CHAPTER 5 OF 54 · START HERE

The three engines

INK is a polyphonic synthesizer and granular sampler built as three engines. Each engine is a complete instrument with its own sound, keyboard and effects; the three share a mixer, a clock and the outputs. This chapter gives the specifications and the signal flow the rest of the guide refers to.

#Where INK comes from

INK grew out of Plinky, an 8-voice polyphonic touch synthesizer. The Grid, the low-pass gate in every voice, the Matrix and its sources, the arp, the sequencer, the Classic delay and the reverb come from Plinky's firmware, and the engines run at Plinky's sample rate. INK imports Plinky presets and samples (Save and share sounds).

#At a glance

Item	Specification
Engines	3, each with its own sound, keyboard, key, effects and MIDI
Polyphony	8 voices per engine, 24 in all
Generators	Supersaw, Pulse, Wavetable, Granular sampler, Phase
Voice	Generator with Noise and Distort, low-pass gate, SEM-style multimode filter
Per engine	Sub oscillator; Chorus or Phaser; Delay (Classic, Reverse, Octave, Ping-Pong); Reverb with Shimmer; three-band Multiband; MIX for the engine's level, high-pass, stereo width and wet/dry balance
Modulation	Matrix with 7 sources: Env (Envelope 2), Prs (pressure), A and B (Macro A and Macro B with their LFOs), X and Y (LFO X and LFO Y), Rnd (random)
Keyboards	Grid (8 × 8 pads in key), Keys (continuous keybed), Chords (chord tiles), Strings (strumplate); one at a time per engine
Note playing	Per engine: held notes as played (Free), arpeggiated (Arp) or strummed (Strum)
Sequencer	Up to 64 steps per pattern; 4 banks (A to D) of 24 patterns per project
Sampler	8 slots per kit; mono samples up to 67.1 s
Engine sample rate	31,250 Hz, converted to the device's rate at the output
Formats	iPhone and iPad app, Mac app; AUv3 instrument INK Synth (outputs Main and Engine 1 to 3); AUv3 MIDI processor INK MIDI
MIDI	In and out per engine, MPE in and out, clock in and out. Clock out from the standalone app. The Mac app opens no MIDI inputs: on a Mac, play INK from MIDI as a plug-in in a host

#Three engines

The All page: one mixer column per engine.
1Engine tabs
2All
3Engine 1 column

An engine is a complete instrument. Each engine has its own sound, keyboard, key (Root and Scale), playing pattern, arp and strum, effects, and MIDI input and output.

Tabs 1, 2 and 3 open one engine. All shows the mixer and a keyboard band for each engine (Mixer and All page).

The engines share the project's pattern banks and, with Sync on, one clock (Clock and sync). Their outputs meet at Main; in a host, each engine can leave on its own bus instead.

#Five generators

The generator is the sound source of a sound. Choose it in the generator box at the top of the Sound tab's first section: OSC, or SAMPLER on the Granular sampler. The choice is saved with the sound.

The first OSC knob is the generator's tone control. Its label and job change with the generator.

AT A GLANCEGENERATORS

SupersawA stack of detuned saw oscillators. The tone control, Detune, spreads the saws apart. See Oscillators.
PulseA pulse oscillator. The tone control, Width, sets the pulse width, from square to narrow. See Oscillators.
WavetablePlays a factory or imported wavetable. The tone control, Position, scans through its waves. See Wavetables.
Granular samplerPlays the samples of the sound's kit as grains. The SAMPLER and SAMPLER JITTER sections lead the Sound tab; OSC has no tone control and no LPG Filter. See Granular sampler.
PhasePhase distortion in the style of the Casio CZ. The tone control, Wave, picks the wave; the PHASE section sets the second oscillator and how the two combine. See Phase.

In the Library, the Engine filter shows sounds by generator, not by Engine 1 to 3.

#Voices and polyphony

Each engine has 8 voices. A note takes one voice; a chord takes one voice per note.

How a new note finds a voice depends on what plays it:

Grid: a touch takes its column's voice. If a finger or a latched note already holds it, the touch takes the first free voice.
Keys: a finger takes a voice that no finger and no latched note holds. With Hold on and every voice latched, a new note replaces the oldest latched note.
Chords: a chord's notes take voices that no finger and no latched note holds, silent voices first. When every voice is ringing, the quietest are taken first.
Strings: a pluck takes the voice already playing its note, else a silent voice, else the voice plucked longest ago.
MIDI: a note takes a silent voice. If none is silent, it takes the quietest voice that no key or finger holds and cuts that voice's release. With all 8 voices held, the new note is dropped. While the sustain pedal is down, the note the pedal has held longest gives up its voice first.

A voice in its release counts as sounding. With a long Release, new notes take voices that are still ringing and cut their tails.

#Signal flow

#Each voice

The generator and the Sub pass through Distort; Noise joins after it. The signal then passes the low-pass gate and the Filter.

