Hindemith wrote seven string quartets and two string trios, among other chamber works. He also performs frequently with trios and quartets and larger orchestral units. A cappella styles range from gospel music to contemporary to barbershop quartets and choruses. His output is dominated by his cycles of symphonies and string quartets, each totaling 15. The alto saxophone is found in the standard instrumentation of concert bands and saxophone quartets. Schubert wrote his earliest string quartets for this ensemble. Three of the six quartets have fugues as finales. It is a standard instrument in concert bands and saxophone quartets. At least two professional bass-clarinet quartets exist. It later became popular with college glee clubs and barbershop quartets. Schoenberg went so far as to orchestrate one of Brahms's piano quartets. They form the last complete set of string quartets that Haydn composed. This is particularly common for barbershop quartets and Gospel quartets. Brahms was slow in writing his first two string quartets. To this period also belong his first two Piano Quartets (Op.