Tremelo arm

A vibrato system on a guitar is a mechanical device used to temporarily change the pitch of the strings.

Guitar makers have developed a variety of vibrato systems since the 1920s. They 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 and temporarily vary the tension, and sometimes length of the strings, 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, many guitarists have used them—from Chet Atkins' subtle bends, to the exaggerated twang effects of Duane Eddy and the buoyant effects of surf music aficionados like The Ventures, The Shadows, and Dick Dale.

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