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Access Virus

Virtual Analogue Synthesizer By Paul Nagle
Published May 1998

Access Virus

Offering more multitimbrality than its virtual analogue rivals, plus a combination of knobs for instant gratification and an LCD for accessing more advanced features, will the Virus leave the competition feeling a little sick? Paul Nagle finds out.

If you can cast your mind back as far as November last year, you may recall a preview of a red Virtual Analogue Synthesizer from German company Access. I was impressed with it at the time, despite the fact that its operating software was at an early stage, and I've been using it on a regular basis ever since. But it was only a couple of weeks ago that I got hold of a major softwareupdate — version 1.51 — which awakened many slumbering features and implemented several welcome new ones. Now that the Virus is finally up and running, the time has come to take our long‑promised tour.

Anatomy Of A Virus

Access Virus

The first thing you notice about the Virus is its size — or, rather, lack of it. It's designed as a tabletop instrument (though distributors Turnkey can supply a rack adaptor kit) and measures a neat 18.5 x 7 x 2.5 (inches). Framed by wooden end‑panels, it's beautifully put together. The 32 knobs are smooth and even, and as you turn them the results feel convincingly 'analogue'. The switches (27 in all) are positive, the 52 LEDs a cheery bright yellow, and the 2‑line x 16‑character backlit display clear and sharp. To edit values for which no dedicated knob is available, two value switches and a value knob are positioned to the right of the display.

The panel is laid out logically in the manner of a traditional analogue synthesizer. From left to right, there are two LFO sections, two Oscillators, a Mixer, the Filter section (with a dedicated envelope), and the output envelope. A Volume knob, Transpose switches and two freely assignable knobs make up the rest of the controls. These latter two knobs are fully user‑definable and can either be assigned individually for each Virus patch or have a global setting for use in all patches. They can control almost any Virus parameter, which effectively means that if there's something hidden away behind the LCD that you'd like to be able to reach instantly, this is how you'd do it. They can also transmit the MIDI controller of your choice.

The rear panel features no less than six audio outputs (in three stereo pairs) plus stereo external inputs. There are MIDI In and Out sockets but no Thru (the MIDI Out can function as a soft Thru, but surely we deserve a hardware Thru on all but budget instruments?). An on/off switch, plus the connector for the external 12V adapter, complete the rear‑panel tour.

Two banks (A & B) of single patches are available, and they're capable of holding a total of 256 user programs, with a further 128 Multi (multitimbral) locations. The Virus has 12 notes of polyphony and yet boasts 16‑part multitimbrality. Why's that, then? Well, when we look at the buss structure and the possible uses of the external inputs a little later, perhaps it won't seem so strange, but for now I'll just say that since notes are allocated dynamically, it's no bad thing to have 16 patches on tap throughout a song, even if only a maximum of 12 can play simultaneously.

Expert Or Easy?

Access Virus

A synth which you program by navigating through the pages of a small display, by its very nature, is less immediately usable than one with a knob for every function. On the other hand, providing a dedicated knob for every function means that either a simplified architecture or a huge control panel is necessary. Presumably with this in mind, the Virus adopts a two‑tiered approach, with the most common features hard‑wired to knobs; the rest are accessed via the LCD. Yes, some sound‑shaping options are less instantly grabbable than others but I think, with only a few exceptions, Access have chosen the division of labour wisely. It's quite possible to program a great number of traditional synthesizer sounds without using the display, if that's your preference. One advantage of an LCD is that new facilities can be added later without needing any hardware modifications — the Virus OS is upgraded by playing a MIDI file containing the appropriate SysEx commands to it.

Below the LCD are four buttons labelled CTRL, EDIT, MULTI and SINGLE, plus a grey button used to store edited programs. Oddly, there is no patch compare facility, but on the plus side the Virus does show you the name of any patch you are about to overwrite. Two arrow/scroll keys are used to navigate through the pages of software, and some useful shortcuts have been implemented, so that when you hold down both of the Value switches to the right of the display the current value is zeroed, and holding a second scroll key whilst one is already held jumps you through the main sections of the edit pages.

The Virus is an infectious beast, offering plenty of programming potential to both the novice and more seasoned campaigner.

To further ease navigation through the LCD pages, Access provide two modes, 'Expert' and 'Easy'. If you pick Easy, some of the options disappear, so it's quicker to get around. Since Expert mode offers the most options, this is themode I'll consider throughout this review. To kick things off, let's look at the components that make up a patch.

