Keyboard concertos by Johann Sebastian Bach soloists, were all adapted into harpsichord concertos by the composer, BWV 1058, 1054 and 1062 respectively. It is often assumed that Bach's extant violin concertos were written in his Köthen period (1717–1723): it can however not be proven from documentary evidence that any of them existed prior to around 1730. In September 1725 Bach performed organ music, accompanied by other instruments, in Dresden. The works he performed there have not been identified. More than a year later he composed several cantatas with an organ obligato part. Several movements of such cantatas were derived from earlier lost concertos, and resurfaced in
Organ concertos, Op. 4 (Handel) however, has favoured the original intimate scoring for chamber organ and small baroque orchestra. In the 1940s the blind organist Helmut Walcha prepared a version for organ and second keyboard giving one possible ornamentation and extemporisitation of the organ part in the slow movements. Modern performing editions of Walsh's 1738 solo keyboard version and the original scoring for organ and orchestra have been prepared by the musicologists William Gudger and Terence Best. Organ concertos, Op. 4 (Handel) The Handel organ concertos Op 4, HWV 289–294, are six organ concertos for chamber organ and orchestra composed by George Frideric Handel in