Designed by Paul A. Bigsby, the B-7 Vibrato Tailpiece is designed for use on an arch top electric guitar. The top mount unit allows musicians to bend the pitch of notes or entire chords with their pick hand for various effects.
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.
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 bridge rocks forward causing the strings to loosen, lowering their pitch. 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 requires little force to operate. It is ideally suited to musicians who use slow, subtle, or extended bends.