Learning how to play dominant 7th chords will allow your guitar playing to have a fully, richer sound. Seventh chords are no more difficult to play than are simple major or minor chords. The sound of the 7th chord is more complex than that of major and minor chords (because they’re made up of four different notes instead of three), and their usage in music is a little more specialized.
Seventh chords come in several varieties, and each type has a different sound, or quality. You can hear the sound of dominant sevenths in such songs as Sam the Sham and the Pharaohs’ “Woolly Bully” and the Beatles’ “I Saw Her Standing There.”
Dominant seems a funny, technical name for a chord that’s called a plain “seven” if you group it with a letter-name chord symbol. If you say just C7 or A7, for example, you’re referring to a dominant 7th chord. The important thing is that you call the chords “dominant 7ths” merely to distinguish them from other types of 7th chords (minor 7ths and major 7ths).
D7, G7, and C7
The D7, G7, and C7 chords are among the most common of the open dominant 7ths. Take a look at the following figure to see the diagrams of these three chords that guitarists often use together to play songs. Notice the Xs above the 5th and 6th strings on the D7 chord. Don’t play those strings as you strum. Similarly, for the C7 chord, don’t play the 6th string as you strum.
If you already know how to play the C chord, you can form C7 by simply adding your pinky on the 3rd string (at the third fret).
Once you get the hang of these chords, you might want to try playing a song using these new chords now. Try “Home on the Range.”
E7 and A7
Two more 7th chords that you often use together are the E7 and A7 chords. The following figure shows the chord diagrams and fingering you'll need to play these two open 7th chords. Notice that this version of the E7 chord, as the figure shows, uses only two fingers.
If you know how to play the E chord, you can form E7 by simply removing your 3rd finger from the 4th string.
These versions of the E7 and A7 chords use only two fingers, making it easier to fret quickly, especially if you’re just starting out. So practice E7 and A7 by strumming each chord four times, switching back and forth between them. Remember to avoid striking the 6th string on the A7 chord.
If you want to try playing a song that uses these two open 7th chords right now, give “All Through the Night” a try.
E7 (four-finger version) and B7
Two more popular open-position 7th chords are the four-finger version of E7 and the B7 chord. Take a look at the following figure to see how to finger the four-finger E7 and the B7 chords. Most people think that this E7 has a better voicing (vertical arrangement of notes) than does the two-finger E7. You often use the B7 chord along with E7 to play certain songs.
Remember to avoid striking the 6th string when playing the B7 chord.
If you know how to play the E chord, you can form E7 by simply removing your 3rd finger from the 4th string.
Practice these chords by strumming each one four times, switching back and forth. As you do so, notice that your second finger plays the same note at the same fret in each chord — the one at the second fret of the 5th string. This note is a common tone (that is, it’s common to both chords). In switching back and forth between the two chords, keep this finger down on the 5th string — doing so makes switching easier.
To use these chords in a song right now, try playing “Over the River and Through the Woods.”