Advanced Chord Scales
Chord scales are an advanced harmonic concept, normally used to describe the available melodic notes for any given chord. This concept applies both to composing melodies and to improvising them.
Because a chord symbol does not normally contain a complete system of harmony, we will treat each chord as though it implies one or more potential harmonies or chord scales. There are several ways of constructing or establishing chord scales.
Since a chord scale is about choosing the melody notes, either expressed or implied by the chord, we can create chord scales using a number of methods. In this lesson, we’ll organize some common methods. We’ll use the methods that are the most consonantA note that is consonant with another will seem to agree and fit well when played together with the first. first, and move towards those that are more dissonantThe quality of harmonic conflict between two tones or groups of tones. The minor 2nd and the minor 9th are considered two of the most dissonant intervals in music.. Note that in this case, consonance and dissonance are essentially determined by how many notes in the chord scale are outside of the chord or key.
Method 1: Chord Tones Only
Consider that the notes in the chord are the only ones that can be played. Although a little boring, this is a good place to start.
| Chord | C | Amin | F/G | Fmin/G |
| Function | I | IImin | IV/2 | IVmin/2 |
| Chord Tone Scale | C, E, G | A, C, E | F, A, C, G | F, A♭, C, G |
Method 2: Tetrachords
This method is partially used as a basis for the Bergonzi improvisation method. A tetrachord is a series of four consecutive notes. Only two tetrachords are needed to cover most situations: major tetrachord and minor tetrachord. The major tetrachord is 1–2–3–5, and the minor tetrachord is 1–♭3–4–5. Therefore, the tetrachord adds tensionA note which, though not an essential part of a chord’s structure, can be added to the chord for additional coloring. 9 to a major (or dominant) chord, and tension 11 to a minor chord.
While we technically should change the chord symbols used to reflect the addition of a tension, it’s not really necessary yet.
| Chord | C | Amin | F/G | Fmin/G |
| Function | I | IImin | IV/2 | IVmin/2 |
| Tetrachord | C, D, E, G | A, C, D, E | F, G, A, C | F, A♭, C, G |
Method 3: Modal Scale, Chord Tones + Tensions from Key
This method takes the chord tones, and adds any applicable tensions so long as they are within the key. This allows the harmony to depart from the key slightly, as in the case of the A♭, but keeps the dissonance under control by only allowing non-diatonic notes that were specifically in the chord.
Another way to think of this is that we’re picking the chord scale that corresponds to a mode of the key, altering the notes only if the original chord had an altered note. For instance, we can’t use the Mixolydian chord scale on the last chord, because it has a ♭6, so we deal with that specially.
Notice that now the chord symbols are starting to change to reflect a more complex harmony. The F/G has just become an extended G chord.
Also notice that all of the resulting scales are modes of the C major scale, with the exception of G Mixolydian ♭9.
| Chord | Cmaj7(9,13) | Amin7(9,11) | G7sus4(9,13) | G7sus4(♭9, 13) |
| Function | Imaj7(9,13) | IImin7(9,11) | V7sus4(9,13)* | V7sus4(♭9, 13) |
| Modal Scale | C, D, E, G, A, B | A, B, C, D, E, F, G | F, G, A, C, D, E | F, G, A♭, C, D, E |
| Scale Name | C Ionian | A Aeolian | G Mixolydian | G Mixolydian ♭9 |
Method 4: Choose a Chord Scale
The chord scale can also be simply chosen, based on the chord’s possible function, the harmonic systems the chord may imply, or even the whims of the composer. In our case, we only have one good example: the final chord has a ♭9. The musician may choose to interpret this ♭9 not as a complete definition of the chord, but as a hint that the chord comes from another harmonic system. In this particular case, the V7(♭9) chord quite often appears as the V7 of a minor key, in which case it would have a ♭13 as well. Now, despite a lack of clear instruction that we should do so, we’ve added another chromatic note to the chord and to the key. Hope you got a signed waiver. Now you’re changing the tune around.
| Chord | Cmaj7(9,13) | Amin7(9,11) | G7sus4(9,13) | G7sus4(♭9, ♭13) |
| Function | Imaj7(9,13) | IImin7(9,11) | V7sus4(9,13)* | V7sus4(♭9, ♭13) |
| Modal Scale | C, D, E, G, A, B | A, B, C, D, E, F, G | F, G, A, C, D, E | F, G, A♭, C, D, E |
| Scale Name | C Ionian | A Aeolian | G Mixolydian | G Mixolydian ♭9, ♭13 |
Coda
You can create multiple complementary systems of choosing chord scales, and use them to add coherence to your process of writing or performing music. By knowing the chords, and what harmonies they imply, you can use your knowledge intelligently, and navigate through increasingly complicated and harmonically rich music.
Key Task
Choose four interesting chords, and see how many different chord scales they might imply. Either improvise or write example melodies for each variation.
As the creator of Hub Guitar, Grey has compiled hundreds of guitar lessons, written several books, and filmed hundreds of video lessons. He teaches private lessons in his Boston studio, as well as via video chat through TakeLessons.