Friedrich Christian Samuel Mohrheim (1719 – 1780) was a German musician. He attended the Thomasschule in Leipzig from 1733 to 1736, and, like other J.S. Bach’s pupils, acted as copyist for him during this period. His handwriting is recognizable in copies of for example the Mattheus Passion. In 1764 he became Kapellmeister in the Marienbasilika in Danzig where he remained till his death.
Mohrheim wrote several works for organ, including 7 Trio’s for organ. They appear in manuscript Mus. Ms. 30190, owned by the Staatbibliothek Berlin. Though these seven composition are all called Trio in the manuscript, only the first four are trios in the actual sense: both hands and the feet play each a single independent line. The other three are actualle chorale preludes. In these the accompaniment (one hand, both feet) is already in three parts, the choral mely adds a fourth part to these. So they are actually quatros, though I don't think that is a genuine musicological term.
Of these 7 trios I have recently played the seventh for the Sonic Groove Live contest. And I played it half a year ago for the Secrets of Organ Playing Contest as well. That might give the impression this seventh one is the only one worth playing. And that is of course not true. The sixth one is great as well.
It features the melody of "Wer nur den lieben Gott lässt walten", one of my favorite choral melodies. Mohrheim turns in into a lively composition. The accompaniment in this trio is almost more important than the choral melody it self. With it's short repeated notes, passages work and trills it draws the attention to itself. I registered the choral melody with a trumpet stop, otherwise it might easily be overlooked in all the frivolous joy of the other parts.
The recording was done with the Hauptwerk software and the sampleset, made by Sonus Paradisi, of the Klapmayre organ in the St. Nikolai church in Altenbruch (http://www.sonusparadisi.cz/en/organs/germany/klapmeyer-organ-altenbruch.html
Edition of all 7 of Mohrheim's trios: http://partitura.org/index.php/friedrich-christian-samuel-mohrheim-trios-fur-die-orgel/