(Fr. registre de luth; Ger. Lautenzug; It. sordino, liuto).
A device found on harpsichords of most periods and schools (though more rarely on Italian instruments) as well as on some pianos, especially square pianos of the 18th and early 19th centuries. It mutes the tone by lightly pressing a piece of buff leather, cloth or felt against the strings near the nut, and has the effect of damping the vibrations, especially the high harmonics, so that the sound takes on a duller, pizzicato quality. In harpsichords, the buff stop usually consists of a sliding batten fitted with a small block of material for each note. Sliding the batten to one side brings the blocks against one register of strings, usually at 8' pitch. In harpsichords by members of the Ruckers family, the buff batten was usually divided into separate treble and bass sections. Occasionally in harpsichords but normally in pianos the buff-stop batten is covered with material along its entire length, so that all the unison strings are damped when the batten is raised or (if placed over the strings) lowered against them. The buff stop should not be confused with the Peau de buffle register, which is a row of jacks equipped with soft leather plectra, nor with a Lute stop, which is a row of jacks plucking close to the nut.
See also Registration, §II.
EDWIN M. RIPIN/JOHN KOSTER