# AI Wiki - Music - Secondary Dominants ## Overview A **secondary dominant** (also called an **applied dominant**) is the dominant chord of a chord that isn't the tonic. For a moment, the music treats that target chord as a temporary home and approaches it with its own V or V7. Open Music Theory calls the process **tonicization**: "making a non-tonic chord temporarily sound like tonic". The key doesn't change; one or two bars later the song is back in its home key. The classic example in C major: **E7 → Am**. E7 isn't one of C major's [[AI Wiki - Music - Diatonic Chords and Roman Numerals|diatonic chords]] (the diatonic chord on E is Em), but E7 is the V7 of A minor, and Am is the vi of C. So E7 is written **V7/vi** ("five-seven of six"). Secondary dominants are the most common chromatic chords in tonal music, from Bach to Bob Dylan, and the first thing to learn after the diatonic set. ## How it works Every diatonic major or minor chord except the tonic can have its own dominant. Diminished chords (vii° in major, ii° in minor) can't be tonicized: there are no diminished keys. In C major: | Target | Secondary dominant | Numeral | Note from outside the key | |---|---|---|---| | Dm (ii) | A7 | V7/ii | C♯ | | Em (iii) | B7 | V7/iii | D♯ | | F (IV) | C7 | V7/IV | B♭ (the seventh) | | G (V) | D7 | V7/V | F♯ | | Am (vi) | E7 | V7/vi | G♯ | The recipe: take the target chord's root, go up a fifth (or down a fourth), and build a major chord or dominant seventh there. D7 is V7/V because D is a fifth above G. The pull comes from one borrowed note, the **secondary leading tone**: the major third of the secondary dominant, which sits a half step below the target's root (G♯ → A, F♯ → G, C♯ → D). Add the seventh and you get the same tritone that makes V7 → I so strong ([[AI Wiki - Music - Seventh Chords]]): in E7 → Am, G♯ rises to A and D falls to C. V/IV is a special case: C is already I in C major, so only the B♭ seventh turns C into C7 and makes it lean towards F. The [[AI Wiki - Music - Triads|triad]] works too: a plain E major before Am is still V/vi, just softer. [[AI Wiki - Music - Pop Music|Pop]] and folk often use the triad; blues, country and jazz prefer the seventh. ### Which ones are common Open Music Theory notes that tonicization follows normal chord frequency: V and the predominants (ii, IV) are tonicized most, vi fairly often, iii rarely. In practice, for the songs a guitarist meets: 1. **V/V** (D7 in C, A7 in G): the most common of all. It turns an ordinary ii into a major II, the "Don't Think Twice, It's All Right" sound (Dylan's II7). 2. **V/vi** (E7 in C, B7 in G): the dramatic one. "The Shoop Shoop Song" uses III7; the Beatles' "Yesterday" (in F) opens F – Em7 – A7 – Dm, a little ii–V into vi. 3. **V/ii** (A7 in C, E7 in G): the turn into ii that opens many old standards. 4. **V/IV** (C7 in C, G7 in G): the I7 of gospel and blues, which pushes to IV. 5. **V/iii** (B7 in C, F♯7 in G): rarer and darker. ### Chains: extended dominants and the ragtime progression A secondary dominant can resolve to another dominant instead of a stable chord. Each dominant then falls a fifth to the next: E7 → A7 → D7 → G7 → C. Wikipedia calls these **extended dominants**; the chain walks counter-clockwise around the [[AI Wiki - Music - Circle of Fifths]]. Its four-chord form, I–VI7–II7–V7 (C–A7–D7–G7), is the **ragtime progression**: "Five Foot Two, Eyes of Blue", "Salty Dog Blues", "Alice's Restaurant", "Hey! Baby". "Sweet Georgia Brown" opens with the chain itself (V/V/V – V/V – V – I), and the bridge of the jazz "rhythm changes" starts one step further back (E7 in C). Jazz goes one step further: it precedes each secondary dominant with its own ii, giving a mini ii–V into the target (Em7–A7 → Dm, Am7–D7 → G). That's what "Yesterday" does with Em7–A7 → Dm. ### Secondary leading-tone chords The other applied chord is the diminished seventh built a half step below the target: F♯dim7 → G (vii°7/V) in C. It has the same leading tone as D7 and is common in ragtime, gospel and old