Improved methods and apparatus of producing vibrato on keyboard percussion/tone bar instruments such as the vibraphone and marimba are provided. Means are disclosed for real time control of the expressive qualities of both the speed and strength of the vibrato of such instruments, while eliminating the need for an electrical motor. According to certain embodiments, methods and apparatus are disclosed to easily produce a change of dynamic level (crescendo and diminuendo) after a single strike of a tone bar or chord.