Abstract: A series of adjustable springs, rigidly suspended above the keys of a piano, provides a downward force which reduces the effort needed to depress the keys. Precise adjustment of the series, and its attachment to the piano are facilitated through the use of existing fastener hardware within the conventional piano architecture.

Abstract: A jig is used in an assemblage between key sensors and an acoustic piano, and the jig has a shutter guide assembled with a casing of optical sensor array for aligning slits with target trajectories of shutter plates and pieces of adhesive double coated tape adhered to the shutter plates for aligning the shutter plates with associated white/black keys, wherein the shutter plates are inserted into the slits so that the shutter plates are placed on the target trajectories, and the white/black keys are moved along the target trajectories until they are brought into contact with the pieces of adhesive double coated tape for temporality tacking the shutter plates to the associated white/black keys.