In this course I have presented the basic game of music as creating pleasing combinations of chords which virtually always resolve back to the root note of the key, the tonic chord. The rules of this game are called diatonic harmony, which is the system of Roman numeral analysis and cadencing you have been learning here. In order to make your arrangements and compositions unique, rich sounding, and more and more interesting it is possible to substitute chords which will add color and character to the music. This lesson will focus on several techniques which will enable you to substitute chords as your playing and writing continually improves.

Chord Quality

The first technique I will deal with is quite a simple one, and deals with the quality (general overall flavor and sound) of a chord. As you already know there are three basic qualities of chords: major, minor and dominant. In my mind a fourth category also exists, which I have heard called a special or undefined category. This special or undefined category contains diminished, augmented and suspended chords. Study the graphic organizer below as we begin our discussion of substituting chords based on chord quality.

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In the graphic just above you will see three families of chord sounds indicated, any chord in a family can substitute for any other chord in that family. In other words all major type of chords produce the same general sound (with variations of course) and therefore do the same job. By the same token all chords in the minor and dominant families substitute for one another as well, the trick is knowing a lot of chords of course. Chords in the special or undefined category do not necessarily work as substitutes for one another, these chords will be dealt with in greater depth elsewhere in this course.

In the example below you see a four bar pattern written in the key of C and using a II – V – I cadence to resolve back to the key of C. It’s fairly straightforward, generic sounding stuff. The second four bar example written in the key of C however gives you a chance to see the principle of chord substitution at work. The first two bars of the example require a major chord sound. Therefore, C major seven and C6 are potential substitutes because they belong to the major family. The third measure calls for a D minor sound so any chord in the D minor family will do the trick. Here I’ve chosen Dmi 7. and last but not least is the dominant sound G 13 and G7 Sharp five do nicely act leading our ears back to the tonic. In this case I’ve substituted C major nine for C major for that sweet dreamy sound.

Use the table below as a means of studying this principle of substituting chords of the same quality, belonging to the same family, for one and other.

Family
Sound Quality Substitution Rules
Major
Major chords sound bright strong and powerful. they can have a happy sound, a very consonant one and promote a feeling of rest and relaxation. In rock and pop music major chords are often used at the beginning of rock anthems and song speaking of triumph. If you are substituting for a major chord you may use C6 or C69 as a substitute for C major. You may also use any chord which has the word major in its name such as C major seven or C major nine. C6 and C69 are considered major chords, not dominant ones.
Minor
Minor chords sound sad, mysterious and gloomy. The minor sound chord can also sound funky and driving, crisp and cool. Songs beginning with a minor chord include Stairway To Heaven, Kryptonite, House Of The Rising Sun and even the jazz flavored rock song Moondance. If you are substituting for a minor chord you may use any chord which has the word minor. In the example above I used a D- seven chord to substitute for a plain old D minor chord. If however I wanted to I could have chosen D minor 6 or D minor 9.
Dominant
Dominant seven chords sound funky and earthy. They are closely associated with blues and funk music. More often than not when you hear a twangy cord in a funk or blues song it is some type of dominant seventh chord such as Play That Funky Music White Boy or the break of the famous blues standard Hideaway by Freddie King. When choosing a substitute for a dominant seven chord any court in the dominant family will do the job. Dominant chords do not contain the word major or minor in their name so if you are substituting for a C7 you would choose accord with a name like C9, C 13 or some chord not belonging to the major or minor family. The exception to this rule would be C6 which is considered a major and not a dominant chord.

 

Chord Of Like Function

Next we will explore a substitution technique I call chords of like function. Since all chords in a musical composition perform a job, we may be able to find even more chords capable of performing that same job. The key to understanding this principle is to remember how important, and how influential cadences involving the three primary chords of I – IV and V actually are. Study the graphic below to review the way that chords function in music.You may be surprised to see that I have listed additional chords in each of the three main columns, these chords will indeed do their respective jobs while providing more color and interest to your playing and writing.

