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Access Virus B & KB

Modelled Analogue Synth Module, KB Keyboard & v3.0 Software By Paul Nagle
Published February 2000

Access Virus B module

The Virus modelled analogue synth has received a hardware upgrade to complement its ever‑evolving software feature set, and is now available in a keyboard version.

Since its preview in November 1997's Sound On Sound, the Access Virus analogue modelling synth has continued to evolve, courtesy of the admirable efforts of the Access programming team (and an operating system that can be instantly upgraded via the synth's MIDI port). The free, web‑downloadable upgrades weren't minor OS tweaks, either — some serious features have been added, among them a classy 32‑band vocoder, of which more anon. But there's only so far you can go with software upgrades, and in the time since the original Virus was released, newer, faster DSP chips have become available. By embracing these, Access have been able to build turbo‑charged Viruses (Virii?) with increased polyphony and effects far beyond the scope of the original model. In this way, the so‑called Virus  and KB were born.

B Here Now

The Virus B is a desktop (rackable) module, while the KB, logically, is the keyboard version (I used both for this review, though the bulk was written using the KB). Both offer 24‑bit D‑A and 18‑bit A‑D converters, 24‑note polyphony and up to five effects for each multitimbral part. Happily, both keyboard and module have a hardware MIDI Thru (unlike the old Virus) and the housebrick power supply that accompanied the original module for review has been superseded by something more compact (and the keyboard's power supply is internal!). In fact, excluding their physical differences and the KB's master controller functions, the keyboard and module are the same animal; the Virus KB is essentially a Virus B encased in a solidly‑made, rounded black metal body. This is impressive, although the way the module has been developed into a keyboard does mean that a few features don't work in quite the same way as you might expect on a device that was designed as a keyboard from the word go. For more on the KB, see the 'Virus With Keys' box later on.

Despite the new hardware and software, much of the basic feature set of the new Virus will be familiar to owners of the original, so I don't intend recapping in too much detail. To anyone who is not familiar with the original Virus, I therefore recommend a brief refresher course in Virology before we kick off. Dig out the review from SOS May 1998. For now, it's enough to remember the original Virus as a 12‑note polyphonic, 16‑part multitimbral 'advanced simulated analogue synthesizer'. Its two main oscillators featured the expected sawtooth and square waves, augmented by 64 digital waveforms. With three LFOs, a sub‑oscillator, and onboard delay and chorus effects, it certainly merited the 'advanced' tag. Best of all, its twin multi‑mode filters were configurable into serial or parallel operation, affording the end‑user a wide tonal palette.

Panel Games

The physical layout of the new Virus is broadly similar to that of its previous incarnation, although the red paint is a little brighter, the knobs are squarer and the old‑style buttons (some with integral LEDs) have yielded to smaller, smoother ones, their LEDs shifting onto the control panel itself. Several extra buttons have sprung up, one of which opens a dedicated menu for the effects, while two others perform part selection when in multimode. In the LFO, Oscillator and Filter sections, buttons which were formerly tied to specific tasks now bear a generic 'Edit' label. This is an application of the same concept that Novation adopted with their Supernova and Nova — ie. pressing them activates submenus related to that area of the synth. Fortunately, in conjunction with the parameter keys, skipping through the menus (even with the Virus's two‑line display) is pretty painless. The original Virus offered so‑called 'Expert' and 'Easy' modes of use (selecting the Easy mode removed some of the more detailed edit parameters in the LCD sub‑menus), but this distinction has been abolished, although, for neatness, many parameters only reveal further pages when specifically activated.

However, a few cosmetic changes and a keyboard do not a new synth make. The Virus has received far more than a lick of paint and some new knobs and to appreciate what exactly has been gained, we need to delve into the labyrinthine world of its software...

KB: The Virus With Keys

Access Virus kb

The Virus KB's semi‑weighted action is a pleasure to play — I would put it right up there with my previous personal fave keyboard, the one on Kawai's K5000 additive synth. I could happily live with the KB as my main controller — and cosmetically, the KB's pleasingly contoured wooden end cheeks and wood panel above the keys are attractive embellishments (at the risk of annoying Swampy and his chums, I'd say that most synths would benefit from a tasteful slice of tree at either end...).

