Harken Microtone Compass

Tap anything to see and hear its pitch

User Guide

The Harken Microtone Compass is a listening tool for exploring pitches finer than the usual 12. It shows nine rings of colored pitches, from 12 TET on the outside to 3,072 TET at the center, and plays them in time as a needle sweeps around the face. Each ring splits every step of the ring outside it in half, and every ring is measured from the same fixed tonic, 0. You can hear the rings together, pick which ones play, choose the order the pitches come in, add harmony, and draw your own paths through the tiny spaces between the notes. At its center is a harmonic compass: the main needle is the Tonic needle, and each harmony voice has its own needle, so you can see the harmony turn as you hear it.

It is a lab, not a game: there is nothing to win. Listen, change one thing, and listen again.

Getting started
Reading the face
Tapping to hear a pitch
Settings
Choosing TETs
Harmonize
The Mixer
The Path Maker
Interval selection and the Cycle Tween
Saving your work
Quick reference
Things to try

1. Getting started

Open the app. The Settings panel appears first.
Press Start. The panel closes and the face is ready. The instrument sounds begin to download; they come from harkenmusic.com, so you need an internet connection. Nothing plays until you press Play.
Press Play. If the sounds are still downloading, the button reads Loading… for a moment first.
Listen. The needle in the center turns, and each pitch lights up and sounds as the needle reaches it.

Four buttons sit under the face:

Settings stops the playback and opens the Settings panel again. Press Start to close it, then Play when you are ready.
Play / Stop starts and stops the playback. Playback always starts from 0 at the top.
Mixer opens the Mixer, where each ring gets its own instrument and volume (section 7).
Guide opens this guide. Press Done to close it. Opening the guide stops the playback.

On a computer, the Space bar also plays and stops.

On a phone or tablet, turn the volume up. If you hear nothing on an iPhone, check that the ring/silent switch is not set to silent.

2. Reading the face

The rings

There are nine rings. The outside ring is 12 TET, the twelve pitches 0 to 11. Moving inward, each ring has twice as many pitches as the one outside it:

Ring	Pitches in the octave	What it adds
12 TET	12	The twelve pitches 0, 1, 2 … 11
24 TET	24	A tween halfway between each pair: 0+, 1+ … 11+
48 TET	48	A new pitch in every gap of 24: 0°, 0+°, 1°, 1+° …
96 TET	96	Halves the gaps of 48 (no names yet)
192 TET	192	Halves the gaps of 96
384, 768, 1,536, 3,072 TET	384 to 3,072	Finer and finer, until the pitch seems to glide

Because each ring holds every pitch of the ring outside it, the rings nest inside one another, and all of them are measured from the same tonic. The 48 TET names read like this, going up from 0: 0, 0°, 0+, 0+°, 1, 1°, 1+, 1+° … The mark ° means “one 48 TET step above.”

Lights and dots

Rings 12 to 192 are made of separate round lights. When a pitch plays, its light glows and swells for a moment. Rings 384 and finer are made of small dots that are so close together they run into lines; a dot brightens when it plays.

Every pitch has its own Harken color. The 12 and 24 TET pitches use the 24 Harken colors, and each finer pitch takes the color halfway between its two neighbors, so the colors flow smoothly all the way in.

The 12 and 24 TET lights carry their numbers. The 48 TET lights carry their names in very small type, which only shows when the face is large enough to read it (on a phone they are hidden). You can change or hide these labels with the Labels setting.

The harmonic compass

The Tonic needle points at the pitch the line is playing. It always starts on 0 when you press Play. Its color matches the 24 TET pitch it is passing (or the 12 TET pitch, if 24 is not chosen).
Each Voice needle belongs to one Harmonize voice. It is thinner and shorter than the Tonic needle, wears the color of the lamp it points at, and that lamp lights softly while the line’s lamp lights at full strength.
Together the needles form a harmonic star that turns with the Tonic needle. In Scale and Cycle the star keeps one shape as it turns. In Balanced, Substitute and Shifting it re-forms at each step around the same harmony, because the pitches sit in a different order on the face.
With no Harmonize voices, only the Tonic needle shows.
While a path plays on the face, the Voice needles show only when the Path Maker’s Harmonize is ticked: they point at the chord of each 12 or 24 TET path note and hold while the finer notes move over it.
The center is the tonic, 0. It wears 0’s color and flashes each time the low tonic bass note sounds.
The faint rays behind the rings point at the 12, 24 and 48 TET pitches. A ray set only shows while its ring is chosen.

