guitar scale
D♭ double harmonic
Two augmented seconds in one scale, one above the tonic and one below the octave.
The same sounds spelled from the other side are C♯ 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
What is true of it
D♭ double harmonic is D♭, E♭♭, F, G♭, A♭, B♭♭ and C, and back to D♭.
Its steps are H – W+H – H – W – H – W+H – H, where W is a whole step and H a half.
Written correctly it needs 7 alterations, E♭♭ and B♭♭ among them. That is what the letters force, and it is also why nobody writes music in this key: the same notes spelled from the other side are easier to read.
On the same tonic, D♭ harmonic major differs from it by exactly one note.
Across the first twelve frets of the guitar its notes fall in 44 places, which is what makes a scale a shape rather than a list.
Chords made only of these notes
Found by testing every chord in the catalogue against these 7 sounds, not chosen.
Other scales on D♭
C dbl harmD dbl harmD♯ dbl harmE♭ dbl harmE dbl harmF dbl harmF♯ dbl harmG♭ dbl harmall 374