Timpani, kettledrums, unlike most other drums, have a definite pitch, tuned nowadays by pedals, but in earlier times by taps that served the same purpose, tightening or slackening the skin to produce higher or lower notes. In the later 18th century pairs of timpani were generally used in conjunction with pairs of trumpets, both instruments being of military origin. Beethoven made novel use of the timpani, as in his Violin Concerto, where they play an important part. Other composers made still greater use of the timpani, most eccentrically Berlioz, who calls for sixteen timpani and ten players in his Grande Messe des morts (Requiem).