Bach’s Brandenburg Concerto No. 5 in D major (BWV 1050) is special. It is considered as one of his fifteen concerti for harpsichord(s), yet it stands apart as the only one that is not an arrangement he made from an earlier concerto.
Composed in Cöthen in 1719, the Concerto No. 5 is scored for harpsichord, flute, violin, viola, cello and violone. The harpsichord performs dual roles as both a concertino (obbligato) instrument and a ripieno (continuo) instrument. And, to spice things up further, Bach includes a lengthy, virtuosic harpsichord cadenza in the first movement.
It is believed that Bach composed the work to demonstrate the new harpsichord that he had brought back from Berlin for the Cöthen court. A keyboard virtuoso himself, Bach was, most likely, the harpsichord soloist for the premiere.
Listen to a performance from the "Spiegelsaal" Castle in Cöthen by the Freiburger Barockorchester here.