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The Thayer Axial-Flow Valve is a replacement for the traditional rotary valve found on trombones with F attachments. Invented by Orla Ed Thayer (with assistance from Zig Kanstul) in 1976, it was the biggest advance in the design of the trombone since the rotary valve was added (creating the F attachment) in the mid-19th century. The valve was the subject of a protracted legal battle between Orla Ed Thayer and James Nydigger, an early business partner. A U.S. patent No. 4,469,002 was filed in May 1982 and issued in September 1984, and is now expired. Orla Ed Thayer died on June 3, 2009, at the age of 89. ==The Problem== When engaged, a rotary valve deflects the air flow through the instrument at least four times, and at least twice at rather sharp angles, leading to a stuffy response and audible tone colour changes, compared to the "open" instrument. These drawbacks are especially severe with the trombone, because the instrument's characteristic timbre is a direct result of its construction, which is mostly completely straight: Apart from any possible valve tubing, there are only two bends, and the bore is almost completely cylindrical. In contrast, the softer sound of "horn-like" brass instruments, so readily distinguishable from that of the trombone, is at least partially a result of their more or less ''conical bore'' and their intricate construction with many bows and bends. The change in timbre and response was made even more severe by the ''traditional wrap'' of the valve tubing in narrow curves between bell and gooseneck that was the norm until the 1980s. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Axial flow valve」の詳細全文を読む スポンサード リンク
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