View source for Effects unit

{{Short description|Electronic device that alters audio}}
{{Use dmy dates|date=October 2019}}
{{Confused|Software effect processor}}

[[File:Pedalboard (995939579)-2.jpg|thumb|upright=1.10|300px|A [[guitar pedalboard]] allows a performer to create a ready-to-use chain of multiple pedals to achieve certain types of sounds. [[Signal chain]] order: [[Electronic tuner|tuner]], [[Dynamic range compression|compressor]], [[pitch shift|octave generator]], [[wah-wah pedal]], [[distortion (music)|overdrive]], [[distortion (music)|distortion]], [[fuzzbox|fuzz]], [[equalization (audio)|EQ]] and [[tremolo]].]]

An '''effects unit''', '''effects processor''', or '''effects pedal''' is an electronic device that alters the sound of a [[musical instrument]] or other audio source through [[audio signal processing]].

Common effects include [[distortion (music)|distortion/overdrive]], often used with electric guitar in [[electric blues]] and [[rock music]]; [[dynamics (music)|dynamic]] effects such as [[volume pedal]]s and [[Dynamic range compression|compressors]], which affect [[loudness]]; [[linear filter|filter]]s such as [[wah-wah pedal]]s and [[graphic equalizer]]s, which modify frequency ranges; [[modulation]] effects, such as [[Chorus (audio effect)|chorus]], [[flanger]]s and [[phaser (effect)|phasers]]; [[Pitch (music)|pitch]] effects such as [[pitch shifter (audio processor)|pitch shifters]]; and time effects, such as [[Reverb effect|reverb]] and [[Delay (audio effect)|delay]], which create echoing sounds and emulate the sound of different spaces.<ref name="art">{{cite web|url=http://www.museumofmakingmusic.org/stompbox-effects|title=The Art of the Stompbox|year=2010|publisher=The Museum of Making|access-date=13 September 2010}}</ref><ref name="guitfx">{{cite web|url=http://tripatlas.com/Guitar_effects#Samples|title=Guitar effects|publisher=Trip Atlas|access-date=18 September 2010|archive-url=https://web.archive.org/web/20081208132342/http://tripatlas.com/Guitar_effects#Samples|archive-date=8 December 2008|url-status=dead}}</ref>

Most modern effects use [[solid-state electronics]] or [[digital signal processor]]s. Some effects, particularly older ones such as [[Leslie speaker]]s and [[spring reverb]]s, use mechanical components or [[vacuum tube]]s. Effects are often used as [[#Stompboxes|stompboxes]], typically placed on the floor and controlled with footswitches. They may also be built into [[guitar amplifier]]s, instruments (such as the [[Hammond B-3]] organ), [[#Multi-effects and tabletop units|tabletop units]] designed for DJs and record producers, and [[#Rackmounts|rackmounts]], and are widely used as [[audio plug-in]]s in such common formats as [[Virtual Studio Technology|VST]], [[AAX (Avid Audio eXtension)|AAX]], and [[Audio Units|AU]].

Musicians, [[audio engineer]]s and record producers use effects units during live performances or in the studio, typically with electric guitar, bass guitar, [[electronic keyboard]] or [[electric piano]]. While effects are most frequently used with [[Electronic musical instrument|electric or electronic instruments]], they can be used with any audio source, such as [[Acoustic music|acoustic]] instruments, drums, and vocals.<ref>{{Cite book|last1=Horne|first1=Greg|title=Complete Acoustic Guitar Method: Mastering Acoustic Guitar c|url=https://books.google.com/books?id=cHALQ_CO5P0C|year=2000|publisher=Alfred Music|page=92|isbn=9781457415043}}</ref><ref>{{Cite book|last1=Yakabuski|first1=Jim|title=Professional Sound Reinforcement Techniques: Tips and Tricks of a Concert Sound Engineer|url=https://books.google.com/books?id=QwcLdjCCXHkC|year=2001|publisher=Hal Leonard|page=139|isbn=9781931140065}}</ref>

==Terminology==
[[File:Matt's Pedals.jpg|thumb|right|300px|Various type of guitar and bass effect pedals]]
An effects unit is also called an ''effect box'', ''effects device'', ''effects processor'' or simply an ''effect''. The abbreviation ''F/X'' or ''FX'' is sometimes used. A pedal-style unit may be called a ''stomp box'', ''stompbox'', ''effects pedal'' or ''pedal''. Unprocessed audio coming into an effects unit is referred to as ''dry'', while the processed audio output is referred to as ''wet''.<ref>Hodgson, Jay (2010). ''Understanding Records'', p.95. {{ISBN|978-1-4411-5607-5}}.</ref>

A musician bringing many pedals to a live show or recording session often mounts the pedals on a [[guitar pedalboard]], to reduce set-up and tear-down time and, for pedalboards with lids, protect the pedals during transportation. When a musician has multiple effects in a [[rack mount]]ed [[road case]], this case may be called an ''effects rack'' or ''rig''. When rackmounted effects are mounted in a roadcase, this also speeds up a musician's set-up and tear-down time, because all of the effects can be connected together inside the rack case.

