What Are Secondary Dominants and How to Use Them?

If you've ever listened to a piece of music and noticed a sudden shift in the harmony that catches your ear, there's a good chance it was a secondary dominant chord.

These chords can add a surprising and exciting element to a harmonic progression and are found in almost all genres. So regardless of your preferred musical style, understanding how to analyze a secondary dominant, and knowing when to use them in your own music will be extremely valuable.

Like everything in music, being able to understand the theory is important – but the real benefit comes when you can recognize these elements using your ear. In this article, we will cover both aspects and give some insight into the best approach for applying these ideas to your own music.

Let’s get started!

What is a dominant chord?

To understand what a secondary dominant chord is, we must first understand what a dominant chord is.

The chord built on the fifth degree of the major scale (V) is known as the dominant chord.

When you build a triad starting from this degree you get the dominant chord (V), adding the flat 7th to the chord creates a dominant 7 chord (V7). This is usually just called a 'seventh' chord, for example: a C dominant seventh would simply be said as: C7.

The dominant chord (V) is one of the most important in western music. Its main characteristic is the strong sense of tension – it really wants to resolve to the tonic (I) chord. This is because the dominant chord contains what’s known as the leading tone (the 7th degree of the scale), this note is what creates that strong pull towards the tonic as it’s only a semitone away. It’s important to know that there is only one dominant 7th chord that could be built within a key.

What are secondary dominant Chords?

A secondary dominant is when we take a chord of the key, that is not the 5th degree chord, and we turn it into a dominant chord, ideally a dominant 7th chord.

This allows us to create the sense of a key change, without actually changing key. The secondary dominant chord acts as if it was the V chord of another key and creates a strong sense of tension that pulls toward its relative (I) chord – which is not the tonic chord of the main key. This briefly changes the listener's perception of where “home” (tonal center) is, making for an interesting harmonic shift.

It’s important to understand that secondary dominant chords are used as transitory passage chords and they don’t create an actual key shift. Indeed, the main tonal center of the piece still remains the same, the secondary dominant chord only creates a momentary sensation of pulling toward a note that’s not the tonic note of the piece, and then, as the piece goes on, this sensation goes away and the gravitational center is felt again on the tonic note of the main key.

If it sounds a bit confusing right now, don’t worry – all will become clear. We’re about to show you how to use, and build a secondary dominant chord.

Why do we use secondary dominants?

One of the main reasons we use secondary dominants is to add elements of suspense, tension and surprise in our music.

Whenever writing music and thinking about harmony, we’re always looking for ways to make it more interesting, secondary dominants are one way to achieve this. Introducing a secondary dominant chord gives the listener something unexpected.

It’s a great way to keep your music fresh and engaging, so remember secondary dominants when you want to add a little surprise into your next chord progression.

How to build a secondary dominant chord?

Let’s say we want to use a secondary dominant in the key of C major.

We’ll focus on the most commonly used – known as the “five of five” (also written as “V of V” or “V/V”).

1. First, we need to establish our five (V).

2. We do this by counting up 5 degrees from C – D, E, F, G. Now we know G is the root note of our 5th degree chord.

3. Next we need to know what the five (V) of G is.

4. We do the same as before, counting up the major scale degrees – this time starting from G.

5. The fifth degree in G major is D – so the D chord is our “V of V” secondary dominant.

6. It’s common (and sometimes necessary) to add the 7th to dominant chords – which is shown as D7 (V7).

Below is a diagram to help visualize this.

Two important things to remember when using this method:

• It does not apply to the 7th degree – which is part of the reason a V of vii is considered invalid as a secondary dominant (more on this later).

• If a secondary dominant matches a triad from within the key, it must be made into a dominant 7 to distinguish it from the diatonic chord.

Examples of building secondary dominants

Let’s see how these chords look on a piano:

How to use secondary dominant chords in music?

You can use a secondary dominant to lead into other diatonic chords within the key too – not only the V.

A five of four (V/IV) is also quite common – this is when we use a secondary dominant that pulls toward the subdominant chord (IV).

For example, in the key of C major, the IV chord is F. The V chord in the key of F major is C7. This still creates that sense of tension but resolves to the IV chord instead of the tonic.

Although using secondary dominant chords doesn’t change the key, they can be used as a way to smoothly move to a new key, if desired.

