coursethere will not be an audible RELEASE phase.

The amplifier envelope can be described as avariable curve which, depending on the typeand duration of attack, hold and release data,automatically influences an imaginary volumepot (turns it up or down). At the beginning of thenote, ATTACK controls the rise or rate of in-crease to the maximum level. Once the maxi-mum level is achieved, DECAY determines thefall or rate of decrease to the SUSTAIN value,which is infinitely variable between the mini-mum and maximum levels. The amplifier enve-lope may remain at this value until the end ofthe note, fall towards the minimum level as de-termined by the variable TIME value, or evenrise again towards the maximum level. After theend of the note, RELEASE controls the fall orrate of decrease to the minimum level. Conse-quently, the control pots labeled ATTACK, DE-CAY, TIME and RELEASE control a speed orrate, where as SUSTAIN actually controls a lev-el.

THE FIRST FILTER

Now we will take a look at a component of asynthesizer that is generally regarded as themost important functional unit as it enablesdrastic sound shaping measures: the filter - orin the case of the VIRUS, the two filters.

But first we will concentrate on just one of thetwo filters.

Locate the Cutoff pot (not to be confused withCutoff 2!) in the section labeled FILTERS, direct-ly above the section labeled AMPLIFIER. Rotatethe pot to the left and right and note how thesound becomes muddier and clearer in re-sponse to the direction in which you turn thepot. (To ensure this effect and the following au-ral experiments are most pronounced, adjustthe amplifier envelope so that the VIRUS gener-ates a constant level while you hold a keydown).

This is how a low pass filter works: it suppress-es, or in technical jargon, attenuates the higherfrequencies in a signal and allows the lower fre-quencies through. Think of the Cutoff pot as abouncer and the VIRUS as your pub. You cantell it which frequencies to let in and which fre-quencies to keep out. The frequencies abovethe so-called cutoff or filter frequency are sup-pressed, those below it remain unaffected.

-100%-100%

0

100%100%

6-

0

6

1

1+21+2

2

FILTER BALANCEFILTER BALANCECUTOFFCUTOFF RESONANCERESONANCE ENV AMOUNTENV AMOUNT

CUTOFF 2CUTOFF 2 SELECTSELECTMODEMODEFILT 1FILT 1 FILT 2FILT 2EDITEDIT

BPBP

BSBS

HPHP

LPLP

FILT 2FILT 2FILT 1FILT 1

0

6

1212 0

6

1212

FILTERSFILTERS

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Filter Modulation

Now locate the FILT 1 MODE switch, which isalso located in the FILTERS section. It enablesyou to select a filter operating mode from thefour available options:

- LP

the low pass filter we have just discussed.

- HP

the high pass filter which works in the op-posite manner of the low pass filter: It sup-presses the lower frequencies in a signal andlets the higher frequencies pass.

- BP

the band pass filter which suppressesboth ends of the tonal spectrum and allowsonly a narrowly defined bandwidth of theoriginal sound to pass.

- BS

The band stop filter, band reject filter ornotch filter which works in the opposite man-ner of the bandpass filter. It allows all of thefrequencies of a signal except for a narrowfrequency band around the cutoff to pass.The term notch is fairly descriptive; youmight say this filter chops a notch out of thesound spectrum.

Now activate the different operating modes androtate the Cutoff pot to get a feel for the wayeach filtering option works.

Along with the Cutoff pot, the RESONANCE potis the most important control feature of a filter.The filter resonance increases the volume of thefrequencies located near the cutoff frequenciesand suppresses the more remote frequencies.This sound shaping feature has a striking effect- especially when used in conjunction with thelow pass filter: it produces a nasal or honkingtype of tone which increases as you turn the

resonance up. Experiment by varying the RES-ONANCE setting in the different operatingmodes in conjunction with different Cutoff set-tings. You will find the effect that the RESO-NANCE pot achieves is markedly different forthe band stop filter in comparison to the effect ithas on the other filter types: as the resonanceincreases, the bandwidth of the notch decreas-es; in other words more frequencies on bothsides of the filter frequency are allowed to pass.

FILTER MODULATION

Of course we dont want to require you to exe-cute every sound modification manually bytwiddling pots. All kinds of sound modificationsin the VIRUS can be executed automaticallymuch in the way of your previous experimentswith the volume controls: The amplifier enve-lope can be described as a variable curvewhich, depending on the type and duration ofattack, hold and release data, automatically in-fluences (turns it up or down) an imaginary vol-ume pot.

Similar procedures are applicable to the filterfrequencies. The FILTERS section features itsown envelope, the structure of which is identi-cal to the amplifier envelope, located directlyabove the amplifier envelope on the control fea-ture panel. Much like the amplifier envelope, thefilter envelope automatically rotates the Cutoffpot.

However there is one significant difference be-tween the two envelopes. With the amplifier en-velope, you are always dealing with an initialvolume level of 0 because of course you wantabsolute silence prior to the beginning of anote. After the RELEASE phase, it is again

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CHAPTER 4

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highly desirable that your box is silent. With thefilter envelope, the situation is somewhat differ-ent: It always starts at the Cutoff value that youdetermined manually. And it is definitely not al-ways desirable that the filter frequency isbrought to the maximum level.

Consequently, you need a tool that limits the ef-fective range of the fi lter. This is why weequipped the VIRUS with a control labeled ENVAMOUNT (short for Envelope Amount). Whenthe pot is turned counter-clockwise to the farleft, the filter has no effect on the cutoff fre-quency; the further you turn the pot to the right,the greater the effect the filter envelope has onthe filter frequency. The maximum level of theenvelope may lie outside the audible rangewhen the filter has already been partiallyopened via the Cutoff pot or was manipulatedvia other control options. In extreme caseswhere the filter is already completely open, thefilter frequency cannot be increased regardlessof how high you set the ENV AMOUNT.

Go ahead and spend some experimenting withdifferent ENV AMOUNT, Cutoff and RESO-NANCE settings for the diverse filter operatingmodes. Also try varying the settings for the am-plifier envelope. You will find that with just thesefew parameters you are able to come up with avast amount of sound settings. If you areamong the many musicians who are associativelisteners, you might say many of the settingsproduce sounds reminiscent of stringed-instru-ments; some sound picked, p lucked orsnapped, others sound bowed.