==Form factors==
Effects units are available in a variety of [[form factors]]. Stompboxes are used in both live performance and studio recording. Rackmount devices saw a heavy usage during the later 20th century, due to their superior processing power and desirable tones as compared to pedal-style units. However, by the 21st century, with the advent of digital plugins and more powerful stompboxes for live usage, the use of rack-mounted effect units has declined.<ref name="books.google.com">Clement, V (2007). [https://books.google.com/books?id=FHOskiubkx0C ''How to Succeed As a Female Guitarist''], Alfred Music. p.&nbsp;30–31.</ref>{{failed verification|reason=source doesn't give any history|date=December 2021}} An effects unit can consist of [[Analogue electronics|analog]] or [[digital electronics]] or a combination of the two. During a live performance, the effect is plugged into the electrical ''signal'' path of the instrument. In the studio, an instrument or another sound source — possibly an [[aux-send|auxiliary output]] of a [[Mixing console|mixer]] or a [[Digital audio workstation|DAW]] — is patched into the effect.<ref>{{Cite book|last1=Gibson|first1=Bill|title=The Ultimate Live Sound Operator's Handbook|url=https://books.google.com/books?id=r86J_aNNReEC|year=2007|publisher=Hal Leonard|page=366|isbn=9781423419716}}</ref><ref>{{Cite book|last1=McCormick|first1=Tim|last2=Rumsey|first2=Francis|title=Sound and Recording|url=https://books.google.com/books?id=8JH6Z5c6-OUC&q=%22auxiliary+output%22+recording+effects|year=2009|publisher=Focal Press|page=131|isbn=9780240521633}}</ref> Whatever the form factor, effects units are part of a studio or musician's [[outboard gear]].<ref>Editors, Guitar Player Magazine (2001). [{{AllMusic|class=artist|id=p5474|pure_url=yes}} ''How to Play Guitar: The Basics & Beyond'']. Hal Leonard. p. 82.</ref>

=== Stompboxes ===
[[File:Ts9-stompbox-2-2.jpg|thumb|left|upright=0.50|[[Ibanez Tube Screamer]] TS9 overdrive pedal]]

Stompboxes are small plastic or metal chassis that usually lie on the floor or in a pedalboard to be operated by the user's feet.  Pedals are often rectangle-shaped, but there are a range of other shapes (e.g., the circular [[Fuzz Face]]). Typical simple stompboxes have a single footswitch, one to three [[potentiometers]] for controlling the effect, and a single [[LED]] that indicates if the effect is on. A typical distortion or overdrive pedal's three potentiometers, for example, control the level or intensity of the distortion effect, the tone of the effected signal and the output level of the effected signal. Depending on the type of pedal, the potentiometers may control different parameters of the effect. For a [[chorus effect]], for example, the knobs may control the depth and speed of the effect. Complex stompboxes may have multiple footswitches, many knobs, additional switches or buttons that are operated with the fingers, and an alphanumeric [[LED]] display that indicates the status of the effect with short acronyms (e.g., DIST for "distortion").<ref name="books.google.com"/><ref>Mangum, Eric; Stubbs, Dean (2000). [https://books.google.com/books?id=pp6xpWAgjFcC ''Dod Presents 100 Superstar Guitar Sounds on a Stompbox Budget'']. Hal Leonard. p. 8.</ref>

[[File:Anders pearson's pedalboard (2010-03-20 11.07.50).jpg|thumb|300px|An example of an ''effects chain''. <div style="line-height:110%;">{{smaller|From the input [''right''] to the output [''left'']: }}{{unordered list|''Tuner'' {{smaller|[''upper right''] (tc electronic Polytune)}} ⇒ |''Wah pedal'' {{smaller|[''lower right''] (Morley Bad Horsie Wah)}} ⇒ |''Overdrives/distortion'' {{smaller|[''lower row''] (Rocktron Short Timer Delay → Danelectro CTO-1 Transparent Overdrive → Boss HM-2 → Boss MT-2)}} ⇒ |''Modulations/delay'' {{smaller|[''upper row''] (Digitech Hyper Phase → Danelectro CV-1 Vibe → Danelectro CT Tremolo → Digitech Hyper Delay)}}}}</div>]]

An '''{{vanchor|effects chain}}''' is formed by connecting two or more stompboxes forming a [[signal chain]]. Effect chains are typically created between the guitar and the amp or between the [[preamplifier]] and the power amp. When a pedal is off or inactive, the electric [[audio signal]] coming into the pedal diverts onto a ''bypass'', an unaltered ''dry'' signal that continues on to other effects down the chain. In this way, a musician can combine effects within a chain in a variety of ways without having to reconnect boxes during a performance.<ref>
{{cite web
 | last= Egnater
 | first= Bruce
 | author-link= Bruce Egnater
 | title= Bruce Egnater on Effects Loops
 | publisher= guitarplayer.com
 | date= 16 December 2009
 | url= https://www.guitarplayer.com/miscellaneous/bruce-egnater-on-effects-loops 
 | archive-url= https://web.archive.org/web/20181130155133/https://www.guitarplayer.com/miscellaneous/bruce-egnater-on-effects-loops
 | archive-date= 30 November 2018
 }}
</ref>
A ''controller'' or ''effects management system'' lets the musician create multiple effect chains, so they can select one or several chains by tapping a single switch. The switches are usually organized in a row or a simple grid.<ref>
{{cite book
 | last= Kahn
 | first= Scott
 | title= Modern Guitar Rig: The Tone Fanatic's Guide to Integrating Amps and Effects
 | publisher= Hal Leonard Corporation
 | series= MusicPro Guides
 | year= 2011
 | location= Milwaukee
 | page= 146
 | url= https://books.google.com/books?id=hjHKTIhVWosC
 | isbn= 978-1-4234-9944-2
}}
</ref>

