project name:	spre
project url:	https://github.com/puyoma/spre
author:	Puyoma
description:	generative synthesizer with evolving melodies, polyphonic voicings, strum, MIDI, grid, and loopers
documentation url:	https://github.com/puyoma/spre/blob/main/README.md
tags:	synth generative engine midi grid looper softcut

spre

A generative synthesizer for monome norns.

spre combines a 12-voice SuperCollider synthesis engine with five melody generators, eight polyphonic voicings, adjustable chord strum, scale quantization, MIDI and grid performance modes, and two kinds of looping. It can play by itself, respond to an external MIDI keyboard, or become a scale-aware instrument on a 16×8 grid.

The sound moves between clean, resonant tones and saturated, dusty, tape-worn textures. Melody and harmony can be reshaped while the instrument is running.

日本語マニュアル

Requirements

monome norns
16×8 grid: optional
USB MIDI keyboard/controller: optional

spre includes its own SuperCollider engine. After the first installation, shut norns down completely and turn it back on; a software restart may not be sufficient.

Project structure:

spre/
├── spre.lua
├── README.md
├── README_ja.md
└── lib/
    └── Engine_Spre.sc

Installation

In the Maiden REPL:

;install https://github.com/puyoma/spre

After installation, shut norns down completely, turn it back on, then launch spre from SELECT. If only a software restart is performed, norns may report AUDIO SYSTEM FAIL until the next full power cycle.

Quick start

spre starts in AUTO mode and begins generating notes automatically.

Turn E2 to select a parameter.
Turn E3 to change the selected parameter.
When FILTER is selected, turn E1 to choose AIR, GLASS, AMBER, or WOOD.
Press K3 to open the MEL / POLY / STRUM page.
Set FLOCK to zero to stop new AUTO notes.

Start with the norns output/headphone level low. Saturation, resonance, chords, and high FLOCK and RAIN settings can create sudden level changes.

norns controls

These controls work from the main parameter page unless noted otherwise.

Control	Action
E1	When FILTER is selected: choose AIR / GLASS / AMBER / WOOD
E2	Select parameter
E3	Change selected parameter
K2	Jump to the next parameter row
K3	Toggle between parameter and MEL / POLY / STRUM pages
K1 + E1	Cycle parameter, MEL / POLY / STRUM, and visualizer pages
K1 + K2	Octave down
K1 + K3	Octave up
K2 + K3	Clear the selected audio loop, or note-loop slot 1

When LOOP is selected, K2 operates the loop instead of jumping to the next row.

On the MEL / POLY / STRUM page:

Control	Action
E2 or K2	Select MEL, POLY, or STRUM
E3	Choose the melody algorithm or voicing, or adjust strum amount
K3	Return to the parameter page

The visualizer page shows an animated rainy alley and has no dedicated editing controls. Use K1 + E1 to leave it.

Modes

AUTO

The internal generator creates notes from the selected ROOT and SCALE.

FLOCK controls how frequently events are generated. Zero stops new notes.
RAIN is the probability that a generated event will be skipped. At zero, every event plays; at maximum, all events are skipped.
ATK / DEC shape the percussive envelope.
MELODY chooses how pitches move.
POLY chooses how each pitch is voiced.
STRUM spreads notes within generated chords for a looser, human feel.

MIDI

Incoming MIDI notes are quantized to ROOT and SCALE, then played with an ADSR envelope. ATTACK, DECAY, SUSTAIN, and RELEASE become available on the parameter page. A connected grid can also be played as a scale keyboard without leaving MIDI mode.

GRID

A connected 16×8 grid becomes a scale-based keyboard. Notes sound while held and use the same ADSR envelope as MIDI mode.

Melody generators

Name	Behaviour
RAND	Uniform random notes, with occasional octave jumps
GAUSS	Random movement weighted toward the middle of the range
MRKV	Markov-like movement that tends to stay near the previous note
ORBIT	Movement attracted to chord tones, with approaches and occasional jumps
FOLD	A four-note motif that gradually climbs and descends

Polyphonic voicings

Intervals follow degrees of the selected scale.

Name	Voicing
MONO	Single note
OCT	Note plus octave
5TH	Note plus four scale degrees
TRIAD	Note plus two and four scale degrees
7TH	TRIAD plus six scale degrees
RAND	One or two random upper scale tones
ADD4	Note plus two and three scale degrees
JAZZ	Note plus two and six scale degrees

Strum

STRUM controls the timing between notes in AUTO-mode chords. At zero, every note starts together. Higher values spread the note-ons with slight random variation, up to approximately 130 ms, for a strummed or humanized feel. It does not change single-note MONO voicing.

