Treble clef in the context of "Cello"

In Western musical notation, the staff (UK also stave; plural: staffs or staves), also occasionally referred to as a pentagram, is a set of five horizontal lines and four spaces that each represent a different musical pitch or in the case of a percussion staff, different percussion instruments. Appropriate music symbols, depending on the intended effect, are placed on the staff according to their corresponding pitch or function. Musical notes are placed by pitch, percussion notes are placed by instrument, and rests and other symbols are placed by convention.

The absolute pitch of each line of a non-percussive staff is indicated by the placement of a clef symbol at the appropriate vertical position on the left-hand side of the staff (possibly modified by conventions for specific instruments). For example, the treble clef, also known as the G clef, is placed on the second line (counting upward), fixing that line as the pitch first G above "middle C".

The euphonium (English: /juˈfoʊniːəm/ yoo-FOH-nee-əm; Italian: eufonio; Spanish: bombardino) is a tenor- and baritone-voiced valved brass instrument pitched in 9-foot (9′) B♭ an octave below the B♭ trumpet or cornet, employed chiefly in brass, military, and concert bands. The euphonium is a member of the large family of valved bugles, along with the tuba and flugelhorn, characterised by a wide conical bore. Most instruments have four valves, usually compensating piston valves, although instruments with four or five rotary valves are common in Eastern and Central Europe.

Euphonium repertoire can be notated in concert pitch in the bass clef, or in the treble clef as a transposing instrument in B♭. In British brass bands, it is typically treated as a treble-clef instrument, while in American band music, parts may be written in either treble clef or bass clef, or both. A musician who plays the euphonium is known as a euphoniumist, a euphonist, or simply a euphonium player.

The bass oboe or baritone oboe is a double reed instrument in the woodwind family. It is essentially twice the size of a regular (soprano) oboe so it sounds an octave lower; it has a deep, full tone somewhat akin to that of its higher-pitched cousin, the English horn. The bass oboe is notated in the treble clef, sounding one octave lower than written. Its lowest sounding note is B₂ (in scientific pitch notation), one octave and a semitone below middle C, although an extension with an additional key may be inserted between the lower joint and bell of the instrument in order to produce a low B♭₂. The instrument's bocal or crook first curves away from and then toward the player (unlike the bocal/crook of the English horn and oboe d'amore), looking rather like a flattened metal question mark; another crook design resembles the shape of a bass clarinet neckpiece. The bass oboe uses its own double reed, similar to but larger than that of the English horn.