Single action

Single action name given to the square-piano action of Johann Zumpe, in which the jack is fixed to the key and the hammers are hinged to a hammer rail, pointing away from the player. The comb-like damper system was of whalebone. Érard and other makers also used this action, an adaptation of that of Cristofori (89 Harding). Grove's Dictionary of Music and Musicians, 5th edition. London, 1954.