A tuning apparatus for a musical instrument is provided. The apparatus includes a clamp, a plurality of string-contacting members, and a string-contacting member spacing adjustment mechanism. The clamp removably attaches to a desired longitudinal position on the instrument's neck. Each member is rotatably supported by the clamp and rotates thereon independently of the other members. Each member also adjustably impinges upon and urges a given string or course thereof on the instrument toward a user-selectable one of three different longitudinal positions on the neck's front surface, these positions including a home position, a home−1 position, and a home+1 position. The mechanism allows a user to adjust the location of the members as a group on the clamp so as to substantially center the plane of rotation of each member over a different string or course thereof, and to maintain substantially equal spacing between each different adjacent pair of members.