14 Credits and licences

Lunar Modulator stands on other people’s work. This chapter names it, and the terms it is used under.

14.1 Sound engines and effects

Mutable Instruments, code by Emilie Gillet, MIT licence. Macro, Macro Heavy and Six-Op FM are built from the engines of Plaits; Shapes from the macro-oscillator of Braids; Plate from the reverb of Rings, its Freeze after the one in Elements; Room from the reverb and diffuser of Clouds; Ensemble and Diffuse from Plaits’ ensemble and diffuser. Their code is included unmodified; the wrappers that make it polyphonic and fit it to the FM-1 are this project’s own, and Macro Heavy’s speech model adapts one of Plaits’ classes. Lunar Modulator is not affiliated with or endorsed by Mutable Instruments, and as Mutable Instruments asks of work derived from its code, the engines carry names of their own.
Six-Op FM’s patches are the three banks distributed with Plaits’ code. Their origin is not stated there. In public builds, the twenty-three patches whose stored names are trademarks or a person’s name are shown under descriptive names of this project’s own.
msfa, the FM synthesizer core of Google’s Music Synthesizer for Android, by Raph Levien for Google, Apache License 2.0: FM6’s envelopes, LFO, operators, algorithms and tables. Its code is included unmodified, its tables computed ahead of time as its own code computes them; the voice built from it, its amplitude modulation, the feedback loops of algorithms 4 and 6 and its controls are this project’s own. FM6 reads voices in the format of Yamaha’s DX7 and is not affiliated with or endorsed by Yamaha.
FM6’s name is borrowed, with thanks, from the FM engine of Felucca by hugelton (Hügelton Instruments), open firmware for the FM-1; Felucca’s Apache-2.0 port of the same core checks FM6 in the tests (below).
FM6’s built-in voices are this project’s own, written for it and under the MIT licence.
Sophie by Matt Estela, MIT licence, included unmodified.
Drums: its kicks, toms, snares and hi-hats are Plaits’ drum models by Emilie Gillet (Mutable Instruments, MIT licence), included unmodified, which model the circuits of Roland’s TR-808 and, in their synthetic kick and snare, borrow from the TR-909’s. Its rim shot, clap, cowbell and cymbals are this project’s own code, with three small pieces of Plaits’ hi-hat in the cowbell and cymbals (its swing VCA curve, its oscillators’ ratios and its clocked noise): the cowbell and cymbals follow the circuit models of Kurt James Werner, Jonathan Abel and Julius O. Smith (“More cowbell”, AES 137th Convention, 2014; “The TR-808 cymbal”, ICMC/SMC 2014, CC BY 3.0), and the clap and rim shot published descriptions of the TR-808’s circuits, among them Baratatronix’s. No code or text is taken from the papers or the descriptions. The two kits are inspired by those drum machines; Roland’s names appear here only as credit.
Acid Bass is the 303 bass of fm1-x0x, open firmware for the FM-1 by Charles Vestal, GNU GPL version 3 (built in only with the GPL switch on; see Licences). It ports Open303 by Robin Schmidt (MIT licence), with the Devilfish modifications’ ranges after jc303 by midilab and a drive after dm-Rat by Dave Mollen (both GNU GPL version 3), by way of Charles Vestal’s schwung-303. Two small changes of this project’s let it run at the instrument’s rate and take smooth settings; the rest of its code is included unmodified. It is after Roland’s TB-303, whose name appears here only as credit.
Acid Gen is TB-3PO, the line generator of fm1-x0x by Charles Vestal, GNU GPL version 3 (built in only with the GPL switch on), which ports his schwung-tb3po and, through it, the TB_3PO applet of the Phazerville Hemisphere Suite by djphazer and its contributors (GNU GPL version 3). Its code is included unmodified; playing it as an effect in front of a sound is this project’s own.
Comet Kit is the 909 kit of fm1-x0x by Charles Vestal, GNU GPL version 3 (built in only with the GPL switch on). It ports 9W9 by athousanddetails, a drum machine for Schwung that models the TR-909’s circuits, which grew out of ER-99 by Matthew Cieplak (both GNU GPL version 3); its hi-hat, ride and crash are ER-99’s recordings, under the same licence. Two small changes of this project’s let it run at the instrument’s rate and take smooth settings; the rest of its code, its recordings and the script that turns them into data are included unmodified. The pads, voicings of the second snare, toms and pedal hi-hat, and playing it as a pad kit are this project’s own. It is after Roland’s TR-909, whose name appears here only as credit.
Crater Kit is the 808 kit of fm1-x0x by Charles Vestal, GNU GPL version 3 (built in only with the GPL switch on), which ports 8W8 by athousanddetails (GNU GPL version 3). Fifteen of its sixteen sounds are models of the machine’s circuits, built from the TR-808’s service notes and the analyses of Kurt James Werner, Jonathan Abel and Julius O. Smith; the rim shot is sc808’s, by Yoshinosuke Horiuchi, adapted for Sonic Pi by Sam Aaron (MIT licence). Two small changes of this project’s let it take smooth settings and keep no shared state; the rest of its code is included unmodified. It is after Roland’s TR-808, whose name appears here only as credit.