pop as a passing chord. See [[AI Wiki - Music - Reharmonization]] (passing chords). ## In guitar-friendly keys The five secondary dominants in each key (dominant sevenths; triads work too): | Key | V/ii | V/iii | V/IV | V/V | V/vi | |---|---|---|---|---|---| | C | A7 → Dm | B7 → Em | C7 → F | D7 → G | E7 → Am | | G | E7 → Am | F♯7 → Bm | G7 → C | A7 → D | B7 → Em | | D | B7 → Em | C♯7 → F♯m | D7 → G | E7 → A | F♯7 → Bm | | A | F♯7 → Bm | G♯7 → C♯m | A7 → D | B7 → E | C♯7 → F♯m | | E | C♯7 → F♯m | D♯7 → G♯m | E7 → A | F♯7 → B | G♯7 → C♯m | C and G are the friendliest: A7, B7, C7, D7, E7 and G7 are all open shapes. In D, A and E, the V/vi and V/iii need a barre (F♯7, C♯7, G♯7, D♯7: the E-shape or A-shape dominant seventh from [[AI Wiki - Music - Barre Chords]]). The three most useful moves in C, as pairs (dominant, then target): ```chord E7 020100 020100 --- Am x02210 x02310 --- A7 x02020 x02030 --- Dm xx0231 xx0231 --- D7 xx0212 xx0213 --- G 320003 210003 ``` Each pair is a one- or two-finger change: E7 → Am moves the same shape over one [[AI Wiki - Music - Triads on the Fretboard|string set]]; A7 → Dm and D7 → G keep the hand near the nut. In G, the ragtime and V/vi moves: ```chords {title: Secondary dominants in G} {key: G} {time: 4/4} {comment: V7/vi: B7 pulls to Em} | [G] . . . | [B7] . . . | [Em] . . . | [C] . [D7] . | [G] . . . | {comment: Ragtime progression I–VI7–II7–V7 (extended dominants)} | [G] . . . | [E7] . . . | [A7] . . . | [D7] . . . | [G] . . . | {comment: V7/V in a I–IV–V song (the major II)} | [G] . . . | [C] . . . | [A7] . . . | [D7] . . . | [G] . . . | ``` ## How to spot them on paper 1. **An accidental in the chord**, usually one that raises a note (F♯ in C, G♯ in C). Open Music Theory: applied chords "nearly always involve accidentals, and especially accidentals that raise the pitch". 2. **A major chord or dominant seventh on a degree that should be minor**: II, III or VI instead of ii, iii, vi. In a chord chart in C, D7, E or E7 and A or A7 are the giveaways. A7 in a song in D is just V7; A7 in a song in C is V7/ii. 3. **The next chord's root is a fifth below** (E7 → Am, D7 → G). If it is, write V7/x where x is that next chord's numeral. 4. **Exceptions**: a secondary dominant can resolve deceptively. Elizabeth Cotten's "Freight Train" (in C) moves from C to E7 in its third bar and then on to F, not to Am; Radiohead's "Creep" (G – B – C – Cm) does the same with B → C. The chord is still V/vi; the surprise is part of the sound. ## How to hear them - **The "lean"**: a secondary dominant sounds like a door opening sideways. The chord is brighter than expected (major instead of minor), and the next chord lands like a small arrival. - **The bass falls a fifth** (or rises a fourth) into the next chord, like V → I but somewhere other than the tonic. - **One note changes**: Am → A7 in C is C → C♯ (the third rises a half step), then C♯ → D. Sing that line. Same with Em → E (G → G♯ → A) and Dm → D7 (F → F♯ → G). - **Name it from the target**: when you hear the lean, wait for the chord it lands on, identify that chord's numeral (vi, ii, V...), and you know the secondary dominant. This is the [[AI Wiki - Music - Functional Ear Training]] approach: hear each chord against the key. The A7 that tonicizes Dm, with the raised third (C♯, the secondary leading tone) marked: ```keyboard chord: A7 labels: intervals highlight: 3 range: C4-B5 ``` On piano, the resolution of E7 to Am shows the two half-step moves (G♯ → A, D → C): ```chord instrument: piano --- symbol: E7 pitches: E3 D4 G#4 B4 title: E7 (V7/vi) --- symbol: Am pitches: A3 C4 E4 A4 title: Am (vi) ``` ## In pop, folk and jazz - **Folk and country**: the major II (V/V) and the I7 → IV move (C7 → F in C) are everywhere, usually as plain [[AI Wiki - Music - Guitar Open Chords|open chords]]. The ragtime progression drives Piedmont blues, fingerpicked folk (Travis-style pieces) and [[AI Wiki - Music - Bluegrass Rhythm Guitar|bluegrass]] standards. These sound "old-timey", not jazzy. See [[AI Wiki - Music - Folk Music]] and [[AI Wiki - Music - Country Music]]. - **Pop and [[AI Wiki - Music - Rock Music|rock]]**: the III (V/vi) for a dramatic turn into the [[AI Wiki - Music - Relative and Parallel Keys|relative minor]] ("Creep", "Yesterday"), and the major II for lift before a chorus. Usually triads. - **Blues**: every chord is a dominant seventh, and the I7 in bar 4 works as V7/IV ([[AI Wiki - Music - Blues Music]]). - **Jazz**: chains of dominants, ii–V pairs into every target, and altered dominants (A7♭9 → Dm). See [[AI Wiki - Music - Jazz Music]]. ## How to practise 1. **Play the five in C and G** as pairs (dominant → target), 2 minutes each, eyes on the target's root. 2. **Swap and compare**: play C – Am – Dm – G7, then C – A7 – Dm – G7. Then C – Am – D7 – G. Hear what one raised note does. 3. **Add one to a song you know**: before the vi of an I–V–vi–IV song, insert III7 (E7 in C, B7 in G) on the last beat of the V bar. Check the melody: E7 clashes with a melody note G (it contains G♯). 4. **Ear drill**: have someone (or an app) play I–vi–ii–V and I–VI7–II7–V7 at random; name which chords became dominants. 5. **Charts**: in your song charts, circle every chord that isn't diatonic and label it V/x if the next chord is a fifth below. ## Common mistakes - **Thinking the key changed.** One or two bars of A7 → Dm in C don't make the song in D minor; the music returns at once. - **Analysing from the wrong end.** Name the secondary dominant from the chord it resolves to, not from the key: D7 in C is V7/V, not "II7 of C". - **Clashing with the melody.** The secondary leading tone is a note outside the key; if the melody holds the diatonic version (G over E7), it grates. - **Overusing chains.** Four dominants in a row sound like ragtime or swing; that's a style choice, not a neutral move. ## Key Points - A secondary dominant is V or V7 of a chord other than I, written V/x or V7/x; it tonicizes x without changing key. - Every major or minor diatonic chord can be tonicized; diminished chords can't. - The pull comes from the raised third (secondary leading tone) and, with the seventh, the same tritone as V7. - Most common: V/V (major II) and V/vi (major III), then V/ii and V/IV. - Spot them on paper by an accidental and a major chord on ii, iii or vi; by ear by a brighter chord that leans into a fifth-below arrival. - Chains of dominants (VI7–II7–V7–I) form the ragtime progression; jazz adds a ii before each. ## Open Questions - Which secondary dominants appear in the songs Sébastien is currently learning (to collect real examples from his repertoire)? - How do secondary dominants work in minor keys (V/iv, V/♭VI, V/♭III), and which are common in rock and folk? ## References - Wikipedia, "Secondary chord": https://en.wikipedia.org/wiki/Secondary_chord - Gotham et al., *Open Music Theory* 2e, "Tonicization": https://human.libretexts.org/Bookshelves/Music/Music_Theory/Open_Music_Theory_2e_(Gotham_et_al.)/04%3A_Diatonic_Harmony_Tonicization_and_Modulation/4.14%3A_Tonicization - Wikipedia, "Ragtime progression": https://en.wikipedia.org/wiki/Ragtime_progression - Review of Elizabeth Cotten, *Folksongs and Instrumentals with Guitar* (the C → E7 contrast in "Freight Train"): https://onlysolitaire.substack.com/p/review-elizabeth-cotten-folksongs ## Related - [[AI Wiki - Music - Diatonic Chords and Roman Numerals]] - [[AI Wiki - Music - Seventh Chords]] - [[AI Wiki - Music - Circle of Fifths]] - [[AI Wiki - Music - Common Chord Progressions]] - [[AI Wiki - Music - Cadences]] - [[AI Wiki - Music - Reharmonization]] - [[AI Wiki - Music - Borrowed Chords and Modal Interchange]] - [[AI Wiki - Music - Extended Chords]] - [[AI Wiki - Music - Functional Ear Training]] - [[AI Wiki - Music - Chord Progression Recognition]] - [[AI Wiki - Music - Barre Chords]] - [[AI Wiki - Music - Jazz Music]] - [[AI Wiki - Music - Folk Music]] - [[AI Wiki - Music - Beginner Songs by Chord Set]] - [[AI Wiki - Music - Ear Training Tips and Tricks]] - [[AI Wiki - Music - Finding the Key of a Song]]