Brass instrument can be very useful for a 1st or 3rd horn player, who uses the F side less. Another approach was the addition of two sets of slides for different parts of the range. Some euphoniums and tubas were built like this, but today, this approach has become highly exotic for all instruments except horns, where it is the norm, usually in a double, sometimes even triple configuration. Some valved brass instruments provide triggers or throws that manually lengthen (or, less commonly, shorten) the main tuning slide, a valve slide, or the main tubing. These mechanisms alter the pitch of notes
Roman tuba Gaul," The Pennsylvania State University. 2.John Ziolkowski, The Roman Bucina: A Distinct Musical Instrument? Roman tuba The "tuba" of ancient Rome is a military signal trumpet, quite different from the modern tuba. The "tuba" (from Latin "tubus", "tube") was produced around 500 BC. Its shape was straight, in contrast to the military "buccina" or "cornu", which was more like the modern sousaphone in curving around the body. Its origin is thought to be Etruscan, and it is similar to the Greek salpinx. About four feet in length, it was made usually of bronze, and was played with a detachable mouthpiece.