Solid body in the context of Instrument amplifier

An electric violin is a violin equipped with an electronic output of its sound. The term most properly refers to an instrument intentionally made to be electrified with built-in pickups, usually with a solid body. It can also refer to a violin fitted with an electric pickup of some type, although "amplified violin" or "electro-acoustic violin" are more accurate then.

Lester William Polsfuss (June 9, 1915 – August 12, 2009), known as Les Paul, was an American jazz, country, and blues guitarist, songwriter, luthier, and inventor. He was one of the pioneers of the solid-body electric guitar, and his prototype, called the Log, served as inspiration for the Gibson Les Paul. Paul taught himself how to play guitar, and while he is mainly known for jazz and popular music, he had an early career in country music. In the 1950s, he and his wife, singer and guitarist Mary Ford, made numerous recordings, selling millions of copies.

Paul is credited with many recording innovations. His early experiments with overdubbing (also known as sound on sound), delay effects such as tape delay, phasing, and multitrack recording were among the first to attract widespread attention. His licks, trills, chording sequences, fretting techniques, and timing set him apart from his contemporaries and inspired many guitarists of the present day.

A sound box or sounding box (sometimes written soundbox) is an open chamber in the body of a musical instrument which modifies the sound of the instrument, and helps transfer that sound to the surrounding air. Objects respond more strongly to vibrations at certain frequencies, known as resonances. The frequency and strength of the resonances of the body of a musical instrument have a significant impact on the tone quality it produces. The air inside the chamber has its own resonances, and these interact with the resonances of the body, altering the resonances of the instrument as a whole. The sound box typically adds resonances at lower frequencies, enhancing the lower-frequency response of the instrument.

The distinctive sound of an instrument with a sound box owes a lot to the alteration made to the tone. A sound box is found in most string instruments. The most notable exceptions are some electrically amplified instruments like the solid body electric guitar or the electric violin, and the piano which uses only a sound board instead. Drumhead lutes such as the banjo or erhu have at least one open end of the sound box covered with animal skin (or a skin-like acrylic material). Open back banjos are normally used for clawhammer and frailing, while those used for bluegrass have the back covered with a resonator.