It is common to put [[#Dynamics|compression]], [[wah-wah (music)|wah]] and [[Distortion (music)|overdrive]] pedals at the start of the chain; modulation ([[chorus pedal|chorus]], [[flanger]], [[Phaser (effect)|phase shifter]]) in the middle; and time-based units ([[delay (audio effect)|delay]]/echo, [[Reverb effect|reverb]] at the end.<ref>{{cite web
 | last= Ross
 | first= Michael 
 | author-link= 
 | title= Pedal Order by the Numbers – Plus, the Pros on Pedal Order 
 | publisher= guitarplayer.com
 | date= 28 August 2020 |url=https://www.guitarplayer.com/gear/pedal-order-by-the-numbers-plus-the-pros-on-pedal-order}}</ref> When using many effects, unwanted noise and hum can be introduced into the sound. Some performers use a [[#Dynamics|noise gate pedal]] at the end of a chain to reduce unwanted noise and hum introduced by overdrive units or vintage gear.<ref>{{Cite book|last=Rogers|first=Jerry|title=Your Band's First Gig: Getting The Sound Right|date=25 May 2010|publisher=Jerry Rogers |isbn=9781445766249|url=https://books.google.com/books?id=tSXSg-_o_OcC|access-date=10 September 2010}}</ref>

===Rackmounts===
[[File:FOH Racks-2.jpg|thumb|left|Rackmounted effects in [[road case]]s. These road cases have the front protective panels removed so the units can be operated. The protective panels are put back on and latched shut to protect the effects during transportation.]]
[[File:Eventide H3000 SE Ultra-Harmonizer (left view).jpg|thumb|right|The [[Eventide, Inc|Eventide]] HE3000 Ultra-Harmonizer pictured here displays the entire name of an effect or setting, which helps users to find their preferred settings and effects.]]
Rackmount effects units are typically built in a thin metal chassis with ''rack ears'' designed to be screw-mounted into the rack rails of a [[19-inch rack]] that is standard to the [[music technology (electronic and digital)|music technology]] industry. Rackmount effects have a standardized 19-inch width, and height of 1 or more [[Rack unit|rack unit(s)]]. Devices that are less than 19 inches wide can sometimes be made rackmount-compatible via special rackmount adapters.<ref>{{Cite book|last=Ashton|first=Adrian|title=The Bass Handbook|publisher=Hal Leonard|year=2006|page=92
|isbn=9780879308728|url=https://books.google.com/books?id=I97xJYZC2lIC&pg=PA92}}</ref>

A rackmount effects unit may contain [[electronic circuit]]ry identical to a stompbox's, although its circuits are typically more complex. Unlike stompboxes, rackmounts usually have several different types of effects.<ref>{{Cite book|last=Ashton|first=Adrian|title=The Bass Handbook|publisher=Hal Leonard|year=2006|pages=91–92|isbn=9780879308728|url=https://books.google.com/books?id=I97xJYZC2lIC&pg=PA92}}</ref> Rackmount effects units are controlled by knobs, switches or buttons on their front panel, and often remote-controllable by a [[MIDI]] digital control interface or pedal-style ''foot controller''.<ref>{{Cite book|last=Levitin|first=Dan|title=From Demo Tape to Record Deal: Handy Guide|publisher=Alfred Music|year=1992|page=26|url=https://books.google.com/books?id=IxeGcwKrJUUC&pg=PA26|isbn=0-88284-494-6}}</ref>

Rackmount effects units are most commonly used in recording studios and [[front of house]] [[live sound mixing]] situations. Musicians may use them in place of stompboxes, as use of a rack can offer space for conveniently mounting additional rackmount equipment or accessories. Rackmounted effects units are typically mounted in a rack, which may be housed within a road case, a durable case with removable access panels that protect the equipment within during transportation. Because of this, rackmount effect units are not always designed with durable protective features such as corner protectors which are used on stompboxes and amps that are designed to be transported as standalone units.

===Multi-effects and tabletop units===
[[File:Boss ME-5 Guitar Multiple Effects.jpg|thumb|left|[[Boss Corporation|Boss]] ME-5 multi-effects from 1988 included several pedal effects in one unit, with the ability to write and recall presets.]]
A multi-effects (MFX) device is a single electronics effects pedal or rackmount device that contains many different electronic effects. multi-effects devices allow users to ''preset'' combinations of different effects, allowing musicians quick on-stage access to different effects combinations.<ref>Hunter, Dave (2004). [https://books.google.com/books?id=7DjYrk7Vap4C ''Guitar Effects Pedals: The Practical Handbook'']. Hal Leonard. p. 125.</ref> Multi-effects units typically have a range of distortion, chorus, flanger, phaser, delay, looper and reverb effects. Pedal-style multi-effects range from fairly inexpensive stompboxes that contain two pedals and a few knobs to control the effects to large, expensive floor units with many pedals and knobs. Rack-mounted multi-effects units may be mounted in the same rack as preamplifiers and power amplifiers.