For your next experiment set the amplifier enve-lope so that you hear a constant level when youpress and hold a note. Now deactivate the filterenvelope by setting the ENV AMOUNT to 0. SetFilter-1Filter-1 to low pass mode and decreasethe filter frequency until you just barely hear amuddy signal when you play notes in the mid-range.

Now play a few higher and lower notes. You willfind that the lower notes have a greater over-tone content, whereas the higher notes soundmuddier and their volume decreases until thenotes are completely inaudible. You might al-ready suspect what this is all about: As thenotes are transposed ever lower, more portionsof the signal fall below the cutoff frequency,whereas with the notes that are transposed ev-er higher, more portions of the signal rise abovethe cutoff frequency and subsequently are sup-pressed until the root note and the last audibleportion of the signal is silenced.

To avoid this effect - or if desirable, to amplify it- you have the option of influencing the cutofffrequency via the pitch of the note, i.e. the notenumber. The degree of influence is determinedby the KEY FOLLOW. You find this parameterwithin the Filter Edit menu.

Please note that KEY FOLLOW is a so-calledbipolar parameter: Its control range is not limit-ed to the positive end of the spectrum (0 to amaximum of 127). Bipolar controls effect nega-tive values as well, in this case from the nega-tive maximum of -64 through 0 an on to thepositive maximum of +63. Consequently, if thispot is set to the center position (12 oclock or 0)the pitch of the notes corresponding to the keyson your keyboard has no effect on the cutofffrequency. If on the other hand you turn the KEYFOLLOW pot clockwise towards the positivecontrol range, you will find that the filter opensup increasingly as the pitch increases with high-er notes. At lower notes, the filter closes downagain. If you turn the pot counter-clockwise to-

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The Saturation Stage

wards the negative control range, the KEYFOLLOW effect is reversed. With the VIRUS,you will encounter this feature - intensity controlvia a bipolar parameter - again in conjunctionwith other modulation sources and targets.

Now experiment as much as you like with differ-ent KEY FOLLOW settings and tune the set-tings via the Cutoff pot. And remember to bringall of the other parameters you have encoun-tered thus far into play.

THE SATURATION STAGE

In the signal chain of the VIRUS, Filter-1 is fol-lowed by a saturation stage. It enables you toadd overtones to the filtered signal via distor-tion. Locate and press the button labeled EDITin the FILTERS section.

01111111111111111112

1 SATURATION Curve Off 61111111111111111154

The display will read SATURATION CURVEOFF, which means exactly what it says. Withthe VALUE buttons or the VALUE pot, you cannow select from a number of saturation/distor-tion curves. Next to the distortion curves, theSATURATION stage offers further DSP effectssuch as the shaper, rectifier and filter. These areexplained in detail in the section on the SATU-RATION stage.

At this point we would like to mention the OSCVOL pot in the MIXER section. The portion ofthe control range from the far left to the center

position (12 oclock) determines the volume ofthe filter sections input signal. The portion ofthe control range located to the right of thecenter position (12 oclock) does not achieveany increase in volume; it simply intensifies thedegree of saturation or distortion. This effect isonly achieved when you have activated a satu-ration curve. The intensity of the remainingavailable DSP effects is also controlled via theOSC VOL knob.

Feel free to experiment with the diverse satura-tion curves and be sure to vary the OSC VOLsettings. Note how the different Cutoff andRESONANCE settings influence the saturationcurve.

THE SECOND FILTER

You probably noticed that by a adding a bit ofsaturation to the signal you can come up with apretty heavy, aggressive sound - especially witha low filter frequency level and high resonance.Youre probably thinking these types of soundscould do with some more filtering. We had thesame idea, which is one of the reasons why weequipped the VIRUS with another filter pervoice.

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CHAPTER 4

Introduction

The technical design of this second filter isidentical to the first, so we wont discuss it inas much detail as we did the first filter. Howev-er, there are few differences in how you handlethe second filter:

Only two control features of the VIRUS are al-located exclusively to Filter-2: Cutoff-2 and FILT2 MODE.

The RESONANCE, ENV AMOUNT and KEYFOLLOW pots can be allocated to either of thetwo filters or both simultaneously. Use the twoSELECT-buttons located at the far right of theFILTERS section to select the desired operatingmode. For instance, if you press the FILT 2 SE-LECT button, then the values you set via theRESONANCE, ENV AMOUNT and KEY FOL-LOW pots apply exclusively to Filter-2. Thecorresponding parameters of Filter-1 remain un-affected. On the other hand, if you press bothSELECT buttons at the same time, the valuesthat you dial in apply by the same measure toFilters 1 and 2.

In the sound program we are using for our ex-periments, the LEDs of both buttons are illumi-nated, so that all adjustments to the givenparameters affect both filters. However, youhave yet to actually hear the effect of Filter-2 onthe signal because it is mixed out of the audiblesignal path of the VIRUS.

Before we get started with our next experiment,deactivate SATURATION, set the ENV AMOUNTof the filter envelope to zero and set Cutoff 2 tothe center position (12 oclock) so that Filter-2always has the same cutoff frequency as Filter-

1 (well explain Cutoff 2 a bit later). Set Cutoff toa medium or middle value and turn the RESO-NANCE pot counter-clockwise to the far left toachieve a relatively muddy sound. Now locatethe FILTER BALANCE pot at the upper righthand of the control panel and rotate it from theleft to the right. You will note the sound be-comes muddier as you turn the pot towards thecenter position (12 oclock) and that the soundis somewhat brighter at the far right of the con-trol range then at the far left.

The reason for this effect is that when you turnthe FILTER BALANCE pot to the far left, only Fil-ter-1 is audible. When you rotate the pot to theright, Filter-2 is blended in so that it follows Fil-ter-1 in the signal chain. When you turn the FIL-TER BALANCE pot clockwise, Fi l ter-1 isblended out of the signal chain until at the farright position only Filter-2 is active and audible.

Each filter in the VIRUS normally features 2poles. However in the FILTER ROUTING oper-ating mode SER 6, Filter-1 operates with 4poles, so the signal patched through Filter-1(FILTER BALANCE to the far left) is trimmedmore drastically than when it is routed throughFilter-2 (FILTER BALANCE to the far right).When you set the FILTER BALANCE pot to thecenter position (12 oclock) - as we mentionedbefore - the two filters are routed in series,which means they respond as if they were a sin-gle filter with 6 poles and consequently a greatdeal of slope. This is why the input signal istrimmed substantially when you set the pot tothis position.

