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Lesson 9 - Isolated chords

An isolated chord is a non-diatonic chord which clearly establishes a new key center but is not preceeded or followed by any other chords from the new key center. For example:

CΔ → BØ → Am7 → G7 → EbΔ → FΔ → G9

The EbΔ is an isolated chord (more specifically it is a chromatic mediant). Notice that no other chords from the keys of Eb or Ab (the two keys in which EbΔ is a diatonic chord) are present. Consequently, the EbΔ must be treated as an isolated chord. Isolated chords are primarily important because they pose interesting improvisational problems.

Major sevenths
Isolated major sevenths (or major ninths, major elevenths, and major thirteenths) are usually treated in the same manner as a I chord. Some jazz musicians prefer to treat an isolated major seventh as a IV chord, but the first approach is more widely used. Either is acceptable.

Sixths and six/nine chords
Sixths and six/nine chords are also treated as I chords. They can, as a second choice, be treated as IV chords.

Minor sevenths
Minor sevenths and their extensions (minor ninths, minor elevenths, minor thirteenths) are generally treated as IV chords when occurring as isolated chords. However, a great many modern jazz musicians prefer to treat the minor seventh as a II chord even though it is isolated and not part of a II-V progression. This lends a modal quality to the improvisation because you are effectively using a dorian mode (see lesson on modes). This occurs most commonly when two or more isolated minor seventh chords occur in succession. The minor seventh chord is rarely treated as a III chord when isolated.

Minor sixths
An isolated minor sixth is generally considered as a Im6 of a minor key. Use a melodic minor scale (ascending form only) when improvising; i.e. Cm6 requires C melodic minor.

Minor seventh flat-five
The minor seventh flat-five chord rarely appears as an isolated chord. However, if you should come across it as an isolated chord treat it as a VII chord.

Dominant sevenths
Isolated dominant sevenths can be treated in a number of ways. They can be treated as normal V chords of a major key; however, I prefer to use another method. If the root of the isolated dominant seventh is III, VI, or VII (E, A, or B in C major), use the harmonic minor a fifth below the root of the V dominant seventh. For example, if you are in the key of G major the proper scale to use on a B7 (V7 of VI) is E harmonic minor. The reason for this is that the chord tones of the dominant seventh are included in the harmonic minor scale, but the passing tones are closer to the original key than if you use the major scale. Because the passing tones are closer to the original key center, the transition from the original key to dominant seventh is smoother and more pleasing. If the isolated dominant seventh is built on the fourth scale degree (IV7) use the melodic minor a fourth below. Here is an example in the key of C:

CΔ → Dm7 → FΔ → (any isolated dominant seventh) → G7

If the root of the isolated dominant seventh is:

  • C use F major scale
  • D use G major scale
  • E use A harmonic minor scale
  • F use C melodic minor scale
  • G use C major scale
  • A use D harmonic minor scale
  • B use E harmonic minor scale

All extensions (ninths, elevenths, and thirteenths) should be carefully considered when determining the proper scale for more complex versions of isolated dominant sevenths.

Diminished seventh chords
A diminished seventh is always an isolated chord unless it is to be used as the VII chord of a minor key. The diminished scale should be employed when soloing over a diminished seventh chord. The diminished scale consists of 1-2-b3-4-b5-#5-6-7-8.

Augmented chords
Augmented chords are always isolated chords unless used as the III chord of a minor key. The whole-tone scale is used with this chord. The four-note version of this chord, the augmented seventh or seven sharp-five chord, is discussed under altered dominant chords.

Altered dominant chords
An altered dominant is a seventh chord with a sharp or flat fifth and/or a sharp or flat ninth. Here is a list of all possible altered dominants:

Possible altered dominant chords
V7(#5) V7(b5) V7(b9) V7(#9)
V7(#5/b9) V7(#5/#9) V7(b5/#9) V7(b5/b9)

Altered dominant chords are found most often as the V chord of a minor key. Be sure that this is not the case before treating the chord as an isolated altered dominant.

The seventh (or ninth) with a sharp or flat fifth (example: C7(#5), C7(b5), C9(#5), C9(b5) can take a whole-tone scale in improvisation.

The seventh with a flat ninth (example: C7(b9)) can be improvised over with a diminished scale a half step above the root.

The seventh sharp nine (example: C7#9) can also take a diminished scale, but because of its use in primarily jazz-rock oriented progressions I prefer to use a pentatonic scale a minor third (one and a half steps) above the root.

In addition to the methods for improvisation already mentioned for altered dominants, many modern jazz players use the "altered scale" (also called "super-locrian") over isolated altered dominants. The altered scale is similar to the diminished scale but it. has a sharpened fifth degree. The scale is 1-b2-b3-3-#4-#5-6-b7-1. Notice that this scale includes a sharp and flat fifth and a sharp and flat ninth (second). This scale functions well over any altered dominant chord.

Of course, all generalizations regarding altered dominants also apply to extensions of altered dominants such as 13(b9#5), 11(#9#5) and so on.

Isolated chords

Exercises

  1. Play the following progressions.
  2. Analyze each progression and determine key centers.
  3. Practice soloing ever these chord sequences by using a tape recorder to make a rhythm track or have a friend play the progression while you solo.

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