The Scale Choice series of articles are intended to highlight the construction of different scales, the structural basis of which will then be expanded and applied to different chords in a musical setting. As we modify the basic scale with additional notes we will explore the relationships which these notes have with the original scale and discuss the structure of the new scales or modes and their application.
The content of these articles is intended as an introduction to this topic and is therefore not exhaustive. While much of the information will relate to genres such as Jazz and Fusion, it can also be applied to other styles of music.
Perhaps the main focus of this series is to encourage the use of your ears to guide your note selection. After all, to achieve complete freedom when composing and improvising we must gain an understanding of how all twelve notes may be applied to different musical situations.
All of the following discussion will be related to the A natural minor scale, the A minor triad, and the A minor triad with extensions.
The Natural minor scale is one of the ‘relative minor’ family of scales – this means that all scales in this family possess the same notes, with some slight modifications, as their relative major. While the natural minor scale contains exactly the same notes as its relative major the other two scales in the relative minor family (the Harmonic minor and Melodic minor) do not.
The A natural minor scale contains the same notes as C major.
When harmonised it contains the same chords as the harmonised C major scale.
The natural minor scale is also known as the Aeolian mode: the sixth mode of the major scale. This means that the A minor scale, or A aeolian mode, also contains the other major-scale modes.
The A natural minor scale also contains the A minor pentatonic scale.
The application of the A natural minor and A minor pentatonic scales with A minor triads and extended A minor chords, without alterations ‘works’ because all of the notes of an A minor chord are found in the A natural minor scale.
By replacing the B note of the A natural minor scale with a B flat we produce the A Phrygian mode. The Phrygian mode is the third mode of a major scale, therefore, the ‘parent’ scale of A phrygian is F major. Because the third chord in F major is an A minor chord we can also use A Phrygian over A minor chords, when we want a Phrygian sound.
If we add a C sharp to the A Phrygian mode we create A Phrygian Dominant (also known as Mixolydian flat 9, flat 13). Phrygian dominant is the fifth mode of the harmonic minor scale. In other words, the parent scale of A Phrygian dominant is D harmonic minor.
Because the seventh arpeggio built on the root of the Phrygian dominant mode is a dominant seventh arpeggio the Phrygian dominant’s application is typically over dominant seventh chords and their extensions. This usage gives the flat 9 and flat 13 extensions reflected in the Mixolydian flat 9, flat 13 name (the name Mixolydian reflects the fact that the mode is found on the fifth degree of the harmonic minor scale).
If we include an E flat note with the A natural minor scale we have added a so-called ‘blue’ note. The flat 5 of a scale is often called a blue note because it is part of the Blues scale, which is essentially the minor pentatonic with the added flat 5.
If we also add an F sharp to the A natural minor scale with added E flat we produce one of the Dorian Bebop Minor Scales.
The Dorian mode is the second mode of the major scale. Therefore, A Dorian mode is the second mode of G major; the note E flat, in this context, still reflects the Blue note related to A (flat 5) but can also be heard as a chromatic passing note between the fourth and fifth degrees of the Dorian mode.
If we sharpen the fourth degree of an A Dorian mode, we create Dorian sharp 4: the fourth mode of the harmonic minor scale.
When played over an A minor chord, the D sharp note doesn’t sound like the blue note of the previous example, even though it is the same (D sharp = E flat). Because of the augmented second interval between C and D sharp, in this context, the D sharp’s ‘pull’ is towards the E note.
If we raise both the sixth and seventh degrees of the natural minor scale we get the melodic minor scale.
The raised notes mean that the melodic minor’s application is typically over minor sixth chords and minor-major seventh chords. The melodic minor scale may also be used over the relative major chord. Over C major the F sharp of A melodic minor would produce a Lydian sound, while the G sharp would produce a sharp five sound. Collectively, the notes of a melodic minor scale played over the relative major produce Lydian sharp 5, the third mode of the melodic minor scale (see Scale Choice: Major Chords)
Combining the melodic minor scale with the flat 5 and flat 6 produces the whole-half Octatonic scale, also known as the Diminished scale.
