DISC Dave Smith Instruments Tetra Polyphonic Synthesizer Module

Full Description

The Tetra has four assignable parameter controls per program and a row of controls dedicated to the most commonly used performance parameters. All parameters are accessible from the front panel and the synth is fully programmable. More comprehensive tweaking is available via the free downloadable editor for Mac OS and Windows. The Cutoff and Resonance controls are potentiometers, allowing full sweeps with a single turn, while the other rotary controls are detented encoders.

Audio and M.I.D.I

The four audio output jacks offer output in mono, stereo or per voice, plus there is a headphone out. Standard MIDI in and out jacks and USB provide MIDI communication, plus the dedicated MIDI output Poly Chain Out is used to chain multiple instruments for increased polyphony.

Oscillators and Envelops

The Tetra's voice output is based on the Prophet '08, but it adds a sub-octave generator for each oscillator and a fully-programmable feedback loop for each voice. It breaks down to two DCOs, a resonant low-pass filter, three DADSR envelope generators, four LFOs, deep modulation routing, an arpeggiator and a 16 x 4 analogue-style step sequencer per voice. Feedback produces effects ranging from mild distortion to extreme harmonic instability, and the audio signal path is 100 analogue.

Program Modes

Tetra has three different modes: Program, Combo and Multi. In Program Mode, it functions as a four-voice polyphonic synthesizer with four banks of 128 programs. Each program contains two layers that can be used to create keyboard splits or stacked sounds. Banks 1 and 2 are the Prophet '08 factory programs, while banks 3 and 4 are a combination of Mopho and new programs.

In Combo Mode a different program can be assigned to each of the four voices. Combos can be used for mammoth unison patches or for triggering up to four different 16 x 4 sequences simultaneously. They can also be used to create polyphonic patches where each voice plays a different program with a slight variation on the same sound or even a drastically different sound.

The Tetra in Multi Mode is a multitimbral sound module capable of playing four monophonic parts on four MIDI channels, with separate outputs for each voice. When coupled with a MIDI sequencer and DAW it can play complex arrangements or analogue drum parts with each part individually processed and recorded to its own track.

Expansion

Up to four Tetras can be poly chained for eight, twelve or sixteen voices in total. When used with a Prophet '08 up to two Tetras can be poly chained for a maximum of sixteen voices, with the Prophet actings as programmer and control surface. For five-voice operation, a Mopho can be connected to the Tetra.

Features/Specifications:

• Multitimbral four-voice analogue synthesizer
• 100 analogue signal path
• Two oscillators per voice (sawtooth, triangle, saw/triangle, square with variable pulse width) with hard sync
• White noise generator
• One classic Curtis low-pass filter (switchable 2- or 4-pole) per voice, self-oscillating in 4-pole mode
• Analogue VCAs
• Three envelope generators (ADSR plus delay) per voice
• Four LFOs per voice
• Two sub-octave generators (one octave down and two octaves down) per voice
• Feedback loop per voice with programmable level and gain
• Four assignable performance controls per program
• Gated 16 x 4 step sequencer (one sequence per program)
• Arpeggiator
• Fully programmable (free downloadable software editor for Mac OS and Windows)
• 512 programs organized into four banks of 128; 128 combos
• I/O: USB 2.0 (type B receptacle), MIDI In, MIDI Out/Thru, Poly Chain Out, Audio Outs 1/Left, 2/Right, 3, and 4 (1/4" unbalanced), 1/4" Headphone Out