Bösendorfer (L. Bösendorfer Klavierfabrik GmbH) is an Austrian piano manufacturer and, since 2008, a wholly owned subsidiary of Yamaha Corporation. Bösendorfer is unusual in that it produces 97- and 92-key models in addition to instruments with standard 88-key keyboards. Along with C. Bechstein, Blüthner and Steinway & Sons, Bösendorfer is frequently referred to as one of the "Big Four" piano manufacturers. History Bösendorfer, one of the oldest piano manufacturers, was established in 1828 by Ignaz Bösendorfer. It has a history of producing highly respected instruments. In 1830, it was granted the status of official piano maker to the Emperor of Austria. Ignaz's son Ludwig Bösendorfer (1835–1919) assumed control in 1859, operating from new premises from 1860. Between 1872 and its closure in 1913, the associated Bösendorfer-Saal was one of the premier concert halls of Vienna. In 1909, Carl Hutterstrasser purchased the company and was succeeded by his sons Alexander and Wolfgang in 1931. In 1966, the Jasper Corporation (later renamed Kimball International), parent company of Kimball Pianos, assumed control of Bösendorfer. In 2001 Bösendorfer returned to Austrian hands, when the BAWAG PSK Gruppe purchased it. On 21 December 2007 BAWAG signed an agreement to sell 100% of Bösendorfer to Yamaha Corporation. Bösendorfer continues to make handcrafted pianos in the same Vienna factory. Almost 300 of these premium pianos are made each year. Characteristics Bösendorfer pioneered the extension of the typical 88-key keyboard, creating the Imperial Grand (Model 290), which has 97 keys (eight octaves). Ferruccio Busoni initially ordered this innovation in 1909 as part of a custom piano, as he wanted to transcribe an organ piece that extended to the C below the standard keyboard. This innovation worked so well that this piano was added to regular product offerings and quickly became one of the world's most sought-after concert grands. Because of the 290's success, the extra strings were added to Bösendorfer's other line of instruments such as the 225 model, which has 92 keys. The extra keys, at the bass end of the keyboard, were originally hidden beneath a hinged panel mounted between the piano's conventional low A and the left-hand end-cheek to prevent their being struck accidentally during normal play; more recent models have omitted this device and simply have the upper surface of the extra natural keys finished in matte black instead of white to differentiate them from the standard 88. The Bösendorfer sound is usually described