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This is a preview of the educational program A Jazz Improvisation Almanac which is under development for the Outside Shore Music Online School. Feel free to browse this preview and learn what you can from it. For a more completed product, though, check out the original freely browsable jazz textbook, A Jazz Improvisation Primer.

In music that has a well-defined key center, the relationship of a chord to the key of the piece, or of the particular phrase, can affect scale choice. If a sequence of chords is diatonic to the key, it may make sense to simply use the scale of the key over that entire sequence. This is what I have previously called the diatonic approach to improvisation. It is also referred to as harmonic generalization.

The most important application of this principle is in major key ii-V-I progressions. The major scale of the I chord works over all three chords, as it contains the same notes as the scales that the chart suggests - the dorian mode built on the ii chord and the mixolydian mode built on the V chord:

[EXAMPLE]

When building a melody over this progression, you might treat it as a single expression of the key center, rather than as three separate chords:

[EXAMPLE]

In minor keys, you might try the harmonic minor scale of the i chord over a ii-V-i progression:

[EXAMPLE]

This assumes that the ii chord is half-diminished and the i chord is a tonic minor, as is usually the case. However, the augmented second interval between the sixth and seventh degrees of the scale is a bit awkward melodically, and the effect is so distinctive that it can tend to overwhelm the sound of the line:

[EXAMPLE]

A good alternative is to add the flatted seventh to the scale as well. The resultant scale is actually the major bebop scale of the relative major:

[EXAMPLE]

This scale is perhaps the best choice for minor key progressions when playing diatonically. Besides being smooth meloidcally, it also fits the harmony better than the harmonic minor if the i chord should happen to be a minor seventh rather a tonic minor. Furthermore, the flat seventh becomes the raised ninth of the V chord, which creates additional tension. The overall effect is very strong:

[EXAMPLE]

The natural minor may be used as well, although this does not fit a tonic minor i chord well, and omits the major third of the V chord completely:

[EXAMPLE]

Also, the melodic minor works if the ii chord is a minor seventh and not a half-diminished chord:

[EXAMPLE]

Sometimes, the desire to play diatonically can lead you to play scales you might not have played had you taken a modal approach. For example, the scale normally associated with Em7 is E dorian. However, if Em7 occurs in a piece that is in C major, it would make sense to use the C major scale - or, more particularly, the third (phrygian) mode - over the Em7 in this context. Despite the fact that the F is somewhat dissonant against the Em7 chord, using the phrygian mode over the Em7 chord allows you to construct a melodic line that is totally diatonic:

[EXAMPLE]

Whereas using the E dorian mode would introduce two chromatic alterations to your melody - F# and C#:

[EXAMPLE]

The color of the F and C is a little awkward for the Em7 when considered in isolation, but they fit the color of the overall C major key better than the F# and C# do.

When playing a composition where the chords change quickly, it can sound smoother to use a single scale over several successive chords. In fact, you may choose to use the scale over the progression even if one chord it does not quite fit all the chords. A common example of this is in a I-vi-ii-V progression in which either the vi or the ii chord has been made into a dominant seventh chord:

[EXAMPLE]

Here, you can use the major scale of the I chord over the whole progression, as if the vi and ii chords were still minor seventh chords:

[EXAMPLE]

Diatonic lines created in this fashion can sound rather generic, and if you choose your notes with complete disregard for the underlying chords, you may create unintended dissonance as you inadvertently land on "avoid" notes such as the fourth of a major chord:

[EXAMPLE]

It is usually a good idea to attempt to relate your line to the chord progression in a more significant way. This still does not mean you must change scales with every chord, however. There are devices that can help even completely diatonic lines work better with the harmony. Perhaps the most important such idea is to control tension and release by focusing on the V chord rather than the I chord. In a ii-V-I progression, the V chord is the focal point. Your line over that chord should create tension that will be released when you get to the tonic:

[EXAMPLE]

This is a fairly subtle point, but it is one that I believe can make a huge difference in how an improvised melody is perceived. By shaping the contour of your melody so that you are creating tension and release along with the chord progression, your melody will appear to be a natural extension of the harmony rather than being merely in the same key. Here is another example:

[EXAMPLE]

Ultimately, you may wish to capture the sound of the whole progression rather than acknowledging it only for the V chord. Since the thirds and sevenths of the chords in a tonal chord progression are the most important tones from a functional perspective, one way to outline the changes is by emphasizing the thirds and sevenths of the original chords in your line:

[EXAMPLE]

When the chords resolve upward by fourth, as is most common, this has the added benefit of creating good voice leading:

[EXAMPLE]

While harmonic generalization is a powerful tool, you may wish to introduce additional contrast within your lines by further exaggerating the change from one chord to another. You can do this by changing scales from chord to chord, choosing scales with relatively few notes in common. For example, consider a major key ii-V-I progression. Again, since the V chord is the focal point of the progression, it is usually best to start by concentrating on it. Rather than use the mixolydian mode, you may wish to choose the lydian dominant, HW diminished, diminished whole tone, or any other scale associated with altered dominant seventh chords:

[EXAMPLE]

Any of these scales introduce notes not in the scales used for the other chords. Of course, in order for this to have any effect, you will have to actually play the non-diatonic notes. Here is an example line:

[EXAMPLE]

You could also make a tritone substitution on the V chord:

[EXAMPLE]

You may also choose to use the lydian mode instead of the major scale for the I chord to provide additional contrast:

[EXAMPLE]

In minor keys, the diatonic chords are already rich, but you can still increase contrast by choosing alternate scales for any of the three chords. For example:

[EXAMPLE]

You might also considering substituting chords, such as using a plain minor seventh ii chord rather than half-diminished:

[EXAMPLE]

Or, you might choose to make it a secondary dominant. Adding the sharp ninth helps preserve the minor sound:

[EXAMPLE]

As another example of choosing scales to increase contrast, consider a IV-V vamp in the key of C:

[EXAMPLE]

Harmonic generalization would suggest C major, or F lydian and G mixolydian:

[EXAMPLE]

However, this approach does not provide the contrast you might want to achieve in a vamp. Instead, you might use F major and G lydian dominant. These scales differ in two places:

[EXAMPLE]

This allows you to exaggerate the change between the chords in your lines by emphasizing these points of difference as well as the thirds and sevenths of the respective chords:

[EXAMPLE]

Copyright 2000 Outside Shore Music
Authored by Marc Sabatella

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