Understanding Secondary Dominants in Guitar Music Theory

Secondary dominant chords are dominant 7th chords that resolve to non-tonic chords in the key. In C major, the primary dominant is G7; secondary dominants appear on ii through vi chords. The secondary diminished seventh chord is always a half step below the root of its corresponding secondary dominant. A7 and C#dim7 share identical notes and function identically in jazz contexts. The general formula is: to find any secondary dominant, go up a perfect fourth from the target chord's root; to find the corresponding diminished chord, go down a half step from the secondary dominant's root. Back cycling inserts secondary dominants into the same measure as the original chord for harmonic interest. When soloing, use tension notes (flat 9, flat 5, sharp 5) rather than just scale tones for more interesting lines. On diminished chords, use root-to-double-flatted 7th intervals and add color tones like major 9ths and flat 6ths.

The half diminished chord can function as a secondary dominant, leading to any target chord within the key. Every dominant chord has a corresponding half diminished chord (the dominant minus its root), allowing substitution. To lead to any target chord, play a half diminished chord a semitone below it. For example, to lead to G in C major, use F# half diminished (containing D7/D9 chord tones). This technique provides a smooth voice-leading alternative to traditional secondary dominants while maintaining harmonic directionality.

This segment covers secondary dominant chords and diminished chord substitutions. The instructor explains that secondary dominants function as dominants leading to chords other than the tonic, such as C7 functioning as V of F. The diminished 7th chord substitution is demonstrated, where Bb7dim can substitute for Gm (ii) in F major because they share most notes, differing by only one note. The instructor shows how to create dominant 7th passing chords and demonstrates improvisation techniques using these harmonic concepts.

A diminished seventh chord a half step below a target chord can be used to approach it smoothly. The voice leading works because all notes of the diminished chord are a half step away from notes in the target chord. For example, B diminished 7 approaching C: B steps up to C, F steps down to E, and Ab steps down to G. Functionally, this can be thought of as borrowing the diminished seven chord from the parallel harmonic minor scale rather than the parallel major scale.

Modulation by pivot chord uses a chord that exists in both the original and new keys as a bridge. For example, when modulating from C major to A minor, the G7 chord serves as a pivot because it contains notes from both keys. Modulation by secondary dominant is the most common technique, using a dominant chord that doesn't belong to the current key to prepare a new key. For example, modulating from F major to B major uses B7 (B-D#-F#-A), which resolves to B major. The armature changes to reflect the new key. Most modulations occur between neighboring keys, though distant keys are also possible.

Secondary dominant chords, which are the five chords of chords other than the tonic in a scale, can serve as pivot chords that share notes between keys, making modulation between keys on the circle of fifths straightforward by reinterpreting the secondary dominant as a chord in the new key rather than resolving it traditionally.

Secondary dominant chords create tension that resolves to a target chord, and can be used to modulate to new keys. The dominant and subdominant chords are particularly important in this process. By using these chords strategically, musicians can create smooth transitions to new keys, often used in choruses to build excitement and anticipation.

A pivot chord is a chord that exists in both the original key and the target key, serving as a transitional bridge during modulation; when modulating from C major to related keys, one can use pivot chords such as C major (which is IV in G major, V in F major, and VI in A minor) to create smooth transitions by placing the pivot chord at the transition point and introducing accidentals that establish the new key, making the key change feel natural rather than jarring.

Common chord modulation (also called pivot chord modulation) is a smooth and subtle technique for changing keys in music by using a chord that exists in both the original and destination keys as a bridge or 'door' between tonal centers; this method involves five key steps: (1) choosing the original key, (2) determining closely related keys using the circle of fifths, (3) selecting the destination key, (4) identifying shared chords between both keys, and (5) choosing a pivot chord that serves as a predominant chord in the destination key to lead smoothly into the new key's progression.

Tritone substitution is a common jazz reharmonization technique where one chord is substituted for another that is a tritone away. This is most commonly done with the fifth chord of the key—for example, substituting G7 for D flat 7 in C major. Both chords contain the same tritone and share the same effective resolution back to the tonic chord.

