Writing a good and attractive bicinium is perhaps one of the most difficult tasks in writing music for the organ. Playing a bicinium is definitely one of the most difficult tasks in playing the organ. Both lines can be heard clearly and the player has to pay close attention to his articulation and phrasing. Johann Bernhard Bach's prelude on the melody of "Helft mir Gottes Güte preisen" is such a difficult to play bicinium. Beautiful to listen to, hard to get right. The manuscript of this pieces leaves the left hand part without notes for two bar's. To get a playable score I had to fill in the missing notes.
The recording was done with the Hauptwerk software and the sample set of the Mascioni organ of the parish church in Azzio, made by Piotr Gabrowsky.
Score available here: http://partitura.org/index.php/johann-bernhard-bach-helft-mir-gottes-gute-preisen