As seen in the discussion of the harmonic series, the fundamental pitches of brass instruments depend on the length of their tubing (as opposed to the tubing diameter, known as the bore). Trumpets, trombones, euphoniums, and tubas used in beginning instrumental classes all have tubing lengths that produce a Bb fundamental. Players will produce a sounding Bb when playing the lowest possible sound in the harmonic series when not depressing any valves or moving a slide. In comparison, an F horn player, not surprisingly, will produce a sounding F as the lowest pitch without depressing valves.
Bass clef euphonium, trombone, and tuba read in concert pitch, so their sounding fundamental pitches correspond to the pitches they read. Since fundamental pitches are actually pedal tones on brass instruments, the first overtone (an octave above the fundamental) serves for these examples:
As transposing instruments, the Bb trumpet and F horn work differently with respect to reading. Their fundamental sounds are Bb and F respectively, but each is written as C for that instrument. When a Bb trumpet plays a written C, it sounds like a Bb. When an F horn plays a written C, it sounds like an F.
Because the fundamentals of these instruments are lower than concert C, they sound lower than the written pitch, which means that their notation needs to be written higher for a player to sound the correct pitch. In other words, the notation must bring the pitch of the instrument up to sound the correct concert pitch. The Bb trumpet sounds a whole step lower than C, so notation must be written a whole step higher (Bb to C). Notation for horn must be written a Perfect 5th higher (F to C):
A third case involves the euphonium, which can read treble clef notation as well as bass clef. Euphonium players reading in treble clef play transposed parts in Bb. This stems at least in part from the fact that many euphonium players start on trumpet and then switch to the low brass instrument. By reading transposed treble clef parts, players do not have to learn a new clef and new fingerings at the same time they work through technical development on the instrument. Advanced players must have the ability to read in both bass and treble clefs. The transposition for treble clef euphonium from sounding pitch is the same as the trumpet (up a whole step) except for the addition of an octave displacement:
