A recent addition to the Virsyn product line is Matrix, a vocoder plug-in that is available in all popular formats for both Mac and PC. While Matrix is relatively new, it has already reached version 1.1.1 and, in this release, becomes one of the first plug-ins to support Steinberg's new VST3 technology.

Traditionally, vocoders provide a means of applying the spectral characteristics of one sound (usually termed the modulator) to another sound (termed the carrier — see Gordon Reid's 'Synth Secrets' article from the July 2000 issue of SOS for a detailed explanation of vocoding). The carrier determines the basic tonal character of the sound, but the amplitude and frequency content is modified by the modulator. Many vocoders, Matrix included, also include their own synthesis engine (termed the Generator in Matrix) to generate the carrier, and this internal carrier can usually be controlled, via a MIDI keyboard, to pitch the output.

When it comes to applications, perhaps the most common modulator is provided by a vocal source, while the carrier might typically be a synth sound or other instrument such as a guitar — and the robotic or synthetic vocal sounds created can vary from the joke record cliché to the dance-track hit. So is the output from Matrix novelty naffness or Daft Punk cool?

Matrix performs a spectral analysis of the modulator signal using a 32-channel filter bank and identifies the spectral energy in each channel. The signal is also analysed to detect the voiced (with a distinct pitch) and unvoiced elements of the modulator input. At the output end, the analysis of the modulator input is applied, via a synthesis filter bank, to the carrier signal. The supplied PDF documentation indicates that the software uses very precise analogue modelling eight-pole filters, extremely fast envelope followers and high-quality algorithms for the detection of the voiced/unvoiced elements and pitch extraction. A white-noise generator is also included for the processing of...