The Bigsby was the first successful design of what is now called a whammy bar or tremolo arm, although vibrato is the technically correct term for the musical effect it produces. In standard usage, tremolo is a rapid fluctuation of the volume of a note, while vibrato is a fluctuation in pitch. The origin of this nonstandard usage of the term by electric guitarists is attributed to Leo Fender, who also used the term "vibrato" to refer to what is really a tremolo effect (see vibrato unit).
The Bigsby vibrato unit is installed on the top of the guitar and works in conjunction with a rocker bridge. The arm of the Bigsby is spring loaded and attached to a pivoting metal bar, around which the strings of the guitar are installed. In the neutral or unused position, the pressure of the spring counterbalances the pull of the strings, resulting in constant pitch when the strings are played. When the arm of the Bigsby is pushed down towards the top of the guitar, the strings loosen, the bridge rocks forward, and the pitch of the strings is lowered. When the arm is released, the strings return to normal pitch. The arm may also be lifted slightly to raise the pitch of the strings. The Bigsby is highly controllable within its range of motion and usually requires little force to operate. Lifting the arm too much, however, will result in the spring falling out of the unit making the Bigsby more suitable for downbends, rather than upbends. It is ideally suited to musicians who use slow, subtle, or extended bends. It has limited range compared to tremolo units using longer springs contained internally. Competing units, like the Floyd Rose and the Fender synchronized tremolo (or strat-style) are therefore preferred by some players.
Bigsby vibratos are still factory installed on electric guitars, such as those manufactured by Epiphone, Fender, Gibson, Gretsch, Guild, and Hamer. Many electric guitars can also be retrofitted with a Bigsby (requires no routing of the body), and there are different varieties of the unit designed to fit different styles of guitar, such as a hollow body or solid body guitar. Bigsby units ship with their own rocker bridges, though these are often discarded in favor of more adjustable alternatives such as the Tune-o-matic style bridge or Jazzmaster style bridge. The rocker bridges that come with the Bigsby do not offer individual string intonation adjustment, and have relative string length preset for string sets with a wound G string, rather than for the plain G string preferred by many electric guitarists today.
Notable guitarists recorded using the Bigsby unit include John Lennon, Cliff Gallup, Horton Heat, Les Paul, George Harrison, Keith Richards, Jimmy Page, Greg Sage, Brian Setzer, John Lowery, Andrew Stockdale, Neil Young, John Cipollina, Billy Zoom, Joe Perry, and Bernard Butler. It is a key component to some players' Rockabilly, Surf rock and Country sounds.