Harmonic analysis of the 1st B section of Boplicity
If you haven’t already, read the analysis of the first A section first. It has definitions for my terms.
Other than the first bar, the B section is similar in texture and orchestration to the opening of Boplicity. The chord symbols above the bass part are from the original lead sheet.
Boplicity Bars 17&18
The B section opens with the saxophones in octave unison before they are joined by the rest of the ensemble. All of the chords here are target chords. The last chord (F7b9) would often be changed for another chord so that each instrument can move onto a new pitch. However, in this instance the change in tessitura takes away the need for this.
In the original lead sheet the only chord is Bb, so there are many chords added in these two bars. The F9 I consider to be a functional chord as it is the V of Bb, even though it doesn’t immediately resolve it is strengthened by the bass part and influences the chords preceding it.
The Cmi7/F and Bbmaj7/F are diatonic, although the Eb pitch is not in Fmajor I feel they are part of the F9 or Bbmajor harmony area. The two F’s in the bass line suggest that Gil thought of these chords as part of the F9 sound especially as they have the same vertical structure.
The A7#9 is a non-functioning secondary dominant. The Fmi9 is a look forward to the tonality of the next bar, and notice how nice the melody of that part is in that line because of the Ab.
The G#maj7 and Amaj7 chords are chromatic planning chords into the Bbmaj7 target chord. The Cdim7 is a common passing chord technique, although one could argue that is functioning as a F7b9 without the F here.
These bars are similar to the A section, the target chords are obvious with diatonic chords outlining the arpeggios. The substitution of the A7 for a Emi6/9 is interesting and again echoes the A sections where a dominant chord was substituted. The Eb7b9 is the V or the next target chord in bar 23.
There is only one other chord in these two bars and its created by an omission of an Ab. changing the Ab for an A here allows for more chromatic movement.
The Eb7b9 of the previous bar contributes to the Abmi9 target chord. The F9sus I consider to be a diatonic chord. It is most likely that Gil wrote the bass line and then filled in the inner parts here, as all of the notes fit nicely within F major. The A7b9 and Bbmaj9 are also from F major.
That only leaves the Emi#11 chord. I’m not sure why Gil didn’t opt for a dominant chord here (E7#11), but the result is a rather nice dissonance and a great melodic bass line. I recommend playing the melody and bass together. The final chord should read C6b9#11.