Abstract: There is described a musical instrument such as a piano comprising a plurality of vibratile members such as wires capable of vibration to produce notes of selected frequencies, a hammer mechanism for each said vibratile member for causing vibration thereof, and an actuating mechanism for selectively rotating each hammer from a rest position to strike the vibratile member associated therewith and a return mechanism for rotating the hammer back to its rest position. A hammer rail is provided to support the hammer in a rest position. A control mechanism for the hammer includes a pivotally mounted adaptor having an inertial mass movable in a substantially vertically upwards direction and active upon the hammer when struck thereby to absorb the kinetic energy of the hammer moving towards the hammer rail to thereby exert a decelerative force upon the hammer. The hammer rail has a surface of resiliently deformable material such as felt which the hammer abuts in the rest position thereof.