Guide
How to read the circle
Five ideas, in the order you meet them in the instrument.
1. The circle of fifths
The twelve notes sit in fifths: C, G, D, A, E, B, F♯, D♭, A♭, E♭, B♭, F. Neighbours share the most; a scale becomes a shape. The more compact the shape, the more consonant the collection tends to sound.
2. A Circle number for every shape
Walk the chain of fifths from its first note and write 1 for each occupied position, 0 for each gap. The diatonic collection fills seven fifths in a row: 1111111, which reads as127. F G A♭ B♭ C D E gives 101111101: Circle 381.
The walk always starts where it is shortest, so every collection has exactly one number, whatever its transposition. There are 4,095 collections and 351 shapes. The first note of the walk is theanchor; you never type it.
3. Tonic and position
A shape does not say where home is. You choose the tonic, and the positionit occupies in the chain. Changing the position keeps the tonic and moves the notes around it: on Circle 127, C at position 1 is C Ionian, C at position 3 is C Dorian.
Chordfields proposes a position — the middle of the first three consecutive fifths — but it is only a proposal. Clicked notes never decide the tonic for you: the instrument offers each reading and lets you pick.
4. Modes only where they belong
Lydian, Ionian, Mixolydian, Dorian, Aeolian, Phrygian and Locrian are the seven positions of anunbroken chain of seven fifths. On any other shape, borrowing those names would be wrong, so the instrument speaks of positions, and nothing else.
5. Chord fields
A chord field is the set of chords whose notes all belong to a collection: its major and minor triads, or its seventh chords. On the circle, each chord is a small polygon inside the field, drawn in the colour of its root; minor chords are dashed. A chord being present says nothing about its function — the field shows what you can play, not what you should.
Other numbers you will see
- Forte label — Allen Forte’s classification, which also merges a set with its inversion.
- Prime form — the most compact spelling from 0 (Rahn’s convention), with t = 10 and e = 11.
- Interval vector — how many of each interval class the collection contains.
- Ian Ring — the scale number in A Study of Scales, counted from the tonic.
None of these replaces the Circle number: they are cross-references.