▪ All chords are six chords. In the Barry Harris method, we tend to view all chords in their major or minor 6th chord presentation:
▪ Major 7th chords we will typically (not always) turn into major 6th chords (or we treat the 7th as a borrowed diminished note from its scale of chords. Details in the next chapter).
▪ Minor 7th chords are already inversions of a major 6th chords (e.g: Dm7 = F6).
▪ Dominant chords can be substituted — by the minor 6th chord on their 5th scale degree (not always, it is a matter of style). Barry Harris calls this minor 6th chord the important minor.
▪ Minor7♭5 is already an inversion of a 6th chord 3 half steps above it (e.g: Dm7♭5 = Fm6).
▪ Remember: fully diminished 7th chords, ♯5 chords and ♭5 chords are by definition not chords – as they are not intervals on the major or dominant scale.
▪ When playing a 6th chord, you can use the root of the original chord or the new root (e.g: Dm7 = F6. Play Either D or F in the bass).
▪ The Major 6th chords on the I and the V are interchangeable (e.g: C6 and G6). It sounds better to keep the original root in the bass if choosing the major on the 5th.
▪ Tritone dominants: dominant chords a tritone up or down from the root position of a dominant chord are interchangeable (they come from the same fully diminished 7th chord family).
▪ The pentatonic major and pentatonic minor scales are in essence an arpeggiated 6-chords. They should be viewed in this context.