Features & specifications

General

  • included power supply:
    110-220V AC, 50-60Hz > +15V DC 2.5A
    DC plug : 5.5 × 2.5 × 10mm, center positive

  • 404×227×57mm

  • 3.8kg

  • hi-gloss transparent plexiglas + powder coated steel

Voices

  • analog

  • stereo panning per oscillator (OSC2 - OSC5)

  • • 5-voice polyphony with ALT’s mechanical keys or sliders

    • monophonic or voice splitting (4-voice polyphony) with midi keyboard

  • • 1 VCO - sine waveform

    • 4 DCOs - saw or triangle waveforms

    • 1 white noise generator

  • OSC2 - OSC5 can be quantized individually to a scale

    15 scales preset - all can be edited and microtuned.

    • chromatic

    • minor 7th

    • minor pentatonic

    • minor diminished

    • minor natural

    • major 7th

    • major pentatonic

    • major

    • whole tone

    • just intonation (5-limit) major

    • sanza

    • anchi hoye

    • hijaz

    • balinese pelog

    • insen

  • • OSC1 (sine): 8 Hz to 8372 Hz

    • OSC2- OSC5 (saw or tri): 16 Hz to 9000 Hz with matrix modulation

  • • OSC1 (sine): 8 octaves with coarse, 1.5 octave with fine

    • OSC2-OSC5 (saw or tri): 2 octaves

  • amplitude trigger for each voice

Alter

  • 2 stereo Sallen-Key type in series

    hi pass / lo pass crossfade transition - allows for band pass / low pass (4 poles) / high pass (2 poles) depending on filter 1 and filter 2 configuration

    self oscillating at maximum resonance

  • BBD based emulation, analog core with digital repeats 30ms to 1.5s

Movement

  • 4×19 matrix

    connections made with provided 2mm banana pins

  • 4 sources:

    • 2 LFOs - square to triangle shapes (morphing) + high rate switch for FM and AM

    • 1 random step generator (sample and hold) with +/-2V offset + slew switch

    • 1 envelope follower (Outline) with amplitude, release, and invert control

    Outline sources: built in electret microphone / internal gates (oscillators keys) / 3.5mm jack external source (audio or CV +/-5V)

  • 19 destinations:

    • master volume (pre-delay)

    • OSC amplitude (5)

    • OSC frequency (5)

    • noise amplitude

    • LFO1 frequency

    • LFO2 frequency

    • Random frequency

    • filter cut off (2)

    • delay time

    • arp

  • • LFOs: +/-10V
    lo 0,01Hz - 10Hz
    hi 0,7Hz - 1190Hz

    • Random: +/-10V
    0.1Hz – 30Hz
    MIDI clock (1/8, 3/4, 1/4 , 1/2, 1, 2, 3/2, 4, 8)

    • Outline: 10V/0V or 0V/+10V (invert switch)

  • 2 light sensors modulating pitch and volume

    (theremin-like gestures)

Inputs & Outputs

  • • 3.5mm TS - Outline in - cv or audio - (assignable to the pin matrix as a modulation source)

    • 3.5mm TS - CV master pitch, ±5V, 1V/octave

    • 3.5mm TS - CV gate VCA master, ±10V

  • • 3.5mm TRS or USB-C

    features: master pitch, pitch bend, velocity, aftertouch, clock, adsr, portamento

    mode 1: voice splitting - 4 voices polyphony

    mode 2: monophonic

    mode 3: monophonic transpose only (no velocity)

    mode 4: real time scale edit (chord progressions)

    adsr envelope (cc 73/75/70/72)

    portamento (cc 5)

    MIDI oscillators selection: OSC2-OSC5

  • • 3.5mm TRS – headphones

    • 6.35mm TS – left/mono

    • 6.35mm TS - right

Every ALT is carefully built
and tuned in our workshop in Paris,

with lots of love

and sometimes a few tears.