piano scale
C♯ Mixolydian
C♯1D♯2E♯3F♯4G♯5A♯6B♭7
Major with a flattened seventh: the scale that fits a dominant seventh chord without altering it.
The same sounds spelled from the other side are D♭ Mixolydian.
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
C♯WD♯WE♯HF♯WG♯WA♯HBWC♯
What is true of it
C♯ Mixolydian is C♯, D♯, E♯, F♯, G♯, A♯ and B, and back to C♯.
Its steps are W – W – H – W – W – H – W, where W is a whole step and H a half.
It costs 6 alterations to write — near the limit of what a key signature can carry.
On the same tonic, C♯ major differs from it by exactly one note.
Chords made only of these notes
C♯majorC♯7dominant seventhD♯mminorD♯m7minor seventhF♯majorF♯maj7major seventhG♯mminorG♯m7minor seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.