A tabletop unit is a type of multi-effects device that sits on a desk and is controlled manually. One such example is the [[Pod (amp modeler)|Pod]] guitar amplifier modeler. Digital effects designed for DJs are often sold in tabletop models, so that the units can be placed alongside a [[DJ mixer]], turntables and [[scratching]] gear.<ref>Bartlett, Bruce; Bartlett, Jenny (2008). [https://books.google.com/books?id=E0uy8adetQoC ''Practical Recording Techniques: The Step-by-step Approach to Professional Audio Recording'']. Focal Press. p. 226.</ref>

===Built-in units===
[[File:1968 Fender Bandmaster front.jpg|thumb|left|200px|A 1968 [[Fender Bandmaster]] amplifier. Note the four inputs, two for regular sound and two which are run through the onboard [[tremolo]] effect unit.]]
Effects are often incorporated into [[instrument amplifier]]s and even some types of instruments. Electric [[guitar amplifier]]s often have built-in reverb, chorus and [[distortion]], while acoustic guitar and [[keyboard amplifier]]s tend to only have built-in reverb. Some acoustic instrument amplifiers have reverb, chorus, compression and equalization (bass and treble) effects. Vintage guitar amps typically have [[tremolo]] and [[vibrato]] effects, and sometimes reverb. The Fender Bandmaster Reverb amp, for example, had built-in reverb and vibrato. Built-in effects may offer the user less control than standalone pedals or rackmounted units. For example, on some lower- to mid-priced [[bass amplifier]]s, the only control on the [[dynamic range compression|audio compression]] effect is a button or switch to turn it on or off, or a single knob. In contrast, a pedal or rackmounted unit would typically provide ratio, threshold and attack controls or other options to allow the user additional control over the compression.

Some guitar amplifiers have built-in multi-effects units or digital [[amplifier modeling]] effects. Bass amplifiers are less likely to have built-in effects, although some may have a [[Dynamic range compression|compressor]]/[[limiter]] or [[fuzz bass]] effect.<ref>Eiche. Jon; Fliegler, Ritchie (1993) [https://books.google.com/books?id=NgG8bmBayLwC ''Amps!: The Other Half of Rock 'n' Roll''], Hal Leonard. p. 25, 40, 52, 74.</ref>{{Better source needed|reason=some of what's discussed in this paragraph was not available or common in 1993 when this ref was published|date=August 2022}}

Instruments with built-in effects include [[Hammond organ]]s, [[electronic organ]]s, [[electronic piano]]s and [[digital synthesizer]]s.<ref>{{Citation|last=Reid|first=Gordon|date=January 2004|title=Synthesizing Hammond Organ Effects: Part1|periodical=Sound on Sound|url=http://www.soundonsound.com/sos/jan04/articles/synthsecrets.htm|access-date=12 September 2010}}</ref> Built-in effects for keyboards typically include reverb, chorus and, for Hammond organ, vibrato. Many [[clonewheel organ]]s include an overdrive effect. Occasionally, acoustic-electric and electric guitars will have built-in effects, such as a preamp or equalizer.<ref>{{Citation|last=Pinksterboer|first=Hugo|title=Tipbook: Acoustic Guitar|url=https://books.google.com/books?id=xIT_PpFqz_4C|year=2001|publisher=Hal Leonard|page=51|isbn=9789076192376}}</ref><ref>{{Citation|last=Brewster|first=David M.|title=Introduction to Guitar Tone and Effects: A Manual for Getting the Sounds from Electric Guitars, Amplifiers, Effects Pedals and Processors|publisher=Hal Leonard|url=https://books.google.com/books?id=q99-bY3cL8YC|year=2003|page=7|isbn=9780634060465}}</ref>

