page_title: Effects unit
section_title: Modulation
hierarchical_section_title: Effects unit / Types / Modulation
caption_attribution_description: Modified Dunlop/MXR M-101 Phase 90.
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: Modulation, in general electronics, means the altering of signal strength. In audio devices, modulation is a control feature that varies the strength of some effect over time to alter tonal properties. Some modulation effects mix ("modulate") an instrument's audio signal with a signal generated by the effect called a carrier wave. Other modulation effects split an instrument's audio signal in two, altering one portion of the signal and mixing it with the unaltered portion.
  Chorus: Chorus pedals mimic the effect choirs and string orchestras produce naturally, by having slight variations in timbre and pitch, by mixing sounds with slight differences in timbre and pitch. A chorus effect splits the instrument-to-amplifier audio signal, and adds a slight delay and frequency variations or vibrato to part of the signal while leaving the rest unaltered. A well-known usage of chorus is the lead guitar in "Come As You Are" by Nirvana.
  Chorus effects: Boss CE-1 Chorus Ensemble, Electro-Harmonix Small Clone, TC Electronic Stereo Chorus.
  Flanger: A flanger creates a "whooshing" "jet plane" or "spaceship" sound, simulating a studio effect that was first produced by recording a track on two synchronized tapes and periodically slowing one tape by pressing the edge of its reel (the "flange"). When the two tapes' audio signals are later mixed, a comb filter effect can be heard. Flanger units add a variably delayed version of the audio signal to the original or signal, creating a comb filter or Doppler effect. Some famous uses of flanger effects include "Walking on the Moon" by The Police, the intro to "Ain't Talkin' 'Bout Love" by Van Halen, and "Barracuda" by Heart.
  Flanger effects: Electro-Harmonix Electric Mistress, MXR Flanger, Boss BF-3 Flanger.
  Phaser: A phaser or "phase shifter" creates a slight rippling effect—amplifying some aspects of the tone while diminishing others—by splitting an audio signal in two and altering the phase of one portion. Three well-known examples of phaser are the two handed tapping part on the Van Halen instrumental "Eruption" and the keyboard parts on Billy Joel's "Just the Way You Are" and Paul Simon's "Slip Slidin' Away".
  Phase shift effects: Uni-Vibe, Electro-Harmonix Small Stone, MXR Phase 90.
  Ring modulator: A ring modulator produces a resonant, metallic sound by mixing an instrument's audio signal with a carrier wave generated by the device's internal oscillator. The original sound wave is suppressed and replaced by a "ring" of inharmonic higher and lower pitches or "sidebands". A notable use of ring modulation is the guitar in the Black Sabbath song "Paranoid".
  Ring modulator effects: Moogerfooger MF-102 Ring Modulator.
  Tremolo: A tremolo effect produces a slight, rapid variation in the volume of a note or chord. The tremolo effect should not be confused with the misleadingly-named tremolo bar, a device on a guitar bridge that creates a vibrato or pitch-bending effect. In transistorized effects, a tremolo is produced by modulating an instrument's audio signal with a sub-audible carrier wave in such a way that generates amplitude variations in the sound wave. Tremolo effects are built-in effects in some vintage guitar amplifiers. The guitar intro in the Rolling Stones' "Gimme Shelter" features a tremolo effect.
  Tremolo effects: Demeter TRM-1 Tremulator, Fender Tremolux.
  Slicer: Combines a modulation sequence with a noise gate or envelope filter to create a percussive and rhythmic effect like a helicopter.
  Vibrato: Vibrato effects produce slight, rapid variations in pitch, mimicking the fractional semitone variations produced naturally by opera singers and violinists when they are prolonging a single note. Vibrato effects often allow the performer to control the rate of the variation as well as the difference in pitch (e.g. "depth"). A vibrato with an extreme "depth" setting (e.g., half a semitone or more) will produce a dramatic, ululating sound. In transistorized effects, vibrato is produced by mixing an instrument's audio signal with a carrier wave in such a way that generates frequency variations i
caption: An MXR-101 Phaser pedal
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