Drawbar, Trio and Phase Bend are the WHEEL, TRIO and PHASE engines of Felucca, open firmware for the FM-1 by Leo Kuroshita (@kurogedelic), Hügelton Instruments, GNU GPL version 3 (built in only with the GPL switch on; see Licences). Felucca’s code for them, its shared DSP and its tables are included unmodified; PHASE is a port of the oscillator of CrispyZebra, the same author’s (GNU GPL version 3). The code that plays them through Lunar Modulator’s engine interface is this project’s own, and the test that holds them to Felucca’s own voice code uses that code too. The engines’ names here are this project’s (“Trio” is Felucca’s own, borrowed with thanks); Felucca’s factory sounds appear in chapter 5 as settings.
PSX Verb by Charles Vestal, MIT licence, included unmodified.
Schwung, Charles Vestal’s host for modules on the Ableton Move, MIT licence. Lunar Modulator includes Schwung’s plugin interface unmodified, with a compatibility layer of its own, so that Schwung modules such as Sophie and PSX Verb build from their own source. Schwung’s licence notes that it began as a fork of Move Anything by Bobby Digitales.
Crush is this project’s own code. Pairing a sample-rate reducer with a bit reducer follows DaisySP’s Decimator and Bitcrush, by Electro-Smith, MIT licence; none of DaisySP’s code is used.
Fold is this project’s own code, after the wavefolders of Serge and Buchla synthesizers and the folding in Mutable Instruments’ Warps and Plaits by Emilie Gillet; its anti-aliasing follows the method of Parker, Zavalishin and Le Bivic (DAFx-16). No code is taken from any of them.
Drive is this project’s own code: its curves are written here, its tape emphasis follows tape’s record and replay equalisation, and its anti-aliasing follows the method of Parker, Zavalishin and Le Bivic (DAFx-16). No code is taken from anyone.
Echo is this project’s own code. Its ping-pong layout is the textbook one, after Udo Zölzer’s DAFX, and its 16-bit delay memory follows Emilie Gillet’s effects engine in Rings and Clouds; none of their code is used.
Filter is this project’s own code: zero-delay-feedback filters after Vadim Zavalishin’s The Art of VA Filter Design, Andrew Simper’s (Cytomic) state-variable filter, Antti Huovilainen’s ladder model (DAFx-04) and the diode-ladder circuit; its Sallen-Key type is after the Korg-35 filter of the later MS-20, and its SK Mixed type after the Steiner-Parker Synthacon’s filter (their makers’ names appear here only as credit); its non-linear solver follows a method Teemu Voipio published, and its vowels are the measurements of Peterson and Barney (1952). No code is taken from any of them.
Comb is this project’s own code: Udo Zölzer’s universal comb (DAFX), with Filter’s saturating loop. It was one of Filter’s types until October 2026. No code is taken from anyone.
Comp is this project’s own code, after the compressor design of Giannoulis, Massberg and Reiss (Journal of the Audio Engineering Society, 2012). No code is taken from anyone.
Limiter is this project’s own code, after Geraint Luff’s look-ahead limiter design (Signalsmith Audio, 2022). No code is taken from the article or from Signalsmith’s library. Its Round mode ports the loop of Airwindows ClipOnly2, by Chris Johnson, MIT licence (“Copyright (c) 2016 airwindows, Airwindows uses the MIT license”; the licence is in the source tree with the effect).
DJ Filter is this project’s own code: the state-variable filter of Andrew Simper (Cytomic) and Vadim Zavalishin, in the form of stmlib’s by Emilie Gillet (MIT licence). No code is taken from anyone.
Tilt is this project’s own code. A tilt built from first-order sections follows Airwindows’ ToneSlant (MIT licence) and the spectral tilt of the Faust libraries; none of their code is used.
Master Sat is this project’s own code. Its two curves use the coefficients of Airwindows PurestSaturation and TapeHack2, by Chris Johnson, MIT licence (“Copyright (c) 2018 Chris Johnson”; the licence’s notice is in the effect’s source), and its Glue follows the idea of Airwindows Compresaturator, whose code is not used.
Isolator is this project’s own code. Its three bands are split as in the Faust libraries’ three-band Linkwitz-Riley crossover, with Andrew Simper’s (Cytomic) and Vadim Zavalishin’s state-variable filter; none of their code is used.
EQ is this project’s own code. Each band is the state-variable filter in the form Andrew Simper (Cytomic) published, whose maths is in the public domain, and its curves are checked against Robert Bristow-Johnson’s Audio EQ Cookbook. No code is taken from either.
Hall is this project’s own code. It is a feedback delay network after Jean-Marc Jot and Antoine Chaigne (1991); its structure follows schwung-work’s Voidspace and Geraint Luff’s Signalsmith basics library (both MIT), its input diffusion Manfred Schroeder’s all-passes with Jon Dattorro’s coefficients, and its 16-bit delay memory Emilie Gillet’s effects engine in Rings and Clouds; none of their code is used.
Gate is this project’s own code. Its controls follow the operator manuals of Drawmer’s DS201 and DS301 noise gates (the maker’s name appears here only as credit); its key filters are Vadim Zavalishin’s state-variable filter. No circuit or code is taken from anyone.
Squash ports three Airwindows plug-ins by Chris Johnson, MIT licence (“Copyright (c) 2016 airwindows, Airwindows uses the MIT license”): its Snap type is Pop3, Mu is Pressure4 and Split is ButterComp2, rewritten in single precision for the FM-1, with their noise taken out and the few changes the effect’s notes list.
Transient is this project’s own code, on the classic two-follower principle of transient designers, as noted from legsmechanical’s Bus Driver (MIT licence). No code or measurement is taken from it.