Time on the face

One trip of the needle around the face is a lap. At normal speed (1x) a lap takes 60 seconds. The lap is cut into:

12 wedges of 5 seconds each, one for each 12 TET pitch;
48 beats of 1.25 seconds each (4 beats to a wedge). The Click ticks on every beat.

Every ring finishes its lap in the same time. So in one wedge, 12 TET plays 1 pitch, 24 TET plays 2, 48 TET plays 4, 96 TET plays 8, 192 TET plays 16, and so on. The low tonic bass note sounds under everything, sixteen short notes per wedge at start (you can change this with the Pedal setting).

3. Tapping to hear a pitch

Tap any light (rings 12 to 192). It glows and sounds, and the bar under the face (the readout) shows its ring, its name and its distance from the tonic in cents. For example: 24 TET · 3+ · 350 cents. For the finer rings, which have no names yet, the readout gives the step number, such as step 3 of 48.
Tap the center to hear the tonic bass note on its own.
Double-tap a light on the 12, 24, 48 or 96 TET ring to open the Path Maker for that wedge (section 8). The first tap still sounds the pitch.
Press and hold a light on the 12 or 24 TET ring to choose an interval for the Cycle Tween (section 9).

Only rings that are turned on can be tapped. The finest rings (384 and up) are too small to tap.

4. Settings

Press Settings to open the panel. Every change takes effect at once. Press Start to close the panel, then Play to hear the changes.

Tonic

The pitch that 0 stands for. The menu lists the twelve starting notes by their letter names (C at start). Changing the tonic moves the sound and the colors together; 0 is always the tonic, and all the numbers stay the same.

Interpolate

The order in which the pitches are placed around the rings, and so the order you hear them. Every ring follows this setting, and every finer ring fits exactly inside the one outside it. Shown here for 12 TET, going up (clockwise):

Choice	12 TET order	What it is
Balanced (at start)	0 7 5 2 10 9 3 4 8 11 1 6	Two strands, one stepping up by 7 and one stepping down by 7, take turns from 0 until they meet at 6.
Cycle	0 7 2 9 4 11 6 1 8 3 10 5	Steps of 7 all the way round.
Substitute	0 1 8 3 4 11 6 7 2 9 10 5	The Harken Clock’s substitute cycle: the cycle with six of its pitches swapped for the pitch 6 away.
Shifting	changes each lap	Balanced, then Cycle, then Substitute, one per lap, round and round.
Scale	0 1 2 3 4 5 6 7 8 9 10 11	In order, step by step.

The finer rings use the same idea in their own steps. For example, 24 TET in Cycle order begins 0, 3+, 7, 10+ …

Direction

Ascending ↻ — the needle turns clockwise.
Descending ↺ — the needle turns counter-clockwise, and the face becomes the mirror image of Ascending across the 0–6 line. For example, Cycle descending is 0 5 10 3 8 1 6 11 4 9 2 7.
Alternate ⇅ (at start) — one lap Ascending, the next Descending, and so on.

TET

Shows which rings are playing (12, 24, 48, 96, 192, 384 at start). Tap it to open the TET panel and choose (section 5).

Pitches

Hide redundant (at start) — each ring shows only its new pitches, the ones no ring outside it already shows. Every pitch appears on the face just once, so it is easier to see how each ring fills the gaps of the one before. The sound does not change.
Show all — every ring shows all of its pitches.

Labels

What is written on the lights, in the readout and in the Path Maker.

Harken — Harken numbers: 0 to 11, tweens with +, and the 48 TET names with °.
Serial — each ring simply counts its own steps from 0: 0–11 on 12 TET, 0–23 on 24 TET, 0–47 on 48 TET.
Letters (at start) — traditional letter names, as a bridge for musicians who know them. 12 and 24 TET only (with quarter-tone signs on the 24 TET tweens); sharps going up, flats going down; the 48 TET lights are left blank.
None — no labels. The readout shows only the ring and the cents.

Speed

Speed	¼x	½x	1x (at start)	2x	3x	4x
One lap	4 min	2 min	60 s	30 s	20 s	15 s

The slow speeds are good for careful listening to the finer rings. You can change the speed while it plays; the needle carries on from where it is.

