Understanding dominant chords and how to use them will add more interest to a simple chord progression. Let’s use the popular I, vi, IV, V progression, again in the key of C major, for our example. From Doo Wop in the 50’s and teen love songs in the 60’s, this progression has stood the test of time and remains a widely used chord progression in modern rock music. Now, let’s ‘beef it up’ a bit by utilizing secondary dominant chords .
Secondary dominant chords are dominant seventh chords that do not belong to the key in which the song is written, but which do relate to the chords in the progression. Keeping in mind how tritones resolve , you can add a V7 chord before any of the major or minor chords in the original progression. In the key of C, the I, vi, IV, and V chords are C, Ami, F, and G. So, to add the secondary dominants, you’ll have to think about which V7 chords resolve to Ami, F, and G, respectively. As usual, knowing key signatures and understanding scale harmonization will come in handy.
The following chart shows all of the secondary dominants for the chords in the key of C. Adding an E7 before the Ami is termed a “V7 of vi”; a C7 before F is a “V7 of IV”; and a D7 before G is a “V7 of V”. The chord combinations are also commonly noted as V7/vi, V7/IV, and V7/V.
You can add even more creativity to your composition by using ii/V interpolation (meaning the addition of new material). Remember that the foundation of jazz is the ii, V7, I chord progression, and the same chords sound great in other music genres, as well. Now that you’ve added secondary dominants , go a step further and place a minor or minor seventh chord in front of each new dominant chord . Again, you’ll have to think about what the ii chord is as it relates to Ami, F, and G, so you really must consider three individual keys.
The chord progression, below, starts with the simple I, vi, IV, V progression, then adds secondary dominant chords in measures five through eleven, and ends by employing ii/V7 interpolation in the final nine measures. Of course, when playing this exercise, feel free to experiment with different rhythms, number of beats on each chord, etc. I think you’ll have fun with this. Also, the ii chord in the key of Ami should really be a B diminished, but I opted to use a Bmi instead since it’s the one you’d use when going to an A major chord – try both. And, when soloing over this progression using a C major or C major pentatonic scale, be careful – don’t hang on a G if a chord contains a G# (as in E7)!
Finally, there’s just one more thing to mention about dominant seventh chords – tritone substitution . Instead of using the typical V7 chord to resolve to a I chord, use a flatted II7 as a substitute for the V7. Let’s compare the two dominant chord options. A G7 chord contains the notes G, B, D, and F; a Db7 chord contains the notes Db, F, Ab, and Cb (B, enharmonically). Note that the tritones, B to F and F to Cb are the same notes! So the tritones sound exactly the same! And, it provides chromatic root movement, too. Although the tritone substitute works very well, I suggest using the bII7 chord sparingly – mostly for a change of pace and effect.
Hopefully, understanding dominant chords and the way they function will trigger some new creativity and inspiration for your songwriting. Try a few secondary dominants and ii/V’s to see what happens. It’s easy to overdo it, though, and you sure don’t want the song to sound forced or cluttered. But, as always, trust your ear and have fun!