Sixt[us] (formerly Joseph Sigmund Eugen) Bachmann (1754-1825) was a Benedictine monastery pupil in Oberelchingen from 1766. In the same year, the highly talented twelve-year-old piano and organ player had an organ competition with Wolfgang Amadeus Mozart in the monastery church in Biberbach. Bachmann entered the Marchtal Abbey in 1771. He continued his musical education as an autodidact. In the monastery he worked as a choirmaster, music and theology teacher.
A detailed CV (in German): https://www.oberschwaben-portal.de/files/tl_filesOPO/Autoren/Buechele/opo_KomponistenAusDerRegion_BachmannPSixtus_buechele2015.pdf
Settings: front/rear 50/60, pipe detuning 40.
Registration: plenum on both manuals +/- coupler, with Cromorne in the final section. Middle section with Cromorne + 8 in dialogue with "Voxho" +8+4