A jazz orchestra is typically a large ensemble of musicians that focuses its musical talents on performances and concerts. The most well known jazz orchestras are formal groups made up of professional artists, often anchored in the arts scenes of large cities around the world. Not all orchestras are so formal, however. Groups of students or casual musicians can correctly be called a jazz orchestra if they support sections of jazz instruments and engage in regular performances.
The main difference between a jazz band and a jazz orchestra is size. An orchestra, jazz or otherwise, is defined by the presence of complete instrumental sections. A traditional orchestra contains sections of strings, percussion, brass, and woodwinds. Most of these sections are represented in a jazz orchestra, with heavy emphasis on brass. Trombones, saxophones, and trumpets are all essential. Tubas, bass, and flutes are also common and, depending on the orchestra’s size, a piano and drums may also be present.
Jazz music is typically played on brass. It is characterized by irregular rhythms, often expressing the emotions of the musician through adapted blues melodies. In an orchestra setting, musicians play different jazz numbers en masse. Orchestral jazz pieces are usually written to optimize the sound of multiple instruments at once.
Most orchestras contain at minimum two musicians per instrument, with the exception of drums and piano. A conductor works with the musicians to coordinate their contributions and arranges pieces to create a rich fabric of sound. Many of these pieces are traditional jazz standards, but others are numbers composed specifically for complete jazz orchestra play.
Large orchestras — typically those with 100 or more musicians — are generally called "symphony orchestras." Smaller groups are usually referred to as chamber orchestras. A chamber jazz orchestra is typically made up of 50 or fewer musicians and may include vocalists. These groups can be formally organized in cities just as symphony orchestras are, but they are also common on university campuses and in more informal community settings. Most of the musicians in these kinds of groups participate as a hobby, not as a career.
Music performance is usually the primary task of any jazz orchestra. The jazz style of music originated in the American South, but has since spread in popularity throughout the United States and the world. Most major cities throughout North America, Europe, and Asia have formal symphony jazz orchestras. The groups are usually deeply entrenched in the city’s arts culture and perform concerts on a regular basis.
Symphony jazz orchestras typically make some revenue through ticket sales, though the majority are considered non-profit organizations. In most cases, this is because they are heavily involved in the local arts scene and often donate their resources to the promotion of music appreciation in schools and in the wider community both. Many are also supported by arts-minded benefactors or philanthropists.