Experiment with the diverse FILTER BALANCEpositions to get a feel for the different degreesof slope. Rotate the Cutoff pot or activate thefilter envelope (for both filters!) to hear the filtersin action.

The Cutoff 2 pot is a special feature: It controlsthe cutoff frequency of the second filter, but issubordinate to the Cutoff pot located above it.

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The Second Filter

In other words, at the center position (12oclock) the manually selected frequency of Fil-ter-2 is identical to that of Filter-1. When you ro-tate the pot to the left the cutoff frequency levelof Filter-2 is increased relatively to Filter-1,when you turn to pot to the right the cutoff fre-quency level is decreased relatively. Now whenyou adjust the Cutoff pot, you adjust the cutofffrequency of both filters by the same measure!This feature lets you determine a difference invalues in the filter frequencies (called an offset)via the Cutoff2 pot which remains constantwhenever you adjust the Cutoff pot.

Yet another experiment in which you can comeup new filtering characteristics that are typicalof the VIRUS:

Set the FILTER BALANCE pot to the center po-sition (12 oclock) and Cutoff 2 to the maximumlevel. The FILTER ROUTING operating modemust remain SER 6. Set Cutoff and RESO-NANCE to a middle value and select a clearlyaudible SATURATION curve.

Now you can filter this complex signal pro-duced by a combination of the saturation stageand the Filter-1 yet again. Rotate the Cutoff 2pot slowly towards the center position (12oclock). You can hear how Filter-2 graduallymodifies the distorted signal. You can set aRESONANCE value for Filter-2 if you press theFILT 2 SELECT button and rotate the RESO-NANCE pot to the desired position. Set the Cut-off 2 pot to a position to the right of the centerposition. This configuration can be describedas a complex non-linear filter set up where thecutoff frequency is controlled via the Cutoff pot.You can dial in a wide range of sound-shapingoption via Cutoff 2. Also try modifying the reso-nances of both filters as well as the SATURA-TION curve to come up with different filteringcharacteristics.

Now experiment with the diverse filter modesand listen closely to the effect of the parame-ters RESONANCE, ENV AMOUNT and KEYFOLLOW in conjunction with the SELECT but-ton. Please also keep in mind that the chancesof choking a sound off are substantially greaterwhen you are using both filters: For instance, ifthe first filter is used as a low pass with a lowcutoff frequency and the second as a high passwith a high cutoff frequency, the VIRUS will notgenerate an audible signal when you set theFILTER BALANCE pot to the center position (12oclock).

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Introduction

FILTER ROUTING

The final parameter well discuss for the timebeing is FILTER ROUTING. This feature offersseveral filter routing options which allow you tooperate the filters in series, i.e. patch one afterthe other in the signal chain, or in parallel, whichmeans side by side in the signal chain:

- SER-4 The filters are switched in series; withtwo poles each (12dB/Okt.), both filters havethe same slope for a total of four filter poles(24dB/Okt.).

- SER-6 The filters are switched in series; Fil-ter-1 has four poles (24dB/Okt.), Filter-2 hastwo poles (12dB/Okt.) so the overall slope isequivalent to six poles (36dB/Okt.).

- PAR-4 The filters are switched in parallel andfeature two poles each (12dB/Okt.).

- SPLIT The filters are switched in parallel andfeature two poles each (12dB/Okt.). Addition-ally, they receive independent input signals(more on this later). Each of the two oscilla-tors routes its signal into one of the two filterswhose signals can be spread in the panoramavia a parameter called UNISON Pan Spread.

Regardless of which FILTER ROUTING op-tion you chose, the SATURATION stage is al-ways post-Filter-1, i.e. after Filter in the signalchain.

ACCESS VIRUS OS5 25The First Oscillator

THE FIRST OSCILLATOR

To this point, we have turned our attention ex-clusively to sound-shaping functions and havealways started with the same basic material: aso-called sawtooth wave. This waveshape isespecially well-suited as a neutral starting pointas it contains all of the so-called natural scale ofovertones, which give the filter plenty of qualitymaterial to work with.

The filters, with the exception of a notch filter orband stop (BS), trim the far reaches of the tonalspectrum, so for instance a signal sounds mud-dier after it has been routed through a low passfilter. You can well imagine that this type ofsound modification is substantial but insuffi-cient for shaping more subtle differences intone. For instance the tone of a trumpet differssignificantly from that of a saxophone eventhough no one would seriously claim that eitherof the instruments has a muddier tone than theother.

26 CHAPTER 4Introduction

What you need is a sound-shaping option forthe portion of a signal that a filter allows topass. And of course you also need a tool for de-termining the pitch of a signal. In synthesizers,both of these tasks are executed by oscillators.They oscillate at a variable pitch that can bemodulated and they also generate differentwaveshapes which give the filters a wider varie-ty of material to work with.

The VIRUS is has two main oscillators and a so-called suboscillator. Lets take a look at Oscilla-tor 1, the one you have already heard in actionduring your experiments so far:

Start with the same basic sound you used atthe very beginning. Now modify the amplifierenvelope to make the sound less grating, buthold back on any other filter or saturation modi-fications for the moment so you can hear thepure, unadulterated oscillator.

Oscillator 1, the one you have already heard inaction during your experiments so far:

Start with the same basic sound you used atthe very beginning. Now modify the amplifierenvelope to make the sound less grating, buthold back on any other filter or saturation modi-fications for the moment so you can hear thepure, unadulterated oscillator.

Press the OSC 1 button in the OSCILLATORSsection to enter the edit pages for oscillator 1.Directly above this button are the SHAPE andWAVE SEL/PW controls which determine thewaveform and therefore the basic sound of os-cillator 1. The SHAPE parameter is currently setto the exact center (value 64), and if you look atthe panel directly above the SHAPE conrol, youwill see a symbol representing a sawtoothwave.

You can definitely see why this waveshapebears the name sawtooth. Press and hold akey and slowly turn the pot clockwise. Youshould be able to hear how the tone becomesincreasingly more hollow-sounding. You mightsay this effect thins the sound out, but in anycase, the entire tonal spectrum is affected by anequal measure, which is an audio result filtersare unable to achieve.

