Six-valve Trombone

Depressing valves on a brass instrument adds additional lengths of tubing to that instrument.  The exact length of each valve loop is precisely calculated to proportionately elongate the overall length of tubing.  However, this system creates intonation problems when players simultaneously depress more than one valve at a time.  In an effort to deal with this problem, Sax submitted a patent in 1852 for an instrument in which seven independent tubes (each with its own bell) were joined to the mouthpiece.  The seven-bell instrument was heavy and cumbersome to play.  Consequently, Sax designed and patented (1859) a single-belled instrument with six independent, ascending valves.  In this example--a valve trombone--the longest tubing is engaged when no valve is depressed.  Each separate valve activates a shorter length of tubing and raises the pitch by a semitone.