==History==
===Studio effects and early stand-alone units===
The earliest sound effects were strictly used in studio productions. Microphones placed in [[echo chamber]]s with specially designed acoustic properties simulated the sound of live performances in different environments. In the mid to late 1940s, [[audio engineer|recording engineers]] and experimental musicians such as [[Les Paul]] began manipulating [[Reel-to-reel audio tape recording|reel-to-reel recording tape]] to create echo effects and unusual, futuristic sounds.<ref>{{cite web|last=Tianen|first=Dave|url=https://www.pbs.org/wnet/americanmasters/les-paul-chasing-sound/100/|date=13 August 2009|title=The Wizard Of Waukesha|website=[[PBS]] |access-date=13 September 2010}}</ref><ref>{{Cite book|last=Roads|first=Curtis|title=The Computer Music Tutorial|url=https://books.google.com/books?id=nZ-TetwzVcIC|year=1996|publisher=MIT Press|pages=437, 476|isbn=9780262680820}}</ref> In 1941, [[DeArmond]] released the Model 601 Tremolo Control,<ref>Presto Music Times, August 1941</ref> the first commercially available stand-alone effects unit. This device produced a tremolo by passing an instrument's electrical signal through a water-based electrolytic fluid.<ref>{{cite web|last=Chester|first=Paul|url=http://www.paulvernonchester.com/VintagePickups.htm|archive-url=https://web.archive.org/web/20111009131601/http://www.paulvernonchester.com/VintagePickups.htm|url-status=dead|archive-date=9 October 2011|title=Acoustic Guitar – Early Pickups|access-date=3 January 2011}}</ref><!--This source gives 1948 as the release date for Trem-Trol, the successor to the Model 601 and identifies it as "the first ''widely available'' external effects unit."--> Most stand-alone effects of the 1950s and early 1960s such as the Gibson GA-VI vibrato unit and the Fender reverb box, were expensive and impractical, requiring bulky [[transformer]]s and high [[voltage]]s. The original stand-alone units were not especially in-demand as many effects came built into amplifiers. The first popular stand-alone was the 1958 [[Watkins Copicat]], a relatively portable [[Delay (audio effect)|tape echo effect]] made famous by the British band, [[The Shadows]].<ref>Hunter, D (2004). [https://books.google.com/books?id=7DjYrk7Vap4C ''Guitar Effects Pedals: The Practical Handbook'']. Hal Leonard. p. 11–12.</ref><ref>[http://www.vintagehofner.co.uk/britamps/watkins/copicat.html "THE WATKINS/WEM COPICAT"] 13 September 2010</ref>

===Amplifiers===
[[File:comboamp.jpg|thumb|left|A [[Fender amplifier#Early solid-state models|Fender Vibrolux]] Reverb amp and a ROSS amp]]

Effects built into [[guitar amplifier#Vacuum tube|tube-powered guitar amplifiers]] were the first effects that musicians used regularly outside the studio. From the late 1940s onward, the [[Gibson Brands|Gibson]] began including [[vibrato]] circuits in [[combo amplifier]]s that incorporated one or more speakers with the amp. The 1950 Ray Butts EchoSonic amp was the first to feature a [[tape echo]],<ref>{{Cite web|title=All About... Ray Butts|url=https://guitar.com/guides/essential-guide/ray-butts/|date=2018-04-23|website=Guitar.com {{!}} All Things Guitar|language=en-GB|access-date=2020-05-24}}</ref> which quickly became popular with guitarists such as [[Chet Atkins]], [[Carl Perkins]], [[Scotty Moore]], [[Luther Perkins]], and [[Roy Orbison]].<ref>{{Cite web|title=10 Things You Didn't Know About Scotty Moore|url=https://www.americanbluesscene.com/10-things-you-didnt-know-about-scotty-moore/|date=2016-12-28|website=American Blues Scene|language=en-US|access-date=2020-05-24}}</ref> Both [[Premier]] and Gibson built amplifiers with [[spring reverb]]. [[Fender Musical Instruments Corporation|Fender]] began manufacturing the tremolo amps Tremolux in 1955 and Vibrolux in 1956.<ref>Hunter, D (2004). [https://books.google.com/books?id=7DjYrk7Vap4C ''Guitar Effects Pedals: The Practical Handbook'']. Hal Leonard. p.&nbsp;11–13.</ref>

[[Distortion (music)|Distortion]] was not an effect originally intended by amplifier manufacturers, but could often easily be achieved by ''overdriving'' the power supply in early [[tube amplifier]]s. In the 1950s, guitarists began deliberately increasing [[Gain (electronics)|gain]] beyond its intended levels to achieve ''warm'' distorted sounds.<ref name="rubin61">{{Cite book|last1=Dave|first1=Rubin|title=Inside the Blues, 1942 to 1982|url=https://books.google.com/books?id=0amzAiwBmOcC|year=2007|publisher=Hal Leonard|page=61|isbn=9781423416661}}</ref> Among the first musicians to experiment with distortion were [[Willie Johnson (guitarist)|Willie Johnson]] of [[Howlin' Wolf]],<ref name="rubin61"/> [[Goree Carter]],<ref name="palmer14">[[Robert Palmer (American writer)|Robert Palmer]], "Church of the Sonic Guitar", pp.&nbsp;13–38 in Anthony DeCurtis, ''Present Tense'', [[Duke University Press]], 1992, p. 19. {{ISBN|0-8223-1265-4}}.</ref> [[Joe Hill Louis]],<ref name="decurtis_phillips">{{cite book|last=DeCurtis|first=Anthony|title=Present Tense: Rock & Roll and Culture|year=1992|publisher=[[Duke University Press]]|location=Durham, N.C.|isbn=0-8223-1265-4|url=https://books.google.com/books?id=bsT3RQ9e58kC|edition=4. print.|quote=His first venture, the Phillips label, issued only one known release, and it was one of the loudest, most overdriven, and distorted guitar stomps ever recorded, "Boogie in the Park" by Memphis one-man-band Joe Hill Louis, who cranked his guitar while sitting and banging at a rudimentary drum kit.}}</ref><ref name="rolling_memphis">{{cite book|last=Miller|first=Jim|title=The Rolling Stone illustrated history of rock & roll|year=1980|publisher=[[Rolling Stone]]|location=New York|isbn=0-394-51322-3|url=https://archive.org/details/rollingstoneillu00mill|url-access=registration|access-date=5 July 2012|quote=Black country bluesmen made raw, heavily amplified boogie records of their own, especially in Memphis, where guitarists like Joe Hill Louis, Willie Johnson (with the early Howlin' Wolf band) and Pat Hare (with Little Junior Parker) played driving rhythms and scorching, distorted solos that might be counted the distant ancestors of heavy metal.}}</ref> [[Ike Turner]],<ref>{{Cite book|last=Shepard|first=John|title=Continuum Encyclopedia of Popular Music of the World|publisher=Continuum International|series=Performance and Production|volume=II|year=2003|page=286|isbn=9780826463227|url=https://books.google.com/books?id=pJvzEzjahkQC&pg=PA286}}</ref> [[Guitar Slim]],<ref>{{cite book|last=Aswell|first=Tom|title=Louisiana Rocks! The True Genesis of Rock & Roll|year=2010|publisher=[[Pelican Publishing Company]]|location=[[Gretna, Louisiana]]|isbn=978-1-58980-677-1|pages=61–5|url=https://books.google.com/books?id=BSHTGsnI8skC&pg=PA61}}</ref> and [[Chuck Berry]].<ref>{{Cite book|last=Collis|first=John|title=Chuck Berry: The Biography|publisher=Aurum|year=2002|page=38|isbn=9781854108739|url=https://books.google.com/books?id=0AgUAQAAIAAJ}}</ref>

