piano scale
B♭ double harmonic
B♭1C♭♭2D3E♭4F5G♭♭6A7
Two augmented seconds in one scale, one above the tonic and one below the octave.
The same sounds spelled from the other side are A♯ double harmonic.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
B♭HC♭W+HDHE♭WFHG♭W+HAHB♭
What is true of it
B♭ double harmonic is B♭, C♭, D, E♭, F, G♭ and A, and back to B♭.
Its steps are H – W+H – H – W – H – W+H – H, where W is a whole step and H a half.
On the same tonic, B♭ harmonic major differs from it by exactly one note.
Chords made only of these notes
Found by testing every chord in the catalogue against these 7 sounds, not chosen.
Other scales on B♭
B♭ Phrygian dominantexoticB♭ Lydian dominantexoticB♭ alteredexoticB♭ majormajorB♭ natural minorminorB♭ harmonic minorminor
C dbl harmC♯ dbl harmD♭ dbl harmD dbl harmD♯ dbl harmE♭ dbl harmE dbl harmF dbl harmall 374