Typically these scales are used over either dominant or diminished chords: Over an A flat/G sharp Dominant seventh chord you can play the A octatonic scale (the octatonic scale a semitone above the dominant seventh’s root note), while over an A diminished seventh chord you can play an A octatonic scale. And, because diminished seventh chords have four possible root notes, the A octatonic scale may also be used over C, E flat and F sharp diminished seventh chords.
Although the typical application of the octatonic scale is over dominant or diminished harmony, you can also use it over minor chords with the same root note: A octatonic over A minor. This application needs to be treated with care, however, as we have seen, all of the notes in the A octatonic scale ‘work’ over an A minor sound world. Further discussion on how these notes can be treated in this type of application is found at the end of this article.
Adding a B flat and A flat note to the melodic minor scale gives us the following whole-tone scale.
Notice that the A note is not included in this scale. However, because all of the notes can be found in other scale choices which are typically applied to minor chords, our ear accepts the lack of the root note. The whole-tone scale begun on an A note produces notes too far removed from our A minor tonality
which is why it is not used.
Probably two of the best ways to remember this scale choice is to play a whole-tone scale which begins either a semitone above or below the root (G sharp), or on the fifth degree of the minor scale (E).
Whole-tone scales are typically used over dominant harmony: when begun on the same root as the dominant chord they produce both flat 5 and sharp 5 extensions. If we begin our whole-tone scale on E, the dominant of A minor, we can see these extensions.
Because an altered dominant seventh chord is included in this whole-tone scale we can imply V – i resolutions over A minor harmony.
Or, we can simply enjoy the various colours available with this scale choice.
We have now combined all twelve chromatic notes with the A natural minor scale (There are other combinations of chromatic notes which can be applied to the natural minor scale, however, a full discussion of these is beyond the scope of the present article).
Of all chromatic notes it is probably C sharp which can potentially cause the biggest problem when used with A minor scales and chords. C sharp, being the third of a major triad counteracts and clashes with the sound of the minor third of A minor. Just as we saw with the D sharp in the context of the Dorian sharp 4 mode, when used over an A minor chord, C sharp is probably best treated as either a lower neighbour note to D,
or as a passing note from C to D.
When used in this way the major third ‘quality’ of the C sharp is lessened.
The lower, or upper, neighbour and passing notes are probably the most common means of including chromaticism over a chord when the use of a complete scale or mode choice is not desired. A solo or melody needs to have shape and direction, and simply playing the notes of a scale consecutively is not always the best way to achieve this. The use of neighbour notes and passing notes can facilitate melodic shape and direction while also effectively incorporating chromaticism into the sound world of the underlying chord, or chords.
A further example can be drawn from the octatonic scale discussed previously. Playing the entire octatonic scale over an A minor chord may produce a sound which is too far removed from the A minor sound world. However, by concentrating on the upper tetrachord (from E flat to G sharp) of the scale we can use these notes, along with passing notes, to lead the ear into the octatonic sound world. This ‘works’ because the notes of the octatonic scale’s upper tetrachord already includes F sharp and G sharp, which are diatonic to the melodic minor and harmonic minor scales, and the E flat is familiar to most people as the blue note. Therefore, by using existing ‘chromatic’ notes such as these, we are able to introduce other notes which could sound ‘out’ when unprepared.
This method of introducing chromatic notes can be applied to other scales also, such as the whole-tone scale and the Dorian bebop minor.
Remember: often the characteristic sound of a mode or scale may be implied when a chromatic passing note or neighbour note is used in conjunction with a mode. In the following example the mode being used is A Dorian, however, in the second bar the inclusion of the B flat upper neighbour note gives this bar a Dorian flat 2 sound.
Below is a summary of the scales and modes which we have discussed.