Harmonic Analysis of C. M. von Weber Clarinet Concerto No.1

Question

My question is regarding this passage from C. M. von Weber's Clarinet Concerto No. 1. The passage is taken from the exposition of the first movement and has so far been established in F minor.

Bars 20 - 25 seems to be a modulation and transition to the next section in Db Major (starting at Bar 26). Bars 24 - 25 are in the dominant of the new key of Db major (Abdom7), and Bars 26 - 27 are in the tonic of Db major.

Now for the harmonic analysis:

Bar 20: i - V7 - i ( fmin - cdom7 - fmin )
Bar 21: V7 - i - [V7] ( Cdom7 - fmin - Fdom7 )
Bar 22: ? - ? - ? ( Bbmaj - Dbdom7 - fmin)
Bar 23: ? - ? - ? ( bdim7 - Cdom7 - Fmaj)
Bar 24: Db major: V7 - V7 ( Abdom7 - Abdom7 )

So my question is what is happening with the chords in bars 22 - 23 before the Fmaj (6/3) at the end of Bar 23 leads to Abdom7 (7/5/3) by the lower and upper parts falling and rising by a semitone, respectively.

The first violins and cellos are playing in contrary motion by scale, so was it a case of harmonizing between these parts or can these chords be given a harmonic function by way of roman numerals. Are these chords just chromatic ones chosen for their bass notes and such to fit the scale? Or were they chosen with a chord progression in mind?

Answer 1

The last chord of bar 21 is a secondary dominant, leading us to the first chord of bar 22.

The second chord of bar 22 is actually an augmented sixth chord. Notice the fact that the C flat is spelled as a B natural, which is in the 1st violins, which then resolves up to the C. On the other hand, the D flat in the cellos and basses resolves down to also a C. This is exactly how, traditionally, in classical music, how aug6 intervals resolve. So we have a typical Ger+6 - I64 progression.

As for bar 23, the bdim7 functions as a secondary dominant, replacing the usual G7 since it also contains the crucial tritone B-F, which resolves to C-E (up to ordering of the notes in both pairs). The Fmaj is a borrowed tonic from the parallel major, and the subsequent Ab7 is a dominant seventh chord built on the chromatic mediant of the previous F major chord.