Pedal

Sets how the low tonic bass note (the pedal on 0) plays under everything. A wedge is one bar.

Whole notes — one long note per wedge.
Half notes — two per wedge, each ringing its full length.
Quarter notes — four per wedge, on the Click's beats, each ringing its full length.
Eighth notes — eight per wedge, short and muted.
Sixteenth notes (at start) — sixteen per wedge, short and muted.

The pedal follows the Speed setting. You can change it while it plays. Tapping the center always plays one long tonic note.

Harmonize

Adds harmony voices above the line (section 6).

Click and Save Settings

Click (on at start) — a soft tick on every beat, 48 per lap.
Save Settings (off at start) — keeps your settings and paths on this device (section 10).

5. Choosing TETs

Tap the TET button in Settings. A panel opens with nine tick boxes, one for each ring from 12 to 3,072.

Tick any group of rings you like. They do not have to be next to each other: 12 and 48 alone, or 24 and 192, are fine.
All ticks all nine rings at once.
Done closes the panel. The TET button then lists the rings you chose.

Rings that are turned off go dim and silent. A few things follow your choice:

Harmonize follows 24 TET if it is chosen, otherwise 12 TET. With neither, Harmonize is not available.
The needle’s color follows 24 TET, otherwise 12 TET, otherwise the outermost ring chosen.
The Path Maker uses the chosen rings from 12 to 384.

The finest rings can be a lot to take in at first. Start with 12, 24 and 48, listen for a while, then add one ring at a time.

6. Harmonize

Harmonize adds voices that move in parallel with the line. Each voice stays a fixed distance above the pitch being played, so the whole chord travels around the face together.

At start there are five voices: Voice 2 = 4, Voice 3 = 8, Voice 4 = 6, Voice 5 = 2, Voice 6 = 10.
+ Add Voice adds another voice, up to Voice 12.
Each voice has a menu to choose its distance above the line. The list runs in the same order as Interpolate (and is mirrored for Descending).
✕ removes a voice.

Which ring is harmonized: if 24 TET is chosen, the voices follow the 24 TET ring, and their distances can be any of the 24 pitches (0 to 11 and 0+ to 11+). If only 12 TET is chosen, they follow the 12 TET ring, with distances 0 to 11. Either way, any finer rings that are on keep playing over the harmony. (The 12 TET list also shows each distance’s letter name, as a bridge.)

Harmony voices play on that ring’s instrument from the Mixer. Each voice has a needle on the compass and lights its lamp softly. See “The harmonic compass” in section 2.

7. The Mixer

Press Mixer to open it, and Done to close it. There is one row for each ring:

Instrument menu — choose the ring’s sound from the Harken instrument collection (52 instruments), plus Sine Wave, a pure tone that is useful for hearing the fine rings clearly.
M (Mute) — silences the ring.
S (Solo) — while any ring is soloed, only soloed rings are heard.
Level slider (0–100) — the ring’s volume.

Mute and Solo change only the sound; the lights keep lighting, so you can watch a ring while listening to another. The 3,072 TET row has no instrument menu: that ring is so fine that it plays as one smooth, gliding tone of its own. Rows for rings that are turned off appear dimmed.

Ring	Instrument at start	Level
12	Piano	75
24	Piano	75
48	Synth Pad (New Age)	75
96	Synth Pad (New Age)	75
192	Electric Guitar (Muted)	30
384	Harp	40
768	Steel Drums	15
1,536	Piccolo	40
3,072	its own gliding tone	10

The Mixer is not saved: each visit starts with this mix.

8. The Path Maker

The Path Maker lets you draw your own line through the fine pitches between two 12 TET pitches. A wedge of the face is one gap of time: in Cycle order, for example, the wedge that starts at 0 carries the line from 0 to 7. A path decides which of the pitches in that gap sound, and when.

Opening it

Double-tap any light on the 12, 24, 48 or 96 TET ring. The Path Maker opens for the wedge that light sits in, and the playback stops.

