E♭ Diminished 7th Chord

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Formula R – ♭3 – ♭5 – 𝄫7

Summary

E♭ Diminished 7th is built from the notes E♭, G♭, A, C. The interval from E♭ to G♭ is a minor 3rd (3 semitones), from E♭ to A is a tritone (6 semitones), from E♭ to C is a major 6th (9 semitones). This chord contains 2 flatted notes.

The diminished 7th is pure symmetry and pure tension. It's built entirely from stacked minor thirds, and only three unique dim7 chords exist — move the shape up 3 frets and you get the same chord. It's the ultimate dramatic device, common in classical music and film scores.

Theory

The formula is R, ♭3, ♭5, ♭♭7 (the double-flat 7th sounds the same as a major 6th). Four minor thirds stacked perfectly means every note could be the root — giving you four chords for the price of one. It frequently acts as a passing chord, resolving up by a half-step to the next chord. It's also closely related to the dominant 7♭9, which means you can use it to set up dramatic resolutions.

On the guitar

Learn one diminished 7th fingering and slide it up in groups of 3 frets to get inversions of the same chord — this is extremely useful for quick modulations and chromatic passing movements. The classic shape on the middle four strings is compact and movable everywhere. Because only three unique dim7 chords exist, mastering three shapes literally covers every diminished 7th in every key.

Advanced

The classic move — C → C♯°7 → Dm7 — creates a smooth half-step passing motion that sounds like old Hollywood. In gospel, diminished 7ths connect chords with elegant half-step movement. In classical music, Bach used them for moments of anguish and dramatic tension. Don't overuse them — the drama comes from surprise.

Piano