Using Extended Chords
Many guitarists play the same set of chords every time they pick up a guitar. While it can be difficult to break out of old habits, one way you can vary your chord progressions is to take a page from the jazz cats’ book and employ simple chord substitutions. A chord substitution is exactly what it sounds like: within a chord progression, you substitute a chord for another chord.
One of the easiest ways to do this is to substitute extended chords for simpler chords with the same letter name. Let’s start with the C–Am–Dm–G (I–vi–ii–V) progression that has been used in countless songs (Example 1). You can give this progression a different feel by substituting four-note versions of the same chord type (major or minor) and letter name for each chord (Example 2). Since dominant-seventh and major-seventh chords both have a major third—as a standard major chord does—either of these can work as a substitute for a major chord, although which one of them is the better choice depends on the situation. For instance, a major- or dominant-seventh chord substitution sounds fine over the C chord, though I like Cmaj7 better moving into the Am7. However, a G7 sounds much better moving back to C at the end of measure 2. There’s a long list of reasons why, but the short version is this: it just sounds better! When substituting seventh chords for regular major and minor chords, a good rule of thumb is to simply trust your ears—if it sounds good to you, it’ll probably sound good to your listeners.
Example 2 used only seventh chords, but to create a more jazzy or contemporary folk sound you can use almost any extended chord—9 chords, 11s, and 13s.
In Example 3, I’ve substituted a Dm9 chord for the Dm and a G13 for the G chord. Not every extended chord works in every context, so experiment with these types of substitutions until you find something that sounds good to you.