Abstract: A rotary valve for selectively inserting and removing a slide loop from the sound path of a musical instrument is disclosed. The valve includes a cylindrical rotor housed in a cylindrical casing coupled to the instrument's lead pipe, main bore and slide loop leading and trailing ends. The rotor has two passages extending through it. The first passage is generally "Y" shaped with two leading ends and a trailing end, while the second passage is generally straight having a leading end and a trailing end. In a first valve position, the first leading end and the trailing end of the "Y" shaped rotor passage coaxially align with the instrument's lead pipe and main bore, respectively, providing an air pathway excluding the additional slide loop.