Organ prelude in F minor

The task

Compose a organ prelude in F minor, 72 BPM adagio, 4/4, about 72 bars and about three minutes, scored for organ in 3 voices. Texture: harmonic motion over a sustained pedal note. Open with 4 bars of organ alone, then layer the other parts in one at a time. The main section runs on a 4-bar diatonic loop of i–iv–V–i,…