Chords

The dominant 7 chord, in every key

By Oliver Duschka, the developer of Drop2

The dominant seventh is the chord that pushes — the V that makes the next chord feel like home. This page holds every drop-2 shape of it: twelve fingerings across three string sets, each one playable, re-spelled and re-fingered for whichever root you pick.

Four notes, one restless sound

A dominant seventh is a major triad with the minor seventh stacked on top: C, E, G and B♭ — degrees 1, 3, 5 and ♭7. The major third says settled; the ♭7 argues. That argument is the sound: a chord that leans toward the next one instead of sitting still. The symbol is the bare number on the root — C7 — and an unmarked 7 always means dominant: every other seventh chord has to qualify itself, maj7, m7, while this quality is the default the others are marked against.

Two of the four do the talking: the 3 makes it major, and the ♭7 makes it dominant. Those two are the guide tones — and on this chord they have a relationship of their own, six semitones wide, that a section below takes apart. The root names the chord and the fifth fills it out.

Pick a root

Everything below follows this selector. Pick a root and the cards re-finger to the nearest workable frets, the note names re-spell the way the new root demands, and the progression links at the bottom re-point to the right keys. The order is the circle of fifths, the app's own — stepping one chip to the right moves everything up a fifth.

On the top four strings

The top four strings — D, G, B and e — are where comping mostly lives: clear of the bass register, quick to speak. This is the set the practice pages' voice-led progressions use. The four inversions climb the neck in order of their top note — the same ladder the app's Learn screen shows — and here they are the most compact grips on the page: two of the four sit inside two frets.

On the middle four

One set down — A, D, G and B — the same chord sits lower and rounder, still clear enough to comp with. The four inversions ladder up the neck here too. One of them — the first inversion, whatever the root — runs four frets end to end, and that is the farthest this chord ever asks a hand to open: like the m7, and unlike the maj7 with its five-fret stretches down here, the 7 keeps every grip inside four frets.

On the bottom four

On E, A, D and G the voicing turns dark. Four close voices this low can blur — the same register problem that makes a six-string barre chord collide with a bass player — so these grips earn their keep in solo playing, or when nobody else is holding the low end.

Every sound on this page is the Drop2 app's own sampled guitar and bass — from the MuseScore General sound library, used under the MIT license.

The top note picks the shape

Four inversions are not four flavors of the same choice; each puts a different chord tone on top, and the top note is what a listener follows. Root position carries the 3 — E — on top. First inversion carries the 5th, G; second inversion the ♭7, B♭; third inversion the root itself. Comping under a melody, choose the shape whose top note is the note you want heard. Moving between chords, choose the one nearest your hand — each voice taking its shortest path is the whole craft of voice leading, and it is why the practice pages' progressions barely move between grips. And every card here keeps its name: as on the m7, the ♭7 sits a whole step under the root, so the third inversion carries none of the sting that renames the maj7 page's third-inversion cards to 6.

The tritone inside it

Between the 3 and the ♭7 — E and B♭ — lies an interval of six semitones: the tritone, exactly half an octave, the most restless interval in the system. The two notes that define this chord's quality are the two that itch. That is the engine of the dominant seventh, and it is worth hearing on purpose: play any card above and let the middle of the chord grind.

The itch has a direction. Send the root up a fourth — a V landing on its major I, the cadence every ii–V–I ends with — and the tritone closes: the 3 rises a half step to become the new chord's root, and the ♭7 falls a half step onto its third. The name says the rest. Harmonize a major scale in seventh chords and exactly one of the seven comes out dominant — the one on the fifth degree, the dominant — holding the key's only tritone and aiming it at the tonic. When a V7 sounds, the ear knows where home is.

The tritone has one more property: turn it upside down and it is still a tritone. So the dominant seventh built six semitones away holds the same two notes with their jobs swapped — its 3 is this chord's ♭7, its ♭7 this chord's 3 — and the two chords pull toward the same place. Swapping one for the other is the tritone substitution, and the reharmonization article plays it before and after.

Twelve fingerings, fewer sounds

Twelve cards, but fewer chords than that: from this root, the twelve fingerings make seven distinct sounds. The guitar repeats itself — the same four pitches recur on different string sets, at different heights up the neck — and every recurrence is in the cards above. Bottom note first, the duplicates right now are:

• E B♭ C G — Top 4 · 1st inversion, Mid 4 · 1st inversion, Bottom 4 · 1st inversion
• G C E B♭ — Top 4 · 2nd inversion, Mid 4 · 2nd inversion
• B♭ E G C — Mid 4 · 3rd inversion, Bottom 4 · 3rd inversion
• C G B♭ E — Mid 4 · root position, Bottom 4 · root position

This is worth a minute of disbelief with the play buttons: the grips look nothing alike, and the notes are the same. It also shrinks the job. Learn where the seven sounds live and the twelve fingerings become routes to them — when a chart calls for this chord, the useful fingering is whichever sits nearest your hand.

Where the 7 does its work

Shapes are only half a chord; the other half is what it does in a progression — and no quality does more. Two qualities appear in all five forms on the practice pages, the two halves of the ii–V: the m7 that winds the tension up, and this chord, which spends it — in eleven places to the m7's six. It is the V of the cadence in the key a fourth above its root, major and minor alike. In the jazz blues it holds four jobs at once — the blues makes the dominant its home sound, so from one root this chord is the I of one blues, the IV of a second, the VI of a third and the V of a fourth. And in rhythm changes even the tonic turns dominant for half a bar to point at the IV. From the root selected above, C7 is:

• the V of the major ii–V–I in F
• the I of the jazz blues in C
• the IV of the jazz blues in G
• the VI of the jazz blues in E♭
• the V of the jazz blues in F
• the V of the minor ii–V–i in F minor
• the VI of the turnaround in E♭
• the V of the turnaround in F
• the VI of rhythm changes in E♭
• the V of rhythm changes in F
• the I of rhythm changes in C

Each link opens that practice page already set to the key in question, band ready to loop. If you want the 7's job in one sound, take the major ii–V–I and listen to the middle bar lean into the last — the V spending the tension the ii gathered, the tritone closing onto the I.

Where Drop2 comes in

These twelve shapes are the dominant slice of what the Drop2 app teaches — and the slice every form leans on hardest. Learn lays the shapes out the way this page does, every quality, inversion and string set in the same degree colors; Train turns them into a drill — it calls out a voicing, you find it, and the app checks by ear, through the microphone, that the strings said what you meant. Play-Along, part of Premium, then puts the band from the practice pages behind you while you comp the changes yourself.

Next: The m7♭5 chord, in every key →