In the previous harmony tutorial, The Basic Functions of Harmony, we introduced the idea that harmony is about a balance between tension and release. If you haven't yet read that tutorial I suggest you do before moving on to this one.

For this tutorial we're going to explore the idea of Secondary Dominants and how they can be used to create tension and release in more harmonically complex and interesting ways. We'll discuss what they are, some of the different ways they can be used, and then show some examples from real music.

Republished Tutorial Every few weeks, we revisit some of our reader's favorite posts from throughout the history of the site. This tutorial was first published in October of 2009.

It is critical that you not only read the tutorial but that you listen to the examples. Reading about music theory is meaningless unless you can hear and internalize what the ideas actually sound like in music.

What is a Secondary Dominant?

A Secondary Dominant is a Dominant 7th chord that is the dominant of a diatonic chord other than the tonic. Yes I just used the word "dominant" three times. Let's see if we can clarify that a little.

You'll remember from last time that in a given key the tonic is the I chord and the dominant is the V chord. In the key of C the tonic is C and the dominant is G. Going from G to C feels like a very satisfying move from tension to release.

We'll call the chord that the secondary dominant lands on the Target Chord. So in the key of C the Target Chord of a G is C. Since a Secondary Dominant is the dominant of a chord other than the tonic, it is the dominant (V chord) from the Target Chord's key.

Let's say that we want to figure out the secondary dominant for the Target Chord Am. In the key of Am the dominant, or V chord, is E. We also said that a secondary dominant is a Dominant 7th chord, so the secondary dominant of Am is E7.

Similarly if our Target Chord is G, the dominant or V chord in the key of G is D, so the secondary dominant of G is D7.

Here is a list of the Secondary Dominants in C Major:

Target Chord Secondary Dominant V7/ii Dm A7 V7/iii Em B7 V7/IV F C7* V7/V G D7 V7/iv Am E7

*Not that this chord requires the 7th to sound like a secondary dominant, otherwise it just sounds like the tonic

Make sure you understand how we came up with each Secondary Dominant before moving on.

What does a Secondary Dominant Sound Like?

We've seen that for basic harmonic functions the Dominant chord is the most tense and the Tonic the most relaxed. What a Secondary Dominant does is create tension that relaxes on a new tonic.

Listen to the following two examples. In the first example the progression from Em to Am is relatively neutral. We expect it to keep sauntering along.

In the second progression, however, the E7 to Am feels like a great build up and release of tension. Not only does the Am feel like a welcome release from the tension of the unexpected E, it also feels like it could function as our new home chord if we continued to stay on it. This feeling of the new chord being like home is called Tonicization, essentially making the Target Chord the tonic. This tonicization can be permanent (i.e.. a modulation) or just passing before returning the the original home key (i.e.. used for color).

As shown in the example above, we'll be using a curved arrow to show where the secondary dominant's Target Chord is.

So why are Secondary Dominants typically Dominant 7th chords? In a dominant 7th chord the 3rd and 7th notes of the chord create an interval of a tritone, which is the interval of greatest unrest. It's the tritone that most wants to resolve into the Target Chord. For example in an E7 chord the 3rd and 7th of the chord make up a tritone (G# and D). The G# wants to resolve up to A and the D wants to resolve down to C# (or in the case of a minor chord, down to C). Listen to this modified progression without the 7th to hear how the E chord still pulls us into the Am but lacks color and is not as strong. We don't get the satisfying resolve down of the D to C.

How Secondary Dominants Are Used

There are a variety of ways you can use Secondary Dominants. They can be passing and primarily used for an interesting color, to build tension, for modulations or even for surprise. Let's look at a few examples to hear how they've been used before.

Mozart's Piano Sonata #12 in F

Listen to the first phrase from Mozart's Piano Sonata #12:

To make it really clear here's a reduction of just what the harmony sounds like:

As you can already see from the curved line, the F7 in the 2nd measure is a Secondary Dominant of the Bb chord in the 3rd measure. Hopefully you can also hear this as well as see it. This Secondary Dominant is being used for color. The Eb from the F7 chord is a beautiful and unexpected tone that lands nicely into the Bb chord. The F7 is clearly not being used to modulate to the key of Bb because by the end of the phrase we still feel like we are very firmly in the key of F.

