Composable Monosynth

Six oscillator models, five filters, four knobs each

Composable Monosynth

The Monosynth is a tracker instrument. It plays one note at a time. It has three oscillators, one filter, two envelopes, one LFO, and a set of stages that colour the result.

Each oscillator chooses one of six synthesis models. The filter chooses one of five topologies. The number of controls does not change when you change the model or the topology. Each one has four controls, and each one interprets those four controls in its own way.

This page states what each control does in each model. Read it beside the instrument.

Why the controls are reinterpreted

A synthesizer that gives every model its own controls ends with sixty of them. This one keeps four per model and pays for that in this page.

The benefit is that a stage written once works everywhere. Unison applies to any oscillator. The sweep envelope points at any of four destinations. Ring modulation multiplies any two slots. You can therefore build combinations that no instrument ships, and they cost nothing to build.

The cost is that Timbre means pulse width on one model and modulation index on another. The table below is that cost, paid.

The oscillator controls

Three oscillators, called Osc 1, Osc 2 and Osc 3. Each has a model and four controls.

Control	Analog	Supersaw	Wavetable	2-op FM	Additive	Phase distortion
`Shape`	Saw to square to triangle	The same, for every copy	Which waveform to read	Carrier-to-modulator ratio, in steps	Tilt of the harmonic series	Which warp curve
`Timbre`	Pulse width	The same, for every copy	How far the waveforms blend	Modulation index	How many harmonics sound	How far the phase bends
`Character`	Sub-oscillator level	The same, for every copy	Automatic sweep through the waveforms	Modulator feedback	Odd against even harmonics	Resonant window
`Detune`	No effect	Spread of the copies, in cents	Spread of the copies	Spread of the copies	Spread of the copies	Spread of the copies

Notes on the table:

Supersaw is the analog model with more than one copy. Every other model can also run several detuned copies, through the same Detune control. A detuned additive oscillator is available and no instrument ships one.
Timbre at zero is the plainest form of every model. Four of the six produce a plain sine there. Turn it up before judging a model.
The FM model gets quieter at the top of Timbre on high notes. That is deliberate. The alternative is a cluster of tones unrelated to the note.
The additive model drops harmonics as the note rises. A harmonic above half the sample rate cannot be played, so it is not played.

The filter controls

One filter. It has a topology and four controls.

Control	Ladder	Diode	State-variable	MS-20	Formant
`Cutoff`	Corner frequency	Corner frequency	Corner frequency	Centre frequency	Which vowel
`Resonance`	Feedback	Feedback	Q	Feedback	Formant sharpness
`Filter drive`	Stage saturation	Stage saturation	No effect	Input drive	Input drive
`Filter type`	No effect	Tone	No effect	Distance between the two corners	Voice: adult to child

Notes on the table:

The ladder loses bass as Resonance rises. That is what a ladder does and it is the reason to choose one.
The diode whistles a fifth above its Cutoff, not at it. Three poles instead of four put the whistle there and no setting moves it.
Four of the five whistle at all. Turn Resonance past about 95% and the filter sings on its own, with or without a note. The formant filter does not, and is not meant to.
The formant filter reads Cutoff as a vowel. Sweep it and the instrument speaks. Point the filter envelope at it and it speaks by itself.

The rest of the panel

Control	What it does
`Note`	The note. Playing a note while one sounds slides to it
`Volume`	How hard the note is struck
`Drive / Fold`	Below halfway it saturates. Above halfway it folds, which is a different sound and keeps adding harmonics as you turn it
`Env mod`	How far the filter envelope opens the cutoff
`Attack`, `Decay`, `Sustain`, `Release`	The amplitude envelope
`Osc 2 level`, `Osc 2 tune`	Level and transpose for the second oscillator. Level at zero switches it off
`Osc 3 level`, `Osc 3 tune`	The same for the third

The three macros

A macro moves controls you already have. None of them adds anything you cannot reach by hand, so you can turn one up, find the sound, then turn it down and set the controls yourself.

Macro	What it moves
`Devilfish`	Filter resonance up, filter drive up a little, `Drive / Fold` up, note level up, and the output limiter tighter
`DX7ify`	Fades in a fixed chain: oscillator 1 modulates oscillator 2, and oscillator 2 modulates oscillator 3
`Analogify`	Each oscillator drifts slowly and independently, the timing wobbles, and every stage saturates a little

Devilfish pushes the filter drive by less than you might expect. That control saturates the filter's input, and saturating a waveform makes it darker. The bite comes from Drive / Fold instead, which adds harmonics rather than removing them.

Three things to know before you report a problem

The instrument aliases more when the machine is busy. It measures how much of each audio block it is using and spends the remainder on quality. Oversampling is the first thing it gives up, and oversampling is what keeps Drive / Fold and ring modulation clean. On a loaded machine those two paths get grittier. That is a deliberate choice: a late audio block is a click, and grit is not.

Feedback and maximum resonance are not stable, and are not supposed to be. Turn Feedback up with Resonance at the top and the instrument will scream. It is guarded so it cannot produce a damaged signal, run away, or stall the audio thread. If it screams, that is the control working.

It plays one note at a time. That is what makes three oscillator models at once affordable. A chord needs three instances of the instrument.

What is not on this page

The quality budget's thresholds, because you cannot set them. The safety limits, because they exist to keep the instrument usable and quoting a number invites a request to raise it. The way the instrument is built, because that is not how it is played.