alm-busy-circuits/mco

MCO (mkII)

ALM Busy Circuits

Compact digital multi-voice synthesiser in 6HP with 8 synthesis engines (wavetable, additive, JP-style digi-synth, vocoder, virtual analog, bass/kick, SID chip emulation, vocal formant), 4-voice chords, internal envelopes and LFOs, dual audio outputs, and assignable CV inputs.284

Capabilities 4

Additive Synthesisadditive-synthesis
ToneSum voice produces tones from twelve combined sine waves with harmonic distribution, detuning, and spectrum shaping controls.284
Chord Generatorchord-generator
Global chord parameter supports up to 4-voice chords with standard 12-tone shapes plus 4 unison detune options; chord inversion supported; controllable via external CV.284
Vocodervocoder
Sylon voice provides full vocoder and FFT-based reconstruction with Classic and Spectral modes, bit crushing, slew control, and formant shifting.284
Wavetable Oscillatorwavetable-oscillator
DigiWave voice produces two simultaneous morphing waveforms from factory or user-uploaded wavetable bank with sub oscillator output.284

Jacks 6 — 4 in / 2 out

NameSignalVoltageDescription
Inputs (4)
CV1cv0V to 5V284
Ext InmixedAudio-rate input for FM, hard sync, ring mod, or external audio processing (e.g. vocoding). Function depends on the currently selected voice program.284
Trig InmixedCan function as gate (triggers ADSR envelope) or trigger (triggers AD envelope) for the internal VCA; can also be reassigned as a direct CV input for VCA level or as a general assignable CV input.284
V/Octcv284
Outputs (2)
Out Aaudio284
Out BaudioSecondary output; in DigiWave outputs the sub oscillator (1 octave down) with selectable shape; in other voices outputs stereo or sub depending on voice program settings.284