Each engine’s and effect’s credits are also built into the firmware, and are printed under its table in chapters 5 and 6.

14.2 The sequencer

Movy by megadake, MIT licence. Lunar Modulator’s sequencer is a new implementation, written in C, of the behaviour of Movy’s sequencer core, and its design follows Movy’s. Movy’s own core, run unmodified on a computer, is used to check Lunar Modulator’s, event for event.

14.3 The arpeggiator

The arpeggiator is this project’s own code, after published designs: its loop, rhythms, Euclidean patterns and latch follow the arpeggiator of Mutable Instruments’ Yarns by Emilie Gillet (MIT licence); its note orders and its TRG rate follow MCL’s by Justin Mammarella (BSD-3-Clause); its seeded, repeatable chances follow Super Arp by Handcrafted Media (MIT licence). No code is taken from any of them.
The stock FM-1’s arpeggio modes, whose names the presets keep, are as AL-255’s disassembly reads them.

14.4 Modulation

The rack’s modules are this project’s own code, after published designs, chiefly those of Mutable Instruments’ Peaks and Braids by Emilie Gillet (MIT licence). Three are ports of that code: Bounce from Peaks’ bouncing ball, Burst from Peaks’ pulse shaper and randomizer, and Quantize from Braids’ quantizer and its scales.
The LFO’s shapes follow Schwung’s LFO by Charles Vestal and Peaks; the envelope follows Peaks’ multistage envelope; Chance follows DaisySP’s sample and hold (Electro-Smith, Paul Batchelor) and Music Thing Modular’s Workshop System Computer card 106 (Matt Allison); Register follows Tom Whitwell’s Turing Machine (Music Thing Modular), Chris Johnson’s card 20 and Phazerville’s Turing code (Patrick Dowling). Divide, Burst, Compare, Logic, Calc, Slew and Mix follow Phazerville’s applets (Jason Justian and others), and the Resonator Andrew Simper’s (Cytomic) state-variable filter. No code is taken from any of them but the three ports above.
Some modules follow only the published behaviour of other instruments, whose makers’ names appear here only as credit: Function after Make Noise’s Maths, Joranalogue’s Contour 1, Serge’s DUSG and Befaco’s Rampage; Coin after Mutable Instruments’ Branches and Marbles; the LFO’s modes after Elektron’s instruments; Slew, Compare and Logic after Expert Sleepers’ disting and Mannequins’ Just Friends. No code of theirs is used.

fm1-render --list-mod prints each module’s credits in full.

