Jazz Theory 19
and Skeleton Chords

  1. The Essential Chord tones
  2. Skeleton Chords
  3. Chord Plurality
  4. Tritone Chord Substitution
  5. Chromatic Chord Progressions
  6. The IIm7 - bII7 - Imaj7 Progressions
  7. Quiz - Quiz Answers
  8. Ear test 24 - Answers
  9. Lesson Material - General files
    Double Tritone Chord Substitution (Appendix)

    Jazz Theory lessons online

Rhythm Class - In Focus - Learn to Read Music - Jazclass Links

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JT 19.1 - The Essential Chord tones

The three most common 7th chords are the major 7th chord, the dominant 7th chord and the minor 7th chord.

Comparing these three chords side by side you see that they all have the root and the 5th in common. The differences occur in the 3rd and the 7th of each chord.

Audio 1

These are the essential chord tones that reflect the quality of each chord.

The essential chord tones for the three most common chord qualities are :

  • 3 and 7 for the major 7th chord

  • 3 and b7 for the dominant 7th chord

  • b3 and b7 for the minor 7th chord

These two notes do not spell out the chord quality by themselves. They must be played (and heard) in the right musical context.

E and B, heard on their own could just as well be the root and 5th of an E chord. But as soon as the bass player plays a C, or the melody indicates C as the tonic note, E will be heard as a major 3rd and B as a major 7th, and the C major 7th chord is established.

The same effect is achieved when these two tones are heard in a distinctly C major key setting (without the bass note present).

The essential chord tones are not only important for keyboard players and guitarists, but for all Jazz performers.
The essential chord tones are the most powerful tones in any improvisation, because they firmly anchor the improvised line onto the underlying chord progression.

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JT 19.2 - Skeleton Chords

The 3rd and 7th are also the essential notes to form a skeleton chord (a chord in which one or more chord tones are missing).

The two notes can form a skeleton chord by themselves, or an additional note is added. Such as the root, the 5th, the 9th or the 13th.

Audio 2

When a skeleton chord contains only one of the two essential chord tones the chord quality becomes ambiguous.
To define the chord quality the missing tone (3rd or 7th) must be played in the melody or the improvisation (in the right hand for keyboard players).

Audio 3


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JT 19.3 - Chord Plurality

Through previous lessons it has become clear that a scale (or mode) and the scale-tone chord built on the tonic of that scale are closely related.
They are in fact two different expressions of the same tonality.

The scale is a horizontal expression, the chord a vertical expression of that tonality.

The complete chord contains, like the scale, all the notes that constitute the tonality.

Here an example of the tonality of the C Lydian mode :

  • the horizontal expression of the tonality is the 7-note C Lydian mode.

  • the vertical expression of the tonality is the 7-note Cmaj13#11 chord.

Audio 4


As shown above any chord can be extended upwards by stacking alternate notes of the related scale on top of the chord.

It is important to understand that these additional notes do not alter the chord quality but merely add more colour to the chord.
The quality of the chord, once set by the essential chord tones (3 and 7), remains the same!

This means that keyboard players and guitarists can always substitute 7th chords by their equivalent 9th, 11th or 13th chords.

Within the complete chord a variety of smaller chords with different roots are present.

Audio 5


This is called plurality.

For the three important chord qualities the complete 7-note chords are :

Audio 6


To achieve a better, more open (Lydian) sound the 11th is always sharpened in the major chord and most of the time in the dominant chord.

To construct chords that extend beyond the 9th use therefore these scales :

  1. major chords : the Lydian mode = 1 2 3 #4 5 6 7

  2. dominant chords : the Lydian Dominant scale = 1 2 3 #4 5 6 b7 (see Lesson 20)

  3. minor chords : the Dorian mode =1 2 b3 4 5 6 b7

Modern chord voicings and chord substitutions use pluralities built on the chord's 3rd.
This means that the root is omitted, but both essential tones, the 3 and 7, are present in the chord.