The keyboard transmits channel aftertouch plus attack and release velocity, and is adorned with chunky modulation and pitch wheels, but sadly there's no sign of any ribbons, pads or log controllers. The end result is a simple but admittedly classic appearance. At the rear, in addition to three stereo output pairs and stereo input, the KB has sockets for a hold pedal and an assignable pedal (initially set to control volume). It is a pity that there is no headphone socket nor dedicated controls for the arpeggiator. In the case of the former, headphone operation involves removing both main audio leads and plugging your phones into the left channel. Surely it can't only be me who enjoys turning on just one keyboard in the studio and playing into the early hours on headphones? Having to unplug to do this is an inconvenience (although I did eventually figure out a workaround by using Multimode and redirecting the output to one of the other stereo pairs).

Access Virus KB rear panel connections.Access Virus KB rear panel connections.

While I'm on the subject of minor KB‑related gripes, the Virus's development path from module to keyboard is evident. Certain parameters which on a master keyboard you would expect to affect the MIDI notes transmitted only work on the sounds produced internally — for example the Transpose functions accessed via the buttons on the left‑hand side of the front panel. This is fine for Local use, but might cause a few slightly raised eyebrows if you were attempting to use the Virus as a master keyboard. Finally, hiding the arpeggiator under one of the menus makes sense for a module but in a keyboard is harder to forgive — especially as the current OS software does not allow any arpeggio controls to be assigned to the two 'user‑definable' knobs.

No matter whether you own the B or KB, you download the same OS when you want to upgrade — the system detects which hardware you're using. If you have the KB, more menus are accessible via the Ctl button. These relate to master keyboard functions and include transposition, sensitivity settings for aftertouch and Local On/Off (set independently for knobs and keyboard). Finally, MIDI transmission mode tells the keyboard to send on one channel or multiple channels, their key ranges corresponding to those of the current Multi. If you choose this, a new option appears when defining the multi patch, 'KeybToMIDI', which allows you to layer internal and external sounds across definable keyboard zones. Any combination you need should be achievable but there was one point where I got a little confused. Any zone set with Enable=Off still responds to incoming MIDI notes whenever its transmit option is active. The manual suggests deactivating the part by setting the low and high key to C2 which seems a little bizarre — I'd personally rather set Enable to Off and have it truly mean off! A handy shortcut to set low and high key ranges is as simple as pushing both value keys at once then hitting the appropriate note on the keyboard — another of those nifty shortcuts that all synths should have.

Virus v3.0

When installed, version 3.0 of the Virus OS boosts polyphony to a healthy (in Virtual Analogue terms) 24 notes — double that of the original Virus. It isn't just polyphony that's increased either; there are new effects, a third oscillator and many other refinements.


In synthesis terms, this extra oscillator is probably the most welcome new addition to the Virus and yet, if you look at the photo accompanying this review, you'll find no hint of its existence on the front panel. The secret is found under the Edit button in the Oscillator 2 section, where all the oscillator‑related menus are to be found.

Oscillator 3 is not quite as fully featured as the two main oscillators and works closely with Oscillator 2. It can be set to work as a Slave or can function more independently, in the latter case getting its own waveform, level and tuning. However, if you modulate Oscillator 2 using the Virus's fixed modulation routings (LFO 1 to Oscillator 2 Pitch or Envelope 1 to Oscillator 2 Pitch), Oscillator 3 is modulated also. Independent modulation can be performed using the freely assignable routings (which we'll cover shortly) but some of the options available to the two main oscillators (pulse width, wave selection, wave shape and so on) are lacking. When acting as Slave, the new kid adopts all Oscillator 2's settings except detune, so it can be controlled without delving through menus. In this mode, turning the detune knob automatically detunes Oscillators 2 and 3 in opposite directions, fattening things up nicely.

For programming purposes, hearing Oscillator 3 on its own is not easy because the two main oscillators don't have level controls, just a balance between them (although you can bodge a solution by carefully setting up Oscillators 1 and 2 to produce inaudible outputs, leaving 3 playing in isolation). Switching the third oscillator on also reduces polyphony by six notes, but the results are definitely worthwhile — it's certainly more versatile than the Virus's sub‑oscillator and, of course, you can still use that too! Within the limitations I've mentioned, the Virus can happily pass itself off as a 4‑oscillator synth.

