s. leach

“To create a major 7th chord we simply extend the ‘1 3 5’ formula by an extra note so it becomes ‘1 3 5 7’.”
― Joseph Alexander, Guitar Chords in Context: The Practical Guide to Chord Theory and Application

“As the major 7th’s chord formula is 1 3 5 7, you might expect that the minor 7th’s formula would be 1 b3 5 7. This, however, is not the case.   To create a minor 7 chord we add a b7 to a minor triad. The formula is 1 b3 5 b7.”
― Joseph Alexander, Guitar Chords in Context: The Practical Guide to Chord Theory and Application

“Finally, there are two types of triad that do not include a 3rd. These chords are normally named ‘suspended’ (or just ‘sus’ chords), as the lack of the 3rd gives an unresolved feel to their character.   In a ‘sus’ 2 chord the 3rd is replaced with the 2nd of the scale, and in a sus4 chord, the 3rd is replaced with the 4th of the scale.   In C, the notes generated by the formula 1 2 5 are C D and G   Example 1g     The notes generated by the formula 1 4 5 are C F and G.   Example 1h  ”
― Joseph Alexander, Guitar Chords in Context: The Practical Guide to Chord Theory and Application

“As the focus of this book is on 7th chords, which are more common in jazz,”
― Joseph Alexander, Guitar Chords in Context: The Practical Guide to Chord Theory and Application