The Virus has two oscillators, a sub‑oscillator and a noise source as its main signal generators. Modulation duties are handled by three LFOs. With two envelope generators and two filters, this seems to add up to a fairly standard synthesizer architecture, but this Virus is a little more potent than that, as we shall see.


The oscillators feature the obligatory sawtooth and variable square waves. The most notable departure from the usual path taken by virtual analogue synths is the inclusion of an additional 64 digitally‑stored waveforms which extend the range of the Virus considerably. These are selected via the WaveSel and WaveShape knobs which are present for both oscillators. Turning the WaveShape knob through its full rotation causes a fade from the digital waveform to a sawtooth wave at the 12 o'clock position, then through to a square wave at the furthest rotation. If the knob is positioned such that the square wave is audible (ie. anywhere after the halfway mark), the dual‑function WaveSel/PW knob underneath it sets Pulse Width. And if the digital waveform is audible (ie. the knob is anywhere before the halfway point) this same knob functions as a wave selector for the digital waves. It probably sounds more complicated than it is. The Oscillator Volume knob, which I'll come to later, also functions in a similar way, where half its travel is dedicated to an additional function.

The digital waveforms are not described anywhere in the manual (they are created via sampling rather than modelling techniques) but sound like the kind of short waveforms that Korg used in their DW series of synthesizers — single‑cycle waves of the bell, electric piano, organ, and 'buzzy' type, all of which benefit from some treatment by the filter section. It can be surprising to hear obviously digital, PPG‑like tones coming from a synth which looks like this.

Key Follow can be set so that an oscillator tracks the keyboard in odd intervals, or can be inverted, can span up to two octaves for one octave on the keyboard, or can even be turned off. A third oscillator, which operates an octave below Oscillator 1, offers a choice of triangle or square waves (but no sawtooth) and is a handy fattening agent, rather like lard. The mixer stage controls the balance between Oscillators 1 and 2, and there's a dedicated level control for the sub‑oscillator and an overall volume control which, after its mid‑point, functions as a saturation amount control for Filter 1. This is one area where I feel things could have been better laid out, with separate level controls for each oscillator, plus a dedicated control for the noise level and then a saturation level pot.

Oscillator 2 has some extra features, namely Frequency Modulation (FM) amount, for those bell‑like or harsher tones, and detune and semitone knobs to set intervals with Oscillator 1. Oscillator sync is on hand for any who wish to pay homage to Jan Hammer. The Filt Env Mod switch allows you to modulate Oscillator 2's pitch and/or FM amount using the Filter envelope (the button toggles the display between Pitch and FM amount). This feature works well if combined with oscillator sync, forcing Oscillator 2 to restart its own wave cycle each time Oscillator 1 does, for harmonically rich effects.

Twin Mode is an LCD‑accessed means of allocating two voices to every note, with detune, phase and panorama spread options, and adds a swirly thickness to the raw sound. If activated, Twin Mode halves polyphony to six notes, but it may be worth doing this for the extra depth.

I'd have to say that the oscillators are the least convincing weapon in the Virus' armoury, despite the welcome addition of the digital waves. The bass and lead sounds I was able to create seemed to lack a certain warmth and fullness, especially in the lower registers, although the vast majority of polyphonic synth voices, effects and percussive/sequencer patches were achievable with ease.


Two of the three available LFOs have dedicated panel sections and each perform slightly different tasks. LFO 1 can control the pitch and pulse width of Oscillator 1 and 2, resonance for Filters 1 and 2, and filter gain. Depending on the saturation setting (more on this when I come to the filters, in a moment) in the Mixer/Filter section, this gain amount introduces either tremolo (level modulation) or distortion. The LFOs may operate in polyphonic or monophonic mode; if they're in polyphonic mode, a separate LFO is allocated per voice played. The Key Follow switch is used to set the amount by which LFO speed varies according to key position — play a big chord and the LFOs for the highest notes will run faster, which is effective for thickening ensemble patches. If you activate Envelope Mode, each LFO can also operate as a simple one‑shot envelope, running through a cycle once, then stopping, so an LFO's sawtooth wave could be used as a simple percussive modulation source for, say, Oscillator 2's pitch.

LFO2 can modulate the waveshape of Oscillators 1 and 2, FM amount, Filter 1 and 2 cutoff, and pan. Setting the LFO modulation amounts isn't totally straightforward because they have no dedicated knobs, and are instead set by the Value knob and switches. A switch steps downwards through the different LFO modulation destinations, each represented by a labelled LED (see photo). If the amount setting for the current destination is anything other than zero, the corresponding LED lights up (so if there are no lit LEDs in this section, it means there's no modulation). If some of these LEDs are lit, you need to flick downwards through them to see their value in the display. For LFO2 there's a Key Trigger switch instead of the Key Follow option of LFO1, and this restarts the LFO after each Note On event.

