Top-Down View

The chord-scale compatibility approach can be applied to all seventeen modes of the four scale types, which will organize hundreds of compatible chord types, giving us a lot less information to keep track of, yet preserving the nearly endless possibilities of scalar, tonal music.

Scale Types

We explained in detail how the different triads and seventh chords fall out of the modes of the diatonic scale, then we showed extended chords of the diatonic scale. Here we continue where we left off for the other scale and mode types. As mentioned in a previous tutorial, four scale types are the focus of jazz theory and the focus of Harmonious.


These simple, unordered scale objects distill over two hundred named modes into an easier-to-remember set of four patterns of whole-tone and semitone intervals that span the octave. (See Beyond Diatonic.)

Since the set classes for the four scales are symmetric, we can think of them as either OPTC- or OPTIC-equivalent objects.

Mode Types

From the four scale types we derive seventeen mode types by starting on each scale degree and naming off the different patterns of semitone or whole-tone steps (see Diatonic Modes & Chords for a simpler example of just diatonic modes and chords).


We can see that the diatonic and acoustic (melodic minor) scales have seven modes each. The diminished scale has two modes, and the whole-tone scale has only one mode. These last two are modes of limited transposition.

Voice-leading relationships between all of these mode types (for the seven-note scales, including modes of the harmonic major and harmonic minor scales) are illustrated by the following diagram, where moving from one shape to a neighboring shape equals single-semitone voice leading:

More Scale-tone Chords and Avoid Notes

A few previous sections listed the chords compatible with the modes of the diatonic scale, and here we list scale-tone chords and avoid notes of the modes of the C Melodic Minor scale, as well as the C Diminished (Octatonic) scale and the C Whole-tone scale.

Melodic Minor (Acoustic)

5 7 9 (or 2) 11 (or 4) 13 (or 6)
Avoid 9 (E)
Avoid 13 (C)
Avoid 13 (E)

Diminished (Octatonic)

5 7 9 (or 2) 11 (or 4) 13 (or 6)

Whole Tone

5 7 9 (or 2) 11 (or 4) 13 (or 6)

Where do all these chord names come from? We have seen how chords relate to modes, which notes of the modes are important or can be avoided, but how do we ensure we are being exhaustive? The next two sections will introduce a few more rules (more notes that can be left out—simplified voicings with fewer notes) and then embark on a final attempt to connect the musical set theory to more conventional (jazz) harmony, so we can use conventional names for chords.