SAB or SAT. Bach composed the six Trio Sonatas for Organ BWV 525 - 530 probably between 1727 and 1730 when he was Cantor at the St. Thomas Church in Leipzig. The trio sonata as a baroque genre usually employs four players: two solo parts (violin, flute or oboe), a bass part (violoncello, violone or bassoon) and the continuo part (organ, harpsichord or lute).