The Well-Tuned Piano is an improvised work for solo piano by La Monte Young, begun in 1964 and developed over decades of performances. Young retunes an Imperial Bösendorfer, a concert grand with extra bass keys, to a just-intonation system of his own built on simple whole-number ratios, with a reference pitch on E-flat; he kept the exact tuning secret until 1993. In this tuning, dense sustained clusters produce shimmering tones that seem to hover above the keys actually struck.
The piece had its world premiere in Rome in 1974. Its best-known document is the performance given in New York on 25 October 1981, timed from 6:17:50 to 11:18:59 in the evening and released by Gramavision in 1987 on five compact discs, with calligraphy by Marian Zazeela on the discs. Critics at the time ranked it among the major recordings of American piano music, and Young’s student Michael Harrison learned to tune and prepare the instrument with him.