Tritone substitutions are harmonic techniques where a dominant seventh chord is replaced with another dominant seventh chord a tritone (three whole tones or six semitones) away, which works because both chords share the same third and seventh intervals (though inverted), allowing them to function interchangeably while adding chromatic tension; these substitutions can be applied to any dominant chord in a progression, including secondary dominants, and are commonly used in jazz, gospel, and classical music to create interesting voice leading and harmonic interest.

Tritone substitution is a jazz harmony concept where a dominant chord can be replaced by another chord a tritone (three whole steps) away. For example, in the key of C major, the dominant G7 can be substituted by Db7 (or C#7). This works because both chords share the same tritone interval (B-D and F-Ab), creating similar tension and resolution patterns. The substitution creates interesting voice leading where the root of the substitute chord resolves to the root of the target chord, while other notes resolve predictably. Adding a raised ninth (minor third of the chord) creates a bluesy color typical in jazz harmony.

Tritone substitution is a jazz harmony technique where a dominant seventh chord a tritone away from the original dominant chord (e.g., Db7 instead of G7) can substitute for it, creating a more colorful sound while maintaining the same harmonic function; this works because both chords share the same tritone interval, which is inherently dissonant and drives resolution to the same target chord.

Tritone substitution is a jazz harmony technique where a dominant chord (like G7) is replaced by another dominant chord a tritone away (like Db7), which shares the same 3rd and 7th notes but creates more tension and surprising sounds; this technique works specifically for dominant chords that resolve and can be applied to both chord progressions and improvisation, with the Db7 substitute in a C major context using Db Lydian dominant scale (equivalent to Ab melodic minor or G altered), and the arpeggios from Db7 (F half diminished, Ab minor major 7, B major 7 sharp 5) can be used for G altered soloing.

Secondary dominants are extremely common in jazz standards and form the basis of many harmonic progressions. They create temporary tonal shifts through V-I progressions, allowing musicians to temporarily change keys within a piece. Understanding secondary dominants is essential for analyzing and improvising over jazz standards, as they create the characteristic harmonic movement and tension-resolution patterns that define jazz harmony.

Secondary dominants are non-diatonic chords that function as dominant chords leading to diatonic chords other than the tonic. In a C major context, the secondary dominants are: D7 (leading to E minor), A7 (leading to D minor), B7 (leading to E minor), C7 (leading to F major), and E7 (leading to A minor). These chords create tension and resolution that is characteristic of jazz harmony. The video explains that secondary dominants and their resolutions constitute approximately 70-80% of jazz standards, making them essential knowledge for learning jazz songs.

The jazz standard 'All of Me' demonstrates secondary dominants effectively. The A7 chord functions as V of Dm7 (the ii chord in C major), creating a secondary dominant that adds harmonic sophistication. Similarly, E7 functions as V of Am7 (the vi chord), showing how multiple diatonic chords can be tonicized within the parent key. This technique enhances voice leading, color, and tension-release throughout the progression. Recognizing secondary dominants in jazz standards helps musicians understand how composers create harmonic interest beyond basic diatonic patterns.

This segment examines deceptive cadences and secondary dominants in 'Ripples.' A secondary dominant is a dominant seventh chord built on a scale degree other than the fifth, creating temporary harmonic tension. When this chord resolves unexpectedly to the tonic rather than its expected target, it creates a deceptive cadence. The presenter analyzes how these devices add harmonic sophistication to the song, demonstrating how functional harmony principles create dramatic emotional effects. Understanding these concepts reveals the compositional depth behind seemingly simple chord progressions.

Classical cadences (tonic-subdominant-dominant-tonic) are adapted in popular music to create tension and resolution. Drexler uses these principles in 'Asilo' with ternary rhythm contrasting his usual binary style. Secondary dominants transform any degree into a dominant chord resolving to the chord four degrees away. Drexler demonstrates transforming secondary dominants into minor second degrees before resolution, creating sophisticated harmonic flow characteristic of his style.