One of the characteristic aspects of Bennett’s guitar works is his use of exclusively pandiatonic pc sets, and of his treatment of tone rows as generating complexes rather than as themes. Richard Cohn defines pandiatonicism (after Slonimsky) as “using diatonic scales without triads.” I use the term principally to refer to diatonic, non-triadic sets that are combined in (often freely) chromatic combinations. In the first of the Impromptus, the pandiatonic quality of the row’s constituent sets represents an almost incidental facet of the overall musical argument, which privileges more standard means of post-tonal motivic development. Pandiatonic sets account mostly for the relative consonance of the surface, although they can still be understood abstractly to frame sections in ways almost suggestive of a tonal center. In the final Arioso, however, a single, prolonged set class, intoned melodically, is juxtaposed with and contextualized by a number of different pan-diatonic verticals. The levels of relative dissonance or consonance that result are dependent on scalar proximity or distance (as determined by the cycle of fifths). Furthermore, the unfolding of the piece is determined by the “prolonged” pandiatonic set class’s becoming increasingly “denatured” (i.e., turned into a fully chromatic pitch grouping) in its middle section, before being restored at the beginning of the movement’s final section.
In the opening Allegro of the Sonata, by contrast, a twelve-tone row is arguably supplanted by an initiating eighteen-note gestural shape, which is then transformed serially. Bennett’s new, more extensive row ultimately carries his earlier pan-diatonic arguments one step further, modeling a vectored motion from pan-diatonic overdetermination to pan-diatonic specificity. Even where strict serialism is decentred, in sections of the Allegro and the work’s other movements, this is in aid of creating a richer harmonic argument, juxtaposing pan-diatonic sets with chromatic, octatonic, hexatonic, and whole-tone sets (thus building on the “denaturing” process encountered in the Arioso).