Finger Positions

Root Note A

Name A diminished seventh over B

Intervals 1P-3m-5d-7d

Relative Minor F#m

Notes B, A, C, Eb, Gb

Aliases Adim7, A°7, Ao7

How to play the Adim7/B Chord

The Adim7/B is a fundamental dominant chord in guitar music. To play this chord correctly, ensure your fingers are placed precisely on the frets indicated in the diagram above.

Music Theory Analysis

From a theoretical perspective, the A diminished seventh over B is built using the 1P, 3m, 5d, 7d intervals. In the key of A Major, this chord functions as the I chord.

Common Progressions

In music composition, the Adim7/B chord is often used to create tension or resolution.

I-V-vi-IV

A → E → F#m → D

vi-IV-I-V

F#m → D → A → E

The Diatonic Family

Understanding the "family" of chords that belong to A helps with transposition and ear training.

Triads

A Bm C#m D E F#m G#dim

7ths

Amaj7 Bm7 C#m7 Dmaj7 E7 F#m7 G#m7b5

Scale Compatibility

View All Scales

Diminished Ultralocrian Locrian 6 Dorian #4 Lydian Diminished Hungarian Major Lydian #9 Half-Whole Diminished Composite Blues Messiaen's Mode #7 Chromatic

* 11 scales found containing the notes B, A, C, Eb, Gb.

Acoustic & Digital Analysis

Digital footprint of the Adim7/B chord for MIDI programming and synthesizer sound design.

MIDI Numbers 71, 69, 60, 63, 66

Frequencies (Hz)

493.8833012561241, 440, 261.6255653005986, 311.1269837220809, 369.9944227116344