The waveshape that is audible when you turnthe SHAPE pot to the far right is a so-calledpulse wave. The graphical representation of thiswaveshape on the control panel gives you agood idea of its appearance. It is unique be-cause the duration of the negative pulse isequal to the duration of the positive pulse: It hasa so-called pulse width of 50%. The tone of apulse wave is different to that of a sawtoothwave because it does not contain all overtonesin the natural overtone scale, only the odd-numbered tones, i.e. the first (the root note thatdetermines the pitch), third, fifth, and so forth.By turning the SHAPE pot from the sawtoothcontrol range towards the pulse control range,you are actually dialing every other overtone outof the mix, which explains why the sound be-comes thinner.

You can continue modifying the sound by re-ducing the symmetrical width of the pulsewave. In the VIRUS, you can execute thissound-shaping measure via the WAVE SEL/PW

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ACCESS VIRUS OS5 27The Second Oscillator

(PW = pulse width) pot, PROVIDED THE SHAPEPOT IS SET TO A POSITION IN THE RIGHTHALF OF ITS CONTROL RANGE (LATER THAN12 OCLOCK). Rotate the WAVE SEL/PW potslowly from the left to the right and leave theSHAPE pot at the far right position. You canhear how the treble content of the sound in-creases while the sound becomes ever thinner.At the far right position, the signal is no longeraudible because the pulse width is equivalent to0% and consequently the wave no longer oscil-lates.

Starting at the center position (12 oclock) indi-cated by the sawtooth, turn the SHAPE potcounter-clockwise towards the left. You canhear how the overtones are increasingly mixedout of the signal until you can only hear the rootnote. This sound is produced by a so-calledsine wave, one of 64 other waveshapes thatyou have at your disposal for sound generationpurposes. These waveshapes can also be acti-vated via WAVE SEL/PW (WAVE SEL: Wave Se-lect), PROVIDED THE SHAPE POT IS SET TO APOSITION IN THE LEFT HALF OF ITS CON-TROL RANGE (EARLIER THAN 12 OCLOCK).Regardless of the current SHAPE setting, youcan also select a wave in the EDIT menu underOSCILLATOR 1 WAVE.

Go ahead and check out the different wave-shapes. The second of the 64 waves is a trian-gle wave, the remainder of the waveshapes areeach a unique tonal blend. After you have famil-iarized yourself with this raw material, experi-ment with the parameters of the FILTERS andAMPLIFIER sections you have dealt with thusfar (dont forget about SATURATION and thecorresponding function of the OSC VOL pot), toget a feel for how the diverse waveshapes re-spond to filtering, saturation and amplifier mod-ifications.

THE SECOND OSCILLATOR

As already mentioned above, the Virus has asecond oscillator (as well as several other basicsound sources which will be described later inthis manual). Press the OSC 2 button in the OS-CILLATORS section to enter the edit pages forthe oscillator 2. The controls in this section nowapply to oscillator 2 only oscillator 1 parame-ters cannot be changed now (although the os-cillator can still be heard).

Dial in the basic sound program that you had atthe very beginning; change the amplifier enve-lope to suit your taste. In the sound program,the OSC BAL (Oscillator Balance) pot in theMIXER section is preset to the far left. In orderto hear Oscillator 2 in action, rotate the OSCBAL (Oscillator Balance) pot in the MIXER sec-tion to the right. Towards the center position (12oclock) you will hear how the tone is modifiedand as you rotate the pot further to the right,how the intensity of this modification is re-duced. This effect is known as the comb filter-ing effect. It occurs when two signals with thesame frequency but different phase lengths aremixed. Press the same key on your keyboardseveral times with the OSC BAL set to the cent-er position (12 oclock). You should notice thateach note has a slightly different tone. The os-cillators are the source of this effect. The oscil-l a to rs o f the V IRUS osc i l l a te f r ee ly,consequently every time you play a note, thephase constellation between the two oscillatorsis different. For now, leave the OSC BAL POT atthe center position (12 oclock).

You are already familiar with Oscillator 1sSHAPE and WAVE SEL/PW pots. These func-tions are identical for Oscillator 2, so we wontgo into detail on them again.

28 CHAPTER 4Introduction

Locate the pot labeled DETUNE and slowly ro-tate it to the right from the far left position(which is preset in the sound program). You canhear the tone start to waver and as you turn thepot further to the right, how this vibrato effectincreases until Oscillator 2 sounds distinctly outof tune with Oscillator 1. This wavering or vibra-to-type effect has a popular traditional in syn-thesizers. It is used to achieve chorus effects,create sounds reminiscent of stringed instru-ments/ string sections or simply beef up thesound.

The SEMITONE pot enables you to transposeOscillator 2 by plus/minus four octaves in semi-tone steps while Oscillator 1 maintains thepitch. This feature is especially interesting whenused in conjunction with two other oscillatorfunctions: synchronization and frequency mod-ulation.

Locate and activate the SYNC button in theOSCILLATORS section (the LED must illumi-nate). The synchronization function forces Os-cillator 2 to restart its wave cycle at the sametime as Oscillator 1 waveshape starts its cycle.The initial effect of this measure is that the wa-vering tone that resulted from detuning andmixing the oscillator signals disappears.

The SYNC effect really becomes interestingwhen you transpose Oscillator 2 upwards incomparison to Oscillator 1 via the SEMITONE

pot. What happens is that the wave cycle of Os-cillator 2 is interrupted as soon as Oscillator 1starts its cycle. The pitch of the second oscilla-tor no longer has the expected effect, instead itgenerates special tones, in some cases for lackof a better description screaming type effects.

The other effect that benefits from manipulatingthe interval between the oscillators is frequencymodulation (FM). It generates new tonal spectrain which the signal of the first oscillator controlsthe frequency of the second oscillator similar tothe manner in which filters can be controlled viaenvelopes. And here too you have a pot whichallows you to control the intensity of: FMAMOUNT. Basically, this effect is similar to a vi-brato, although here youre dealing with an ex-tremely fast vibrato featuring a frequency withinthe range of human hearing. This signal is notactually audible as a vibrato effect. Instead,youll hear a sound modulation, in some cases,a very drastic one at that. Choose the pure sinewaveshape for Oscillator 2. In conjunction withthe sine wave, the frequency modulation gener-ates very clear, in some cases bell-like, spectra.