In 1954, [[Pat Hare]] produced heavily distorted [[power chord]]s for several recordings (including [[James Cotton]]'s "Cotton Crop Blues"), creating "a grittier, nastier, more ferocious electric guitar sound,"<ref name="palmer">[[Robert Palmer (American writer)|Robert Palmer]], "Church of the Sonic Guitar", pp.&nbsp;13–38 in Anthony DeCurtis, ''Present Tense'', [[Duke University Press]], 1992, pp.&nbsp;24–27. {{ISBN|0-8223-1265-4}}.</ref> accomplished by turning the volume knob on his amplifier "all the way to the right until the speaker was screaming."<ref>{{cite web|url={{AllMusic|class=artist|id=p84274/biography|pure_url=yes}}|title=Pat Hare|author=Koda, Cub|publisher=[[AllMusic]]|access-date=25 January 2010}}</ref> Link Wray's 1958 recording "[[Rumble (instrumental)|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.<ref>{{Cite book|last1=Gracyk|first1=Theodore|title=Rhythm and Noise: An Aesthetics of Rock|url=https://books.google.com/books?id=HUB7Wu-Kn1QC|year=1996|publisher=I.B.Tauris|pages=121–123|isbn=9781860640902}}</ref> 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.<ref>{{Cite book|last1=A. J.|first1=Millard|title=The Electric Guitar: A History of an American Icon|url=https://books.google.com/books?id=zUlt7Q71_ssC|year=2004|publisher=JHU Press|page=136|isbn=9780801878626}}</ref><ref>{{Cite book|last=Doyle|first=Michael|title=The History of Marshall: The Illustrated Story of "The Sound of Rock"|publisher=Hal Leonard Corporation|year=1993|pages=28–33|url=https://books.google.com/books?id=E90tMBs9_FEC&pg=PA20|isbn=0-7935-2509-8}}</ref>

===Stompboxes===
[[File:FuzzFace Effect Pedal.jpg|thumb|left|170px|The [[Fuzz Face]] effect pedal]]

The electronic [[transistor]] finally made it possible to fit effects circuitry into highly portable stompbox units. Transistors replaced [[vacuum tubes]], allowing for much more compact formats and greater stability. The first transistorized guitar effect was the 1962 Maestro Fuzz Tone pedal, which became a sensation after its use in the 1965 Rolling Stones hit "[[(I Can't Get No) Satisfaction]]".<ref>{{cite web|title=The Art of the Stompbox|year=2010|url=http://www.museumofmakingmusic.org/stompbox-birth|access-date=13 September 2010}}</ref><ref>{{cite web|title=FuzzEffect: The Fuzz Story and Photos|url=http://www.fuzzeffect.com/|access-date=13 September 2010}}</ref>

