Switching one chord for another – done most easily when both chords belong to the same class.
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The Eagles’ first hit single, “Take It Easy“, nicely demonstrates how replacing one chord with another can subtly change the character of a chord progression. The song is in the key of G major, and the chord progression of the opening line is: G D C. Harmonically speaking, that’s a very strong way to start: tonic chord (I) followed by dominant chord (V), followed by subdominant (IV), before returning to the I-chord for the second line.
After the instrumental break that follows the second verse, they swap the IV-chord for a ii-chord, changing the progression to: G D Am. (In fact, the third chord is Am7, the 7th being created by the melody note G.)
The reason that a IV-chord can be replaced with a ii-chord so easily is that both chords fulfill a similar subdominant function. They are both considered to be members of a chord class called subdominant. The two chords have two notes in common with each other:
Two chords that belong to the same chord class can usually be interchanged, as long as the melody note that you’re harmonizing belongs to both chords. In the case of “Take It Easy”, a 7th was added to the ii-chord in order to make the melody note fit. Adding a 7th, or indeed any extra pitch, to a chord does not usually change its function.
There are a few tips to consider when substituting one chord for another.
First, both chords should be members of the same chord class. There are three main classes of chords: Tonic, subdominant and dominant, named after their most common chord members:
Second, while it’s definitely worth experimenting with your chord progressions to familiarize yourself with the way the character of your music changes with each substitution, don’t get too heavy-handed with doing chord substitutions throughout a song. Particularly in the pop music genres, audiences like a good deal of predictability. Switching chords throughout a song may create an unsettled feeling in the listener.
Third, it’s possible to switch chords from different chord classes. “Help Me Rhonda”, written by Brian Wilson, Mike Love, recorded by the Beach Boys, demonstrates this. The second chord is a dominant chord (V7, the 7th being created by the melody note). The 7th of a dominant chord is a note that also exists in the IV-chord. So when Johnny Rivers recorded his version of “Help Me Rhonda”, he switched the dominant chord for a subdominant one.
That kind of switching between chord classes is often difficult to do, and so be sure that you’ve given it a good listen before you go with it.
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Good post Gary
If I may say so, I think an easier to understand for the average musician explanation why this form of substitution works, is that you can substitute a chord with its relative minor and vice versa.
The substitute of C with Am7 is not realy a chord substitution. It is in fact a chord extention where the C chord is extended downwards by adding a bass tone one third down. All other chord notes for the C chord remains the same.
Another great example of where the chord progression of G D Am / G D C is done very effectvely, is Dylan’s knocking on heaven’s door. This progression is so recognisable that Dylan should be awarded patent rights on it.
Hello Eric, and thanks so very much for writing. Just to respectfully quibble with you on one point: a chord is named for its root, so substituting a C with an Am7 is, by definition, a true chord substitution. Though C and Am7 share 3 notes in common, it would be erroneous to think of one as simply an extension of the other.
The Dylan tune is a great example.
Thanks again for writing!
-Gary