Keyboard concertos by Johann Sebastian Bach left Weimar in 1717. Many of Bach's orchestral harpsichord concertos are adapted from a model with one or more violin solo parts. Several of these earlier models are extant. The oldest of these is Vivaldi's concerto for four violins, RV 580, published in 1711, model for Bach's concerto for four harpsichords, BWV 1065. Bach replaced the part of his fourth "Brandenburg Concerto", BWV 1049, composed in 1721 or earlier, by a harpsichord part when he reworked it to the harpsichord concerto BWV 1057. Bach's extant violin concertos BWV 1041–1043, two for a single violin soloist and one for two violin
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