The biggest irony in these arrangements is that the pianist playing the primo part, Bach’s original Sinfonia, does not need to “swing” anything. Sixteenth and eighth notes can remain even and no rhythmic alteration is necessary. Some articulatory chutzpah may be added, as in accenting upbeats (for example, the first G in the treble clef of Sinfonia 1), but overall the same articulation, dynamics, and tempo used in a solo performance of the Sinfonias may be replicated when performing these jazzed-up duet arrangements.
And, since J. S. Bach used a wide range of keyboards when performing (organ, harpsichord, and clavichord, with an astounding variety of instruments within each subclass), different keyboards can be used when performing these duets. Anyone who has visited the historical keyboard collections in Bad Krozingen, Germany or the National Music Museum in Vermillion, South Dakota will begin to appreciate the sonic cornucopia Bach had at his disposal when playing his own keyboard works. It is not hard to imagine that the Affekt of certain pieces may suggest certain keyboards, for example the sadness of the F Minor Sinfonia played on the expressive clavichord. Of course, volume and balance must be considered when picking instruments. If the primo part of Sinfonia 9 is played on a clavichord, the secondo part should probably not be played on a concert grand Steinway.
But many auditory possibilities can be explored. What if the primo player of Sinfonia 15 used a Hammond C3 organ while the secondo player used a Mason & Hamlin baby grand? I was pleased by Brian Koenig’s exploratory MIDI realizations of Jazz Up the Inventions (jazzuptheinventions.com), which set my arrangement of Invention 11 as an electric guitar with a Yamaha electric piano, Invention 12 as a marimba ensemble, and, most daringly, Invention 9 as a goth band (sure to offend many purists!). The point is to be open-minded and exploratory when selecting instruments.
Bach’s own lack of tempo, dynamic, and articulation markings, while liberating, is certainly not a mandate to omit them from interpretive consideration. Following Bach’s practice, I have offered virtually no articulation markings (except for one small suggestion at the end of Sinfonia 2) and no dynamic or tempo suggestions, although pianists must, of course, make these interpretive decisions. Some things should be clear from the notation. For example, regarding touch in bar 1 of the secondo part of Sinfonia 8, the right hand will play the sixteenth-note chords shorter than the eighth-note and quarter-note chords which precede them, and the final thirty-second-note chord, as a startling syncopation, will be accented. The left hand of bars 1–2 of Sinfonia 8 will best imitate a walking bass line by a legato articulato touch.
Finally, pianists should feel free to add or change anything I have written. For instance, the optional introductions and endings can easily be expanded or adorned. Be a co-creator as well as interpreter. As I have said before, make the Urtext your text!