The positioning of instruments in a symphonic orchestra is vital to a piece of music's success. If similar instruments are placed in multiple areas and not grouped together, the sound can become jumbled and incoherent to the listener. Likewise, if quiet instruments are placed near loud ones, their sound can be lost. Not every arrangement is alike (some orchestras have fewer instruments, for example), but organization and synchronicity is always a requirement.
Stringed instruments, such as violins, cellos, basses, and violas, are positioned in the front of the orchestra, nearest to the conductor. If the orchestra contains a harp, it is often positioned in the back of this section. The first violins, which are primarily concerned with the melody, are always placed to the left of the orchestra conductor (from his perspective). The violinist closest to the conductor is the concertmaster, who aids in tuning the other violins and manages the communication between conductor and orchestra.
Often directly behind the string section are the woodwind instruments. These instruments include flutes, piccolos, clarinets and oboes. In a typical orchestra setup, which is arranged in a semicircle, woodwinds are often placed right in the center. As solo instruments, they are often higher-pitched than other types of instruments. Therefore, placing them in the center aids in sound balance and reduces the risk of drowning out the other instruments.
Brass instruments, such as horns, trumpets, and tubas, are typically placed near the back of the orchestra. This is mainly due to their high volume, particularly when grouped together. One brass instrument, the saxophone, is only sometimes used in symphony orchestras. When it is, it is often placed closest to the woodwind instruments, due to its parts usually doubling up with the woodwinds and requiring the proper sound balance.
Percussive instruments, such as the drum, triangle, and timpani, provide the rhythm, tempo, and beat of a piece. Drums are usually placed in the very back of a symphonic orchestra, so their booming sound does not interfere with the other instruments. Higher-pitched percussion, such as the xylophone, will often be placed at the front, close to the woodwind section, while the timpani often complements the bass notes of the brass section, and will be placed nearby.