Notes: 18 Points

The Idea

On some past albums, I’ve dabbled a little in xenharmonic tuning without really understanding the theory. (That is, scales that either don’t have 12 chromatic notes per octave, or which don’t repeat at octaves.) A few pieces of gear (the ER-301 Sound Computer, 4ms Ensemble Oscillator and Bitwig Micro-Pitch especially) had introduced me to the concepts just a little, but then I’d try to read articles at Xenharmonic Wiki and was intimidated by a thorny hedge of jargon.

As I was patching parts for what became the first track on this album, I set up a switch to transpose a drone, tuning the interval by ear. I decided out of the blue that I wanted to choose a microtonal scale to match it. After some exploration I found a match within 18edo, which could sound intriguingly exotic. And yet, it’s pretty easy to relate to — instead of dividing the octave into semitones like 12TET, it divides into third-tones. They coincide on whole tones, making it partly compatible with 12TET instruments (like my fretted bass).

18edo is not really a common one that gets talked about in microtonal circles. 19edo seems to be favored for various nerdy reasons. All the more reason to dig in and see what I could do with it.

And of course, my mystery interval was just an ordinary whole tone all along. But I enjoyed working with the scale enough to think “Can I use this for every track on the album?” as well as “I really need to catch up on tuning theory.

Microtonal Tools

Of course choice of 18edo influenced my compositional technique, but also my choice of instruments as not everything could support microtuning easily.

  • I relied a lot on Bitwig Micro-Pitch at first. It has its limits but it got the job done. It only works with MPE-capable synths so that limited me to Bitwig’s native devices plus Noise Engineering Vereor and Iteritas plugins, Madrona Labs Aalto, Dawesome Kult and Vital Audio Vital — still a pretty good set.
  • Scale Workshop‘s display of scales in cents helped me set up Micro-Pitch in “12 note” mode when I wanted to map a subset of 18edo to the keyboard instead of the entire gamut. It also exports Scala files which I used with both Aalto and Plogue Chipsounds.
  • Late in the project I discovered Entonal Studio. This is far more flexible than Micro-Pitch, and I find it easy to work with and quite inspiring. It can send monophonic MIDI, which let me use the rest of my synths with it (though depending on playing style/sequence you might get the Pitch Bend message a bit after Note On which causes a slide into the correct tuning… which can honestly be interesting at times).
  • On the Eurorack side, I used Monome Teletype to quantize to 18edo. Any equal division is a simple one-line script; other tunings are less simple but can be done.
  • Noise Engineering Univer Inter works well with Entonal Studio. They’re asking for feature ideas so maybe microtuning isn’t out of the question…?
  • I could have programmed Mutable Instruments Marbles for 18edo or a subset (as long as I gave it the correct voltages in the first place), but it was simpler to just quantize its output in Teletype.
  • Likewise, just attenuating a pitch signal already quantized to 12TET so that each step is 1/18 of a volt instead of 1/12 would have worked, but I didn’t need to resort to that.
  • Other modules: from what I’ve heard, Tubbutec uTune is top-of-the-line for microtonal quantization in Eurorack; Ornament & Crime and ER-301 Sound Computer can also do the job.
  • Similar techniques should also work in VCV Rack, but I used a module called “Equal Divisions” instead.
  • In Bitwig Grid, you can multiply a pitch signal by 12000 to convert it to cents, then quantize it and divide again. In practice, this works okay for sequenced pitches but poorly for MPE controller data that already includes pitch bends.

    For reading material, I was looking for a “Microtuning For Dummies” book and instead found these. If anyone has suggestions for other, friendly reading on the subject — or on music theory generally — I’d love to hear them.
  • Kyle Gann, The Arithmetic of Listening: Tuning Theory and History for the Impractical Musician. While I skimmed quite a bit, it taught me the history, rationale and jargon.
  • William Sethares, Tuning, Timbre, Spectrum, Scale. This gets into the science of the perception of consonance and dissonance, and how this changes when working with sounds that have an inharmonic spectrum rather than a harmonic one — for instance, metal percussion and additive or FM synthesis. This one gave me some inspiration for future projects.
  • Xen Wiki’s article on 18edo is a lot… but some of the info was useful or inspiring.