Chord progressions using the secondary dominants

A great way to understand the sound and feel that a secondary dominant can give to a piece of music is to listen to them in action.

Let’s keep it simple for now and stay in the key of C major. Play the progressions on your instrument and pay attention to the sense of tension and resolution.

• C - Am - D7 - G7 (V/V)
• C - G7 - A7 - Dm - G7 (V/ii)
• C - Am - G7 - C - E7 - Am (V/vi)
• C - F - G7 - C - B7 - Em - Am (V/iii)

Here’s a famous example if you would like to listen to the function of a secondary dominant in the context of a familiar song:

"What a Wonderful World” - Louis Armstrong

Played in the key of F the progression is as follows:

• F - Am - Bb - Am - Gm7 - F - A7 - Dm
• I - iii - IV -iii - iim7 - I - III7 - vi

The A7 is the secondary dominant leading to the vi chord making this a five of six (V/vii)

How to analyze a secondary dominant chord?

The most difficult part about recognizing a secondary dominant chord progression is being sure you have the main key right when you begin analyzing it. The nature of secondary dominants means they don’t belong in the key (because of this, they are called non-diatonic chords) – this can make finding the main key a little more challenging than usual.

Now you’re aware of secondary dominant chords you can take them into consideration when trying to figure out a progression. If you think you know what key the song is in but one of the chords doesn’t seem to fit, check if it’s the V of another chord in the key.

Secondary dominant chart

Here you can see all the possible secondary dominant examples within the key of C major followed by the diatonic chord they resolve to.

You may have noticed that the V of vii is missing from the notation above. Let’s look at a chart to figure out why.

Below are the notes for each diatonic triad and their dominant chords. Notice the leading tone in each V7 chord is only one semitone beneath the root note of the triad it resolves to – hence why there is such a strong pull toward it. You can see there is no leading tone with the V of vii and therefore it doesn’t function as a secondary dominant.

How to find a secondary dominant chord?

Besides some little clues (like a dominant 7 chord that isn’t built on the 5th degree of the key), it can be tricky to know how to recognize a secondary dominant at first.

Here’s a quick guide to help identify secondary dominants in music:

1. Determine the main key. This will help you identify the chords in the piece and the scale degree they are built on.

2. Find the non-diatonic chord (a chord that doesn’t belong to the key). They usually jump out from the other chords because they sound a little bit off – this is quite probably a secondary dominant.

3. Identify which degree of the scale the non-diatonic chord is built on.

4. See if this non-diatonic chord is a dominant 7th chord or a major chord that should have been minor in its diatonic chord form.

5. If it is then you have successfully identified a secondary dominant – nicely done!

How to recognize chord progressions including secondary dominants by ear?

To identify chord progressions by ear, it is important to start with simple chord progressions that only use chords within the key.

Being able to recognize these progressions without the help of any instruments is a fundamental skill that must be mastered before moving on to more complex progressions.

Once you are comfortable recognizing simple progressions, you can gradually introduce non-diatonic chords, such as secondary dominants, into your ear training practice. However, it is important to approach this slowly and not to overwhelm yourself – avoid complex progressions with multiple key shifts when first starting out.

Recognizing chords by ear requires the development of various cognitive processes and sub-skills. While this task is accessible to anyone, many musicians benefit from clear guidance and a step-by-step approach to developing intuitive chord recognition skills.

It is important to note that you may need to work on more basic ear training skills before you can confidently recognize secondary dominant chords by ear, without the help of any instruments.

What’s the best way to practice ear training?

To really master ear training, the first step is selecting the most up-to-date method. The older, more common approaches (such as interval ear training) lead most musicians to give up out of frustration.

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Conclusion

Hopefully this has made the world of secondary dominants a bit easier to understand.

They are a useful tool that can add emotional complexity and interest to your music. Having a better understanding of chord progressions including secondary dominants will let you create additional tension and resolution in your music – giving that extra level of sophistication to your compositions.

Whether used in classical, or modern genres, understanding secondary dominants can help musicians and composers make more compelling, dynamic, and surprising music. That’s exactly what we all want, right?

We’re working our hardest to find new ways to make musicians develop their intuitive connection to music – which can only be achieved with a great musical ear. If you want to learn more about the right way to approach ear training, you’ll find everything you need to know here.