The illustration below shows 3 popular progressions formed in the
key of C major.
Notice the first progression in the illustration above. You will find the chords
C, Am, F and G.
This type of progression
(I vi IV V) is one of the
most popular progressions.
In this lesson we will learn a technique to substitute one chord for another. The chord that we
substitute may not be diatonic to the C major scale. Recall that diatonic means belonging to the particular scale
we are working with. In the examples above, each progression is formed within the key of C major. All three of the
progressions above are said to be diatonic to the key of C major.
We know the
chords in the key of C major are, C, Dm, Em, F, G, Am and B diminished. Lets say
we wrote a progression using the chords, C, Am, F and G. Do you think it would
be possible to use the same melody and different chords over that melody?
There's a technique called chord substitution. I'm not going to explain the
theory behind this right now, but I would like to show you a way to substitute
one chord for another. To substitute one chord for another, each chord must
share at least one note. This means that the chord we are substituting for must
have at least 1 note that is natural to the chord we replace.
Our first progression above is C, Am, F and G. We will now substitute another chord for the Am
chord. First we must know the notes that make up the Am chord. This is easy enough, the notes of all minor chords are
the 1, b3 and 5 notes. Minor triads and all chords
are built upward in thirds. So the notes that make up the Am chord are A, C and E.
We now need to find a chord that contains one of these notes. It may be easiest to
find the chords that contain the A note. The easiest note that comes to mind is the A major chord. The notes that
make up the A major chord are A, C# and E. This means that we can now convert our progression of
C, Am, F and G to our new progression of C, A, F and G.
tells me that any time we have a minor chord, we can substitute it for its Major
chord. In this instance we have changed the Am chord to the A major chord.
So far we
have taken the progression of C, Am, F and G and have changed it to C, A, F and
G. You may notice when you look at a sheet of music, say in the key of C major
that there have been sharps added. We know that in the key of C major there are
no accidentals, (sharps or flats). Music may be signatured for the key of C
major, but you will usually find non diatonic notes within the song. Chord
substitution is one reason why. The
key signature just lets you know what key the song is based in, but you
will usually find other notes that are foreign to the key.
Staying with the progression of C, Am, F and G what other chords share the notes of the Am chord?
Recall the notes in the Am chord are, A, C and E. The F chord has the A note, but we can't use two of the same chords
together in a progression. C, F, F, G. This would be redundant, a progression must continue to move or its not
considered a progression. This does not mean we can't use it though.
F#m contains the A note, right? F#, A and C#. So this will give us a new progression.
C, F#m, F and G.
The Dm chord has the A note. D, F and A. This will now give us, C, Dm, F and G. Look below at the
illustration and notice the C, Dm, F and G progression.
The D major chord also has the A note. D, F# and A. This will now give us, C, D, F
What we have done was took the progression, C, Am, F and G and found chords that
contained the notes of the Am chord, A, C and E then substituted those chords in the original progression.