Introduction
In the last module we learned all about Jazz Chords. We discussed 7th chords, and how to add tension (9th, 11th, & 13th) to create 13th chords. Now we move onto Jazz Scales. In this lesson we will learn how chords and scales are related through the Chord-Scale System and discover that chords and scales are actually the same thing. But first, let’s have a quick refresher.
Scales
A scale is simply some subset of the 12 notes of an octave, and have two components:
- the notes they are comprised of; and
- a tonal centre (or root note).
The (diatonic) Major Scale has 7 notes, but there’s no reason to restrict ourselves to only 7 notes. Scales can have fewer or more notes (all the way up to the Chromatic Scale with 12 notes).
If you keep all the notes of a scale the same but change the tonal centre, you create a new scale or mode. So, a mode is a scale created by establishing a new root note within a pre-existing scale. Modes are just a different way of thinking about scales and keys. Using modes allows us to allocate an individual mode/scale (I will use the two words interchangeably) to every single chord in a progression. In Jazz, this is a very convenient way of thinking, as we will see in a moment.
This is the basis of and the idea behind the Chord-Scale System. Every single chord in a progression is allocated a particular scale which can be used to improvise over that particular chord. Of course, there are many different scales you can use over a single chord, but we will get to that soon enough. So technically, when improvising, every time a we change chords we also change scales.
Chord-Scale System
Scales and chords are interrelated. There are two sides of the same coin.
- A scale is a horizontal representation of a particular collection of notes and is built up in 2nds;
- A chord is a vertical representation of that same collection of notes and is built in 3rds.
So, for example,
- If we take all the white notes and we go up in 2nds (or in steps), then we have the C major scale (C D E F G A B); and
- If we take all the white notes again, but we go up in 3rds, then we have the CMaj13 (C E G B D F A) (ignore the fact that the ♮11 is not an available tension for the moment).
Similarly,
- If we take all the white notes except for B♭ and we go up in 2nds, starting and finishing on the C (C D E F G A B♭), then we have C Mixolydian (or F major but starting and finishing on the C); and
- If we take those exact same notes and go up in 3rds, we have C13 (C E G B♭ D F A) (again, ignore the fact that the ♮11 is not an available tension for the moment).
Or again,
- If we take all the white notes except for the note F# and we go up in 2nds, starting and finishing on the C (C D E F# G A B), then we have C Lydian (or G major but starting and finishing on the C); and
- If we take those exact same notes and go up in 3rds, we have CMaj13#11 (C E G B D F# A).
Right, so the
- C Major Scale has all the same notes as a CMaj13 chord;
- C Mixolydian scale has all the same notes as a C13 chord;
- C Lydian Scale has all the same notes as a CMaj13#11 chord.
So, then these are the scales that you would use to improvise over these chords.
Below is a table of all the Major and Melodic Minor modes and their equivalent chords (plus two extra scales)
| Mode | Chord | 1 | 3 | 5 | 7 | 9 | 11 | 13 |
| Major Scale Modes | ||||||||
| C Ionian | CMaj13 | C | E | G | B | D | F | A |
| C Dorian | Cm13 | C | E♭ | G | B♭ | D | F | A |
| C Phrygian | Cm7♭9♭13 | C | E♭ | G | B♭ | D♭ | F | A♭ |
| C Lydian | CMaj13#11 | C | E | G | B | D | F# | A |
| C Mixolydian | C13 | C | E | G | B♭ | D | F | A |
| C Aeolian | Cm11♭13 | C | E♭ | G | B♭ | D | F | A♭ |
| C Locrian | Cm7♭5♭9♭13 | C | E♭ | G♭ | B♭ | D♭ | F | A♭ |
| Melodic Minor Modes | ||||||||
| C Melodic minor | CmMaj7 | C | E♭ | G | B | D | F | A |
| C Phrygian ♮6 | Cm13♭9 | C | E♭ | G | B♭ | D♭ | F | A |
| C Lydian Augmented | CMaj13#5#11 | C | E | G# | B | D | F# | A |
| C Lydian Dominant | C13#11 | C | E | G | B♭ | D | F# | A |
| C Mixolydian b6 | C11♭13 | C | E | G | B♭ | D | F | A♭ |
| C Half-diminished | Cm7♭5♭13 | C | E♭ | G♭ | B♭ | D | F | A♭ |
| C Altered | C7♭5♭9#9♭13 (C7alt) | C | F♭ (E) | G♭ | B♭ | D♭ | E♭ (#9) | A♭ |
| Other Scales | ||||||||
| C Harmonic minor | CmMaj7b13 | C | E♭ | G | B | D | F | A♭ |
| ??? | C7#5♭9#11♭13 | C | E | G# | B♭ | D♭ | F# | A♭ |
So a 13th Chord is it’s own diatonic scale. But this means that chords NOT extended all the way out to the 13th are slightly ambiguous because they are missing a few chord (and therefore scale) notes. And the key that they are in depends on the previous and subsequent chords in the progression. For this reason it is possible to play multiple scales over the same chord (if the chord is not a 13th chord). For example:
- Because a CMaj7 chord (C E G B) does NOT have an F in it, you can use the following two scales to improvise over it:
- C Ionian (C D E F G A B); or
- C Lydian (C D E F# G A B).
Notice that both scales contain all the notes that comprise the CMaj7 chord. Because the CMaj7 does not have a 9th, 11th or 13th we do not know what key it is in, and therefore we can use both scales over this chord. When thinking in terms of keys (rather than modes) we can say that the CMaj7 chord can be derived from both the key of C Major and G Major (C Lydian).
Of course, if we look at the whole chord progression and see that the CMaj7 chord is preceded by a G7 chord, we can pretty comfortably deduce that the CMaj7 chord is in the key of C Major (rather than G Major). But that doesn’t mean that we cannot use the C Lydian mode over the CMaj7 chord. We absolutely can! The Chord-Scale System looks at individual chords in isolation and allocates scales to each individual chord. We do NOT need to know what key a particular chord is in, in order to choose a scale to play over that chord. In the above example, it doesn’t matter what key the CMaj7 chord is in, we can use both scales to improvise over it.
Indeed, it’s often preferable to choose the scale outside the key of the chord progression in order to give a more harmonically complex and jazzy sound.
If we had the chord progression: | G7 | CMaj7 ||
Many Jazz musicians would use the C Lydian mode over the CMaj7 chord precisely because the chord progression is NOT in the key of C Lydian (G Major). (Also, the Lydian mode has fewer avoid notes than the Ionian mode, but we will discuss this further in future lessons).
Similarly:
- You could use the following scales over a Cm7 chord:
- C Dorian (C D E♭ F G A B♭)
- C Aeolian (C D E♭ F G A♭ B♭)
- You could use the following scales over a C7 chord:
- C Mixolydian (C D E F G A B♭)
- C Lydian Dominant (C D E F# G A B♭)
- C Mixolydian♭6 (C D E F G A♭ B♭)
Conclusion
And so hopefully you now see, chords and scales are really the same thing. They are both comprised of the same limited number of notes. As I have mentioned in the past, all music theory can be broken down into notes and intervals. And things like scales and chords are just abstractions from the 12 notes of the octave.
While this begins to explain why you can use multiple scales over the same chord, this only scrapes the surface. In the next lesson we will explore this topic in much more detail.