In the notes below, software is highlighted like this and hardware in italics like this. When a plugin is hosting its own plugin chain or software modular patch I put it in brackets [like this]. Not all utilities and EQ, compression, etc. were noted.

01: Pondside

  1. A simple looped sequence in Madrona Labs Aalto. Bitwig Tremolo, heavy distortion in Soundspot Ravage and heavy reverb in Native Instruments Raum, Melda MAGC to restore the original dynamics coming out of Aalto, and then CraveDSP CraveEQ and Bitwig Delay.
  2. A looped recording of a patch with ALM Akemie’s Castle into Make Noise Spectraphon, with some modulation and various effects that I neglected to take notes on. Sample playback speed is transposed with footswitches. Additional delay from Unfiltered Audio Sandman Pro.
  3. A drone in VCV Rack [Warp Core through CF100 and Ripples into Plateau, modulated by several LFOs from Stages]. Fed through the modular to be processed by Mutable Instruments Beads (for pitch shifting and granular muddling) and back into the DAW for FabFilter Saturn 2.
  4. Noise Engineering Loquelic Vereor, through Noise Engineering Imitor. Played via Roli Seaboard Block quantized to 18edo by Bitwig Micro-Pitch.
  5. Make Noise Function feeding sharp envelopes into Spectraphon in an attempt to “ping” it like a filter, through Noise Engineering Roucha Legio. Minimal Audio Rift, Bitwig Peak Limiter, Aqusmatic Audio Dedalus Delay, and Wavesfactory Cassette. Clocking for the modulation sources (into Slide, Focus, and FM on Spectraphon and the filter cutoff of Roucha) came from Noise Engineering Univer Inter, to synchronize with the software delays.

02: Stem & Marrow

  1. The rhythmic beating, and animalistic trills and howls, came from Schlappi Engineering Interstellar Radio through Mutable Instruments Blades, WMD Synchrodyne and Valhalla Delay. IR’s oscillators and the filters were controlled by Gliss.
  2. Squeaks and sequenced scales from The Harvestman Kermit mk2 through Noise Engineering Ruina Versio and jroo Loop. Sequence from Make Noise 0-Ctrl, quantized to 18edo by Monome Teletype.
  3. Noise Engineering Cursus Vereor through Arturia Jun-6 Chorus, played on Seaboard with 18edo tuning (and a fair amount of slide).
  4. Crackling and fizzing noise from VCV Rack [Surge XT Alias VCO, 2D Rotation, Supercell, two E440 VCFs]
  5. Voice 3 processed through Spectraphon, Make Noise Mimeophon, Gigahertz Lossy and Audiority Plexitape to turn it into a sort of resonant windy noise.
  6. A drone from Whimsical Raps Just Friends through Cosmotronic Peradam, Audio Damage Ratshack Reverb, Saturn 2, and Raum.
  7. A drone at the same pitch as #6, from Noise Engineering Ataraxic Iteritas through Roucha Legio and Micah Frank’s Parallel.

Entire mix processed in ZPlane Peel, with a 1KHz-6KHz band to catch the strongest harmonics of voice 3, twice. The first time, through Audiority Tube Modulator and Bitwig Frequency Shifter; the second time more subtly through Phonolyth Velvet Machine, Bitwig Harmonic Split and Unfiltered Audio SpecOps.

03: Gnomic

  1. The main melody is a generative patch in Madrona Labs Aalto with an 18edo enneatonic scale, through JMG Sound Retronaut, Sugar Bytes Wow2, Wavesfactory Cassette, FabFilter Saturn 2 and Valhalla Delay.
  2. A Bitwig Grid drone patch [two Swarm oscillators mixed mid/side, and two stereo lowpass ladder filters in parallel].
  3. Make Noise Strega and Arturia Minibrute 2S patched together, with Unfiltered Audio SpecOps and Noise Engineering Imitor.
  4. Maurizio Über Basses Miezo (5-string compact “cello range” bass) into Jam Origin MIDI Bass (for distortion & amp sim), Moog MF-103S Phaser, Valhalla Room, Noise Engineering Ruina, UJam UFX Reverb and u-he Runciter.

