Brass instruments are fundamentally long tubes through which players blow. Like a string on a violin, the length of tubing determines the fundamental pitch of an instrument, which is produced when a player funnels vibrations through a mouthpiece. The addition of a bell to the tubing further modifies the sound. A Bb trumpet, at approximately 148 centimeters (slightly more than 4’ 10” not including valve slides), has a concert Bb as its lowest, or fundamental, pitch. A trombone or euphonium has about twice that length of tubing and sounds an octave lower. The tuba sounds yet another octave below the trombone. The F horn is an interesting case in that its tubing length is closest to a tuba and produces an F as its fundamental, yet its typical playing range lies between a trombone and Bb trumpet.
All brass players essentially lower the fundamental pitch of the instruments by adding lengths of tubing. On a valve instrument, each valve directs air through additional tubes. On a three-valve instrument (the default for this conversation), a player has seven possible valve combinations in addition to using no valves; however, the 1-2 combination usually replaces the use of the third valve by itself (see Better Plumbing section). Trombonists increase tubing length by extended their slides (some trombones have one or more valves as well). They likewise utilize seven basic positions, although the nature of the slide offers an infinite number of variations on those positions. If we assume Bb as the fundamental pitch of an instrument, the typical fingering and slide patterns for those seven pitches would look like this:
The fingering patterns remain the same in relation to this chromatic sequence regardless of the fundamental pitch of an instrument (F horn, C trumpet, etc.). Each position of a trombone slide moves the fundamental instrument pitch down by a half step in relation to the previous position. Likewise, the seven combinations of fingerings offer seven chromatic options.