Speed reducing instrument tuner and assemblies thereof

A machine head assembly, comprising:

• a plurality of machine head reducers, each machine head reducer comprising:
• a housing comprising a central axis and a surface comprising a plurality of undulations (n1) that are substantially parallel and equidistant to the central axis;
• a first driven member comprising a central axis that is substantially concentric with the central axis of the housing, the first driven member comprising a second axis that is substantially parallel and eccentric to the central axis of the housing;
• a second driven member comprising a central axis that is substantially concentric with the second axis of the first driven member and comprising:
• a first surface comprising a plurality of undulations (n4) that are substantially parallel and equidistant to the second driven member central axis and being in mesh contact with the undulations (n1) of the housing surface;
• a second surface comprising a plurality of undulations (n2) that are substantially parallel and equidistant to the second driven member central axis;
• and
• a third driven member comprising a central axis being substantially concentric with the housing central axis and comprising a surface comprising a plurality of undulations (n3) where the undulations of the surface of the third driven member are substantially parallel and equidistant to the central axis of the third driven member and are in mesh contact with the second surface undulations of the second driven member (n2).