(Ger. Verschiebung).
A name often used for the left or ‘soft’ pedal on the piano, or, in piano music, a direction to play with this pedal depressed. In a modern grand piano this pedal shifts the action sideways so that the hammers strike only two of the three strings provided for each note in the treble and only one of the two strings provided for each note in the bass, while continuing to strike the single strings of the extreme bass. In pianos of the 18th and early 19th centuries, the una corda pedal caused the action to be shifted so far that the hammers struck only one string throughout the entire range of the instrument, giving the pianist a choice between ‘tre corde’ (when the pedal was not depressed), ‘due corde’ (partly depressed) and ‘una corda’ (depressed completely). In some instruments a stop could be set to limit the shifting of the action to the ‘due corde’ position, but several composers, most notably Beethoven, wrote explicitly for both ‘due corde’ and ‘una corda’.
The effect produced by depressing the una corda pedal on a grand piano is not merely one of reduced volume, but also of a change in timbre, so that the sound is not only softer but less brilliant than that from all three strings. (On an upright piano the corresponding pedal merely moves the hammers closer to the strings, so as to shorten their stroke, and the resulting reduction in volume is not accompanied by any change in timbre.)
The una corda is found on two of the three surviving Cristofori pianos (1722, 1726), but is incompatible with the design of the first (1720). It has been a feature of most grand pianos since the latter part of the 18th century, becoming standard on English instruments rather earlier than on German or Austrian ones.
D. Rowland: A History of Pianoforte Pedalling (Cambridge, 1993)
S. Pollens: The Early Pianoforte (Cambridge, 1995)
EDWIN M. RIPIN/DAVID ROWLAND