
Originally Posted by
tonyknight
An observation: the F13b9 is interesting. As Tom said, it sits under a melody of Ds. If we were to play all the notes of this chord, we’d have 1+3+5+b7+b9+13 = F, A, C, Eb, Gb, D. So the melody makes this chord a 13th if we use a base of F major. Now, if we ignore the root, the F, we have that same F# diminished chord (if it is not a dim7) – there’s no way that this ‘coincidence’ would have escaped Rodgers… so I suspect the chord was chosen to echo or recall the earlier choice. Please correct me if my logic is flawed!!! Of course, if the dim7 is the true implied chord, then I could imagine that the 13th might be based on the major 7th triad and not the dominant 7th?