Welcome to the latest installment of Chord by Chord, a series designed to build your understanding of harmony and the fretboard. In the previous two lessons, I showed you D7 and G7 chords at various locations on the fretboard, and this time I’ll likewise break down C7.
To build a C7 chord, take a C major triad (Example 1) and add the flatted seventh, Bb (Example 2). Example 3 shows how to derive a C7 chord from an open-C shape—all you have to do is add your fourth finger to string 3, fret 3. Keep in mind that you don’t have to play all five strings. For example, just the bottom three notes of the C7 chord will get you a tight, jazzy sound.
The next couple of examples are based on barre chord shapes in the third position. First try Example 4a and then play Example 4b, which shows a less common variation with the flatted seventh added to string 1. By the way, the barre chords you’ve learned so far are all moveable—that is, you can take the same shape and play it anywhere on the fretboard for 12 different chords. For example, if you shift the chords in Examples 4a and 4b up two frets, you’ll have D and D7 chords; move the shapes up to the tenth fret for G and G7.
Example 5a gives you some more barre chords, this time in eighth position, and Example 5b is basically the same, but on the C7 chord, the fourth finger is added to string 2, fret 11. These shapes are also moveable; for instance, play them at the third fret for G and G7 chords, the fifth fret for A and A7, etc.
You should now know how to construct a C7 chord and how to build one from various C-major shapes to C7, as well as how to do same with D7 and G7. A song that happens to make good use of the C7 chord is “Happy Birthday to You” in the key of C. See you next time, when I’ll demonstrate a new seventh chord type—the major seventh.