The present invention relates to a machine for changing the key of a stringed musical instrument. The machine includes a mounting base, a structure for securing the mounting base to the stringed musical instrument, a housing body to provide a space to accommodate tuning mechanisms, a plurality of control rod assemblies to selectively adjustment for several tunings, a plurality of tuner switch rod assemblies to provide mechanisms to switch between tunings, a set of tuning mechanisms on each control rod assembly for fine adjustment of tuning while in use, a plurality of bridge rollers to adjust height and intonation of strings, a top plate with a plurality of tuner switch screw slots that provide access to the tuner switch rod assemblies, which provide a choice from different tunings, and a lever body to relieve string tension while changing tunings.