Reading the grid

The title names the wedge by its two 12 TET pitches, for example | 0 | 7 |. Below it you see the direction, the Interpolate order and the TETs in use.
There is one row for each TET chosen from 12 to 384 (768 and finer are left out; they are too fine to draw with).
Columns are moments in time, left to right, across the 5 seconds of the wedge (at 1x). There is one column for each step of the finest TET chosen; with 384 that is 32 columns. One more column at the right end is the next 12 TET pitch, where the next wedge begins. The faint vertical lines mark the 4 beats.
The colored cells are the pitches the face plays at those moments, exactly as on the face. With Pitches set to Hide redundant, each pitch appears only once.

Drawing a path

Tap a cell to add it to the path. It sounds once. Path cells get a white ring, and white lines join them from left to right.
Only one pitch can sound at each moment, so each column can hold one cell of the path. You can add cells in any order; each one takes its place in time.
Drag a white-ringed cell to move it: up or down to change the pitch, left or right to change its timing (between its neighbors). It sounds as it lands.
Double-tap a white-ringed cell to remove it.

The buttons

Play — plays this wedge’s path once, at the chosen speed. Each pitch holds until the next one; the last one rings on for half a wedge. Press again (Stop) to stop. The Space bar does the same while the Path Maker is open.
Undo — takes back your last action (add, move or remove).
Clear — removes this wedge’s path.
Clear All — removes every path in all twelve wedges.
Done — closes the Path Maker. If there are any paths, the lap starts playing them.

Instrument and Harmonize

Instrument — the whole path plays on this one instrument (Piano at start), whatever row a cell is on. The Mixer does not affect paths.
Harmonize (off at start) — path notes on the 12 and 24 TET rows take the Harmonize voices from Settings. Each chord is struck once and rings until the next 12 or 24 TET note of the path, while the finer pitches move over it. If a path begins on a finer pitch, the harmony waits for its first 12 or 24 TET note. This box is greyed out unless 12 or 24 TET is chosen.

Twelve wedges, twelve paths

Each of the 12 wedges can have its own path. A wedge with no path of its own borrows the last path before it in the lap, so one path is enough to fill the whole lap. When you open a wedge that is borrowing, its path is drawn dashed and the note under the grid says where it comes from; change anything and it becomes that wedge’s own path.

A path is stored as a shape, not as fixed pitches. Each wedge plays the shape on its own pitches, following Interpolate and Direction. Going Descending, the shape is mirrored: a line that rises from 0 toward 7 going up becomes a line from 0 toward 5 going down.

Hearing paths on the face

While any path exists, the lap plays the paths instead of the rings. Only the path’s pitches light up (with Harmonize ticked, the chord’s pitches light softly and the Voice needles point at them), and a thin silk thread is drawn on the face through every note of the paths, wedge by wedge. The tonic bass note and the Click keep going. Where two wedges meet, the shared pitch sounds only once.

If you turn off a TET that a path uses, those notes are kept but go silent; turn the TET back on and they return. To go back to hearing the rings, open the Path Maker and press Clear All.

9. Interval selection and the Cycle Tween

The Cycle Tween takes any two pitches and fills the space between them with the pitches the face meets on its way from the first to the second, in the current Interpolate order. It lays them out as a bar you can play, shape and loop.

Selecting an interval

Press and hold a light on the 12 or 24 TET ring for half a second. It sounds, a white ring marks it as the start pitch, and the readout asks for the landing pitch.
Press and hold a second light on the 12 or 24 TET ring. This is the landing pitch. The Cycle Tween opens, and the playback stops.

To cancel, press and hold the start pitch again.
A short tap is still an ordinary tap: it only sounds the pitch. Moving your finger while you hold also makes it a tap.
The tween is in 24 TET when 24 TET is chosen, and in 12 TET when it is not. With 24 TET on, even two 12 TET pitches are tweened in 24.
The tween follows Interpolate as the face shows it at that moment, and Direction: Descending gives the mirror, and Alternate uses Ascending.

Reading the grid

The title names the interval, for example | 0 → 7 |. Below it you see the TET, the direction, the Interpolate order and the number of steps and tweens.
There is one row for each pitch of the TET (12 or 24), highest at the top. The rows the tween uses are bright.
Columns are moments in time: a bar of 4/4 in 16ths (12 TET) or 32nds (24 TET), numbered by beat across the top. One more column at the right end is the next downbeat, where the landing pitch sits.
The start pitch is on beat 1, and the tween notes are spread evenly across the bar. White lines join the notes. Under the grid, the tween is written out in full.

