Zachow's prelude to the choral "Herr Jesu Christ, waht Mensch und Gott" is an unpretentious 3 part composition. The choral melody is played in the soprano voice, accompanied by the other two voices in what is essentially an with eight notes filled in harmonization. Only in the first bars Zachow writes a fugato introduction to the first phrase of the chorale melody.
The recording was done with the Hauptwerk software and the sampleset, made by Sonus Paradisi, of the Hinsz organ in the Reformed church in the Midwolda (https://www.sonusparadisi.cz/en/organs/netherlands/midwolda-surround-sample-set.html).
Score available here: http://partitura.org/index.php/friedrich-wilhelm-zachow-herr-jesu-christ-wahr-mensch-und-gott-lv-32