There are other LFO options lurking behind the LCD pages, and there too you'll find the third LFO, which is able to modulate oscillator pitch and pulse width only, although it does still have the same waveforms as the other two — namely triangle, sawtooth, square, S&and S&G. This latter waveform is Sample & Glide — a smoothed‑out version of Sample & Hold — presumably fed via a lag processor to enable glides between values. Interestingly, a sine wave is available for the LFOs but must be selected via the MIDI control changes documented in the back of the manual. If a sine wave is used on LFO1 or LFO2, all the waveform LEDs are turned off. And speaking of MIDI, all the LFOs can be sync'ed, with various note‑value options, to MIDI clock.


Probably the Virus's biggest sonic muscles, its two filters, may each be switched into low‑pass, high‑pass, band‑pass and band‑reject modes, all with an impressively realistic resonance. Filter 1 can have either 2 or 4 poles (12 or 24dB), while Filter 2 always operates at 12dB. Four configurations allow the filters to be connected in series, parallel or a rather nifty 'Split' mode. This latter mode processes Oscillator 1 and the sub‑oscillator via Filter 1, and Oscillator 2 and the noise source via Filter 2 (both filters operate at 12dB in Split mode). In every configuration, a Shaper/Distortion process is connected after Filter 1, offering six different Saturation types — Light, Soft, Middle, Hard, Digital and Shaper — each more aggressive and harsh than the previous one. You select Saturation with its dedicated switch, choose the Saturation type you want, and set the required amount with the Oscillator Volume knob in the mixer section, half of whose travel is dedicated to this function. Saturation gives the Virus a very distinctive and dirty sound, which, however, never becomes unusably nasty, and often just a subtle amount will make a dramatic difference to a patch.

If they're connected in series, the first filter and saturation stage can produce a rich output which then becomes the sound source to be filtered again by Filter 2. Filter 2 may be linked so that it always operates relative to Filter 1, or it can work independently. The Filter Balance knob fades between the outputs of the two filters, and directly underneath this a button sets whether the (shared) Resonance, Envelope Amount and Key Follow knobs control just one or both of the filters. Envelope polarity may be set independently for each filter. With the number of combinations of filter type and routing on offer, the Virus can sculpt a range of sounds to keep most people happy for years. Quite simply, this is the best digital filter I have yet heard.


The Virus has two envelope generators — one for the Filter section and one to control the VCA (Voltage Controlled Amplifier) level. Each has five associated knobs — Attack, Decay, Sustain, Time and Release. The Time parameter affects the sustain phase of the envelope, either raising or lowering the level of the signal throughout the duration of the sustain period, and is probably something I'd have left behind the LCD, given the choice. If this knob is set to 12 o'clock it becomes inactive, and the envelope operates as a normal ADSR envelope. A Punch parameter adds extra 'kick' to a percussive envelope.

Quite simply, this is the best digital filter I have yet heard.


In Single Mode, each Virus patch features a simple yet flexible Delay and a Chorus processor. The Chorus features chorus depth, rate, delay and feedback; the Delay parameters are send, time, clock (with different clock intervals available), feedback and rate. Both chorus and delay offer their own modulating waveforms, selectable from sine, triangle, sawtooth, square, S&and S&G. This adds up to a whole bunch of wacky possibilities which soon become a vital component of your sound‑making, especially if you're building a rhythmic patch which uses delay time, perhaps running in sync with an arpeggio pattern and filter‑chopping LFO.

Effects in Multi mode consist of a global delay (for which each part has a level setting) and up to four chorus effects. The chorus is reserved for the first four parts, and therefore any patches in a multi which use chorus but are assigned to parts 5‑16 will lose their chorus.


As I said earlier, the Virus offers a generous 128 Multis. Each consists of up to 16 parts, and each part may be switched on or off, set to any MIDI channel (so layers are possible) and given key (but not velocity) splits. Individual parts may be transposed, detuned, and set to respond (or not) to volume, program change and hold pedal information. The synth responds to MIDI pan information when it's sent to a stereo output pair. In fact, a powerful function of Multi mode becomes apparent when you consider the routing options — see the 'On The Busses' section below. To edit patches within Multi mode, you hold down both the Multi key and the Single key to enter Multi Single mode. From there you can leap from part to part by holding the Multi key and '+' or '‑', then tweak parameters on any part. This is ideal for live sequencer work, because if you set the knob mode to Jump or Relative (see the 'Knob Power' box), you can incremement or decrement any value smoothly, regardless of the settings in other patches.

