The major 7th chord (abbreviated maj7 in chord names) is a four-note chord. In music theory, each note in this scale has what is called a scale degree name, which describes the relationship of that note to the tonic (1st) note. Guitar chords in the key of A include A major, D major, E major, F minor. G7 b9īy now, you have understood that a 7 b9 chord can be replaced by a diminished 7th chord (chord substitution technique) starting on the major third (3), the fifth (5), the minor seventh ( b7) or the flat ninth ( b9) of this 7 b9.Įxample in a C major II-V-I progression where the V7 is extended with a b9 giving a V7 b9. This step shows the E-flat major scale degrees - tonic, supertonic, mediant, subdominant, dominant, submediant, leading note / tone, and octave. So G7 b9 (except the root) has the same notes as A bº, Bº, Dº or Fº. A tritone substitution occurs whenever a dominant 7th chord is being substituted or replaced by another dominant 7th chord with a root a tritone interval away (basically you shift the chord 6 half-steps up) For example G7 is replaced by Db7 as G-D is a fifth so G-Db is a diminished fifth. Dominant 7 b9 contains the same notes as a diminished 7th chord built on any of the chord tones including the flat 9 but without the root. By taking a dominant 7 (Example with G7 : G, B,D and F) and adding the flattened ninth (A b for G7), you built a 7 b9 chord. The dominant 7 b9 chord functions as a dominant (V7) implying in its upper structure the tones of a symmetrical diminished chord.

E flat dominant 7th chord