04: Hyaline

  1. Noise Engineering Loquelic Vereor, played by an LFO-modulated arpeggiator quantized to an 18edo enneatonic scale by Micro-Pitch. Through Bitwig Harmonic Split [Imitor on every 5th harmonic, Bitwig Pitch Shifter and Phonolyth Velvet Machine on other harmonics], MAGC restoring the pre-Split dynamics (suppressing Velvet Machine’s reverb tail) and Newfangled Audio Invigorate. LV’s octave is shifted by an expression pedal, carrying it from the psuedo-frame-drum range to punchy metallic percussion.
  2. “Percussive Splat” is Interstellar Radio through Peradam, with Bitwig Grid [acting as sequencer, envelope/VCA and Sallen-Key filter].
  3. The lead part is Akemie’s Castle played via 0-Ctrl quantized by Teletype, through Mimeophon (modulated by a Mutable Instruments Stages LFO synced to the delay rate for vibrato), and u-he Uhbik-F flanger.
  4. The kick drum is Ataraxic Iteritas through Rabid Elephant Natural Gate, Noise Engineering Lacrima Versio. It’s on a continuous 8th note clock from Univer Inter, but Bitwig Grid [short delay for time sync purposes, lowpass filter controlled by a gate sequence] cuts off some notes. Through Saturn 2.
  5. Shakers/hi-hats are from Xaoc Odessa self-FMing, highpass filtered by Blades. Bitwig Grid [sequence, envelope/VCA and slapback delay], Inphonik PCM2612 Retro Decimator, Noise Engineering Librae and Voxengo OldSkoolVerb.
  6. Mutable Instruments Rings, sequenced in a Bitwig Grid patch via Univer Inter and Teletype quantization. Through Mutable Instruments Beads, Bitwig Transient Split [SpecOps filtering some noise from transients while Velvet Machine adds reverb to tones].

(Moving some envelopes and VCAs into Bitwig allowed me to more easily conquer latency issues between the hardware and software sides.)

05: Prismat

  1. Odessa through Natural Gate in stereo, with modulation from Noise Engineering Clep Diaz. CraveDSP CraveEQ (suppressing Odessa’s fundamental), then Bitwig Pitch Shifter, Moog MF-105S Clusterflux, Audio Damage Ratshack Reverb, u-he Twangström. Odessa’s Tension is tuned so that the harmonic spread partially matches that of the 18edo pentatonic scale.
  2. Just Friends controlled by Tesseract Sweet Sixteen via Monome Teletype — 6 faders control the levels of oscillators tuned to 18edo pentatonic, while another slider transposes them all (quantized to the same scale). Through Xaoc Koszalin, Bitwig Grid [wavefolder and lowpass ladder filter], Moog MF-104S Delay and Raum.
  3. Spectraphon in SAM mode fed with Odessa‘s fundamental, through Beads.
  4. Akemie’s Castle noise patch through Unfiltered Audio SpecOps and Bitwig Convolution Reverb.
  5. Cherry Audio Harmonia through Wavesfactory Cassette.

06: Stunlock

  1. Rings through Lacrima Versio, sequenced by Marbles and quantized to 18edo by Teletype, then looped in a Bitwig Grid sampler. Through Bitwig Harmonic Split [Saturn 2 with different settings for each set of harmonics]. Processed through Plogue Chipcrusher at the start.
  2. The same sequence as above but through Ruina Versio rather than Lacrima, looped in Bitwig Grid [with Chebyshev waveshaper and comb filter]. Just a noisier variant of #1.
  3. An 18edo chord drone in Bitwig Organ through Inertia Sound Systems Hinder, Arturia Plate-140, Minimal Audio Rift.
  4. Akemie’s Castle drone through Koszalin and UFX Reverb.
  5. Odessa through Rings & Beads.
  6. Odessa through Spectraphon, VCV Rack [2D Rotation], Valhalla Delay.
  7. VCV Rack patch [Marbles quantized by Equal Divisions, squencing Instruo Cs-L gated by a pair of E440 VCFs, through Plateau].

07: Which?