On The Busses

The Virus offers very flexible routing, with its total of six outputs and two inputs. But that's not all: there are also two stereo internal busses, Aux 1 and Aux 2. In Multi mode these busses may be used as the output for one patch, then routed to an input of a second patch. This means that you can successively process a signal through different synth sections, either using the internal busses or by patching out (via one of the six outputs), then returning via the external signal inputs. Thisis the key to why it's no bad thing to have more multitimbral parts than polyphony in the Virus: you can use the buss system to 'connect' several patches in this way, effectively processing a sound several times in several parts. And, of course, your sound might not even use the synth's oscillators at all, but instead be taken from one or both of the two external sources.

Input selection works in two ways: Dynamic and Static. The former requires that the envelopes be triggered by playing a key, and treats the external source in very much the same way as one of the Virus's own oscillators. Static Mode is fun because you needn't worry about triggering anything — the envelopes are deactivated, leaving you free to filter the sound and process it via the stereo VCA as you wish. For example, you could patch in a drum machine and have it loop merrily round while an LFO from the Virus slowly sweeps the filter, resonance or pan. Instant trippy fun!

The Fat Controller

The Control Menu is where you find MIDI settings, arpeggiator parameters, velocity and assignable controller destinations, and a few other useful things. Poly or Mono modes are set here, with four mono settings to mimic different triggering and portamento modes of monosynths. There's no unison, however.

A modulation matrix of three assignable controllers and up to six programmable destinations and amounts is accessed via the Control Menu. The sources available are: Pitch Bend, Channel Pressure, Modulation, Breath, Controller 3, Foot Controller, Data Slider, Balance, Controller 9, Expression, Controllers 12‑16, Hold Pedal, Portamento Pedal and Sostenuto Pedal.

Destinations may be chosen from an extensive list of over 70 options, including Volume, Pan, Pulse Width, Digital Waveform Selection, FM Amount, Filter Cutoff, Filter Resonance and Filter Envelope Amount — in fact, pretty much anything you're likely to feel like tweaking during performance. For example, if you want to use a modulation wheel to control something obscure like Twin Mode detune amount, or increase the chorus mix via aftertouch, the Virus makes it possible. You can even get effects similar to a Microwave wavetable sweep with a modulation destination of 'Waveform Select'.

As well as the above controller matrix, velocity can be set to control any (or all) of the following: Osc1 Shape, Osc2 Shape, PulseWidth, FM Amount, Filter1 EnvAmt, Filter1 EnvAmt, Resonance1, Resonance2, Amplitude, and Panorama.

The Virus is well‑endowed in the MIDI department — not only do all the dedicated knobs send and respond to MIDI control changes, but those extra parameters accessed through the LCD are available over MIDI too. Since MIDI has a limit of 128 controllers and some of these are reserved for standard use (Volume, Pan, Sustain, and so on), Access have taken the innovative step of allocating some parameters to Polyphonic Pressure commands. Thus, MIDI controllers are used for the most common functions and the more obscure ones (LFO3 Key Follow, for example) are assigned to a Polyphonic Pressure 'note' (Poly Pressure specifies an individual controller curve for each note and is rarely used). You have the option of using SysEx instead, if you wish, but for ease of editing afterwards, I suggest using the controller/pressure method which is the default (the manual lists all the controller and pressure assignments).

Other slick touches in the MIDI spec include the ability to force an incoming SysEx dump into the Virus patch bank of your choice (A or B), or to the edit buffer if you're ultra‑cautious or just wish to audition patches. This removes any risk that sounds you picked up from the 'net could overwrite valuable stuff already in the synth.

Tucked away in the Control menu, under the CTRL button on the front panel, the arpeggiator is pretty basic, with up, down, and up & down options. It will also arpeggiate notes 'as played' over a range of 1‑4 octaves. The Virus is equipped with a dedicated clock generator which can trigger the LFOs, control the arpeggiator and set the delay in terms of note values. In Single Mode, each patch has its own clock tempo, which is stored along with it. In Multi Mode there's a single clock tempo to which you can sync the LFO and arpeggiator for each part. Each patch has its own arpeggio settings, and in Multi Mode these are maintained, although based on the single 'Multi Clock' setting. Layered arpeggios are cool, and varying the intervals really does extend the capabilities of the arpeggiator, as some of the example Multis demonstrate superbly. If the Virus detects MIDI clock from a connected sequencer it automatically synchronises to it — the internal tempo setting is ignored — and when it's no longer receiving external MIDI clock information the internal tempo setting is automatically activated.