In the VIRUS you have the option of combiningthe two functions called oscillator synchroniza-tion (SYNC) and frequency modulation (FMAMOUNT, to generate new harmonic spectra.Switch SYNC on and experiment with the FMAMOUNT. Also try out different SEMITONE set-tings and the diverse waveshapes of Oscilla-tor.The VIRUS is equipped with a third masteroscillator that lets you create further oscillationsand spectra. You can access the parameters ofthis oscillator, which are described in a laterchapter, via the OSCILLATOR EDIT menu.

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ACCESS VIRUS OS5 29The Third Oscillator

THE THIRD OSCILLATOR

The VIRUS also has a third main oscillator,which can be used to add more movement andbody to the sound. Oscillator 3 is activated us-ing the OSC 3 ON key, and its parameters be-come available after pressing the OSC 3selection button.

Although the oscillator 3 parameters are no dif-ferent from oscillators 1 and 2, there is onething you should keep in mind. Because mostsounds only require two oscillators, the thirdoscillator has been made optional, i.e. it has tobe switched on whenever necessary.

Oscillator 3 takes a certain amount of comput-ing power, and the trade-off is a reduction of themaximum polyphony: Playing a note using os-cillator 3 uses up about an extra third of a voicefrom the available polyphony. In other words:Playing a three-voice chord using a soundwhich includes oscillator 3 would use up four(and not three) of the available voices.

THE MIXER SECTION

You have already come across two parametersof the MIXER section: OSC BAL determines themix ratio between Oscillators 1 and 2; in the lefthalf of its control range, OSC VOL determinesthe master volume of the oscillator mix. In theright half of the control range from the centerposition to the far right, OSC VOL increases thesaturation intensity when a SATURATION curvehas been activated.

Now well take a closer look at the final controlelement, the SUB OSC pot: It controls the vol-ume of the fourth oscillator, the so-called Sub-Oscillator, which always operates an octavebelow Oscillator 1.

The SubOscillator is mixed to the Oscillator 1and 2 master mix signal as determined by theOSC BAL pot. The master volume of the com-posite mix is controlled by the OSC VOL pot.The only other parameter available for the Sub-Oscillator is accessible via the OSCILLATOREDIT menu where you have the option of select-ing a triangle or pulse waveshape (SUB OSCIL-LATOR WAVE SQUARE/TRIANGLE).

The NOISE control determines the level of an-other basic audio source the noise generator.The other parameter belonging to the noisegenerator is its color, which can be set in themenu via NOISE Color in the OSCILLATOR-ED-IT menu. In the central position (+0), the noisegenerator produces so-called white noisewhich includes all frequencies at an equal level.Please note that, unlike the other oscillators,noise level is not affected by OSC VOL it iseven audible when this is turned down to zero.

The fifth control in the mixer section determinesthe level of the Ring Modulator. This is not con-sidered one of the basic sound source, but isthe result of muliplying the output of oscillators1 and 2. Ring modulation can create interestingenharmonic sounds which are highly dependantupon the frequency ratio between the two oscil-lators (adjustable via e.g. OSC 2 SEMITONE) aswell as the waveforms (e.g. use two sine wavesfor pure bell-like tones).

To blend in the ring modulator use EDIT: RING-MODULATOR VOLUME (in OSCILLATOR EDITMenu). If the RINGMODULATOR VOLUME iszero, the ring modulator is switched off. OSCVOL does not affect the ring modulator level (orindeed the noise volume). Therefore the originaloscillator signal can be leveled independently of

30 CHAPTER 4Introduction

the ring modulator. Be sure to check out whatthe ring modulator does when you select a sinewave for Oscillator 1 and 2.

Now we can go on and solve the mysteries ofthe signal flow as determined by the FILTERROUTING operating mode SPLIT: Here Oscilla-tor 1 and the SubOscillator are routed to Filter-1, whereas Oscillator 2 and the Noise Generatorare routed to Filter-2. Although the soundsources are split into two signal paths, you canstill control the volume levels of the different el-ements as well as OSC VOL in the usual man-ner.

THE LFOS

When you first started this series of experi-ments with sounds, we promised that many ofthe functions the VIRUS can be programmedso that they are executed automatically. Youhave already learned how to control the volumeand cutoff frequencies of both filters as well asthe pitch and intensity of the frequency modula-tion of Oscillator 2 via preprogrammed enve-lopes. These options are great, but you havealready encountered a number of functionswhere it would be a helpful if you could alsoprogram them to be executed automatically.And of course envelopes are great modulationsources, but you have to play a note every timeyou want to initiate an envelope. During yourexperiments you probably came across a func-tion or two you would like to be able to controlperiodically - independently of notes. Somefeatures that come to mind are traditional tech-niques such as vibrato (periodic pitch control)and tremolo (periodic volume control). Anotheroption you might like to have at your disposal israndom parameter control.

In the VIRUS, both of these tasks are executedby a so-called LFO (low frequency oscillator)that oscillates at frequencies below the audiblerange. An LFO is similar to the oscillators youhave encountered thus far, but it oscillates sig-nificantly slower so that its output signal is toolow for human hearing. So what good are they ifyou cant hear them? LFOs are used in muchthe same manner as envelopes, with the majordifference that the are repeated indefinitely.

For our next experiment, you should recall ei-ther the basic sound you have always startedwith so far, or a version you have already editedand saved. Look for the RATE control in theLFOS/MOD section. To the left of this knob isan LED, which should be flashing in time withthe LFO 1 (the currently selected LFO see be-low). Turn the RATE control and see the speedof the LED changing. The buttons to the right ofthe RATE knob are used for selecting LFOwaveforms.

The controls in the LFOS/MOD section only ap-ply to the currently selected LFO (like in the OS-CILLATORS section), and you can switch LFOsusing the SELECT button in the top lefthandcorner of this section. When LFO 3 is selected,the LED to the right of the RATE control flashesin time with LFO 3, otherwise it show the rate ofLFO 2

LFO 1Start with the usual basic sound configurationor chose a modified sound to suit your taste.Locate the RATE pot in the LFO 1 section of thecontrol panel. The RATE pot is equipped withan LED that indicates the speed of the LFO aswell as its waveshape. Turn the RATE pot andcheck out how the flash of the LED indicatesthe change of pace as you rotate the pot.

