As you look through charts of blues tunes, you discover innumerable dominant sevenths serving as one chords (tonics).  Music theoreticians explain:  “Many blues melodies are in the Mixolydian Mode:  They use a major scale, but with a lowered seventh degree.  This is harmonized with a dominant seventh chord whose root is the tonic of the song.  The lowered seventh degree is referred to as ‘the first blues note.’”

A far more succinct, accurate, and readily digestible explanation is:  “The Mixolydian Mode begins and ends on SO,” so the scale is best described this way: Continue reading “The Tonic Dominant Seventh Chord” →