piano scale
D Mixolydian
D1E2F♯3G4A5B6C♭7
Major with a flattened seventh: the scale that fits a dominant seventh chord without altering it.
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
DWEWF♯HGWAWBHCWD
What is true of it
D Mixolydian is D, E, F♯, G, A, B and C, and back to D.
Its steps are W – W – H – W – W – H – W, where W is a whole step and H a half.
On the same tonic, D major differs from it by exactly one note.
Chords made only of these notes
CmajorCmaj7major seventhDmajorD7dominant seventhEmminorEm7minor seventhF♯dimdiminishedF♯m7♭5half-diminished seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.