ACCESS VIRUS OS5 31The LFOs

Once you have pressed the lower SELECT-button button, you can scroll forwards or back-wards through the available modulation destina-tions with the PARAMETER buttons. When theEDIT key in this section is held down, modula-tion destinations can be selected by turning theSELECT control.

Currently you are unable to hear the effect ofthe LFO as its modulation intensity is set to 0 inthe sound program. In order to change this set-ting, you must access the second SELECT but-ton which works in conjunction with fivevertically arrayed LEDs labeled OSC 1, OSC 2,PW 1+2, RESO 1+2, FILTER GAIN and ASSIGN:Press the SELECT button repeatedly and ob-serve how the LEDs flash in succession (theLEDs OSC 1 and OSC 2 flash separately as wellas in unison). The corresponding modulationtargets appear in the display, along with themodulation intensity values as determined bythe VALUE pot and VALUE buttons. (You can al-so scroll through the modulation targets via thePARAMETER button after you have pressed theSELECT button once.) Once you have dialed ina value other than 0 for a modulation target, thecorresponding LED illuminates continually. Thisfeature tells you at a glance that a modulation isunderway even when the display indicatessome other type of operation.

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 bothoscillators are controlled in unison

- RESO 1+2 refers to the resonances of bothfilters. Please keep in mind that althougheach set of these parameters is assigned acommon modulation intensity, you can still di-

al in different sound-shaping settings manual-ly. In other words, the audible result of a jointmodulation varies according to the valuesyou have determined for the other parame-ters.

- FILTER GAIN This is the level of signal en-tering the filter section and therefore influenc-es the subsequent sa tu ra t ion s tage .Modulating FILT GAIN therefore causes a pe-riodic change in saturation as well as a tremo-lo i.e. a periodic change in volume. If thesaturation stage is not used, you will onlyhear tremolo. The position within the signalchain (at the input of the filter section) hasbeen deliberately chosen so that both the vol-ume and the amount of distortion can bemodulated by the same source, as is oftenthe case in electromagnetic instruments. Al-so, rapid LFO movements cause sharp im-pulses (transients) within the oscillator signal,which can be used to excite filter resonance.Filter resonance always dies away freely, asthe filter input is affected by modulating FILTGAIN, not its output.

- ASSIGN Here you can freely select any mod-ulation destination.

Modulate these five parameters separately andin combinations with different intensities. Try toanticipate the sound you will come up withwhen you modulate the first oscillator, the sec-ond oscillator or both oscillators at once andsee if the results match your expectations. Ifyou can fairly reliably predict the outcome ofyour sound-shaping efforts, you should have ahandle on the information discussed thus farand can use your knowledge to create specificsounds you have in mind.

During the course of your experiments, it is en-tirely possible that you have generated modula-tions that have no effect whatsoever on thesound, for instance if you modulate the fre-quency of Oscillator 2 although it is dialed out

32 CHAPTER 4Introduction

of the oscillator mix. When you run into thistype of problem, check out the signal routing, ifany configurations conflict with each other andmemorize the situation, problem and solution. Ifyou make a habit out of this, you wont panicwhen you run into similar situations; insteadyoull keep your cool, analyze the unexpectedsound and fix the mix.

You are currently using a triangle as the LFOwaveshape. You shouldnt have any problemassociating the periodic up and down fluctua-tion of the target parameter with this wave-shape. Now activate the other avai lablewaveshapes for LFO 1 and try to picture the re-spective waveshape and associate it with theresults of the modulation.

The third waveshape is a descending sawtoothwave. You can convert it into to an ascendingsawtooth by simply dialing in the requisite neg-ative modulation intensities (AMOUNT).

In the WAVE setting, you have access to 64LFO waveshapes. Select these in the displaysection using the VALUE buttons:

- S&H (Sample and Hold) is a structured ran-dom modulation. Here random modulationvalues are generated. The value is held untilthe next beat impulse, then it abruptly jumpsto a new random value.

- S&G (Sample and Glide) is a continual ran-dom modulation. Here the random valuesglide seamlessly into one another, the rate ofwhich is determined by random modulation ofthe RATE value.

The following 62 waveshapes are identical tothe oscillator sections digital waves. These canbe used to create interesting rhythmic effects.

Continued your experiments with different LFOwaveshapes. Note that after a while you nolonger consciously hear minimal modulation in-tensities - depending on the waveshape andmodulation target (e.g. S&G +1 on OSC 1 or 2).However they do pep up the sound of lend it acertain vitality. The key to many great soundsare these types of minimal modulations.

You may have gathered that the LFOs of the VI-RUS are polyphonic:If several notes are played simultaneously,these are controlled by dedicated LFOs, eachwith a slightly varied rate. This effect livens upthe sound of chords, especially when they aresustained. To enhance this effect, activate theLFO 1 KEY FOLLOW in the LFO-EDIT-Menu.

This function enables you to control the rate ofthe LFOs via the pitch, or more accurately, viathe MIDI note number, so that higher notes gen-erate faster LFO rates. As result, when youpress and hold several notes you will hear allkinds of substantially different periodic fluctua-tions.

Finally, the LFOs can also be used as additionalenvelopes. The control feature for this effect isthe ENV MODE button. When you press thisbutton, two things occur: For one, the LFO nolonger initiates its cycles periodically, but onlyonce at and in sync with the start of a note, andfor the other, the active range of the LFO isswitched from bipolar (in both directions fromthe zero position) to unipolar (from zero in onedirection only). Please note that this applies tothe modulation target but not the modulation in-tensity. Here you can still determine a value inthe entire bipolar range.

This effect is especially prominent when used inconjunction with the sawtooth wave, which en-ables a fade-out type of effect (when you dial ina positive AMOUNT value) or a volume-swelltype of effect (negative AMOUNT) for the availa-ble modulation targets. Using the LFO Curve

ACCESS VIRUS OS5 33The MOD Section

parameter located in the LFO EDIT menu, youcan have the ramp rise or fall exponentially. Ifyou choose a triangle for your waveshape, thedevice will generate an ascending phase (at-tack) and a descending phase (decay). LFOCurve also lets you determine the temporal re-lationship between attack and decay; in otherwords, their respective rates.. Dial in the desiredspeed via the RATE pot.

