Chords
The dim7 chord, in every key
The diminished seventh is the perfectly even chord — four notes a minor third apart, so symmetrical that any of them can claim to be the root. 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 perfectly even sound
A diminished seventh is the m7♭5 taken one step further: flatten the seventh too, and every gap in the chord comes out the same. C, E♭, G♭ and B♭♭ — degrees 1, ♭3, ♭5 and ♭♭7 — sit a minor third apart, each from the next, and the last gap, back up to the root, is a minor third too. No note is closer to home than any other. The symbol is dim7, also written º7; keep it apart from ø — the half-diminished flattens only its fifth, and the two are different sounds entirely. And the double-flatted seventh is not a typo: spelled as some kind of seventh, the chord keeps its ladder of thirds honest on paper, while on the fretboard the ♭♭7 sits on the same fret as the plain major sixth.
The price of the evenness is that nothing in the chord rests. Inside these four notes sit two tritones: C against G♭, and E♭ against B♭♭. The dominant seventh runs on one tritone, held above a root that stays out of the argument; the m7♭5's runs through the root itself. Here nobody is spared — every note of the chord stands inside one of the two, and even the guide tones, the ♭3 and that strange seventh, are a tritone apart, exactly like the dominant's. It is the most restless chord in the vocabulary, and tunes treat it accordingly: half a bar, passing through, gone.
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 link at the bottom re-points to the right key. 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 — but on this chord the ladder does something no other quality's does: the four cards below are one grip, drawn four times, three frets apart. And all four sit inside two frets — no other quality keeps a whole set this compact.
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 same picture again: one grip, four heights, three frets between them. This set's grip runs three frets end to end, and that is the widest this chord ever gets. Alone among the six qualities in the app's library, the dim7 never asks the hand to open past three frets — every other quality reaches four somewhere, and the maj7 five.
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 height
On the other quality pages, four inversions are four different hand shapes; here they are one shape at four heights, so the top note is the whole choice. Root position carries the ♭3 — E♭ — on top. First inversion carries the ♭5, G♭; second inversion the ♭♭7, B♭♭; third inversion the root. Comping under a melody, pick the card whose top note is the note you want heard — or simply the one nearest your hand, since the fingering never changes. And every card keeps its name: the third inversion sets its root a full minor tenth above the bottom ♭♭7, nothing like the minor-ninth sting that renames the maj7 page's third-inversion cards to 6.
One shape, every three frets
Why does one grip serve four times? Slide any shape up three frets and every note in it rises a minor third. On most chords that lands somewhere new. Here a minor third is exactly the chord's own spacing, so each note climbs onto the seat of the note above it — the same four pitches, one inversion higher. Slide again and it happens again; after the fourth slide the pattern has climbed back to where it started, an octave up. The cards above are that fact drawn out: the fretboard turns the chord's symmetry into geography. It is the cheapest vocabulary lesson on this site — one fingering per string set, and the whole neck is covered.
Twelve names, three chords
The evenness has a stranger consequence. Every note sits a minor third from its neighbors — which is exactly the relationship a root has to its ♭3. So any of the four notes can claim to be the root, and the claim always checks out: the same four pitches answer as Cdim7, and as a dim7 built on its ♭3, on its ♭5, or on its ♭♭7. Four names for one sound. Run that across all twelve roots and the arithmetic collapses: twelve names, but only three distinct diminished sevenths in the world. Every dim7 you will ever play is one of three chords.
The selector above can prove it. Start from C, then pick E♭: not one dot moves to a different fret. Pick G♭, then A — still nothing moves. What changes is the copper: the root dot jumps to another corner of the same grip, and the degree labels rotate around it. Which note is the root is not a fact about the fingering; it is a decision about where the chord is going, and the name follows the decision.
The spelling pays for all this symmetry. Each root insists on writing its own ladder of thirds — C spells its seventh B♭♭, and flat-side roots go further still, into double flats on the third and fifth as well — but the fretboard does not care. The ear hears three chords; harmony gives them twelve names because a name says which way the chord is about to lean.
The name a bass player gives it
There is a fifth name, and it needs a bass player. Set any of these grips over a bass note a major third below the root and the four notes become a dominant seventh with a flat nine and no root: the 3, the 5, the ♭7 and the ♭9 of the chord the bass is naming. Trading the root for a color tone is how jazz builds its rootless extended voicings, and this is the oldest trade of them all — many of the diminished chords in the old songbooks are dominants in disguise, and the shapes on this page will keep coming back to you under that other name.
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 — Top 4 · 3rd inversion, Mid 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. And one more mark of the symmetry: on every other quality's page that count shifts with the root — here it is seven from all twelve, without exception.
Where the dim7 does its work
Shapes are only half a chord; the other half is what it does in a progression — and like the m7♭5, this chord keeps exactly one address across the five forms on the practice pages. But where the ø holds a job — the ii of a cadence — the dim7 holds a move. It is the ♯iv of rhythm changes: the passing chord in bar 6 that stands a half step above the IV and carries the bass back toward the tonic. And true to form, the symmetry reaches even the address — the key that contains this chord sits a tritone from its root. From the root selected above, Cdim7 is:
- the ♯iv of rhythm changes in G♭
The link opens rhythm changes already set to the right key, band ready to loop — bar 6 is the one to listen for: the root climbing one fret out of the IV and settling back onto the tonic, a passing note with a harmony built on it. And as with the ø one page back, a short address book means specialized, not rare. Outside these five forms the dim7 is jazz's connective tissue — slipped between chords a whole step apart so the bass can walk the half step between them, or standing in for a dominant under the name the bass player gives it.
Where Drop2 comes in
These twelve shapes — three grips, really, each at four heights — are the diminished slice of what the Drop2 app teaches. Learn lays them 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.
Free to start, no time limit · Works with acoustic and electric guitar
Next: All the chord pages →