Abstract: In the herein illustrated embodiment the harp or tone generator assembly of the piano is supported pivotally at one end so as to pivot in a substantially horizontal plane on its support, and a mechanism manipulated by the player shifts the movable end of the harp thereby to shift the position of the tone generators in the harp relatively to the percussion hammers, so that while the keys of the piano are depressed for playing, the player can selectively change the tone at will; an amplifying circuit compensates for the loss of volume due to the shifting and to the resultant change of the striking line.