You can also use S&H and S&G in ENV MODEto come up with some attractive results: S&Hgenerates a single random value at the start ofa note (in this case, the RATE pot has no effect);S&G works in the same manner although in thiscase the RATE value is crucial. It determines theamount of time it takes to glide from the previ-ous to the new random value.

THE MOD SECTION

You may have noticed that, apart from the threeLFOs, an entry called MOD also appears as anoption when you press the Select button. Thisgives you access to the Virus modulation ma-trix. The six ASSIGN entries (selectable via theSELECT button) represent six freely definablemodulation connections. After you have select-ed one of them, you can set the modulationsource, destination and intensity in the menu.

To maintain compatibility with previous Virusmodels, ASSIGN 2 has two destinations andASSIGN 3 has three. Each of the other AS-SIGNs have only a single modulation destina-tion.

Please note: When MOD is selected instead ofan LFO, the RATE knob will always control LFO1 by default.

SOFT KNOB 1/2

These are the two freely assignable controls.The destination of these controls can be de-fined within the Edit menu (SOFT KNOB 1/2MODE). There are two parameters, one globaland one local i.e. applying only to the currentSINGLE program (which will override the globaldefinition if defined). SOFT KNOB 2 doubles asa value control, and therefore only works as aSOFT KNOB when the Virus is in Play mode i.e.no Edit menu is selected. For each SOFTKNOB, you can choose a short description froma list in the menu, and this will be saved as partof the SINGLE program. In Play mode, this willappear in the display to remind you of whateach SOFT KNOB does when you are playingyour Virus.

(see The SOFT Knobs (Controls) on page 49).

EDITEDIT

AMOUNTAMOUNT

ASSIGN 1ASSIGN 1

ASSIGN 4ASSIGN 4

1 2 / 32 / 3

ASSIGN 2ASSIGN 2

ASSIGN 5ASSIGN 5

ASSIGN 3ASSIGN 3

ASSIGN 6ASSIGN 6

MODMOD

FILTER 2FILTER 2

PW 2PW 2

PANPAN

ASSIGNASSIGN

SYNCSYNCPHASEPHASE

SHAPE 1+2SHAPE 1+2

OSC 1OSC 1

FM AMTFM AMT

OSC 2OSC 2

FILTER 1FILTER 1

PW 1PW 1

OSC 1OSC 1

OSC 2OSC 2

PW 1+2PW 1+2

RESO 1+2RESO 1+2

FILT GAINFILT GAIN

ASSIGNASSIGN

0

6

1212

SELECTSELECT

WAVEWAVE

LFOS / MODLFOS / MOD

321 MODMOD

LFO 1LFO 1

LFO2LFO2

LFO3LFO3

RATERATE SHAPESHAPE

34 CHAPTER 4Introduction

VOLUME AND PANORAMA POSITION

You probably noticed that the many of thesound shaping options available in the VIRUSoccasionally influence the volume level. For in-stance, an unfiltered sawtooth is naturally loud-er than a highly filtered sawtooth becausewhenever you blend a part of the frequencyspectrum out of the mix, you are automaticallyreducing the overall volume of the signal. This iswhy the VIRUS is equipped with a programma-ble volume pot for each SINGLE PROGRAM. Itenables you to balance out the volume levels ofyour sound programs.

Locate the parameter PATCH VOLUME in theCOMMON section of the EDIT menu.

01111111111111111112

1 COMMON PatchVolume 100 61111111111111111154

Its value is set to 100 so that you have a reserveor headroom of 27 volume increments whenyou are dealing with highly filtered sounds.

You have already dealt with the Panorama posi-tion as a modulation target of LFO 2. Here youcan not only modulate it, but also determinesettings manually. For this purpose, use the pa-rameter PANORAMA which is also located inthe OUTPUT section of the EDIT menu. Likemany other parameters, Panorama is a startingpoint for modulations. For instance you canmodulate the Panorama position via LFO 2even if you have already set the Panorama tothe far left position. In this case of course youwill only hear the Panorama position shift to theright.

VELOCITY

Velocity is one of the preferred modulationsources of keyboard players: A light key attackgenerates a low velocity value for the givennote, a heavy touch generates a high velocityvalue. In the VIRUS you have ten modulationtargets available for Velocity. Locate the VE-LOCITY section in the EDIT menu.

01111111111111111112

1 VELOCITY Osc1Shape +061111111111111111154

There you will find the modulation intensitiesfor:

which you can manipulate independently of oneanother in the familiar bipolar control range.

A light key attack generates a low velocity valuefor the given note, a heavy touch generates ahigh velocity value.

OSC 1 SHAPE

OSC 2 SHAPE

PULSE WIDTH

FM AMOUNT

FILT 1 ENV AMT

FILT 2 ENV AMT

RESONANCE 1

RESONANCE 2

VOLUME

PANORAMA

ACCESS VIRUS OS5 35Unison Mode

UNISON MODE

When we talked about the oscillators, we men-tioned that by subtly detuning signals, you canbeef up sounds and achieve string-like sounds.The VIRUS is equipped with features that allowyou to take this type of tonal manipulation astep further. On of these is the so-called UNI-SON MODE. It enables you to initiate two ormore voices for each note played, which in turnlets you detune many oscillators. UNISONMODE also offers the option of spreading thevoices generated by one note in the stereo pan-orama and shifting the phases of their LFOs sothat all types of periodic effects can be used toproduce an even more exciting signal.

Locate the parameter group UNISON in the ED-IT menu.

01111111111111111112

1 UNISON Mode Twin 61111111111111111154

UNISON mode determines how many voicesthe VIRUS will use to render a played note. In anutshell, it determines how fat the sound willbe. You can use the UNISON Detune parameterto determine to which extent the active voicesare detuned. UNISON PanSpread distributesthem uniformly across the stereo panorama, aprocess by which you can also determine thewidth of a sounds stereo base. When you acti-vate UNISON mode for a sound, it can still beplayed polyphonically. However, depending onthe number of voices youve dialed in, its po-lyphony will of course be considerably reducedin UNISON mode. The most efficient and thestandard setting is UNISON mode = Twin,

where two voices are played for every note. Inthe OFF position, one voice per note isplayed.

36 CHAPTER 4Introduction

THE EFFECTS

At the bottom left of the panel is the effectssection, divided into an EFFECTS and a DELAY/REVERB block. This gives you access to Distor-tion, Phaser and Chorus effects as well as De-lay and Reverb.