Although the F7 was merely used for a passing color it made the phrase interesting and unique. Consider how ordinary the phrase would sound if the second measure just stayed on an F major chord:

And again the reduction:

Pretty dull. It's amazing how just one note (the Eb) can add so much. Now let's look at another use from a little further into the piece.

First listen to the section, then we'll discuss what's happening:

At first we are still happily going along in the key of F. Then out of nowhere these C#'s grab us and pull us into an entirely new key (the key of Dm). Although only a single note and not a whole chord, the C# is functioning like an A7 chord. In other words, as the Secondary Dominant to Dm. C# is the 3rd of A7, and the note with the greatest tendency and need to pull up into D.

Not only does this moment act as a modulation into the new key of Dm, it also functions as a surprise. C# is not in the key of F, so it sounds foreign and unexpected but also very exciting. Listen to how it pulls us forward into new and unknown territory and keeps our interest as we are off into Dm.

Hey Jude

We can see that Secondary Dominants can be very useful in classical music for making things more interesting and leading us in new directions, but the concepts can just as easily be applied to contemporary styles as well.

We already took a pretty in depth look at the harmonic functions of the verses from Hey Jude. Now we'll pay attention to the last few bars of the verse leading into the bridge. Here's the end of the verse (the line "Then you begin to make it better" and the first chord of the bridge:

By now you should be able to recognize our secondary dominant as the F7 leading into the bridge. Similar to the Mozart, the Eb stands out as a foreign pitch (even if you don't recognize it as an Eb you can still tell something different is going on). The F7 serves to pull us into the Bb that starts off the bridge. Also like the Mozart we haven't actually modulated to Bb. Although the F7 to Bb resolution is a great release, by the end of the bridge we still feel very much like we're in the key of F. What the F7 has done is increased the tension (remember the unrest that the tritone creates) and pulled our ear forward into the new section.

Here's what it sounds like from the same place if we don't use the Secondary Dominant to lead us into the bridge.

No drama, no excitement. The bridge just kind of shows up as a nice warm Bb chord. Without the Secondary Dominant we lose all sense of the tension and release that creates the excitement of the new section.

In My Life

Another great Beatles example is In My Life, which uses Secondary Dominants in two different ways.

Here are the chords from the first phrase of the verse:

The A7 is the V/IV Secondary Dominant. It leads us into the D chord. This one is yet again like the Mozart example, the D chord feels like a nice place of release from tension but does not actually feel like a new home.

If you're unsure if you're "getting it" yet, consider what it sounds like if the A7 doesn't resolve.

We're left hanging, obviously in need of something more. If the chord were simply an A major triad we wouldn't be feeling that, but the 7 is leading us forward and forcing us to want to hear a release of tension and a D is going to be the most satisfying feeling of release.

Listen to the chords from the next section, and I'll stop on the Secondary Dominant before it resolves:

There are two things happening here. First of all the section has clearly reached a climax. We are at a high point in tension and in great need of release. We also can hear a Secondary Dominant of the V chord; that B7 is really trying to pull is into an E. So let's hear what happens:

Instead of the expected release on an E we get a Dm! The B7 turns out to be a fake-out Secondary Dominant. The Dm completely shatters our expectations but when it finally lands back on our tonic of A we feel like we've come full circle. We have rested at home at last. Compare this resolution to the I V IV I progression we listened to in the previous harmony tutorial and you'll notice it has a similar functional effect. Rather than a build up and release of tension it's more like stepping back or easing down. In this case it creates a dramatic but beautiful moment of nostalgic reflection.

So did John Lennon think "I'll set up a secondary dominant of the V chord but then have a deceptive resolution in a IV minor"? I really doubt it. But just because some geniuses simply feel it in their gut, the rest of us can still benefit from understanding how these devices can be used.

Conclusion

I can't stress enough that the concepts in this tutorial need to be heard to be truly understood. Listen to some of your favorite artists and try to notice moments where the chords seem to come from a different angle and pull you into a new place. If you go back and figure out the chords, do you find that you've got a Secondary Dominant?

Homework assignment: Leave a comment with an example of a song you've found where a Secondary Dominants is being used. The more examples we can point each other to seek out and listen to the more we can all benefit and really drill the sound of Secondary Dominants into our ears.