A virtual analog synth produced by Access Music in Germany, and widely used in electronica. The first Virus models went into production in 1997. The Virus is by far Access' most popular product, and is currently its only product.
Various models and variants have been produced, but these can be divided into four major revision groups, known as A, B, C and TI. The Virus A was the original version that went into production in 1997. Its voice architecture consisted of two oscillators, two filters, three LFOs, and a small modulation matrix for flexible routing of modulation signals. After the introduction of the Virus B models, an operating system update added a third oscillator to the architecture, and all subsequent models have retained this. The selection of onboard effects also improved substantially. The C models increased polyphony to 32 voices, added a vocoder capability, and made numerous improvements in panel layout and I/O. It also greatly expanded the modulation matrix.
The Virus TI models, first introduced in 2007, have introduced a number of new concepts to the line. "Total Integration" (what the TI stands for) allows the synth to appear as a plug-in on a computer; processing can be offloaded to the computer to increase the complexity of possible patches, as well as to exchange waveforms and other purposes. The TI models have began moving the Virus line away from being strictly a virtual analog synth; these models have introduced wave scanning and granular synthesis capabilities, as well as complex filter types such as formant filters.