The term "saxophone orchestra" refers to an ensemble of musicians who play various instruments from the saxophone family. It most commonly refers to a group of only four players, a quartet, but can be made up of any number of saxophone players. Different combinations of the various types of saxophones can be used in different saxophone orchestras.
A saxophone orchestra with only four players usually contains a soprano (S) saxophone, an alto (A) saxophone, a tenor (T) saxophone and a baritone (B) saxophone. Alternately, a four-player saxophone orchestra might contain two altos and no soprano, making an AATB arrangement. An SATB arrangement is more common to professional groups because the soprano is somewhat more difficult to keep in tune and therefore isn’t recommended for beginners. This type of arrangement is comparable to the alto-soprano-tenor-baritone arrangement of a vocal choir. An AATB arrangement is fairly common for beginning to advanced students.
Outside of the SATB or AATB arrangements, probably the most common additions to a saxophone orchestra are the sopranino and bass saxophones. The sopranino is pitched in E♭, one octave above the alto saxophone. The bass saxophone is pitched in B♭, a quarter of an octave below the baritone. Even less-common additions include the sopranissimo or soprillo, pitched in B♭, an octave above the soprano; and the contrabass, pitched in E♭, one octave below the baritone. Some saxophones pitched in nonstandard keys also are used sometimes, but only as a novelty.
Larger saxophone orchestras usually keep the standard voicing of a smaller saxophone quartet. These groups often are put together as band showcases. They typically expand regular SATB or AATB arrangements by assigning multiple players per part. Some of these groups might feature a soloist, however. Typically, as in a regular orchestra, the lowest number of musicians is assigned to the bass and soprano for reasons of acoustical balance, with a higher number of musicians handling the alto and tenor parts.
Regardless of how many players a saxophone orchestra has, its sound somewhat resembles that of a reedy pipe organ. The fact that saxophones are made of brass, however, adds a level of brightness to the timbre. Saxophone players also are able to use a variety of mouthpieces and use variances in embouchure to achieve a wider tonal palette for the group.
Small saxophone ensembles primarily play in the classical genre, often using arrangements of works by masters such as Johann Sebastian Bach, Claude Debussy, Wolfgang Amadeus Mozart and Ludwig van Beethoven. They also are commonly used for jazz. Groups routinely debut new compositions by contemporary composers in all genres, however. In large ensembles, music tends to be slightly less virtuosic, taking into account the fact that more musicians must navigate through the difficult passages cleanly. The works tend to be more popular in nature.