Secondary Dominants Explained: Add Tension That Resolves

What is a secondary dominant?

A secondary dominant is a dominant chord aimed at a chord other than the tonic. Wikipedia defines it as a major triad or dominant seventh chord built and set to resolve to a scale degree other than the tonic.^[1]

The effect is called tonicization. Open Music Theory describes it as making a non-tonic chord temporarily sound like tonic.^[2] For a split second, the listener hears Am or G as a destination, which gives an ordinary chord a sense of arrival.

The notation reads like a fraction. V/V means "the V chord of the V chord" and is spoken as "five of five". The part before the slash is the chord's job, the part after is its target.

The five secondary dominants in a major key

A major key has five secondary dominants, one for each major or minor chord that is not the tonic. The diminished vii° is left out, because Open Music Theory notes that diminished and augmented triads cannot be tonicized.^[2] The chords below match the list on Wikipedia.^[1]

Wikipedia calls V7/V the most frequently encountered of the group.^[1] In producer terms, V/V and V/vi do most of the work in pop, while V/IV is the one you hear in gospel and blues-flavored R&B.

How do you spot a secondary dominant?

Look for a major or dominant seventh chord containing a note outside the key, whose root sits a fifth above the next chord. Open Music Theory puts the first clue simply: chromaticism is an indication that tonicization may be present.^[2]

1. Find the out-of-key note
   Turn on scale highlighting: FL Studio shades the piano-roll grid, Ableton's Scale Mode the piano ruler.^[3][4] Notes outside it are your first suspects.
2. Check the chord quality
   Secondary dominants are always major or dominant seventh. A minor chord with a chromatic note is something else, often a borrowed chord.
3. Look one chord ahead
   If the next chord's root is a perfect fifth below (or a fourth above), you have a V-of relationship. E7 followed by Am fits; E7 followed by F does not.
4. Follow the chromatic note
   In clean resolutions the chromatic note, the target's leading tone, rises a semitone to its root: G# to A, F# to G, C# to D. Per Open Music Theory, the chordal seventh resolves down.^[2]

When the resolution does not happen

Songs do not always deliver the expected target. Radiohead's "Creep" repeats G, B, C, Cm.^[5] In G major, B major is spelled exactly like V/vi, which points toward Em. The song moves to C instead, and that dodge is a large part of the song's uneasy feel. The final Cm is a borrowed chord, a separate trick covered in borrowed chords and modal interchange.

Step by step: turning a flat four-chord loop into a moving progression

Take a diatonic loop and insert a secondary dominant in front of any chord you want to spotlight. We will use C, Am, F, G, the I-vi-IV-V pattern Open Music Theory calls the doo-wop schema.^[6] Split bars 1 and 4 into two half-bar chords.

1. Loop the plain version first
   Program C, Am, F, G at one chord per bar and listen four times. That is your baseline.
2. Add V/vi before Am
   Put E7 on the second half of bar 1 and an E in the bass. The G# only lasts two beats, but it makes Am sound like an arrival instead of a drift.
3. Add V/V before G
   Put D7 on the first half of bar 4. Moving F up to F# is the only change from the F chord, yet the G now lands with weight.
4. Check the melody
   If your lead holds G natural over E7 or F natural over D7, it will clash. Move it to a chord tone for those two beats.
5. Compare A/B
   Bounce both versions and play them back to back. The notes changed in only two half-bars, yet the second loop pulls forward from bar to bar.

How to use secondary dominants in trap and minor-key beats

In a minor key, the same idea works by turning a minor chord major, or adding a flat seventh, just before the chord you want to hit. Trap loops tend to sit on two or three minor chords, so one secondary dominant stands out sharply.

The C7 move is the easiest to hear. Cm7 and C7 share C, G and Bb, so only Eb rises to E, and that E then rises one more semitone to F, the root of Fm. On a sad piano or bell, it sounds deliberate rather than theoretical. The G7 row comes from the raised seventh of harmonic minor, which our sibling guide to harmonic minor for trap melodies covers in depth.

Keep the 808 on the secondary dominant's root, or slide into the target's root, so the bass confirms the move. For voicing the rest of the loop, see how to make trap piano chords.

Secondary dominants in well-known songs

Secondary dominants are common in pop, folk and jazz standards. Wikipedia's secondary dominant article cites several examples you can check by ear.^[1]

• II7 (V/V) Bob Dylan's "Don't Think Twice, It's All Right" uses a II7 chord, the V/V.
• III7 (V/vi) Betty Everett's "The Shoop Shoop Song" uses III7, the V/vi move from the loop above.
• Chains of secondary dominants "Five Foot Two, Eyes of Blue" strings several together, and "Sweet Georgia Brown" opens with V/V/V, V/V, V, I. In C that is A7, D7, G7, C: every chord is the dominant of the next.

Chains are worth trying in a beat because each chord resolves into another tense chord, so the tension keeps rolling until the final tonic. Two chords of the chain are usually enough for a hook; the full chain suits a turnaround or an intro. For more progression templates, see chord progressions for producers.

Common mistakes with secondary dominants

Most problems come from placing the chord without preparing the notes around it. These are the usual culprits.

• Using a minor chord Em before Am is not a secondary dominant; it is just iii. The chromatic G# is the whole point, so make sure the chord is major or dominant seventh.
• Resolving somewhere random An unresolved secondary dominant can work, as "Creep" shows, but do it on purpose. By default, follow it with its target.
• Scale lock left on Snap-to-scale tools will push G# back to G. Switch the lock off for that clip, or the secondary dominant quietly becomes a diatonic chord.
• Using one in every bar Tension works by contrast. One or two secondary dominants per eight bars keeps a loop moving without sounding like a jazz exercise.