Synchronized tremolo

A variety of mechanical vibrato systems for guitar have been developed since the 1930s. They are used to add vibrato to the sound by changing the tension of the strings, typically at the bridge or tailpiece of an electric guitar using a controlling lever (often referred to as a whammy bar, vibrato arm/bar, or incorrectly as tremolo arm/bar). The lever enables 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 have other bridge and tailpiece systems. The mechanical vibrato systems began as a 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, such as the 1980s-era shred guitar "dive bombing" effect.

Since the regular appearance of mechanical vibrato systems in the 1950s, they have been used by many guitarists, ranging from the gentle inflections of Chet Atkins, the exaggerated twang effects of Duane Eddy and the buoyant effects of surf music aficionados like The Ventures, The Shadows and Dick Dale. In the 1960s and 1970s, vibrato arms were used for more pronounced effects by Jimi Hendrix, Jeff Beck, David Gilmour, Ritchie Blackmore, Jimmy Page, and Frank Zappa. In the 1980s, shred guitar virtuosos such as Eddie Van Halen, Joe Satriani and Steve Vai, and metal guitarists such as Ritchie Blackmore and Kirk Hammett used the "whammy bar" in a range of metal-influenced styles. The pitch-bending effects, whether subtle inflections or exaggerated effects, have become an important part of many styles of electric guitar. Terje Rypdal, David Torn and David Duhig have added to the language and extended techniques of vibrato bar usage.

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