Warwick Electronics manufactured the first [[wah-wah pedal]],<ref>{{cite patent |title=Foot controlled continuously variable preference circuit for musical instruments |number=3530224 |country=US}}</ref> The Clyde McCoy, in 1967 and that same year Roger Mayer developed the first [[octave effect]], which Jimi Hendrix named "Octavio".<ref>https://www.roger-mayer.co.uk/octavia.htm{{self-published inline|date=May 2021}}</ref> Upon first hearing the Octavia, Hendrix reportedly rushed back to the studio and immediately used it to record the guitar solos on "[[Purple Haze]]" and "[[Fire (The Jimi Hendrix Experience song)|Fire]]".<ref>{{Cite book|last1=Molenda|first1=Mike|last2=Pau|first2=Les|title=The Guitar Player Book: 40 Years of Interviews, Gear, and Lessons from the World's Most Celebrated Guitar Magazine|url=https://books.google.com/books?id=zu3owmYkpZ0C|year=2007|publisher=Hal Leonard|page=222|isbn=9780879307820}}</ref> In 1968, [[Univox]] began marketing Shin-ei's [[Uni-Vibe]] pedal, an effect designed by noted audio engineer Fumio Mieda that mimicked the odd [[phase shift]] and [[Chorus effect|chorus]] effects of the [[Leslie rotating speaker]]s used in [[Hammond organ]]s. The pedals soon became favorite effects of guitarists [[Jimi Hendrix]] and [[Robin Trower]]. In 1976, [[Roland Corporation|Roland]] subsidiary [[Boss Corporation]] released the CE-1 Chorus Ensemble, the first [[chorus pedal]], created by taking a chorus circuit from an [[amplifier]] and putting it into a [[stompbox]].<ref name="reverb">[https://reverb.com/uk/news/tribute-ikutaro-kakehashi-and-rolands-impact-on-music Tribute: Ikutaro Kakehashi and Roland's Impact on Music], [[Reverb.com]]</ref> By the mid-1970s a variety of solid-state effects pedals including [[flanger]]s, chorus pedals, [[ring modulator]]s and [[phase shifter]]s were available.<ref>Hunter, D (2004). [https://books.google.com/books?id=7DjYrk7Vap4C ''Guitar Effects Pedals: The Practical Handbook'']. Hal Leonard. p.&nbsp;11–15.</ref><ref>{{cite journal|author=Thomas E. Oberheim|title=A Ring Modulator Device for the Performing Musician|journal=AES Convention |volume=38|date=May 1970|page=708}}</ref>

[[File:BossFX.JPG|thumb|right|200px|Several [[Boss Corporation|Boss]] pedals connected together]]
In the 1980s, digital [[#Rackmounts|rackmount]] units began replacing stompboxes as the effects format of choice. Often musicians would record ''dry'', unaltered tracks in the studio and effects would be added in post-production.{{citation needed|date=June 2023}} The success of [[Nirvana (band)|Nirvana]]'s 1991 album ''[[Nevermind]]'' helped to re-ignite interest in stompboxes. Some [[grunge]] guitarists would chain several fuzz pedals together and plug them into a [[tube amplifier]].<ref name="gibson.com">{{cite web |url=http://www.gibson.com/News-Lifestyle/Features/en-us/grunge-guitar-0426-2011.aspx |title=Serve the Servants: Unlocking the Secrets of Grunge Guitar |website=Gibson.com |date=26 April 2011 |access-date=1 April 2016 |archive-url=https://web.archive.org/web/20160331190319/http://www.gibson.com/News-Lifestyle/Features/en-us/grunge-guitar-0426-2011.aspx |archive-date=31 March 2016 |url-status=dead }}</ref> Throughout the 1990s, musicians committed to a [[Lo-fi music|lo-fi]] aesthetic such as [[J Mascis]] of [[Dinosaur Jr.]], [[Stephen Malkmus]] of [[Pavement (band)|Pavement]] and [[Robert Pollard]] of [[Guided by Voices]] continued to use [[Analogue electronics|analog]] effects pedals.<ref>{{citation|last=Atria|first=Travis|title=Stephen Malkmus – Talks Real Emotional Trash|url=http://www.glidemagazine.com/articles/53170/stephen-malkmus-talks-real-emotional-trash.html|periodical=Glide Magazine|date=6 March 2008|access-date=13 September 2010|archive-date=21 May 2013|archive-url=https://web.archive.org/web/20130521164518/http://www.glidemagazine.com/articles/53170/stephen-malkmus-talks-real-emotional-trash.html|url-status=dead}}</ref>

<!--DO NOT ADD EXAMPLES TO THIS SECTION. Replace lesser-known examples with more famous ones. Otherwise it becomes a dumpster for trivia.-->
Effects and effects units—stompboxes in particular—have been celebrated by pop and rock musicians in album titles, songs and band names. The [[Big Muff]], a [[fuzzbox]] manufactured by [[Electro-Harmonix]],<ref>{{cite web|url=http://www.ehx.com/products/big-muff-pi|title=Big Muff Pi Distortion/Sustainer|publisher=Electro-Harmonix|access-date=18 September 2010}}</ref> is commemorated by the [[Depeche Mode]] song "[[Speak & Spell (album)|Big Muff]]" and the [[Mudhoney]] [[Extended play|EP]] ''[[Superfuzz Bigmuff]]''. [[Nine Inch Nails]], [[Pink Floyd]], [[George Harrison]], [[They Might Be Giants]] and [[Joy Division]] are among the many musicians who have referenced effects units in their music.<ref>{{Citation|last=Barker|first=David|title=33 1/3 Greatest Hits |volume=1|url=https://books.google.com/books?id=7v7wJqhaBhoC|year=2007|publisher=Continuum International|page=112|isbn=9780826419033}}</ref>

==Techniques{{anchor|Types}}==
{{broader|Sound effect#Techniques}}
[[File:Jim O'Rourke-6.jpg|thumb|[[Jim O'Rourke (musician)|Jim O’Rourke]] kneeling while operating two stompboxes with his hands]]