In an earlier version of the Virus, thickening was performed using 'Twin Mode', which halved polyphony and gave you detune and spread options for a lusher sound. This has been extended and a full Unison Mode implemented. You can now stack up to 16 voices for some truly monstrous solos and basses. Hooray!

Other parameters now accessed under the Oscillator Edit menu include: waveform type for the sub‑oscillator (triangle or square), levels for ring modulation and noise, noise 'colour', FM type (FM is only an option for Oscillator 2), the option to route Envelope 1 to Oscillator 2 pitch, and more. Of these, the noise colour adjustment allows the noise to be swept smoothly from a deep, dark roar to a high, shrill whistle — and that's even before it reaches the filters. The ring modulator's clangorous tones first rang in an earlier software upgrade but in this version, you can incorporate external signals too — even stereo ones if you wish. New FM sources for Oscillator 2 include external signals and noise, allowing you to create some extreme, raunchy effects. The original FM implementation simply used a triangle wave from Oscillator 1 but this too has been extended, so any of the available waveforms may be used, creating complex DX‑like textures to extend the gritty end of the Virus' tonal palette further than ever.


As you may remember, the purpose of the modulation matrix is to freely connect any modulation source and destination(s), rather like you might patch a modular synth. There are many options to choose from — up to 27 sources and 90 destinations in total (tip: modulate Oscillator 2's pitch from here if you don't want to disturb Oscillator 3). Even the effects parameters are included, potentially opening up a whole new world of integration with effects and synthesis. With this degree of scope theoretically on offer, it's a pity that in practice, just three sources with up to six destinations may be connected in each patch. Once you've routed the mod wheel to control vibrato amount and aftertouch to alter the filter balance, there isn't too much left over for the wild stuff. Perhaps this explains why so few of the factory patches make use of aftertouch or respond to the mod wheel... This said, you can do wonderful things here, for example set one LFO to modulate the speed of another, modulate phaser speed according to key position, or configure envelopes to control delay time — the world's your lobster. One handy mod source is 'random', which generates a new value at each key press. Its uses might include subtly varying oscillator detune or the balance between the two filters with each note. This is great stuff and the sooner Access add more simultaneous matrix routings per patch, the happier I'll be.


The LFOs haven't been neglected either. All of the 64 digital waveforms which can be accessed by the main oscillators are now present as modulation sources via a new entry under the LFO shape selector: Waves. Sample & Hold and Sample & Glide are now demoted to lurk in this menu, but at least the other common waveforms have kept their place on the panel. I wasn't initially convinced of the benefit of having so many LFO waves until I tried them in conjunction with the Envelope Mode button. This forces the LFOs to run through their cycle just once, transforming the LFO into an additional envelope (with a shape matching that of the selected waveform). Behind each LFO's Edit button, the established parameters (key follow, poly or mono mode, and so on) are supplemented by a useful new option, Contour, which bends the waveform's shape. This is a modulation matrix destination too, so you can alter it dynamically if necessary.

As on the original Virus, the two main LFOs have a series of predetermined modulation routings, represented as a series of cute yellow LEDs. If any destination is receiving modulation, its LED is lit and you scroll to it (using the Amount key) to check or vary the modulation amount. Having scrolled through the fixed destinations, a new freely assignable destination pops up in the display so that each LFO can modulate almost any Virus parameter without using valuable modulation matrix routings.


The filter section, already pretty comprehensive in the original Virus, has received several new blessings. The Saturation switch of Filter 1 has been replaced with another Edit button, from which a bundle of new modes can be accessed: Rectifier, Rate Reducer, Bit Reducer, Rate & Keyfollow, and a 1‑pole low‑ or high‑pass filter. On the old Virus, Saturation was applied after Filter 1, and its level was set using the second half of the Osc Vol knob. These new options have their amount set in the same way and each can modify the output of Filter 1 dramatically, ranging from the lo‑fi grunge of the Bit Reducer to the raucous howl of the Rate Reducer. As with the other Saturation effects, they add differing degrees of dirt, and in conjunction with Filter 2 (and its series or parallel routings) there are almost limitless textural variations to explore. Access must have been pleased with these Saturation tools because they included some of them in the effects section where they act as blanket effects for the whole patch — with quite different sonic results than when they are used at voice level.


