|home > music theory > chord families and diatonic substitution|
Chords may be grouped into families based upon the principle chords found in harmony. These principle chords include the Root, Fourth and Fifth. (Notated as: I, IV, V).
In the key of C Major, we have the Root, (or the I chord), occurring as the C Major chord. The fourth step chord, (or the IV chord) occurs as the F Major. And, the fifth step chord, (or the V chord), presents as G Major.
The three main harmonic families:
These families are named as the; Tonic, (I), Sub-Dominant (IV), and the Dominant (V). The notes of each family combined spell out every tone of the major scale. The movement from one chord to another creates the basic harmonic effects of all tonal music.
It is important to memorize the function of each chord as well as the other chords which relate to each chord family.
- Sub Dominant Family
- Dominant Family
DIATONIC CHORD SUBSTITUTION:
Cousins of the Tonic family include the III and the VI. Under the IV chord (the Sub-dominant family) the cousin is the II chord. Under the Dominant family (the family of the V chord) we find the VII chord.
Study the chart below:
To more clearly show Diatonic Substitution in action, I have created two similar chord progressions in the key of C Major.
In Progression One we find harmony occurring as; I, VI, V, IV. In Progression Two I have swapped the Ami chord (the VI) for it's Diatonic Sub. the III (an Emi chord).
Play through each example to hear for yourself how easily the substitute chords can swap out for each other.
Progression One: C Major ( I, VI, V, IV)
Progression Two: C Major ( I, III, V, II)
Upon listening, it is easy to notice that although the progressions are indeed different, they do share a similar emotional effect.
Before I wrap up, it is also important to mention that chord voicings (arrangement and location of chords on the neck) also play a role in how similar the substitutions effect will come across to the listener.