Secondary Dominants
When you're learning about harmony and chord progressions, one of the most interesting and useful concepts you'll come across is the secondary dominant. While the idea may seem a bit complex at first, once you understand how secondary dominants work, you'll see how they can transform your music, adding tension, color, and a sense of movement to your compositions and performances. In this blog post, we'll explore what secondary dominants are, how they work, and how you can use them in your own music to create more compelling harmonic progressions.
Before we continue, we have to make a very important distinction between the Dominant Degree of a scale and a Dominant 7 Chord.
The dominant degree of a scale refers to the 5th note of the scale, which plays a crucial role in creating tension and leading back to the tonic note (1st degree). For example, in the C major scale, the dominant degree is G.
The dominant 7 chord, on the other hand, is a specific chord built on the dominant degree, consisting of the root, major third, perfect fifth, and minor seventh (e.g., G7 in C major: G - B - D - F). While the dominant degree itself can create a sense of expectation, the dominant 7 chord creates stronger harmonic tension due to the tritone interval between its third and seventh notes, compelling a resolution to the tonic.
In essence, the dominant degree is just a note or place in a key/scale, while the dominant 7 chord is a fully-formed harmonic structure that intensifies the pull toward resolution.
What Are Secondary Dominants?
In the most basic sense, a secondary dominant is a chord that temporarily functions as the dominant (V) of a chord other than the tonic (I) in a given key.
Let’s break this down:
Dominant Chord (V):
In any key, the dominant chord is the fifth chord, and it has a strong tendency to resolve to the tonic (I). For example, in the key of C major, the dominant chord (V) would be G major (G, B, D), and it resolves to C major (C, E, G).
Secondary Dominant:
A secondary dominant, however, is the dominant of a chord within the key other than the tonic (the first degree of a key). So instead of focusing on the primary V-I resolution (like G to C in C major), a secondary dominant focuses on other chords in the key, treating them temporarily like the tonic, and applying a dominant (V) to them.
For example, in the key of C major:
G7 is the dominant (V) of C (I).
But if we want to temporarily tonicize (make it sound like the start) D minor (ii), we would use A7—the dominant of D minor (V of ii). This makes A7 a secondary dominant.
In short, a secondary dominant is a way of introducing tension and surprise by borrowing dominant chords from other keys within the same key.
Understanding Secondary Dominants in Action
Let’s look at an example to understand how secondary dominants function in practice.
Imagine you're in the key of C major, and you want to add some excitement by emphasizing D minor (ii). Normally, the ii chord (D minor) would appear in the progression like this:
C - Dm - G - C
But to make the D minor feel like a "temporary tonic," we can use the secondary dominant of D minor, which is A7. This makes the progression look like:
C - A7 - Dm - G - C
In this case, A7 is the secondary dominant (V7 of ii), and it resolves to Dm, creating a temporary sense of tension before moving to the ii chord. This is a great way to add harmonic interest, as the A7 chord leads naturally into Dm and introduces an unexpected resolution.
How to Identify and Build Secondary Dominants
To identify secondary dominants, it's important to recognize the chords you're targeting in your key. Here’s a quick guide to constructing secondary dominants:
Locate the chord you want to tonicize.
In any key, you can choose to tonicize any of the diatonic chords. For example, in C major, the diatonic chords are:I – C major
ii – D minor
iii – E minor
IV – F major
V – G major
vi – A minor
Find the dominant of that chord.
Take the dominant (V) of the chord you want to target. For example, if you want to tonicize D minor (ii) in C major, the dominant of D minor is A7 (V7 of ii).Play the dominant chord before the chord you’re tonicizing.
This creates the effect of introducing tension and leading to the target chord. The A7 leads naturally into Dm, which makes it feel like Dm is the “tonic” for a moment.
Common Secondary Dominants
To give you a clearer idea of how secondary dominants are used, here’s a rundown of some common secondary dominants and their targets:
V7/ii: The dominant of the ii chord. For example, in C major, A7 is V7/ii, leading to Dm.
V7/iii: The dominant of the iii chord. In C major, E7 is V7/iii, leading to Em.
V7/IV: The dominant of the IV chord. In C major, D7 is V7/IV, leading to F.
V7/V: The dominant of the V chord. In C major, D7 is V7/V, leading to G.
V7/vi: The dominant of the vi chord. In C major, B7 is V7/vi, leading to Am.
How Secondary Dominants Affect Harmony
Secondary dominants can be used to introduce a variety of harmonic effects. Here are a few of the ways they affect the overall sound:
Tension and Release:
Secondary dominants work by creating tension with the dominant chord and resolving to the target chord. This “tension and release” is the foundation of much of Western classical and popular music. Using a secondary dominant can make a chord progression feel more dynamic and engaging.Temporary Key Changes (Tonicization):
By introducing a secondary dominant, you're essentially tonicizing a chord, making it feel like the tonic for a brief moment. This creates the illusion of a temporary key change, even though the overall key remains the same. For example, in C major, using an A7 chord (V7 of ii) makes D minor feel like the tonic for a while.Smooth Voice Leading:
Secondary dominants are often used to create smoother voice leading between chords. For example, when you move from a secondary dominant (A7) to its target (Dm), the individual notes in the two chords move smoothly, often by stepwise motion, making the progression more fluid.Expanding Chord Progressions:
Secondary dominants can help you expand and enrich your chord progressions, giving you more harmonic options without changing the overall tonality. They allow you to add color and variety to otherwise predictable progressions.
Using Secondary Dominants in Your Music
Incorporating secondary dominants into your music is a great way to add complexity and color to your harmonic progressions. Here are a few practical tips on how to use them:
Experiment with Chord Substitution:
Try replacing a regular diatonic chord with its secondary dominant. For example, instead of using G (V) in the key of C major, substitute it with D7 (V7/V), which will create a sense of tension before resolving back to G.
Create More Interesting Progressions:
In a standard I-IV-V progression in C major (C-F-G), try adding secondary dominants to spice things up. You could turn the progression into something like C - D7 - G7 - C, where D7 is the dominant of the IV chord (V7/IV) and G7 is the dominant of the V chord (V7/V).
Use Secondary Dominants to Resolve Tension:
Secondary dominants are great tools for creating tension and leading to new chord resolutions. Use them sparingly in your progressions to create moments of surprise and harmonic richness.
Experiment with Modulation:
Secondary dominants are also useful when you want to shift to a new key for a brief moment. By tonicizing a new chord, you can create a temporary modulation or key center shift that adds a new flavor to your music.
Conclusion
Secondary dominants are an incredibly powerful tool in music that can elevate your compositions, solos, and progressions. By introducing temporary tonicizations, adding harmonic color, and creating smooth voice leading, secondary dominants allow for more dynamic and expressive harmonic movement. Whether you’re working in classical, jazz, pop, or any other genre, understanding and using secondary dominants can help you craft more compelling, interesting, and emotionally engaging music.
So the next time you’re writing a progression or improvising over a chord sequence, try adding a secondary dominant. You’ll be amazed at how such a small harmonic shift can make a huge difference in the overall feel of your music!