Sound parameters

Parameter	Description
ATK	Attack
DEC	Decay
FM	Pitch modulation depth
BRIT	Tonal brightness
SAT	Saturation and drive
TAPE	Sample-rate reduction and tape noise
FILTER	E3 controls cutoff/resonance: left is darker and more resonant; right is brighter and more open. E1 selects AIR, GLASS, AMBER, or WOOD
DUST	High-frequency noise
SPREAD	Randomized stereo placement
INTONE	Tuning color: center is equal temperament; turning away introduces interval-dependent offsets
SUSTAIN	ADSR sustain in MIDI / GRID
RELEASE	ADSR release in MIDI / GRID

Filter types

Turn E1 while FILTER is selected, or use FILTER TYPE in PARAMS, to choose a model. A change applies to notes triggered afterward; notes already sounding keep their original filter.

Type	Character
AIR	Bright, open 12 dB low-pass with pronounced resonance
GLASS	Smooth, clean 24 dB low-pass with restrained resonance
AMBER	Thick, warm ladder filter with a little grit
WOOD	Vactrol-style low-pass gate with an organic decay

Loopers

spre has two loop systems.

Note looper

Six slots are available from grid column 16, rows 3–8.
First press: record.
Second press: finish recording and begin playback.
Further presses: stop / resume.
Double press: clear that slot.
Without a grid, select LOOP and press K2 to operate slot 1.

The note looper records AUTO-generated notes and notes played from the grid in MIDI or GRID mode. External MIDI input is not currently captured. Timing is recorded as performed and is not beat-quantized.

Audio looper

Two softcut audio slots are available. Each slot can record up to approximately 30 seconds.

The audio looper receives spre's engine output as well as the norns audio inputs.

Select the audio looper and slot with the LOOP control.
First press: record.
Second press: close the loop on the next clock beat and begin playback.
Further presses: stop / resume.
Double press on grid, or K2 + K3, clears the selected slot.
Direction, speed (×0.25–×4), and level can be changed from the parameter page.

Ending a new audio recording sets FLOCK to zero so the recorded loop can be heard clearly.

16×8 grid layout

AUTO mode

Grid area	Function
Row 1, columns 1–12	Root pitch class
Row 1, columns 15–16	Octave down / up
Row 2, columns 1–16	Scale selection
Row 3, columns 1–8 / 9–15	FLOCK / BRIT
Row 4, columns 1–8 / 9–15	RAIN / SAT
Row 5, columns 1–8 / 9–15	ATK / TAPE
Row 6, columns 1–8 / 9–15	DEC / DUST
Row 7, columns 1–8 / 9–15	FM / SPREAD
Row 8, columns 1–8 / 9–15	FILTER / INTONE
Column 16, rows 3–8	Loop slots 1–6; audio looper uses slots 1–2

MIDI / GRID modes

Grid area	Function
Row 1, columns 1–12	Root pitch class
Row 1, columns 15–16	Octave down / up
Row 2, columns 1–16	Scale selection
Rows 3–8, columns 1–15	Scale-note keyboard
Column 16, rows 3–8	Loop slots

The grid directly plays notes in both MIDI and GRID modes.

Included scales

Minor pentatonic, major pentatonic, major, minor, Dorian, Lydian, Mixolydian, Phrygian, Locrian, Phrygian dominant, blues, whole tone, diminished, Hungarian minor, In Sen, Hirajoshi, Arabic, bebop major, enigmatic, and chromatic.

The norns interface and MIDI CC 20 can access all 20 scales. The 16×8 grid’s second row directly selects the first 16.

MIDI CC

CC	Function
1–12	FLOCK, RAIN, ATK, DEC, FM, FILTER, BRIT, SAT, TAPE, DUST, SPREAD, INTONE
13 / 14	Octave down / up when value is above 63
15 / 16	SUSTAIN / RELEASE
17	Filter type
18	AUTO / MIDI / GRID mode
19	Root, MIDI notes 48–72
20	Scale
21	Octave shift, −3 to +3
22	Melody generator
23	Note / audio looper selection
24–29	Loop slots 1–6 when value is above 63
30 / 31	Selected audio-loop speed / level
32	softcut pre-level
33	Selected audio-loop direction: reverse / forward

MIDI notes generated by spre are also sent to MIDI port 1 on channel 1.

Support

spre is free to use. If you enjoy it and would like to support future development, you can buy me a coffee. Thank you — every cup helps keep the melodies growing.

Author

Puyoma

License

MIT License. See LICENSE.

Status

Version 1.0. Feedback, bug reports, and recordings are welcome.