Shaping the rhythm

Drag a tween note left or right to move it in time. It cannot pass its neighbors. The start and landing notes stay put.

The controls

Play — plays the bar of 4/4 (the start pitch and its tweens), then the landing pitch as a half note in a bar of 2/4. Each pitch holds until the next one. At 1x the 4/4 bar lasts 5 seconds, one wedge of the face; Speed changes it. Press again (Stop) to stop. The Space bar does the same while the Cycle Tween is open.
Instrument — the whole tween plays on this one instrument (Piano at start). It is separate from the Path Maker’s, and the Mixer does not affect it. Changing it stops the tween.
Harmonize (off at start) — the start and landing pitches take the Harmonize voices from Settings. The start chord is struck once and rings until the landing, while the tweens play through and over it. The landing gets its own chord, for its half note.
Loop (off at start) — with it ticked, Play repeats until you stop it: the bar of 4/4, the landing in 2/4, then the start pitch comes round again. Untick it to let the one that is playing finish and stop. Notes you drag while it loops are heard from the next time round.
Invert — swaps the start and landing pitches, keeping the TET, Interpolate and Direction. The tween notes are spread evenly again.
Done — closes the Cycle Tween.

10. Saving your work

Tick Save Settings in the Settings panel to keep your work on this device, in this browser. While it is ticked, the lab saves:

Tonic, Interpolate, Direction, TET choices, Pitches, Labels, Speed and Pedal;
your Harmonize voices and the Click;
all your paths, with their instrument and Harmonize setting.

Settings are saved when you press Start, and paths are saved as you change them. The next time you open the lab, everything is as you left it.

When Save Settings is not ticked, nothing is kept: each visit starts fresh with the start-up settings and no paths. Unticking it forgets anything that was saved. The Mixer is never saved. In a private or incognito browser window, saving is not possible and the box is greyed out.

11. Quick reference

To do this	Do this
Play or stop	Play / Stop button, or Space
Hear one pitch	Tap its light
Hear the tonic bass note	Tap the center of the needle
Open the Path Maker	Double-tap a 12, 24, 48 or 96 TET light
Add / move / remove a path note	Tap a cell / drag its white ring / double-tap it
Play a path in the grid	Play in the Path Maker, or Space
Return to the rings	Path Maker → Clear All
Choose an interval (Cycle Tween)	Press and hold a 12 or 24 TET light, then a second one
Cancel the interval	Press and hold the start pitch again
Move a tween note in time	Drag it left or right
Loop a Cycle Tween	Tick Loop, then Play (or Space)
Change instruments and volumes	Mixer
Keep your work	Settings → tick Save Settings

Start-up settings

Tonic C · Interpolate Balanced · Direction Alternate · TET 12, 24, 48, 96, 192, 384 · Pitches Hide redundant · Labels Letters · Speed 1x · Pedal Sixteenth notes · Harmonize voices 4, 8, 6, 2, 10 · Click on · Save Settings off.

12. Things to try

One ring at a time. Choose only 12 TET, set Interpolate to Scale and listen to one lap. Then add 24, then 48. Listen for how each new ring fills the spaces of the one before.
Slow it down. Set Speed to ½x or ¼x, choose 48 or 96 TET, and solo that ring in the Mixer with Sine Wave as its instrument. Listen closely to how small the steps are.
Compare the orders. Play the same rings in Balanced, Cycle and Substitute. Or choose Shifting and let the lab change the order for you on each lap.
Up and down. Use Alternate and listen to how the descending lap mirrors the ascending one.
Draw a small path. Open the Path Maker on the first wedge and add three notes: the 0 at the start, one 48 TET pitch near the middle, and the 12 TET pitch at the end. Press Done and hear your shape travel through all twelve wedges.
Harmonize a path. Tick Harmonize in the Path Maker and hear the fine pitches move over the held chords.
Tween an interval. Turn 24 TET off. Press and hold 0, then 9, on the 12 TET ring (in Cycle order, the start-up setting, the tween is 0, 7, 2, 9). Drag the tween notes into a rhythm you like, tick Loop and press Play. Then turn 24 TET back on, choose the same interval, and hear it tweened in 24.
Watch the harmonic star. Add voices 4 and 8, play in Scale, then switch to Balanced. Watch the star keep its triangle in one, then re-form at every step in the other, while the harmony stays the same.