Cube FAQ

cube prototype
What’s it for?
The cube translates between the language of chords and the language of scales. Chords and scales are basically the same kind of thing: a selection from the twelve notes in the octave, with one of them identified as the root. It’s a chord if you pile them up and play them together. It’s a scale if you choose notes from it and spread them out across a rhythm. Many scales have their own individual names. We name chords more analytically by naming the basic chord quality and then listing any extensions.
So, with the cube I can choose the right scale to play over a chord?
A lot of assumptions in that question. But yes. At least if it’s a dominant chord, which is when the choices are at their toughest and most exciting.
I already have a chart which tells me that.
There are many such charts. The cube is different because it shows how the various chords or scales are related, and how they fall into families. You can see exactly how the altered scale differs from the whole tone scale, for example, and you can identify situations in which one, or the other, or both might be suitable.
You can also work the other way, from scales to chords. The cube is  a map of part of the space of scales and chords. Like any map, it is versatile. There is no single way to use it.
Why just these eight scales?
I plan to write a longer piece explaining why these eight scales were chosen. But briefly, the cube supplies at least one scale for each plausible choice of extensions on a dominant chord. I have favoured scales where the notes are fairly evenly spread over the octave. That means no big gaps or massive clusters.
In three cases where the cube’s first suggestion was an uneven scale, notes have been added or removed to make it more even. In each case the more even scale turns out to be one that jazz musicians use frequently, and that jazz educators teach.
Which scales are missing?
The cube covers all 6- 7- and 8-note scales which have dominant quality and meet our requirement of evenness. There are other scales of 8 or more notes, right up to the 12-tone chromatic scale. But the additional notes tend to be passing notes, of little harmonic significance. The cube does not feature any scales of 5 tones or fewer.
Eight scales seems a lot. People say you can play jazz with just four scales.
Hal Galper offers a table of  ‘scale equivalents‘ which covers most dominant chord symbols with just four scales. Mark Levine says you can interpret almost all chord symbols using just four scales: the major scale, the melodic minor scale, the diminished scale, and the whole-tone scale. But to make this work, you cannot always treat the same note as the root of the scale. In other words, you may need to use a scale in several modes.
The cube shows three modes of the melodic minor. Each is appropriate in different circumstances. By Hal or Mark’s count, that is just one scale. Having said that, there are two additional scales on the cube: the harmonic minor and harmonic major (in their fifth modes). Treat these as lower-priority if you like. They’ll be there when you are ready for them.
What about blues and pentatonic scales?
That’s probably the biggest omission. I could not find a good way to include these scales on the cube. Perhaps that is because blues harmony is different, and has its own rules.
In the blues, dominant chord quality is not necessarily associated with dominant function. The I, IV and V chords are all dominants. The minor pentatonic, and its embellished version the blues scale, provide a #9 for I and V, but not for IV. Many, but not all, of the #9s in jazz come from blues harmony.
I play lots of sharp ninths, but the cube makes the #9 look much less important than the b9. Why?
The cube is based on the assumption that the three extensions of a dominant chord (the 9th, 11th and 13th) can be altered independently. That turns out to be a good assumption if your choices are 9/b9, 11/#11 and 13/b13. Those three binary choices give us eight possible outcomes, each of which corresponds to a scale that is used in jazz.
However, introducing a sharp ninth is not something you can always do, regardless of other alterations in the scale. To most ears, the sharp ninth doesn’t work well with a natural ninth or a natural eleventh. That part of the scale is just too crowded already. (A sharp ninth does work with a flat ninth. )
If you look at the cube, you will see only two scales with a sharp ninth. Compare that with the four scales which have a flat ninth. That’s not to say the #9 is unimportant in jazz. It is common in blues and pentatonic harmony, but, as the previous answer explains, that is a separate subject that the cube does not attempt to address.
Why don’t you use chord symbols?
Chord symbols can be ambiguous. They do not always indicate clearly which notes you should, or should not be playing. With the cube you can consider each of the three extensions (9th, 11th and 13th) separately, and be absolutely precise about the options which are available for each.
Chord symbols can, of course, be useful clues to comping or soloing, along with other things such as melody notes in the head. But remember that lead sheets tend to be based on one chorus of one particular performance. Never mind other versions, you’ll often hear something different 30 seconds later in the same recording.
Why are the corners of the cube different colours?
  • Purple for diatonic modes.
  • Blue for melodic minor modes.
  • Green for harmonic minor modes.
  • Yellow for harmonic major modes.
  • Pink for symmetric scales.

There are three melodic minor modes and two symmetric scales, and  one each of the other three kinds.

Should I use the cube at gigs, jam sessions and recordings?
Probably not. It’s more useful when you are listening, studying, preparing and practising. But if you use the cube regularly in the practice room, you should be gradually absorbing knowledge that is useful when you are on stage. You will also be learning more of the technical language that musicians use.
Can teachers use it?
We certainly hope so, but we will only know how effective it is when a number of teachers have used it and reported on their experience. Most teachers and jazz schools have decided on an approach to music theory which they don’t like to change without good reason. However, there is nothing about the cube that ties it to a particular method of teaching.
It is no problem if you use different terminology – different names for scales, for example. It is easy to change the wording on the cube. The relationships between the scales and chords are the same, whatever you call them.

Print, cut out and assemble jazz harmony cubes

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Jazz harmony cube by Tony Durham is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.