Dominants

In music theory, the concept of "dominant" is fundamental for understanding harmony and chord progression. The dominant plays a crucial role in creating tension and resolution, being one of the most important tools for composers. This article explores different types of dominants, including primary, secondary, substitute, extended, altered, and relative dominants, elucidating their functions and applications in music.

Primary Dominant

The primary dominant is the fifth-degree chord (V) of a key and has a strong tendency to resolve to the tonic chord (I). In a major key, for example, in C major, the dominant chord is G (G major), which resolves to C (C major).
In minor keys, the dominant is usually a major or major seventh chord to reinforce the sense of resolution.

Examples in Some Keys

Secondary Dominant

The secondary dominant is a dominant chord that is not the V of the main key, but rather the V of another chord within the same key. This concept allows the introduction of additional tensions and more complex harmonic movements.

This type of dominant is known as "dominant of the dominant" because it functions as the dominant for another dominant chord. In terms of notation, it is common to use the notation V7/V to indicate that it is a secondary dominant, specifically of the fifth degree.

Examples in Some Keys

Secondary Dominants in C Major Key

Characteristics of Secondary Dominants

• They are not entirely diatonic: at least one note of the chord does not belong to the key scale.
• They generally resolve to a diatonic chord: located a perfect fifth below.
• They are built from a diatonic fundamental: which is diatonic.

The last characteristic justifies the absence of a V7/VII chord among the secondary dominants. The fundamental note, a perfect fifth above the seventh degree, does not belong to the diatonic scale; for example, in the key of C, it would be an F#.

Substitute Dominant - Sub V7

The substitute dominant is a chord that replaces the traditional dominant chord, usually having the same leading tone (major seventh) and a tritone distance from the original chord. It is most often used to add variety and harmonic interest. The substitute chord is usually an altered dominant.

Let's analyze the key of C major: The primary dominant (V7) of this key is G7, which contains the note B, its major third. In relation to the key of C major, the note B functions as the leading tone, which is the major seventh.

Now let's analyze the chord located a diminished fifth above G7: This chord is Db7, composed of the notes Db, F, Ab, and Cb (B). Note that it contains the tritone of the key (B and F).

The leading tone and the tritone are the two main characteristics of a preparatory chord.
Note that between G7 and Db7, the main difference is the bass note, besides the presence of the note Ab, which is not present in G7.

You can also consider that the Sub V7 is located a semitone above the target chord (Degree I).

Examples in Some Keys

Secondary Sub V7

Other diatonic chords of the harmonic field can also have their own Sub V7. In a C major key, we can prepare an F7M with its Sub V7, creating a secondary Sub V7.
To better understand, consider this example in the key of C major: The F7M has a secondary dominant, which is C7. This dominant that prepares F7M can be replaced by its Sub V7, which is Gb7. Therefore, the Sub V7 that prepares F7M is Gb7. This chord is considered a secondary Sub V7, as the main key is C major, not F.

Secondary Sub7 in C Major Key

Additional Explanation of Resolution in Minor Chords

• Eb7 to Dm: The Eb7 chord contains the tritone Bb-Db, which naturally resolves to the notes of the Dm chord (D - F - A).
• F7 to Em: The F7 chord contains the tritone A-Eb, which resolves to the notes of the Em chord (E - G - B).
• Bb7 to Am: The Bb7 chord contains the tritone D-Ab, which resolves to the notes of the Am chord (A - C - E).

If we compare the tritone notes of A7 (C# - G) with those of Eb7 (G - Db), we see that they share the same tritone interval. This interval creates the same harmonic tension, which resolves similarly to the target chord Dm.
This explains why Eb7 can be used as a substitute for A7 to resolve to Dm, as both share the same harmonic function through their tritones.

Extended Dominant

The extended dominant refers to the use of several dominant chords in sequence, each resolving to the next, creating a chain of resolutions that culminates in the final tonic. This concept is often used in prolonged cadences. They are chords that prepare other dominants that are neither primary nor secondary tones.

We can prepare these secondary dominant chords using extended dominants. Observe this sequence in the key of C major:

D7 -> G7 -> C7

If we prepare this D7, we will use an A7, which is already considered an extended dominant. The D7 is a secondary dominant, as it prepares the G7, which belongs to the harmonic field of C. However, the D7 is not part of the C harmonic field. Therefore, the chord that prepares the D7 (A7) is considered an extended dominant.

A7 -> D7 -> G7 -> C7

The A7 can be prepared by E7, and once again, we have an extended dominant:

E7 -> A7 -> D7 -> G7 -> C7

And so on:

B7 -> E7 -> A7 -> D7 -> G7 -> C7

Examples in Some Keys

Altered Dominant

The altered dominant includes modifications to the notes of the dominant chord, such as altered sevenths, ninths, elevenths, and thirteenths. These chords create even greater tension, increasing the sense of resolution when they move to the tonic.

Examples in C Major

• G7 -> C: (Primary Dominant)
• G7(#9) -> C: (Altered Dominant)

Examples in G Major

• D7 -> G: (Primary Dominant)
• D7(b9) -> G: (Altered Dominant)

Relative Dominant

The relative dominant is a concept that refers to the dominant chord of a relative key. Relative keys share the same notes but have different tonics (one major and one minor).

Examples in C Major and A Minor

• G7 -> C: (Primary Dominant)
• E7 -> Am: (Relative Dominant)

Examples in G Major and E Minor

• D7 -> G: (Primary Dominant)
• B7 -> Em: (Relative Dominant)

Auxiliary Dominant

The auxiliary dominant prepares a modal borrowed chord. For example, in the key of C major, we can use Eb7 to prepare Ab7M (a chord borrowed from C minor). This preparation creates smooth and coherent transitions between different keys.

Eb7 -> Ab7M

Conclusion

The different types of dominants offer a rich palette of options for composers and musicians, allowing the creation of varied harmonic tensions and resolutions. Understanding and applying these concepts can transform a simple composition into a complex and emotionally engaging piece. Experimenting with primary, secondary, substitute, extended, altered, and relative dominants is essential for any musician wishing to expand their harmonic knowledge and compositional skills.