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As I have said many times during this course learning music theory is often about memorizing facts, formulas and spellings. Through this discipline is possible to achieve a greater freedom in an artistic sense. That having been said the next bit of information I would recommend memorizing, and possibly writing down in your music theory notebook would be chords of like function. Here in this lesson we are working in the key of C but of course it’s true for any key.

  • The tonic chords in any major key are I, III and VI. In the key of C that would be C, E minor, and A minor.
  • The sub dominant chords in any major key are IV and II. In the key of C these chords would be an F major chord and a D minor chord.
  • The dominant chords in any major key are V and VII. In the key of C these chords would be the G7 and B mi7 (b5).

Use the graphic below to help you memorize the chords of like function in the key of C. To the right side of the diagram you will notice each chord has been spelled out for you. Notice how many notes in common the chords of like function share with each other. If two or three chords are performing the same function, they are very similar in terms of spelling. To me, that explanation always seemed to make a lot of sense.

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The example below puts this theory of chord substitution into action. Notice the first example in the exercise is simply a generic I – IV – V progression that resolves back to a C major chord in a completely expected manner. The second example in the exercise uses both tonic substitutes in the first two measures to add richness, depth and color. It is important to note that these three chords however do not produce a cadence or a strong sense of chord to chord movement. Rather they add interest and depth to the tonic sound in the first two measures of the composition. Finally, the fourth bar uses G 11 as a substitute for plain old G, the dominant sound in this key.

Tritone Substitution

The final technique we will explore for chord substitution here in this lesson is called the tritone or flat five substitution. This technique is quite often applied to the dominant chord of a particular key. So in our case we will be substituting a new chord for G7, the dominant chord in the key of C. That new chord will be called Db 7, the the root note of that chord is of course Db, and that note is also the flatted fifth taken from the key of G. Another name for a flatted fifth interval is the tritone, therefore substituting a Db7 chord for a G7 chord is called the tritone substitution. To study and understand this concept let’s begin by reviewing the keys of C and G.

 

Analysis
I
II
III
IV
V
VI
VII
I
G Major Harmony
G Maj 7
A mi 7
B min 7
C Maj 7
D 7
E mi 7
F# mi 7(b5)
G Maj 7
C Major Harmony
C Maj 7
D mi 7
E mi 7
F Maj 7
G 7
A mi 7
B mi 7(b5)
C Maj 7

 

The idea that the root note of the new, or substitute chord is located a flat fifth interval away from the root note of the chord to be substituted for is really just a way to locate the substitute chord. Don’t get to caught up in that one little fact, it can be confusing. Just think of it as a shortcut to a great chord substitution. Next, let’s examine compare and contrast the spellings of a G7 chord and its tritone substitute, the Db 7 chord.

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As you study the diagram above remember that all chord spellings are relative to their root notes. Since G7 and Db7 are both dominant seven chords, they share a formula but of course have their own unique spellings. These two particular dominant seventh chords also have two very important notes in common: the third and the flat seven. In any chord the third and the seventh degrees really serve to define the sound of the chord as the root and the fifth are common to major chords, minor chords, and dominant seven chords. What this means is that the true sound of the dominant seventh chord lies in the third and flatted sevenths degrees, precisely the notes that tritone substitutes share. This is why the two chords substitute so beautifully for each other, they share the same defining notes.

Study the musical examples below to hear the tritone substitution in a pop/ rock music setting.

As you study the music above you can quickly identify the secondary dominant, a seven or the V of V, giving character color and interest to an otherwise generic progression. In the second example, the one containing the substitute dominant chords you can see that the substitute dominant chord is always one half step above the diatonic target chord to which it resolves. This is why a string of dominant seventh chords descending one fret at a time sounds good. You are actually playing a string of substitute dominant chords. This also gives rise to another great rule which you must remember:

  • Any chord in a diatonic chord progression, called a target cord, can be preceded by a dominant chord one halfstep higher. This dominant chord is actually called a tritone substitution and is a smooth and modern sounding substitution for the actual dominant chord of the diatonic target.

The musical example below is a typical blues are rock ending which employs a substitute dominant chord just before the final cadence. You must have played this type of thing before, now it is nice to understand why it works.