14.5 Research this project builds on

aroum: the first analysis of the FM-1’s updater, and teardown photos.
AL-255: a disassembly of the FM-1’s firmware, its update protocol, and a safety review whose rules this project follows.
Echomatter: showed that the FM-1’s own update method accepts a rebuilt firmware package with a new version number, and rolled it back again.
kagaimiq: documentation and tools for JieLi chips, including the recovery mode the dongle uses.
czietz and masanaohayashi: reports of reaching that recovery mode on FM-1s with a small USB dongle, and czietz’s tool for it.
probonopd: notes on a sibling keyboard built on the same platform.
benny-sparra: an editor and librarian for the FM-1, and observations of its MIDI.
Baud Girl, whose third-party FM-1 firmware showed how firmware reaches users through the FM-1’s own update method.
hugelton (Felucca), isod89 (SLOOP), Keitark (fm1-nes) and kurogedelic (FM-1-transporter): open firmware and tools that run on FM-1s. Their reports of how the board reads its keys and knobs, where its audio goes and how its recovery mode is reached inform this project’s plans.
Google’s music-synthesizer-for-android and the Dexed family, whose FM engine M-VAVE’s firmware is built on.

The project’s research notes credit each source in detail.

14.6 The simulator, the art and the manual

Audiowide by Brian J. Bonislawsky (Astigmatic), SIL Open Font License 1.1, for the name, the headings and the cover. The font file is included unmodified, with its licence.
IBM Plex Sans and IBM Plex Mono, designed by Mike Abbink with Bold Monday for IBM, SIL Open Font License 1.1, set the printed manual. On the web the manual uses them where they are installed, and your system’s own typeface otherwise.
Rosé Pine, by mvllow and the Rosé Pine contributors, MIT licence: this manual is in the Dawn palette, and the simulator and the art in Moon.
Spleen by Frederic Cambus, BSD 2-Clause licence: the screen’s two smaller typefaces, 8×16 and 6×12. The simulator’s page carries its licence, and so must any firmware built with them.
The simulator’s main screen font, the panel drawings, the banner and the boot screen are this project’s own. The panel drawings follow M-VAVE’s published dimensions and measurements of a unit.
The manual is built with Python-Markdown and WeasyPrint, both under the BSD licence.

14.7 Licences

Lunar Modulator’s own code, and this manual, are under the MIT licence. Code from other projects keeps its own licence, which the repository records beside it with a note of where it came from. Everything listed in this chapter that ships with the simulator or the desktop tools is under the MIT licence, or, for msfa, the Apache License 2.0, or, for the fonts, the SIL Open Font License 1.1, or, for Spleen, the BSD 2-Clause licence. The repository’s tests also use Felucca’s fm6_core.c by Leo Kuroshita (Hügelton Instruments), an Apache-2.0 port of the same FM core, to check FM6 against; it is in no build of the firmware or the simulator.

GPL code, and the GPL switch. Some engines and effects port code that other projects publish under the GNU General Public License: today the sound engines Acid Bass, Comet Kit and Crater Kit (chapter 5) and the MIDI effect Acid Gen (chapter 4), all from fm1-x0x, and Drawbar, Trio and Phase Bend, from Felucca. Each sits in a folder of its own in the repository, with its licence and a note of where it came from, and is built in only while the firmware’s GPL switch is on. While we test, the switch is on in every build, the simulator included. - In the simulator, the page beside the panel then names each module with GPL code in it, and offers the simulator’s module under the GNU GPL, version 3. It links the licence’s text and the complete source: the repository at the commit the page was built from. When no GPL module is in it, the page says nothing. - Firmware for the FM-1 built with the switch on is for the person who builds it: it will not be released or passed on. A shared build is made with the switch off and contains no GPL code.

14.8 Trademarks

M-VAVE, Cuvave and FM-1 are the marks of their owners. Lunar Modulator uses “FM-1” only to say which instrument it is written for, and is not made, endorsed or supported by M-VAVE or Cuvave. The names of Mutable Instruments’ modules identify where code came from. Names such as Ableton Move and DX7 describe origins and compatibility only, and Roland, TR-808, TR-909 and TB-303 the machines that inspired Drums, Comet Kit, Crater Kit and Acid Bass. All other trademarks belong to their owners.