Harmonic Universe
What it’s for
Harmonic Universe turns tonal harmony into a map you can travel. Every key is a star. Step into one and its seven chords orbit the tonic like planets, and the way they move tells you how they behave:
- colour is the chord’s function: tonic, subdominant or dominant;
- size is its harmonic weight;
- distance from the sun is how strongly it pulls home;
- orbit speed is how urgently it wants to move.
Then it shows you what no chord chart can. Hover over a chord and arcs reach out to every other key that contains the same chord. Every ø7 carries its own Protean cluster: the four chords that one ø7 shape can stand for, from GMI’s book The Protean Chord For Jazz Guitar. Every °7 shows the four dominant 7♭9 chords it belongs to. And the guidance on each chord is written for the key you’re in: in F major, the VII card talks about Eø7, not Bø7.
You can collect chords from any keys as you go and send them on to Progression Lab, the Cycle Wheel or Key Builder.
Who it’s for
Anyone who wants to understand why chords move the way they do: players learning keys and harmonic function, improvisers looking for shared chords to pivot through, and arrangers hunting for substitutions.
Free and Pro
Free Everything in Harmonic Universe is free, whether or not you’re logged in.
The one exception is the Selection tray along the bottom: collecting chords and sending them on needs a free account. Sending a progression to Progression Lab opens a Pro app.
Getting around
Harmonic Universe has three levels: the galaxy of all keys, a key’s solar system, and one chord in focus. The strip under the scale buttons always says where you are, for example Galaxy › C Major.
- ← Galaxy returns to all twelve keys.
- ← Previous goes back to the last key you visited.
- Major · Nat. Minor · Harm. Minor · Mel. Minor switch the scale the key is built on. Pressing the scale you’re already in takes you back to the major.
- The control bar at the top right holds ? Guide, Sound, Galaxy Map, Full screen, Legend, Recentre and Protean ON / OFF.
- Zoom + −, bottom left, enlarges or shrinks the view.
- The Selection tray runs along the bottom.
Features
The galaxy
Free
The twelve major keys sit around the outside in cycle-of-fifths order, C at the top. The inner ring holds their relative minors: Am inside C, Em inside G and so on. Hover over a star to see its name, then click (or tap) it to enter that key.
Minor keys are spelt the way players read them: C♯ minor, G♯ minor and E♭ minor, not D♭ minor with its F♭ and B𝄫.
A key’s solar system
Free
The sun is the tonic; the planets are the key’s other six seventh chords, each labelled with its numeral, root and quality. Numerals are written the jazz way, in upper case, with the quality on the chord itself: II with Dm7 beneath it, not ii.
What the planets tell you:
- Colour: function. Blue is tonic, green is subdominant, orange is dominant, and purple is the Protean ø7.
- Size: harmonic weight. The tonic is largest, then V, II and any dominant-function chord.
- Distance: pull to the tonic. V orbits closest, with the leading-tone chords just outside it. Pre-dominant chords sit mid-system. The tonic substitutes, III and VI, drift on the rim: they share most of their notes with the tonic, so they barely pull at all.
- Speed: urgency. Tight, fast orbits want to move soon; wide, slow ones are at rest.
Legend explains all of this on screen at any time.
Chord cards
Free
Hover over a planet (tap it on a phone or tablet) and its card opens:
- a one-line summary of what the chord does;
- its function and numeral;
- its intervals and notes;
- a paragraph of musician’s guidance, using the chords of the key you’re in. In C major the II card reads “Dm7 → G7 → Cmaj7”; in E♭ major it names Fm7, B♭7 and E♭maj7;
- + Add to Selection, which puts the chord in the tray.
Click the planet (or press Open this chord › on a phone) to bring it into focus.
Shared keys
Free
Hover over a chord and arcs reach out to every other key that contains it, major or minor. Each arc is labelled with the chord’s numeral there and, for minor keys, which minor scale it comes from: G7 from C major points to C as V · harm/mel min and to D as IV · mel min, because only D’s melodic minor contains G7.
Chord focus
Free
Click a planet to bring it into focus. The chord becomes the centre:
- the inner ring holds its four notes, each with its interval;
- the next ring holds the other keys that contain it (up to ten). Tap one to travel there;
- + Add to Selection adds it to the tray;
- the chord’s guidance sits beneath.
Zoom + − enlarges a chord in focus. The back button at the top left (← C Major, for example) takes you back to the key; changing the key or scale leaves focus by itself.
The Protean ø7
Free
Every ø7 chord has a Protean cluster orbiting at the edge of its key: the same four notes heard as four other chords. For Bø7 those are G9, Dm6, D♭7♯5♭9 and E7sus4♭9. This is the idea at the heart of GMI’s book The Protean Chord For Jazz Guitar: one shape you already know, redeployed over four different harmonies.
