cyma forma ALT

cyma forma ALT is an analogue synthesizer for drones, soundscapes and generative melodies, built in Paris in a housing of clear plexiglas and powder-coated steel. Its sound sources are one sine VCO, four saw or triangle DCOs, a white noise generator and a built-in electret microphone, and everything is controlled from sliders and a pin matrix, with no screen and no menus.

An instrument that responds to the room it is in

Two light sensors and a microphone turn ALT into an instrument coupled to its surroundings: a shadow over the left sensor controls master volume, over the right it controls the frequencies of oscillators 2 to 5. An envelope follower called Outline takes signal from the microphone, from internal gates or from the minijack input and can modulate any of nineteen destinations. The instrument therefore locks to a voice, a clap, a drum machine or a CV sequencer, which is what solves the usual problem in ambient work and installations: drones that sit still and go dead.

Menu-free control that stays in tune

Oscillators 2 to 5 can each be quantised to one of fourteen scales in equal temperament or just intonation, and scales are editable on the fly, with notes removed and brought back for modal changes mid-performance. The effects section runs two analogue stereo Sallen-Key filters in series, crossfading from lowpass to highpass and self-oscillating at maximum resonance, plus a stereo BBD-style delay capable of infinite feedback. A 4 by 19 modulation matrix patched with 2 mm banana pins puts all of it within reach without digging through a display.

KEY FEATURES

• Five tonal sources: 1 sine VCO and 4 saw or triangle DCOs, plus a white noise generator
• Two light sensors and a built-in electret microphone as modulation sources
• 4 by 19 modulation matrix patched with banana pins
• Analogue stereo Sallen-Key filter, two stages in series, self-oscillating
• Stereo BBD-style delay from 30 ms to 1.5 s
• Fourteen editable scales, equal temperament or just intonation
• Five-key mechanical keyboard plus full CV and MIDI support
• Also usable as an effects processor for external signal

TECHNICAL SPECIFICATIONS

• Oscillators: 1 sine VCO 8 Hz to 8372 Hz, 4 saw or triangle DCOs 16 Hz to 9000 Hz
• Polyphony: 5 voices from the keys and sliders, 4 voices over MIDI in voice splitting mode
• Filters: 2 stereo Sallen-Key filters in series, LP to HP crossfade, self-oscillation
• Delay: BBD emulation, analogue core with digital repeats, 30 ms to 1.5 s
• Modulation: 2 LFOs from 0.01 Hz to 1190 Hz, sample and hold random generator 0.1 Hz to 30 Hz, Outline envelope follower
• CV inputs: 3 x TS minijack (Outline in, CV master pitch 1 V per octave, CV gate VCA)
• MIDI: TRS minijack or USB-C, supports velocity, aftertouch, pitch bend and clock
• Outputs: 2 x 6.35 mm TS left and right, TRS minijack headphone out
• Power: supply included, 110 to 220 V AC to 15 V DC 2.5 A, 5.5 x 2.5 mm plug, centre positive
• Housing: hi-gloss transparent plexiglas and powder-coated steel