Tetrad is a hybrid instrument based on physical modelling and granular synthesis. A unique quad bus signal chain feeds 4 modelled plates alongside a full modulation matrix, creating a soundscape that rewards experimentation.

Tetrad is like no other synth you’ve ever used. Developed in collaboration with composer and transmedia artist Gadi Sassoon, the plugin takes four oscillators, routes them in combination through a Quad AM processor that works like a pseudo-sequencer, a specifically tailored Granulator, and four physically modelled plate resonators.

Inspired by Gadi’s sculpture-based synth installation, as heard on the album Modes of Vibration, Tetrad was originally devised as a complement to the slashed plates and sound generators of the experimental setup, but has grown into a plugin instrument that puts the capabilities of the installation into a single piece of software in a DAW.

How Tetrad Works
It starts with the oscillators, which give a choice of five modes, each with four oscillators per voice (hence the name Tetrad). In the  Macro view, you can change the main oscillator waveshape, and apply frequency modulation. Oscillators can be tuned in  various ways according to the chosen mode, from basic intervals to diatonic inversions. An ADSR provides initial amplitude shaping before heading down to the mixer. There is also a Sidechain audio option, bypassing the oscillators and allowing any signal to be used.

A 4×4 Matrix Mixer blends the four inputs onto four busses. Next is Quad Amplitude Modulation with Depth, Shape and Rate, which works well into the audio range, and Phase set individually per bus. In Tetrad’s Quad Granulator, the signal is split into grains that are replayed in different ways. You can affect the grains’ window shape, Size, Pitch, and change the Feedback of the granulator. Finally this feeds the Plates through a preamp with overdrive.