Abstract: In a harp complete with the usual strings, a device by which the tone of some or all of the strings may be provided with three tones, natural, flat, and sharp, the device including a manually manipulated disk having a partial arc-shaped barrel-like cam at its edge, which when rotated to a degree and impinging on a string, applies stress to the spring if desired, to change from one tone to another, and a pin or peg on the disk, parallel to the disk axis but offset, so that upon additional rotary motion, additional stress is imparted to the string, thereby attaining the third tone.