The TYPE/MIX and INTENSITY knobs in the EF-FECTS block are used to control the distortion,phaser and chorus effects. They always applyto one of the three simultaneous effects only,selectable via the Select button. The followingparameters can be controlled using these twoknobs:

All other effects parameters are defined in themenu by pressing the upper EDIT button.

The lower EDIT button in the DELAY/REVERBsection lets you switch between the Delay andReverb effects. The SEND control determinesthe proportion of the selected effect within thesignal; DELAY/REV TIME controls Delay time or

Reverb decay; FEEDBACK/DAMPING deter-mines the degree of feedback in the Delay sig-nal, or high frequency damping for the Reverb.

If Delay or Reverb are synchronized to theclock, DELAY/REV TIME controls the time ex-pressed as a note value (1/16, 1/8, etc.).

In the next section we are going to take a closerlook at the Virus effects.

DISTORTIONThe Distortion effect is actually a collection ofseveral different algorithms, which are selecta-ble via the TYPE/MIX control:

- OFF No distortion

- LIGHT, SOFT, MIDDLE, HARD Four analogdistortion curves, with differing characteris-tics and intensities.

- DIGITAL Digital distortion with hard clipping.

Shaper. Sine characteristic with multiple wavecycles. Signals sent through the Shaper canbe changed quite drastically; the results areoften similar to the spectra of linear FM (fre-quency modulation).

- RECTIFIER Variable half-wave rectification;input level does not affect the amount of dis-tortion.

- BITREDUCER Variable reduction of the bitdepth; generates digital quantization noise.

Distortion-Effekt:

TYPE/MIX Distortion Curve

INTENSITY Distortion Intensity

Phaser-Effekt

TYPE/MIX Phaser Mix

INTENSITY Feedback

Chorus-Effekt:

TYPE/MIX Chorus Mix

INTENSITY Depth

EDITEDIT SELECTSELECT00

66

12121212

EFFECTSEFFECTS

DISTDIST

TYPE/TYPE/MIXMIX

PHAPHA

CHOCHO

INTENSITYINTENSITY

ACCESS VIRUS OS5 37The Effects

- RATEREDUCER Variable reduction of thesampling rate; generates digital aliasing ef-fects.

- LOWPASS 1-pole lowpass filter; gentle re-duction of higher frequencies.

- HIGHPASS 1-pole highpass filter; gentle re-duction of lower frequencies.

The INTENSITY control is used for setting thedegree of distortion (in distortion algorithms) orthe cutoff frequency (in the two filter algo-rithms). INTENSITY ranges from very slight toextreme.

PHASERThe Phaser effect produces resonant (or evencutting) emphasis on certain frequencies withinthe signal. The frequencies of these resonancesare shifted around the frequency spectrum,causing a distinctive movement in the sound.Tastefully applied, this effect is particularly goodfor pad sounds and for authentic traditionalelectric piano sounds.

The pure Phaser signal is the result of a fre-quency-dependent phase shift together with aslight pitch modulation from the phasers ownLFO. Typical phaser sounds only appear whenthe processed signal is mixed with the dry sig-nal, usually at the same level. The TYPE/MIXcontrol is used to set this balance.

The INTENSITY control changes the level offeedback in the phased signal. Higher feedbacklevels cause higher resonant peaks in the sig-nal. The FEEDBACK parameter is bipolar, be-cause positive and negative feedback havedifferent characteristics.

More phaser parameters can be found in theEDIT menu: RATE and DEPTH control thespeed and intensity of modulation from the

phasers own LFO. The other three parametersaffect the general sound of the phaser: FRE-QUENCY determines the average frequency ofresonant peaks, STAGES is the number of reso-nant peaks and SPREAD is the distance be-tween resonant peaks within the frequencyspectrum.

CHORUSChorus has been a popular effect for a longtime, and is often used to make pad sounds(such as synthetic strings) less static. It is actu-ally a pair of short delay lines (usually no longerthan 50 ms) with continuously modulated delaytime via dedicated LFO. This modulation caus-es subtle frequency shifts in the processed sig-nal, which results in a more complex phasingbetween direct and processed signals. Feed-back in the delay line accentuates the Choruseffect, and because the left side of the signal ismodulated in the opposite direction to the rightside, the Chorus effect is capable of creating astereo signal from a mono input.

When the basic delay is extremely short, this ef-fect is called flanging. The feedback parameteris especially significant here, as higher valuescan create dramatic resonances and couldeven be considered an additional signal source.Like in the Phaser, the FEEDBACK parameter isbipolar, because positive and negative feed-back have different characteristics. At higherfeedback levels (negative or positive) it be-comes obvious that the two sides of the signalare being modulated in opposite directions.

The TYPE/MIX control in the EFFECTS sectiondetermines the balance between the direct andprocessed signals. The RATE and SHAPE pa-rameters control the dedicated LFO, and areavailable in the EDIT menu. Two further parame-ters in the menu are DELAY and FEEDBACK.These are used to set the delay time and feed-back level. The INTENSITY control determines

38 CHAPTER 4Introduction

the DEPTH i.e. modulation intensity of the LFO.Please note that signal paths in the Virus Cho-rus/Flanger are stereo throughout: The stereoposition and any panorama modulation or ster-eo spread values are preserved in the proc-essed signal.

DELAY/REVERBThe DELAY/REVERB section is responsible fortwo different effects. The SEND control deter-mines the relative amount of effect signal:

The DELAY effect delays the input signal, and isusually used for echoes. The nominal delay timeset by the DELAY/REV-TIME control can bemodulated so that stereo phasing effects canappear. The delay time can be synchronized tothe clock so that echoes will be in time andwill automatically adjust to any tempo changes.There are also several fixed-pattern delay algo-rithms, many of which delay the left and rightsides differently i.e. using different note values.Interesting rhythmic patterns can be created byincreading feedback level (via the FEEDBACK/DAMPING control).

REVERB simulates the effect of the boundariesin real spaces such as living rooms or cathe-drals. There are several parameters here whichgo beyond pure simulation of real spaces. Thepredelay parameter normally found in reverbunits is handled by the DELAY section de-scribed above DELAY is in front of REVERB inthe signal path. REVERB can be synchronizedto the clock so you can seamlessly integrate theeffect into the rhy