Physical Audio Tetrad 1.0.2

Tetrad is unlike any sound synthesizer you've ever used. Developed in collaboration with composer and multimedia artist Gadi Sassoon, the plugin uses four oscillators, routing them in combination through a Quad AM processor that acts as a pseudo-sequencer, a custom-designed particle generator, and four physically modeled plate resonators.

Inspired by Gadi's sculpture-based sound synthesis installation, heard on the album Modes of Vibration, Tetrad was originally designed to complement the experimental setup's cutouts and sound generators, but has evolved into an additional instrument, integrating the installation's features into a single piece of software within a DAW.

How Tetrad Works

It starts with the oscillators, offering five mode options, each with four oscillators per voice (hence the name Tetrad). In Macro view, you can change the waveform of the main oscillator and apply frequency modulation. The oscillator can be adjusted in a variety of ways depending on the selected mode, from basic intervals to diatonic inversions. ADSR provides initial amplitude shaping before it is fed to the mixer. There is also a Sidechain audio option, which bypasses the oscillators and allows any signal to be used.

The 4x4 matrix mixer mixes four inputs onto four buses. Next is Quad Amplitude Modulation with Depth, Shape and Speed, which works well in the audio band, and Phase is set separately for each bus. In Tetrad's Quad Granulator, the signal is divided into grains that are played back in a variety of ways. You can affect the window shape, Size, Pitch of the grains, and change the Granulator Response. Finally, this sends the metal plates through a preamplifier with overdrive.