s. leach

“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

“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

“The three triads you have learned so far are   1 3 5 Major 1 b3 5 Minor 1 b3 b5 Diminished or just ‘Dim’ Most chords you come across in music, no matter how complicated can normally be categorised into one of these basic types. Jazz chord progressions however are normally formed from richer sounding ‘7th chords’ which are the focus of this book.   There is, however, one more permutation that crops up occasionally, it is the augmented triad, 1 3 #5.”
― Joseph Alexander, Guitar Chords in Context: The Practical Guide to Chord Theory and Application