A tremolo arm, tremolo bar, vibrato bar, whammy bar, wobbler, or wang bar is a lever attached to the bridge and/or the tailpiece of an electric guitar or archtop guitar to enable the player to quickly vary the tension and sometimes the length of the strings temporarily, changing the pitch to create a vibrato, portamento or pitch bend effect. Instruments without this device are called hard-tail. The term vibrola is also used by some guitar makers to describe their particular tremolo arm designs.
The tremolo arm began as a mechanical device for more easily producing the vibrato effects that blues and jazz guitarists had long produced on arch top guitars by manipulating the tailpiece with their picking hand. However, it has also made many sounds possible that could not be produced by the old technique.
Since the regular appearance of mechanical tremolo arms in the 1950s, artists such as Stevie Ray Vaughan, Richie Sambora, Jimi Hendrix, Eddie Van Halen, Kevin Shields, Jeff Beck, Lonnie Mack, Ritchie Blackmore, Steve Lukather, Duane Eddy, Dimebag Darrell, David Gilmour, Hank Marvin, Jimmy Page, Herman Li, Randy Rhoads, Joe Satriani, Steve Vai, K.K. Downing, Brian May, Yngwie J. Malmsteen, Tom Morello, and many surf music bands have used the tremolo to great effect, and the effects they created using it have become a recognized part of many styles of electric guitar.