In multitimbral mode, each of the Virus's 16 parts can use five effects at once, and there is also a stereo delay working globally (each part having a send level). One part may use the vocoder too and therefore Access boast that a whopping total of 82 effects (5x16 plus stereo delay and vocoder) can be used at once. Impressively, each patch retains the settings for chorus, phaser, analogue boost (of which more in a moment) and distortion which the sound is given at Patch level, even when used multitimbrally. However, since the fifth effect is ring modulation (which requires some kind of input to function), I wonder whether Access's claim of 82 isn't stretching things a little. To my reckoning, the number seems closer to 66 'real' effects (4x16 plus stereo delay and vocoder) — which, to be fair, is still more than respectable. Anyway, the new effects include:

  • Distortion — this includes many of the saturation effects just described in the filter section (the Rectifier, Bit Reducer and so on), each adding its own flavour of grime. Here the results are invariably even nastier, adding a cold, hard edge that Mike Tyson would be proud of.
  • Vocoder — a quality 32‑band vocoder which demands quite a chunk of DSP power, getting its juice by replacing the entire filter section — and hijacking its control knobs! When the vocoder is active, it consumes approximately four notes of polyphony. A handy 'auto sense' feature ensures that if no external signal is received for 10 seconds, the vocoder switches itself off until needed again, thus freeing up the polyphony. The Virus's vocoder is comprehensive and sounds great. To whet your appetite, its controls include: Frequency, Q‑Factor, Frequency Spread Centre, Carrier/modulator Balance, Attack, Release, Spectral Balance and Band Quality. The carrier signal comes from the oscillators or white noise. The manual has a very good explanation of vocoders in general and is well worth a download from the Access site.
  • Stereo Phaser — call me old‑fashioned, but I just love phasers and the Virus's Retro phaser is a cracker, offering all those rich Jean‑Michel Jarre‑type effects for pads with ease. The Phaser has up to six stages and a Spread parameter to set the width of the notches created in the frequency spectrum, producing a wide variety of possible effects. If it's deep, warm swooshiness you want, this phaser is going to see a lot of use!
  • Analogue Boost — this is one of those subtle 'enhancer'‑type parameters that seems to do very little until you turn it off! It is effective at lending some extra depth to the bottom end of anything fed through it, or tuned appropriately, can fill out any analogue patch. Access are not forthcoming on exactly how the process works, but it is pretty safe to say that it is more than just a simple EQ (the Tune parameter is graded from 0 to 127, and does not follow any discernible pattern, such as enhancing low frequencies at low settings and higher ones closer to 127).
  • Stereo Delay — a new filter (low‑ or high‑pass) has been added to the delay feedback parameter so that progressively duller delays can be introduced, or quieter delays with increased harmonics. It's a subtle but welcome enhancement to an already excellent effect. Remember that the delay will sync to MIDI Clock — indeed the Virus provides an Auto mode which (if you choose) can sense incoming clock and sync to it automatically, reverting to internal delay times if the clock stops.
  • Ring Modulator — also appearing as part of the voice architecture, the ring modulator requires a signal input and has just one control to set its level.
  • Input Follower — although not strictly an effect, the input follower takes the level of an external audio input and creates a modulation control signal from it. When active, the input follower replaces the filter envelope, and thus, if you use this as source in the modulation matrix, you can modulate any of the other Virus parameters using the external audio signal.

Sounds Like..?

You're probably starting to get an impression of the programming detail the Virus can offer, but what does it sound like? I managed to upset some amongst the Virus‑owning community with my previous review, daring to suggest the bass end lacked a little depth. Happily I can report that with the additional oscillator, Unison mode and the Analogue Boost parameter, the Virus can now generate a speaker‑shaking bass which would silence even the pickiest of critics. A little endeavour should now bring nearly any analogue texture within your grasp (although to my ears, the sawtooth waves remain a little on the polite side, meaning that the creation of monster‑raving Memorymoog‑style brass patches remains a tough challenge). Generally, though, the Virus has a scope beyond that of any vintage polysynth, and is capable of warm strings, sweeping pads, dirty solos, squelchy basses, alien soundscapes, and that's before we get to the realms of spiky digital tones and bright tinkles.

