Sigiswald Kuijken: Mozart conceived the 3 piano-concerti KV 414, 413 and 415 in 1782, one year after he had settled in Vienna as a more or less free-lance musician. From onset, his idea was to get these works (KV 414, 413 and 415) published; he obviously expected a positive response from the public, not only on the financial level but also as a composer and piano virtuoso. In order to enhance the attraction for his publication, he decided to write these concertos in such a way that they could be performed not only with full orchestra (i.e. strings and winds), but also with a reduced accompaniment of only string quartet. Clearly, Mozart did not consider this strategic starting point as an artistic limitation, but rather as a challenge: in fact, already the score without the wind parts should leave nothing to be desired. This resulted in a very careful and beautiful string writing, matching the solo part in the most effective and intimate way. The wind parts were then conceived to accentuate and “colour” certain passages in the accompaniment with even more depth.
Although Mozart in his announcements and the print of these concerti always mentions the “normal” composition of the string quartet (2 violins, viola and violoncello), I took the liberty to replace the violoncello by a double bass in our performances and our recording of these concertos. My reason was purely musical. Looking and listening to these works, we find a clear difference concerning their string-bass writing compared with Mozart’s own quartets for violin, viola, violoncello and piano, or also his trios for violin, violoncello and piano. In these piano concertos the string bass is only playing the essential bass-line of the whole texture, thus very often doubling in simplified way the soloist’s left hand. Therefore, in fact this so called “violoncello” part shows exactly what the usual “basso” parts show in orchestral works or generally in the more conventional divertimento-style: offering and strengthening the (highly necessary) fundamental bass on which the whole of the construction is resting. So replacing the violoncello by a double bass in this reduced version of these concertos seems to me an obvious choice.