The so-called "standard complement" of double winds and brass in the orchestra from the first half of the 19th century is generally attributed to the forces called for by Beethoven. The exceptions to this are his Symphony No. 4, Violin Concerto, and Piano Concerto No. 4, which each specify a single flute. The composer's instrumentation almost always included paired flutes, oboes, clarinets, bassoons, horns and trumpets. Beethoven carefully calculated the expansion of this particular timbral "palette" in Symphonies 3, 5, 6, and 9 for an innovative effect.
The third horn in the "Eroica" Symphony arrives to provide not only some harmonic flexibility, but also the effect of "choral" brass in the Trio. Piccolo, contrabassoon, and trombones add to the triumphal finale of his Symphony No. 5. A piccolo and a pair of trombones help deliver storm and sunshine in the Sixth. The Ninth asks for a second pair of horns, for reasons similar to the "Eroica" (four horns has since become standard); Beethoven's use of piccolo, contrabassoon, trombones, and untuned percussion—plus chorus and vocal soloists—in his finale, are his earliest suggestion that the timbral boundaries of symphony might be expanded for good. For several decades after his death, symphonic instrumentation was faithful to Beethoven's well-established model, with few exceptions.
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