Access Virus

The Access Virus is a German made virtual analog synthesizer which was first produced in 1997 and has since been upgraded frequently, with the company releasing new models about every two years. The latest of these are the Access Virus TI, Polar and Snow models, the first two of these were released in November 2005, the Snow has been released in February 2008. The term Access Virus can be used to refer to any one of these synthesizers. The Virus series also has come out with two software plugin versions: TDM for Pro-Tools and VST for TC Electronic Powercore series.

Technical details

All of the Viruses are DSP-powered, virtual analog synthesizers. They have classic analog-style oscillators which can be tuned continuously from a pure sine wave to a square wave (with variable pulse-width modulation), as well as 63 "spectral" waveforms which are entirely synthetic, non-analog style waves. With the TI series new oscillator models were added like Hypersaw and Wavetable oscillators. The Virus comes with many different types of analog styles and digital distortion, as well as filter saturation.

The filter section is highly customisable, compared to most other synthesizers, with the Viruses having two independent resonant filters that can be combined in various ways to produce a unique sound. The synthesizer is somewhat a modular synthesizer with many routing possibilities, particularly in the envelopes.

An outstanding feature of the TI series is "Total Integration": It is currently the only synthesizer that can be fully integrated in a current computer based audio workstation as a VST or AU plugin, including the advantages of sample accurate MIDI timing, host automation as well as total recall.

Series comparisons

The Virus has had 3 major hardware revisions since the original Virus A model as well as having numerous features (both minor and major) added via firmware operating system updates. The Virus engine has largely remained the same since the Virus A up until the Virus C. They all utilize a single Motorola DSP chip and the sound is identical between models when not factoring in the additional features provided by each hardware and firmware upgrade.

The latest incarnation of the Virus, The TI, utilizes 2 DSP chips and represents the most significant technical overhaul of the Virus series since its inception.

However and despite the additional features, the Virus is essentially still a virtual analogue subtractive synthesizer with some limited frequency modulation capabilities. That is, a digital synthesizer designed to emulate the characteristic sound and behaviour of analogue synthesizers whilst also retaining some digital features in order to broaden its sonic palette. What separates the Virus from other analogue modelling subtractive synths in its price range is its twin multimode filter design and extensive modulation matrix, both of which are unique to the Virus. As of the Virus B OS4 update, it has 3 oscillators per voice (+1 sub oscillator per voice) with 2 filters per voice.

The basic Virus analogue modelled oscillators between the Virus A and TI are identical with the only difference being the number of voices available as well as the additional Hypersaw oscillator and digital wavetable oscillators of the Virus TI. Additionally, the raw Virus oscillators have much less high frequency content than the oscillators you will find on other subtractive virtual analogues such as the Clavia Nord Lead and Roland JP-8000. This partially explains the Virus's characteristically dark and bass heavy sound.

The twin multimode, highly resonant filter is also an important aspect of the Virus sound, which has remained unchanged between hardware revisions. The only exception is the addition of a new Moog emulation filter type that was added for the Virus C and thereafter.

Both Virus filters can be connected in series, parallel or set to process 2 oscillators independently. The routable nature of the filter allows the Virus to emulate an 18 dB/octave 3 pole filter for instance, by routing a 24dB/octave 4 pole filter in series with a 12dB/octave 2 pole filter, then turning the filter balance to 3 or 9 o'clock. Connecting a 4 pole filter in series with a 2 pole filter also allows for a 36dB/octave 6 pole filter configuration, which is unique amongst similarly priced virtual analogues. The interchangeable filters allow for such things as simultaneous high pass and low pass sweeps and filter modulation effects such as automated filter sweeps whilst still leaving a filter free for manual use.

Perhaps the most integral part of the Virus specification yet to be mentioned is its modulation matrix. Every parameter on the control surface of the synth and every parameter in every sub menu can be set as a modulation destination. The Virus also has a long list of modulation sources, including a random trigger. There are 3 modulation sources on the Virus A and B, which can be set to control 6 destinations. The Virus C and TI both allow for 6 modulation sources controlling a possible 18 modulation destinations. This does not include the 3 LFOs which can be set to modulate oscillators 1 and 2, pulse width, resonance and cutoff of both filters, stereo pan and any parameter you set as a source in the modulation matrix. Simultaneously if desired.

It is possible to emulate the instable tuning of analogue synthesizers by setting a random source to modulate the pitch and detune of 1 or more oscillators such that every time you strike a note, its tuning will be very subtly different. The modulation matrix also allows for recursive modulation - setting a variable to modulate itself. This plays an important role in altering the behaviour of many of the control variables on the synth. For example, the Virus amplifier attack envelope is linear by default but can be changed via setting the amplifier envelope as a modulation source that modulates itself as its destination.

The Virus also has a complement of DSP effects, including a versatile distortion unit that allows for rectification, analogue modelled and digital distortion as well as bit reducing and samplerate reducing effects. Owing to the 'blank slate' nature of many variables on the Virus (until you configure their action in the modulation matrix of course), the effects section is largely presented as yet another set of sound shaping tools on the synth. The Virus C and TI also includes a 3 band EQ for even more sound shaping flexibility.

Lastly, the Virus has always been 16 parts multitimbral for multilayered patches and ensemble performances. However, up until the Virus TI, this aspect of the Virus has been severely flawed and is often considered unusable because of the polyphonic limitations of the Virus A, B and C and the lack of analogue outputs on the synth.

The programming methodology for a Virus A is largely the same as that of a Virus TI and so are the bulk of the sounds produced. The additional oscillators, higher polyphony, extra filter type, the EQ and revised control surface and sequencer integration of the TI however, allow for a greater palette of possible sounds over previous revisions although the Virus B and C models have aged well and still compete favourably with recent iterations of analogue modelling synthesizers. The are hardware alterations made to the TI such as the newly added balanced inputs/outputs, 24 bit/96 kHz output and the new sequencer integrated interface.

The Virus TI Snow has been unveiled at Winter NAMM 2008. It is a stripped down version of the TI Desktop. The Snow is patch compatible with the rest of the TI line. It is much smaller, sporting a minimalist interface and utilizes a single DSP chip giving it about half the polyphony and only 4 parts of multitimbral capability.

External links

* [http://www.access-music.de Official site]
* [http://infekted.org http://Infekted.org ~ The Unofficial Access Virus and Virus TI Forum & Community (formerly Sunesha.nu) since 2002. All The Latest News & Resources.]
* [http://www.vintagesynth.com/misc/access_virus_chart.pdf A side-by-side comparison chart between the various models (in PDF)]
* [http://www.virusti.com Unofficial Access Virus Ti Forum]