Distort is a gain stage before the gate. The engine's saturation after the voice sum turns the extra level into distortion.
The low-pass gate comes from Plinky. It is a resonant low-pass whose cutoff follows the amp envelope, so one stage sets level and brightness together. The amp envelope follows the note's pressure, scaled by ENVELOPE's Sensitivity (Amp envelope). LPG Filter sets the gate's resonance (Oscillators).
On the Granular sampler the gate is a low-pass without resonance, followed by a level stage driven by the same envelope.
The Filter is an SEM-style multimode filter in every voice (Filter).

INK reverses the usual oscillator, filter, amplifier order: the gate, which sets the level, comes before the Filter. The Filter receives the enveloped signal.

The Sub is made once per engine, in the voice that plays the lowest held note. It joins before Distort, so that voice's gate and Filter shape it (Sub oscillator).

#Each engine

The 8 voices sum to one stereo signal. The MIX controls act at different points in the chain that follows.

Stage	Where it acts
Saturation	A soft clipper on the voice sum, with no control of its own. Distort drives it harder.
High Pass (MIX)	After the saturation, before Chorus / Phaser.
CHORUS / PHASER	An insert on the whole engine (Chorus and phaser).
Synth Lvl (MIX)	The engine's level after Chorus / Phaser, into a peak compressor (Reverb and mix).
Stereo Width (MIX)	Mid/side width at the same point as Synth Lvl. Delay and reverb come after it.
Level, Mute, Solo	On the engine strip and the mixer, before the sends. Echoes and reverb tails ring out after the engine is lowered or muted (Mixer and All page).
DELAY, REVERB	Send effects. The delay's Send takes the signal after Level; the reverb's Send takes the same signal plus the delay's output (Delay, Reverb and mix).
Main Wet/Dry (MIX)	The balance of the dry signal against the delay and reverb returns.
MULTIBAND	An insert on the engine's output, after Main Wet/Dry. It adds a small fixed latency at every setting (Multiband).

#All engines

AUDIO OUT sends an engine to Main or, with Multibus in a host, to its own bus, Engine 1 to 3 (INK in a host). It is on the engine sheet, which opens from the key in the top row (Find your way). In the standalone app AUDIO OUT is greyed and every engine goes to Main.

OUTPUT, at the bottom of the Sound and Arp tabs, sets the gain of every output (Mixer and All page). A safety limiter follows on each output.

#Modulation in the chain

The amp envelope modulates the gate only. For a filter envelope, route Env (Envelope 2) to Cutoff in the Matrix. The Matrix sources reach any Matrix row:

Rows inside the voice (OSC, PHASE, SUB, FILTER, PITCH, AMP ENV, ENV 2, and SAMPLER except Sample) read each voice's own Env 2, pressure and Random.
Rows at the engine stages (CHORUS / PHASER, DELAY, REVERB, MULTIBAND, MIX) read the highest Env 2 and the highest pressure of the engine's voices, and one Random value that changes with each new note.
The LFOs run once per engine: every voice reads the same LFO values.

#Base value and modulation

A knob sets the base value. You hear the base value plus all modulation; the knob shows only the base.

Modulation amounts are set in the Matrix, one cell per source and destination (Modulation matrix). The base value and every amount add up, and the sum is held to the control's range.

The guide writes a modulation as source, destination and amount: Prs → Cutoff, +30.

#What belongs where

Where each kind of data lives: the card, a sample, a kit, the pattern list, the project list and Settings.
1Sound
2Sample
3Kit
4Pattern
5Project
6App settings

Kind	What it holds	Chapter
Sound	One engine's generator, every Sound tab section, its Matrix amounts and its arp and strum settings.	Save and share sounds
Sample	One mono recording, imported or recorded, up to 67.1 s.	Import and record
Kit	Eight sample slots. A Granular sampler sound names its kit.	Trim, slices and kits
Pattern	Up to 64 steps of notes, with the pattern's own Tempo, Sync, Division, loop and, when it has one, its key.	Record patterns
Project	The three engines' sounds and keys, Level, Mute and Solo, Audio out, MIDI In and Out, MIDI routes, and four pattern banks.	Projects
App settings	The theme (Paper), touch response, Slide control, each engine's keyboard, MIDI device, bend, MPE and clock settings, and what the Library's play button plays. In a host, the keyboards and MIDI settings are the instance's.	Settings and background audio
Host session	In a host: the project as it plays (sounds, patterns, mixer, held notes) and the instance's keyboards and MIDI settings, saved with the host's song.	INK in a host

Each engine's key (Root and Scale) belongs to the project, not the sound: loading a sound keeps the engine's key (Keyboard, key and scale). A pattern's Tempo belongs to the pattern, so loading a sound leaves it unchanged.

MIDI In and Out and the MIDI routes are set under Settings › MIDI but are saved with the project (MIDI in, MIDI out).

#Try it

QUICK STEPS

On Engine 1, load a Bass from the Library. On Engine 2, load a Pad.
On Engine 1, tap the key in the top row to open the engine sheet, and tap D under KEY. Load another Bass: the key stays D.
On Engine 2, raise Send in DELAY, play a short note and tap Mute (speaker icon) on the engine strip while it echoes. The echoes ring out.
Tap All and play both engines' keyboard bands.