  1. Drone: Ataraxic Iteritas through Rings, Spectraphon, Mimeophon.
  2. Strega with Minibrute 2S. Pitch is controlled by Roli Seaboard, quantized by Entonal Studio, converted to CV by Univer Inter. Expression pedal for volume. Minibrute’s oscillators drone, controlled by its own sliders. A subtle touch of Bitwig Freq Shifter. At the end, it sputters out somewhat violently but Velvet Machine smoothes it out.
  3. Ataraxic Iteritas highpassed by Lacrima Versio, supporting voice #2 at times.
  4. Just Friends rapidly gated by Teletype, through Blades and Beads. Sampled and timestretched 4x, mixed in at low level.
  5. Sub drone from Inear Display Lancinantes.
  6. Kermit through Blades, Ruina Versio, Desmodus and Saturn 2
  7. Beeps are a very simple MIDI sequence quantized by Entonal Studio, controlling Plogue Chipsounds through Voxengo OVC-128, Unfilitered Audio Lofi AF.
  8. A Xaoc Drezno bit output (for noise) through Roucha Legio with high resonance, Koszalin, and Plate-140.
  9. Rumbling noise from Detunized “Noises Universal” sample library, with pops removed and pitched down.

08: Unwaltz

  1. Odessa through Tallin, Mimeophon, Echobode; also Dreadbox Hypnosis spring reverb at the beginning. Sequence is from a Bitwig Grid loop, quantized by Entonal Studio to a subset of 18edo with a slightly stretched octave (ratio 1:2.02) to better fit the inharmonic spectrum, translated by Univer Inter.
  2. New Systems Instruments Harmonic Shift Oscillator through Natural Gate, Beads, Valhalla Ubermod & Valhalla Supermassive. Pitch comes from the #1 sequence, sampled and held by Stages from polymetric triggers in Bitwig Grid.
  3. HSO‘s second output through DigDugDIY Purple Rain into Spectraphon, Blades, NI Raum. Spectraphon pitch played on 0-Ctrl quantized by Teletype.
  4. Interstellar Radio into Rings, Lacrima Versio, Phonolyth Cascade. Pitch (vague as it may be) from an 0-Ctrl channel, slewed by Stages (to prevent legato note changes from sounding a plucked string-like attack in Rings).

09: Moonglare

  1. Bitwig Grid [a single skewed sine oscillator through pressure-controlled VCA], played on Roli Seaboard quantized by Micro-Pitch. Harmonic Split [Saturn 2 on the fundamental, MF-103S on other harmonics] and Twangström.
  2. [filtered swarm oscillator & filtered pulse oscillator] join the Bitwig patch above, tuned to 24:18 and 22:18 ratios of the fundamental.
  3. Odessa drone through Peradam.
  4. Ataraxic Iteritas drone through Lacrima Versio, Mimeophon, Valhalla Delay
  5. Intellijel Shapeshifter through Spectraphon, Koszalin, Raum
  6. Just Friends‘ 6 oscillators tuned to selected 18edo pitches approximated by just-intoned ratios by Teletype, through Beads.

The final mix oveerlaps portions of two takes for a “duet” effect.

10: Equilibrium

  1. Minibrute 2S with Strega delay, Valhalla Room.
  2. Bitwig Grid [5 sine oscillators in a chord manually tuned to match 18edo pitches, lowpass filter controlled by expression pedal]. Fader control over each oscillator’s fold amount but their relative mix is constant. Soundspot Ravage, Raum, Rift.
  3. Dawesome Kult through Velvet Machine, played on Seaboard tuned by Entonal Studio.
  4. Drone from Harmonic Shift Oscillator FMd by self-oscillating Blades.


Standard mastering chain consists of CraveDSP CraveEQ, Wavesfactory Equalizer, DDMF MagicDeathEye, RJ Studios SideMinder ZL, Voxengo Elephant, with metering from Voxengo Span, Voxengo Correlometer and Youlean Loudness Meter.

Also commonly used were Voxengo OVC-128, U-he Uhbik-Q, Izotope RX7 De-Click, FabFilter Saturn 2, Noise Engineering Librae, and Wavesfactory Cassette.

My mastering process typically uses the chain in Bitwig Studio, then switches to Sound Forge Pro 13 for additional analysis and final adjustments.