Omitting the chord root gives the music a less predictable and contemporary quality.
The root of the chord (C in the example below) is either played by another instrument (e.g. the bass in a small Jazz ensemble), or inferred by the melody or improvisation in the right hand.
Note the switch in chord quality :

  • the E minor 7th chord for example is perceived as C major 9th, and
  • the Eb major 7th chord becomes C minor 9th

( In Audio 7 I play the E chord first with an underlying low E bass note, and then with a low C bass note.)

Audio 7

In two handed accompaniment (comping) the keyboard player usually plays 3 and 7 in the left hand and any other notes of the chord or related scale in the right hand.

Plurality is also used by composers to connect two chords in a chord progression.

In this segment at the end of All of Me for example :

- E7 - A7 - Dm7 - Fmaj7 - Fm7 - Cmaj7 - Em7 - A7 - Dm7 - G7 - C

Fmaj7 is a plurality of the D minor chord, and Em7 is a plurality of the C major chord. The two skips connect different Circle of Fifths chord segments.

jt004.gif In many chord progressions the plurality concept is taken even one step further.
For example the song All of Me starts with :

Cmaj7 - E7 - A7 - Dm7 -

Em7 chord is a plurality of Cmaj7, but E7 is not!
However this association of the E root note is enough to produce an agreeable and to the ear 'logical' chord transition.
The unexpected different quality of the E chord becomes an interesting surprise in the progression and represents a temporary shift (modulation) to a new key.

This is the reason why chord movements in steps of M3 and m3 intervals, up or down, are common in the chord progressions of numerous songs.

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JT 19.4 - Tritone Chord Substitution

The essential tones (3 and 7) of the major 7th chord are a perfect 5th apart.
The essential chord tone combinations for each major chord are therefore unique.

The essential tones (b3 and b7) of the minor 7th chord are also a perfect 5th apart.
The essential chord tone combinations for each minor chord are therefore also unique.

(But each essential chord tone combination serves both one minor chord and one major chord.)

However the essential tones of the dominant 7th chord are a tritone (3 whole tones) apart. This interval is symmetric : when inverted the interval remains the same.

Audio 8

This means that the 3 and b7 of one dominant chord are the same as the b7 and 3 of another dominant chord.
In other words there are two chords with the same dominant chord quality that share the same two essential tones.
This relationship between the two chords is so strong that they can be interchanged, substituted, for one another.
This is called Tritone Substitution.

The essential tones for C7 for example, are also the essential tones for another dominant chord : Gb7, a tritone away from C.
  • E is the 3rd of the C7 chord and is the 7th of the Gb7 chord

  • Bb is the 7th of C7 and the 3rd of Gb7

Note that the two dominant chords which can substitute each other are exactly opposite each other on the Circle of Fifths


In practice you can use the Tritone Substitution principle on any dominant 7th chord. Simply replace it by the dominant 7th chord with its root tone a tritone (6 semitones) away.

  • C7 can become Gb7, or vice versa

  • G7 can become Db7, or vice versa

  • Eb7 can become A7, or vice versa

    and so on.

Whether the chord substitution in a given musical context is appropriate or not should be judged by your own musical ear.

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JT 19.5 - Chromatic Chord Progressions

One can apply Tritone substitutions to the Circle of Fifths, substituting alternate chords on a circle of dominant 7th chords.

Audio 9 : Circle of Fifths (starts on C7)
Audio 9a : Chromatic Circle (starts on C7)


This manipulation transforms the Circle of Fifths into a Circle of Semitones, a Chromatic Circle.

Chord progressions that move stepwise down in semitones are therefore tritone variations of chord progressions that follow the Circle of Fifths.
This is why chromatic chord movements always sound good.

Two examples :

  1. In Satin Doll (bars 7 and 8) : C7 - B7 - Bb7 - A7

  2. In Autumn Leaves (6 bars before the end) : Em7 - Eb7 - Dm7- Db7

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JT 19.6 : The IIm7 - bII7 - Imaj7 Progressions

An obvious target for Tritone Substitution is of course the IIm7 - V7 - Imaj7 chord progression.