- Hover over (or tap) a cluster planet, or the ø7 itself, and a Protean Synonyms panel opens at the edge of the screen. Each synonym has its own card: what it is and where it resolves.
- Each synonym can take you to the key it belongs to or resolves into. Travel is always through a button, so nothing jumps to another key on a stray tap.
- Melodic minor has two ø7 chords, so it has two clusters, on opposite sides.
- Protean ON / OFF hides the clusters when you want the key on its own. The ø7’s panel and card still work.
The ø7’s card also gives the book’s practical uses: play it over the altered dominant a whole step above for an instant 7♯5♭9 sound, and over the I chord move to the ø7 on the ♯4 for maj13♯11, the Lydian sound. In natural and harmonic minor, the II chord’s card gives the three-arpeggio II–V–I: in A minor, Bø7 → Dø7 over E7 → F♯ø7 over Am, whose roots spell B minor.
The four scales
Free
Every key can be built on four scales: Major, Natural Minor, Harmonic Minor and Melodic Minor. Switching rebuilds the system with that scale’s chords, so you can see exactly what the raised 7th of harmonic minor, or the raised 6th and 7th of melodic minor, do to the harmony: a true V7, an augmented ♭IIImaj7♯5, a °7 on VII, two ø7 chords in melodic minor.
Borrowed chords. The scale buttons keep the same root, so they’re the quickest way to see where borrowed chords come from. Enter C major, then press Nat. Minor: you’re in C minor, the parallel minor. Compare the chords on IV, ♭VI and ♭VII with C major’s own: Fmaj7 becomes Fm7, Am7 becomes A♭maj7, and Bø7 becomes B♭7. Borrow any of them into C major (Harmonic Universe shows them as sevenths; the triads Fm, A♭ and B♭ are their first three notes) and you get the darker colours heard in countless songs, such as the IVm in C – F – Fm – C, where the top voice falls A – A♭ – G.
Player Projects Unit 3, Borrowed chords, is a free unit built on this; see the Player Projects Guide.
The diminished 7th
Free
A °7 chord divides the octave into four equal parts, so the same four notes belong to four different dominant 7♭9 chords. Hover over the °7 and the Symmetrical Harmony panel shows all four, which note of the °7 is each one’s 3rd, and the minor key each resolves to. B°7 gives G7♭9 → C minor, B♭7♭9 → E♭ minor, C♯7♭9 → F♯ minor and E7♭9 → A minor.
Galaxy Map
Free
Galaxy Map opens a small map of every key, with the one you’re in highlighted, so you can see where you’ve travelled to without leaving it.
Sound
Free
With Sound ON, a chord plays when you bring it into focus. It’s a simple tone so you can hear the chord’s colour; switch it off with the same button.
The Selection tray
Free Needs a free account
Collect chords as you travel:
- + Add to Selection on any card, or in chord focus, adds the chord to the tray. Each one remembers the key it came from and its numeral there.
- The tray holds up to nine chords. A tenth replaces the oldest.
- × on a chord removes it; × at the end clears the tray.
Then send:
- Send to Progression Lab Pro opens Progression Lab with your chords loaded as a progression, in order, with voice leading and playback.
- Send to Cycle Wheel opens the Cycle Wheel on the key. If your chords come from more than one key, you choose which.
- Send to Key Builder builds a key from one of your chords: you choose the chord, and Key Builder uses its root as the new tonic.
Each button tells you what it will do before you press it.
If you’re not logged in, + Add to Selection explains that collecting needs a free account and offers Join free and Log in. Everything else keeps working.
On phones and tablets
Free
- Tap a planet for its card, which slides up from the bottom of the screen. Open this chord › brings it into focus.
- Drag an empty part of the screen to move around the system. Recentre puts it back.
- Full screen hides everything but Harmonic Universe, which helps most on a tablet.
Works with
Harmonic Universe sends to:
- Progression Lab: your tray as a progression Pro
- Cycle Wheel: a key from your tray
- Diatonic Key Builder: one of your chords as the new tonic
Harmonic Universe opens from: the Cycle Wheel and Key Builder, whose Universe buttons open their key here.
Related concepts
Protean chord · Synonym · Half diminished · Diminished 7th · Symmetrical harmony · Chord function · Relative keys · Harmonic minor · Melodic minor
Try it
Enter C major and hover over Am7: count the keys it belongs to. Then switch to Harm. Minor, hover over B°7, and follow one of its four 7♭9 chords into a new minor key.
