The adaptations of Mozart and other past composers prove that the fugues are well playable on string instruments. The preludes too are well playable on string instruments, with two exceptions (No.1 in C major and No.21 in B-flat major). This publication is the first complete edition of all string adaptations presented in 6 volumes. For practical reasons, the volumes follow the order of the line-ups, respectively the number of parts, although most paired movements (preludes and fugues with different voice counts) are separated as a consequence, an all too common problem with adaptations of Bach's piano music.
Concerning the keys: In his other works, Bach moves between A-flat major and E major, between B-flat minor and F-sharp minor. The remaining «distant» keys don't appear outside of the two-part Well-Tempered Clavier, and still demonstrate what has become possible in piano composition and modulation, through the «Revolution» of the new tuning. However, these keys have no typical character in Bach's music, unlike with the later Beethoven, Schubert or Chopin. Bach re-wrote an existing C major composition into the C-sharp major prelude and fugue, and an existing D minor fugue into the D-sharp minor fugue. Because the systematic progression through all keys – in semitone steps – seems little pragmatic in its string adaptation, the movements of «distant» keys were transposed by a semitone step to facilitate performances, if possible, back to the respective original key.
J. S. BACH: The Well-Tempered Clavier I in an edition for strings in 6 volumes.
Johann Sebastian Bach