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Clef B30 Microsynth

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The Microsynth operates in two modes depending on the configuration of VCO2, as shown in the block diagrams. In the first mode both VCOs run at audio frequencies and manual modulation of pitch, etc, is available via the thumbwheel. In the second mode, VC02 is configured as a low frequency oscillator (LFO) and can be used to modulate the keyboard, filter, VC01 mark/space, etc, trigger the envelope shaper, and so on. The thumbwheel can be used to introduce LFO modulation manually.

A notable feature of the Microsynth is that with VC02 switched to "RM" or ring modulator mode, it still runs at audio frequencies and tracks VCO1 very accurately, but its output is via the modulation routes only. Thus instead of being added, the waveforms from the two oscillators are multiplied together producing sum and difference tones. This, together with the sub-octaves, underlies the remarkably rich sounds that the Microsynth can produce.

Having VC02 switchable in this way is not a drawback as it may at first seem. In a unit as compact as the Microsynth it was felt that it was impractical to have a second VCO and an LFO and do justice to both, and so the switchable VCO is felt to be a reasonable compromise. Even with only one VCO operating the sub-octaves can be used to give rich harmonic structures, while waveform modulation or other effects are created by the LFO. Pitch bending can be introduced manually with the thumbwheel. With both VCOs running at audio frequencies the lack of a separate LFO makes little difference — the thumbwheel allows expression of various sorts to be imparted manually, while vibrato may be created by setting the two VCOs slightly apart to give a slow beat.

One feature of the Microsynth which is sadly lacking from many commercial designs is that all modulation routes enable the device being modulated to be swept over its entire range, enabling extreme effects to be produced. Another feature which is unusual in smaller synthesisers but which is very powerful, is the inclusion of a separate sample and hold (or analogue memory). This samples the waveform from VC02 each time the envelope shaper completes a cycle and can be used to create either staircase or random.

Technical Specifications
Type: Analog
Synthesis: Subtractive
Oscillators: 2
Waveforms: Saw Down, Saw Up, Square, Triangle, White Noise
Osc Modulation: Glide / Portamento, Input, Keyboard, LFO, Oscillator, Pitch Wheel
Envelopes: 1
Evelope Paramerters: Initional Level, Attack, Decay
Filters: 1
Types: Low Pass, Resonance
Filter Modulation: Knob, LFO
LFO: 1
LFO Parameters: Saw Up, Saw Down, Square, Triangle
Polyphony & Tuning
Polyphony: 1
Timbrality: 1
Tuning: Standard
Modes: Mono
Case: Keyboard
Keyboard: 25 keys, Non-weighted, Plastic
Controls: Knobs, Switches, Pitch -Wheel
Display Type: LED
Audio Output Connections: 1/4" Phone Jack, Mono Out
CV Ports: CV IN
Control Features: Proprietary Sequencer DIN port
Year Released: 1982
Design Notes:

The PE Microsynth was a series of constructional articles which appeared in Practical Electronics magazine in 1982
Used Price: $700 - $2,000 - convert
References & Sources

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