I think we all agree that names are far better than numbers, but it seems weird to call a synthesizer after something we usually want to avoid! Nevertheless, the Virus is an infectious beast, offering plenty of programming potential to both the novice and more seasoned campaigner. This is a beautifully crafted instrument, its two‑tiered approach producing a balance between power and accessibility.

I've noticed occasional hanging notes or other mysterious glitches with output settings during my time with the Virus, but since I upgraded to version 1.51 these have diminished (though they've not entirely disappeared). And while I'm voicing a few complaints, I don't really find the table‑top format of the Virus useful (although it looks nice) and I think a unit such as this should always be easily rackmountable. If you want to rack the Virus, you have to buy a kit, and I can't report on this as I haven't seen one. However, since the connectors would be at the top of the instrument if it was racked, some extra space would need to be reserved in your rack for them.

Sonically, my only reservation is with the Virus's bass end, which seems to lack a little depth. As a pad machine, or for driving sequences or arpeggios, it's incredibly successful, and the filters are superb — ideal for the dance crowd. The Operating System still hasn't stopped growing, and already an enthusiastic user list has appeared on the 'net comprised of people who are constantly requesting new things they'd like in the next revision (I'd like to see a unison mode implemented, as well as note reserve for multitimbral use).

As a multitimbral analogue synthesizer, the Virus takes some beating. I recently used it for a series of backing sequences for a concert, sometimes for six or seven simultaneously blipping, thudding, tapping and chirping layers. I simply didn't need anything else and can think of no other single instrument that could have achieved the same results with so little fuss. If you've previously decided that all Viruses are harmful, make an exception and risk exposure to this one.

Knob Power

Have Virus solved the eternal problem of knob modes? Until the day arrives when our synths have motorised knobs that leap to their correct positions each time a patch is called up from memory, there will always be conflict between the physical setting of a control and the stored value. Access have thrown all their current answers into this synth, allowing the user to choose from three Knob Modes — Jump, Snap and Relative — according to preference.

  • JUMP does just what it says. You turn a knob and the value jumps instantly to that of the knob's position. The display shows two values — the new value and the stored value — so you can easily return to the original setting.
  • SNAP means that you don't get any change at all until the knob passes the stored value of the parameter. You can see in the display what this value is and a small graphic tells you the direction to turn to reach it (Prophecy owners will be familiar with this approach).
  • RELATIVE is perhaps the cleverest. All knobs are active at all times, and as soon as you start to turn them, the stored value increments or decrements right away. Smoothly. A small black triangle in the LCD shows when the value matches current position. For live use this puts an end to those audible glitches as you play. Knob movements can be sent out as MIDI controllers to record into a sequencer (or control another synth), or the panel can be set to local control only. I'm surprised that there's no 'manual' mode, where the panel settings become the current patch, but I guess it's because there are so many values possible behind the LCD.

Sounds Infectious

The Virus's factory sound set seems to concentrate on resonant, dance‑orientated arpeggios and lush pads, with the expected assortment of basses, leads and wibbly noises. Some of the best examples stand out when you play the demo Multis, with layered arpeggios making much of the simple arpeggiator's capabilities — hold down a chord and get a wash of strings, bassline, kick drum and other rhythm parts, with some note ranges still available for a heavy sync lead higher up the keyboard. Some notable single patches are:

A2 Virus: an arpeggio with a filter sweep. A74 J.Arnold: atmospheric pitched noise. A85 and A99: both usable fat bass drums using filter resonance. B37 IQ Pad: a warm pad livened up by the use of Split filter mode, which adds burbly Sample & Hold effects to Filter 2.

The Factory Multis give a great illustration of what is possible — try Multi M2, Scream, which is a bass drum, hi‑hat pattern and arpeggio with a raunchy lead voice, or M3, Arpeggi, which is another example of the power of arpeggiators when layered.


  • 16‑part multitimbral virtual analogue synthesizer.
  • Excellent filters.
  • A good balance of hidden power and instant tweakability.
  • Excellent 'Relative' knob mode.


  • External power supply.
  • Arpeggiator is a little basic.
  • No patch compare facility.


Well worth the wait, the Virus is a multitimbral 'analogue' toolkit in a neat container. The filters are beautifully implemented and construction is first class.