User sounds may be stored in two banks of 128 patches with a further two banks of ROM patches to get you started. Example patches for vocoder or external input processing are provided to make those features even easier to get to grips with.


As already explained, the Virus's Multimode implementation allows up to 16 patches to play at once. Up to 128 of these Multi setups may be stored and a welcome addition for computer users is the Dump Arrangement facility, which transmits the Multi setup and all associated user patches over MIDI for storage as part of a song.

Previously, the multitimbral mode lacked any means of prioritising important parts — now at least there is an albeit rudimentary 'high priority' option to help prevent embarrassing silences in your thumping bass part as you play one note too many in that string pad.


The new Virus offers very much the same quality of sound and ease of operation that made its predecessor a delight. The new layout is a definite improvement, although perhaps so many new features should have instigated a more drastic redesign of the hardware front panel — such as knobs for that new oscillator for a start! Access have added almost everything that I felt was overlooked in my first review (and much more besides) and development of the OS is continuing. My request for extra modulation matrix slots is in already! The third oscillator is a bonus, and the increased polyphony and enhanced effects will be applauded by many. Amongst the effects, the phaser takes the honours as best newcomer and despite its inscrutability, Analogue Boost still seems to find its way into almost every patch I program. Perhaps some will bemoan the lack of onboard reverb but as this is costly in DSP terms, the existing resources are best shared out amongst the other effects.

The Virus KB's sturdy nature and first‑class keyboard action is also impressive. Sure, I'd have liked dedicated arpeggiator knobs or perhaps a ribbon controller, but actually I yearned most for a humble headphone socket. Mind you, you can tell an instrument is pretty good if this is the reviewer's harshest complaint...

I think the Virus will be regarded as a classic in years to come. It has an uncanny knack of blending seamlessly into the mix, and yet it lends a certain presence to any track with its distinctive filters. Of course these days, it's always tempting to wait a few months in case the next synth to come along offers more effects, a different kind of oscillator, or a free T‑shirt, but sometimes you need to take something that sounds great today and simply use it. There's a lot to master already and the team at Access are no slouches when it comes to squeezing more from the available DSP. If you are shopping for a new virtual analogue synth, you'll be sick if you don't check out the Virus

Old & New

Before all you existing Virus owners rush to download the version 3.0 OS, remember that this version is not compatible with the original hardware. To get the extra oscillator, polyphony and effects, you must have the improved DSP of the B and KB versions. Sadly, there is no upgrade path for existing owners — apparently the case had to be redesigned to house the new processor.

The review of the original Virus review was made using version 1.51 of the Operating System and a lot of things have been added since it was written. As I write this, the current OS for the original model stands at v2.52 and includes much which is also present on the new B and KB: the vocoder, ring modulator, expanded modulation matrix, Unison mode, additional ROM patches, patch compare mode, additional arpeggiator functions (random and 'chord'), extra LFO waveforms and more — all as a free upgrade. There may be yet more to come, but it's fairly certain that the older Virus's feature set will never catch up with that of the newer hardware.


  • 24‑note polyphony.
  • Three oscillators and a sub‑oscillator per voice.
  • 16 patches each with individual effects in Multitimbral mode.
  • High‑quality keyboard (KB) and solid construction.


  • No headphone socket (KB).
  • External power supply (B).
  • No dedicated knobs for Oscillator 3.
  • Some functions on the KB affect only internally generated sounds, not data output via MIDI (eg. Transpose), due to the Virus's development history.
  • No dedicated arpeggiator control (KB).


The Virus nudges its way towards the front of the pack of virtual analogues battling each other to capture your attention (and disposable income). With new effects, an extra oscillator, increased polyphony and other enhancements, there's never been a better time to catch one.


Keyboard version (KB) £1279; Desktop version (B) £899. Prices include VAT.