Exploring 22-Tone Equal Temperament in Electronic Music Production

In 31 equal divisions of the octave (31edo), there are six basic triads: Sus4 (root, perfect fourth, perfect fifth at EDO steps 0, 13, 18), Supermajor (root, supermajor third, fifth at 0, 11, 18), Major (root, major third, fifth at 0, 10, 18), Neutral (root, neutral third, fifth at 0, 9, 18), Minor (root, minor third, fifth at 0, 8, 18), and Subminor (root, subminor third, fifth at 0, 7, 18). Unlike 12edo, 31edo provides two variations of major and minor chords plus a neutral chord, offering richer harmonic possibilities through its superior approximation of just intonation ratios like 5:4 and 7:6.

Standard tuning systems contain inherent imperfections - for example, major thirds on pianos are 14 cents too high. Microtonal exploration moves beyond equal temperament to discover fresh harmonic possibilities. Perfect pitch is essentially a memory of sound, and recognizing that standard tuning is arbitrary opens doors to new sonic landscapes. Voices naturally move with gesture and arrival, and arriving in satisfying places matters more than the exact path taken. This approach finds magic in details that aren't quantized or standardized.

This section explores extreme tuning territories. 7edo achieves complete uniformity where all gaps equalize, eliminating harmonic motion entirely. Mavila tunings (23edo, 11edo) represent anti-diatonic systems where gap sizes invert: major/minor and diminished/augmented chords swap roles, yet harmonic structure remains intact. 13edo can be understood through negative steps or by stacking eight fifths to create LsLsLLsL patterns. Moment of Symmetry describes scales with only two step sizes, enabling diatonic-like structures in various EDOs. 47edo supports two different diatonic structures; 72edo supports two mavila structures. This progression demonstrates how increasing divisions enable unprecedented harmonic complexity and diversity in microtonal composition.

MOS (Moment of Symmetry) scales provide a practical solution for exploring large microtonal tunings like 31 EDO, 39 EDO, and 94 EDO by isolating manageable, efficient subsets of notes that retain the benefits of the larger tuning while reducing complexity. For example, the 19-tone MOS of 31 EDO offers nine harmonic seventh chords and five harmonic 11s, making it far more flexible than the 12-tone MOS of 31 EDO (which only provides two harmonic seventh chords), while remaining playable on standard keyboards. This approach allows musicians to access the harmonic richness of larger tunings without the practical challenges of playing 31+ notes per octave.

The 19-EDO (Equal Division of the Octave) tuning system divides the octave into 19 equally spaced intervals of approximately 63.2 cents each, providing a manageable gateway to microtonality that extends the familiar 12-note tuning by adding seven more notes. Unlike 12-EDO where enharmonic equivalents like C# and Db are the same note, 19-EDO treats them as distinct, enabling new intervals such as the super major third, augmented fourth, and B-sharp. While 19-EDO offers more accurate minor and major thirds compared to 12-EDO (closer to Just Intonation), it sacrifices accuracy in perfect fourths and fifths (about 7 cents off versus 2 cents in 12-EDO). This tuning system creates unique harmonic possibilities including sub-minor triads, super-major triads, and pure-sounding sixths, demonstrating that all tunings have distinct sonic characteristics rather than being universally 'in-tune' or 'out-of-tune.'

Tuning systems in Live are based on Scala files (.scl files), text files defining specific tunings. The Scala software allows users to create custom tunings for any musical scale. Users can download Scala files from the project website, containing thousands of tunings from around the world. Tuning systems can divide the octave into various numbers of equal parts, including 24 and 31 equal divisions, creating microtonal scales with finer granularity. Live implements tuning by using the pitch bend wheel to adjust pitch note by note. With MIDI 2.0 (MPE), Live provides independent pitch control for each note, enabling polyphonic tuning where each note in a chord can be tuned differently according to the selected system.

The Lima software exports tuning systems as Scala files (.scl format). The Base Station 2 has MIDI Tuning System (MTS) support, allowing users to upload custom tuning tables. The Peak synthesizer has 16 built-in tuning tables that can be saved and recalled. Users can create custom tuning systems in Lima by adding notes at arbitrary frequencies, then export the Scala file and upload it to the Base Station 2. This enables musicians to implement custom microtonal tunings on hardware synthesizers, demonstrating the practical application of microtonal theory.

