Among the many many compositions that may or may not have been written by Johann Sebastian Bach, is the little choral partita "Ach, was soll ich Sünder machen". It features a four part setting of the choral, followed by three variations, that have the choral melody in the bass voice,m the tenor voice and the bass voice respectively. The authorship of Bach is dubious. The music might just as well have been written by Johann Heinrich Buttstett, or by Andreas Nicolaus Vetter. Whoever wrote it, it is a charming little partita.
The recording was done with the Sweelinq software and the sampleset of the Müller organ in the Grote Kerk, Leeuwarden (https://sweelinq.com/product/leeuwarden-nl-grote-kerk-muller-organ/).
Score available here: https://partitura.org/index.php/Score available here: https://partitura.org/index.php/
https://youtu.be/qv_035iqFUQ