page_title: Effects unit
section_title: Amplifiers
hierarchical_section_title: Effects unit / History / Amplifiers
caption_attribution_description: English: A Fender Vibralux twin, and a Ross 40w, both with 12" loudspeakers.
context_page_description: An effects unit or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source.
  Common effects include distortion/overdrive, often used with electric guitar in electric blues and rock music; dynamic effects such as volume pedals and compressors, which affect loudness; filters such as wah-wah pedals and graphic equalizers, which modify frequency ranges; modulation effects, such as chorus, flangers and phasers; pitch effects such as pitch shifters; and time effects, such as reverb and delay, which create echoing sounds and emulate the sound of different spaces.
  Most modern effects use solid-state electronics or computer chips. Some effects, particularly older ones such as Leslie speakers and spring reverbs, use mechanical components or vacuum tubes. Effects are often used as stompboxes, typically placed on the floor and controlled with footswitches. They are also built into amplifiers, some instruments, tabletop units designed for DJs and record producers, and rackmounts, and are widely used as software plugins in such common formats as VST, AAX, and AU.
context_section_description: Effects built into guitar amplifiers were the first effects that musicians used regularly outside the studio. From the late 1940s onward, the Gibson Guitar Corp. began including vibrato circuits in combo amplifiers. The 1950 Ray Butts EchoSonic amp was the first to feature the spring reverb "echo" sound, which quickly became popular with guitarists such as Chet Atkins, Carl Perkins, Scotty Moore, Luther Perkins, and Roy Orbison. By the 1950s, tremolo, vibrato and reverb were available as built-in effects on many guitar amplifiers. Both Premier and Gibson built tube-powered amps with spring reverb. Fender began manufacturing the tremolo amps Tremolux in 1955 and Vibrolux in 1956.
  Distortion was not an effect originally intended by amplifier manufacturers, but could often easily be achieved by "overdriving" the power supply in early tube amplifiers. In the 1950s, guitarists began deliberately increasing gain beyond its intended levels to achieve "warm" distorted sounds. Among the first musicians to experiment with distortion were Willie Johnson of Howlin' Wolf, Goree Carter, Joe Hill Louis, Ike Turner, Guitar Slim, and Chuck Berry.
  In 1954 Pat Hare produced heavily distorted power chords for several recordings (including James Cotton's Cotton Crop Blues"), creating "a grittier, nastier, more ferocious electric guitar sound," accomplished by turning the volume knob on his amplifier "all the way to the right until the speaker was screaming." Link Wray's 1958 recording "Rumble" inspired young musicians such as Pete Townshend of The Who, Jimmy Page of Led Zeppelin, Jeff Beck, Dave Davies of The Kinks, and Neil Young to explore distortion by various means. In 1966, the British company Marshall Amplification began producing the Marshall 1963, a guitar amplifier capable of producing the distorted "crunch" that rock musicians were starting to seek.
caption: A Fender Vibrolux Reverb amp and a ROSS amp
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