Audio 10

Substituting the V7 chord (G7 above) for the bII7 chord (Db7) produces the progression :

IIm7 - bII7 - Imaj7

This substitution also requires a new improvisation scale for the substitute chord, the bII Mixolydian mode.

Audio 11


The new scale gives a nice contemporary sound to the improvisation (but also requires more practice to improve your improvisation skills).

Keyboard players note that in a IIm7 - bII7 - Imaj7 chord progression all three chords can be played in root position (as above) or in the same inversion.

Summing up : an understanding of chord substitutions has three major benefits.

  1. It helps you to understand and analyse the chord progression of any song much better.

  2. It provides keyboard players and guitarists with a much wider selection of chords to use for accompaniment.

  3. It enables you to change boring chord progressions by adding some spice.
    (When playing in a band always discuss and agree on such changes with all band members).

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JT 19.7 - Quiz

Name the essential chord tones for each of these chords.

1. Amaj72. Bbm73. G74. Fm75. Dmaj7
6. Eb77. A78.Emaj79. Aø10. F#m7

Identify the chords which belong to these essential chord tone combinations.

1. A + E2. Bb + E3. B + F#4. E + B5. D + A
6. D + Ab7. A + Eb8. C + G9. F + B10. Eb + Bb

What are the pluralities contained within these chords.
1. Gm13

2. A13#11

3. Fm13

4. Emaj13#11

5. G13#11

6. Fmaj13#11

What are the Tritone substitutes for these chords.
1. D7

2. B7

3. C7

4. Eb7

5. A7

Below the first 8 bars of Georgia on my Mind, a beautiful ballad by Hoagy Carmichael.
This Jazz version of the chord progression is quite complex but very interesting.

1. Analyse the chord progression (bar numbers shown underneath the staff for reference).

2. Experiment with and select some suitable tritone substitutions.

Audio 12

Write out the progression IIm7 - IIb7 - Imaj7 on Manuscript paper for all keys. Write the correct chord symbol above each chords.

Mark the essential chord tones (b3, 3, b7 and 7) in all keys on the Keyboard Diagrams.
Like this for the E chords :


Mark the essential chord tones (b3, 3, b7 and 7) in all keys on the Scale Letters Diagrams.

I. (for keyboard players)
Commonly used (left hand or right hand) keyboard voicings use the essential chord tones (3 and 7) plus either the root or the fifths.

Mark these 1 - 3 - 7 and 5 - 7 - 3 'skeleton chords' for the major 7th, dominant 7th and minor 7th in all keys on the Chord Inversion Diagrams.

Example for the C chords.


J. (for keyboard players)
Popular contemporary chord voicings combine the essential chord tones (3 and 7) with either the 9th or the 13th. (The 9th and 13th are one octave above the 2nd and 6th.)

Mark these 3 - 7 - 9 and 7 - 3 - 13 voicings for the major 7th, dominant 7th and minor 7th in all keys on the Chord Inversion Diagrams.

Example for the C chords.


Quiz Answers

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JT 19.8 - Ear test 24

The Audio Demo plays the following chord progressions (in the key of F) :

  1. IIm7 - V7 - Imaj7

  2. IIm7 - bIIm7 - Imaj7

  3. IIø - V7 - Im7

Each progression is played twice.

Ear test 24 - Chord progressions.
Each Progression is played twice. Chords are played in various inversions.

Ear test 24 : 12 II-V-I Chord Progressions

Major - minor - major with tritone substitution

Ear test Answers

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JT 19.9 - Lesson Material

File Name Contents
jt19fac.gif Jazz Theory 19 - Facts sheet




Keyboard Diagrams

Manuscript paper

Scale Letters Diagrams

Chord Inversion Diagrams

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© 1998 - 2008 Michael Furstner (Jazclass)