Parameters 57

NameTypeRangeBehavior
ABMixmenu_settingControls the Morph, Splice or Mix amount setting depending on which MixMode is selected.284
BDetunemenu_settingDetune (in semitones) of oscillator B from oscillator A.284
Biasmenu_settingAsymmetrical bias (positive DC-offset) that causes the positive half of the wave cycle to distort sooner.284
Chordmenu_settingSelects from an array of standard 12-tone chord shapes plus 4 unison detune options. Chord inversion is stacked with this parameter. Both can be controlled by external CV with defined voltage boundaries.284
Chorusmenu_settingSets the mix of the chorus effect. Sub-parameters: Depth (maximum detune) and Rate (speed).284
Clickmenu_settingIncreases the start frequency of the pitch envelope as a multiple of the base frequency, producing an increasingly sharper click transient. Only available when Trig/Gate is active.284
Complex/Harmonicsmenu_settingControls the levels of all added harmonics. Morphs from 0 to 1/n where n is the harmonic number.284
Crushmenu_settingAmount of bit crushing to be applied to the encoded signal in the Sylon vocoder.284
CrushMixmenu_settingAmount of bit-crushed signal to be mixed in with the output.284
Cutoff (BC8000)menu_settingSets the cutoff frequency of the state variable filter in the BC8000 voice.284
Cutoff (Virtana)menu_settingSets the cutoff frequency of the low pass filter in the Virtana voice.284
Detune (ToneSum)menu_settingChanges the ratio between each harmonic so they are no longer whole multiples, producing an inharmonic hollow sound similar to resonating materials like metal or tuned percussion.284
Disttypemenu_settingType of distortion: Soft, Saturate, Hard, Wavefold, Crush.284
Driftmenu_settingAnalog-style random pitch drift amount for vintage instability feel.284
Drivemenu_settingAmount of distortion applied in the Oomph voice.284
Ext Mode (DigiWave)menu_settingSelects between Hard Sync or FM (frequency modulation) at the External input for DigiWave voice.284
Ext. Mixmenu_settingAmount of direct unprocessed External input signal to be mixed into the output.284
ExtMode (AEIOU)menu_settingUses an external audio source to modulate the vocal synthesis engine: Sync (hard sync to Ext in signal) or FM (Ext in signal frequency modulates the vocal engine).284
Fauxpassmenu_settingTurns down the level of each harmonic by a further 1/n, acting like a high cut or low pass-like effect in practice.284
Filter (BC8000)menu_settingSelects between low-pass, high-pass, band-pass and notch filter types for the BC8000 state variable filter.284
Filter (DigiWave)menu_settingSelects the mode of the optional multimode filter: Low Pass, High Pass, Band Pass, or Notch.284
Flipmenu_settingMultiplies the level of every other harmonic by 2(X-50)%. Reduces level of every other harmonic as Flip increases until crossing 50%, then increases with inverted phase.284
FMDepthmenu_settingSets the amount of internal FM in the Oomph voice.284
FMRatiomenu_settingFrequency ratio of the internal FM modulation operator in the Oomph voice.284
Formantmenu_settingAmount of formant shifting up or down; causes frequencies to hit higher or lower FFT bins.284
Gruffnessmenu_settingSimulates a gravelly voice in the AEIOU voice engine.284
Invert Bmenu_settingInverts the phase of Wave B.284
Mix (A/B)menu_settingCrossfades between VoxA and VoxB phonemes in the AEIOU voice.284
MixModemenu_setting5 algorithms used to morph or combine Wave A and Wave B: Morph, Splice, Multiply, Min, Max.284
Mod Typemenu_settingSID-inspired modulation options: Off (no modulation), Mod (SID-style ring modulation), or Sync (SID-style hard sync). Uses either internal triangle wave oscillator or external input depending on Source setting.284
ModDepthmenu_settingLevel (depth) of the internal vibrato LFO that affects the base pitch of the BC8000 voice.284
Mode (Sylon)menu_settingSelects Classic (vocoder/filters) mode or Spectral (FFT reconstruction with sine waves) mode for the Sylon voice.284
ModRatemenu_settingSpeed of the internal vibrato LFO that affects the base pitch of the BC8000 voice.284
Notch/Freqmenu_settingDirectly affects the level of each harmonic, morphing the frequency response into a notch-like or bandpass-like shape that can be swept across the range of harmonics with the Freq parameter. Similar to a parametric EQ band.284
OscillatorShapemenu_settingFixed shape setting per oscillator: Triangle, Ramp and Pulse. When Pulse is selected, PWM parameter becomes available.284
OscMixmenu_settingMix between oscillator A and oscillator B in the Virtana voice.284
Pitchmenu_settingSets the base frequency of the voice across stacked pages for Octave, Semitone, Cents, and Scale (quantizer). Frequency spans approx. 8 octaves from C0 (16.35Hz) to B7 (3951Hz).284
Pre-Gainmenu_settingInput gain stage for setting the External input signal level before vocoder processing.284
PWMmenu_settingReplaces the last X% of the output waveform cycle with silence to produce a Pulse Width Modulation effect.284
Ratiosmenu_settingSelects the ratio of frequencies between harmonics: Odd (1,3,5,7...), Even (1,2,4,6...), or All (1,2,3,4...).284
Rez (BC8000)menu_settingSets the resonant peak of the filter (narrows the width of the Notch filter).284
Rez (Virtana)menu_settingSets the resonant peak of the low pass filter in the Virtana voice.284
Shape (SIDGuts)menu_settingSelects from classic SID Guts waveform shapes: square, ramps, triangle, and pitched noise.284
Slewmenu_settingUpdate speed of the vocoder or reconstructor; slows down the changes in level for each band.284
Spreadmenu_settingAdds stereo spread between outs A and B by panning each harmonic left and right based on its distance from the fundamental.284
Submenu_settingFrequency that the base pitch will droop down to. Once reaching this frequency the voice will remain there until retriggered.284
SubLenmenu_settingThe time it will take to droop to the Sub frequency. Only available when Trig/Gate is active.284
Tablemenu_settingChooses between Factory wavetable (MCO wavetable without the noise wave) and User-definable waves. User tables are split into 4 groups of 16 waves, further divided in half with first half to Wave A and second half to Wave B.284
Thumpmenu_settingTime it takes to drop from the starting click and base frequencies. Only available when Trig/Gate is active.284
Vibratomenu_settingPitch modulation to simulate a shaky voice or controlled vibrato. Sub-parameters: Vibrato (depth), RateHz (rate), Shape (waveshape).284
VoxAmenu_settingThe primary phoneme for the AEIOU vocal synthesis voice.284
VoxBmenu_settingThe secondary phoneme for the AEIOU vocal synthesis voice.284
VoxTonemenu_settingBlends between different voice types in the AEIOU vocal synthesis engine.284
Wave Amenu_setting284
Wave Bmenu_setting284
Waveformmenu_settingSelects from 4 JP8000-inspired waveform types (Supersaw, Triangle Mod, Noise, Feedback) each with 2 sub-controls.284
Whispermenu_settingSimulates a whispering voice in the AEIOU voice engine.284

Firmware history 7 versions

VersionReleasedNotes
106Multi-mode filter added to DigiWave. Preset manager in Settings can now be modulated to load User presets with CV. '+ Random' preset added to end of Voice's preset lists. Setting added for changing AXON-2 A/B functions.284
105New AEIOU voice (formant based vocal engine) added. Stereo mode added to DigiWave under Out B options. Modulation is now smooth for continuous controls.284
104Chord list updated to match new Cizzle list for NOH Modular Pianist module support. Adds Diminished, Minor 9 and Major 9 chords; removes Major 4.284
103Quantizer added to Pitch stack (standard Pam scales + 3 user scales). New LFO One-shot mode added. New LFO shapes: Trapezoid, Exponential, Logarithmic. Chorus added to Virtana voice. Offset and Attenuation pages now show parameter values. Octaves and Fifths swapped in Chord list to match Cizzle.284
102DigiWave resyncs when triggered. Voices that support resync only do so if the envelope is closed. Fixed Sylon hanging on preset load.284
101Boot graphic changed. Level control now saves properly. Smoother envelopes.284
100Initial release firmware.284

References 2

  1. [284]
    ALM046 'MCO (mkII)' Operation Manualmanual
    verified 2026-05-07
  2. [285]
    ALM MCO (mkII) product pageproduct_page
    verified 2026-05-07