To export a Scala tuning file, click File then Save As. Type in the scale name at the top (e.g., '22 EO'). It is important to include a description since some synthesizers may crash if the tuning file lacks one. Click OK to save. If the file already exists, type 'replace' and hit Enter to overwrite it.

The poly wave table mode on the listing ex supports non-equal tempered tunings through scala files, which can be loaded from a micro SD card. Two essential files are required: an SCL file that defines the relationships of notes and pitches within a scale, and a KBM file that maps the pitches in your scale to a MIDI keyboard or CV gate, effectively converting CV signals into note numbers to look up the correct pitch.

MPE-capable instruments like Geos Shred allow each key to have independent pitch bend and modulation, enabling expressive playing techniques similar to how string players use vibrato. This technology can be used with MPE-compatible virtual instruments, allowing iPad controllers to record MPE data into DAWs for use with any MPE virtual instrument.

Deckard's Dream supports MPE (MIDI Polyphonic Expression) capable controllers like the X-Key Air, HAWKEN Continuum, or ROLAND Seaboard. This provides two additional dimensions of control beyond polyphonic aftertouch: the ability to bend the pitch of individual notes separately (not just all held notes together like a standard pitch bend strip), and the ability to control LFO speed or other parameters per note using the Y-axis.

MPE is a MIDI protocol that provides independent control data for each key on a polyphonic keyboard. Unlike traditional MIDI where all keys share the same velocity and aftertouch values, MPE allows each key to have its own velocity, aftertouch, pitch bend, and other parameters. This enables unprecedented expressive possibilities for performers, allowing them to apply different effects to individual notes within a chord. The controller described has 24-note polyphony with separate aftertouch zones for each key, enabling complex articulations like plucked string sounds where each note can be individually brightened or muted.

The Hexboard offers comprehensive MIDI configuration including channel selection, MPE (MIDI Polyphonic Expression) mode for microtonal playing with per-note pitch bend, and bend range settings (default 48 for good accuracy). MPE mode sends notes on separate channels with individual pitch bend, working with many synthesizers but requiring specific software support. Control wheels provide virtual velocity and mod wheel controls with configurable response curves (slow, medium, instant) and sticky/springy behavior. Transpose allows quick key changes, while performance slots save complete configurations for different contexts. The system also includes MIDI channel mapping for multi-synth setups and Roland MT-32 instrument selection.

MPE adds three expressive controls: Pressure (after-touch after initial note strike), Slide (vertical Y-axis movement affecting sound), and Pitch Bend (horizontal X-axis movement changing pitch). You can slide from pad to pad like frets on a guitar neck. These controls enable dynamics similar to guitar or piano performance.

For interval recognition, practice identifying intervals by name rather than by note. Start with a reference note and identify intervals such as perfect fourths, major thirds, minor thirds, perfect fifths, major sixths, and tritones. Practice both ascending and descending intervals. This method develops the ability to recognize interval quality and direction, which is essential for understanding chord progressions and improvisation. Practice for approximately 3-4 minutes of the 10-minute session.

Non-Western musical traditions use microtonal scales that differ from the standard Western chromatic scale. The host explains that Indian classical music uses intervals smaller than semitones, requiring musicians to develop specialized ear training to perceive and reproduce these subtle pitch differences.

Interval training is fundamental for developing musical ear skills. When musicians train intervals, they automatically discover chord qualities and harmonic relationships. This approach helps develop a more open melodic relationship with the instrument, moving beyond purely scalar thinking to interval-based improvisation. The ability to hear intervals and chord qualities enables musicians to understand their instrument's capabilities and limitations, such as recognizing that intervals like fourths are difficult for pianists but easy for bassists due to the fretboard layout.

Aural training develops the ability to identify musical elements by ear. The student demonstrated recognition of intervals (second) and chord qualities (minor). These skills are fundamental for musicians to understand harmonic relationships and melodic structures without visual notation, enabling better sight-reading and improvisation abilities.