Guitar Chord A#dim: Structure, Notes and Theory

A#dim — a chord built on the note “A#” with a tense, sharp tone that adds drama. Often used as a passing chord to boost expressiveness and create intrigue.

Formula and Structure of the A#dim Chord

Interval formula from the root note: 1 — b3 — b5. The chord consists of the following notes:

• Bb — unison and the main tonal anchor.
• Db — minor third with a melancholic character and gentle lyricism.
• E — diminished fifth with tritone tension, best used cautiously in the bass.

Together, these notes form the harmonic foundation of the A#dim chord, defining its sound and role in the musical context.

Alternative Names for the A#dim Chord

This chord may appear under different names:

• A#°

All variants refer to the same harmonic structure.

Using the A#dim Chord

Put the b5 in the middle or top register to avoid overloading the bass. Use as a link between diatonic chords or to create dramatic moments. In slow tempos, you can highlight its symmetrical structure.

Conclusion

A#dim is an expressive and versatile chord. Learn several fingerings, experiment with different positions and voice spacing, then try weaving it into your own playing — this will help you quickly find your unique tone.