===Distortion===
{{main|Distortion (music)}}
{{Listen|filename=DistortionPedalDemo.ogg|title=Distortion effect|description=Electric guitar played first ''clean'' (no effects), then with distortion pedal.|format=[[Ogg]]}}
[[File:Clipping waveform.svg|thumb|right|[[Clipping (audio)|Clipping]] an instrument's [[audio signal]] produces distortion]]

Distortion, overdrive, and fuzz effects units add a ''warm'', ''gritty'', or ''fuzzy'' character to an audio signal by re-shaping or [[clipping (audio)|clipping]] it, which [[distorts]] the shape of its [[waveform]] by flattening its peaks, creating ''warm'' sounds by adding [[harmonics]] or ''gritty'' sounds by adding [[inharmonic]] overtones. Distortion effects are sometimes called [[Gain (electronics)|gain]] effects, as distorted guitar sounds were first achieved by increasing the gain of [[tube amplifier]]s.<ref>{{Cite book|last=Menasche|first=Emile D.|title=Home Studio Clinic: A Musician's Guide to Professional Recording|publisher=Hal Leonard|year=2007|page=[https://archive.org/details/homestudioclinic0000mena/page/80 80]|isbn=9781423418078 |url=https://archive.org/details/homestudioclinic0000mena|url-access=registration}}</ref><ref name="Ross">{{Cite book|last=Ross|first=Michael|url=https://books.google.com/books?id=CddgbKkAoxYC&pg=PA39|title=Getting Great Guitar Sounds|publisher=Hal Leonard|year=1998|page=39|isbn=9780793591404}}</ref><ref name="google171">Aikin, Jim (2004). [https://books.google.com/books?id=_042p3GHkBQC ''Power Tools for Synthesizer Programming''], Hal Leonard. p. 171.</ref>

While distortion effects units produce perfectly flattened peaks or ''hard'' clipping, overdrive effects units produce ''soft'' tube-like distortion by compressing the waveform without completely flattening it. Much like guitar tube amplifiers, overdrive effects units are capable of producing ''clean'' sounds at lower volumes and distorted ''warm'' sounds at higher volumes.<ref>{{Cite book|last1=Zölzer|last2=Amatriain|first1=Udo|first2=Xavier|url=https://books.google.com/books?id=h90HIV0uwVsC|title=DAFX: Digital Audio Effects|publisher=John Wiley and Sons|year=2002|page=117|isbn=9780471490784}}</ref><ref>{{Citation|last=Brewster|first=David M.|title=Introduction to Guitar Tone and Effects: A Manual for Getting the Sounds from Electric Guitars, Amplifiers, Effects Pedals and Processors|publisher=Hal Leonard|url=https://books.google.com/books?id=q99-bY3cL8YC&q=overdrive+tube+amplifier&pg=PA18|year=2001|page=18|isbn=9780634060465}}</ref>

Notable [[List of distortion pedals|examples of distortion and overdrive pedals]] include the [[Boss DS-1]] Distortion, [[Ibanez Tube Screamer]], [[Marshall ShredMaster]], [[MXR Distortion +]], and [[Pro Co RAT]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

A fuzz pedal, or fuzzbox, is a type of overdrive effects unit that clips a signal until it is nearly a [[Square wave (waveform)|square wave]], resulting in a heavily distorted or ''fuzzy'' sound.<ref name="google171"/><ref>Platt, Charles (2009). [https://books.google.com/books?id=PQzYdC3BtQkC ''MAKE: Electronics: Learning Through Discovery''] O'Reilly Media. p. 257.</ref> Fuzzboxes may contain [[frequency multiplier]] circuitry to achieve a harsh [[timbre]] by adding complex [[harmonics]].<ref>{{Cite book|last1=Holmes|first1=Thom|title=The Routledge Guide to Music Technology|publisher=CRC Press|year=2006|page=177|url=https://books.google.com/books?id=iH1tZ64riu4C&q=%22frequency+multiplier%22&pg=PA117|isbn=0-415-97324-4}}</ref><ref>{{Cite book|last1=Manning|first1=Peter|title=Electronic and Computer Music|publisher=Oxford University Press US|year=2004|page=170|url=https://books.google.com/books?id=P2dClS4LdPQC&pg=PA170|isbn=0-19-514484-8}}</ref> [[The Rolling Stones]]' song "[[(I Can't Get No) Satisfaction]]", with a fuzz effect featured prominently on the main electric guitar riff played by Keith Richards, greatly popularized the use of fuzz effects.<ref name="museumofmakingmusic1">{{cite web|title=The Art of the Stompbox|publisher=The Museum of Making|year=2010|url=http://www.museumofmakingmusic.org/stompbox-effects|access-date=13 September 2010}}</ref> [[Fuzz bass]] (also called bass overdrive) is a style of playing the [[electric bass]] that produces a buzzy, overdriven sound via a tube or transistor amp or by using a fuzz or overdrive pedal.

Notable examples of fuzz effect units include the: [[Fuzz Face|Arbiter Fuzz Face]], [[Electro-Harmonix Big Muff]], [[Shin-ei Companion FY-2]], [[Univox Super-Fuzz]], [[Tone Bender|Vox Tone Bender]], [[Z.Vex Fuzz Factory]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians. Wikipedia is NOT a free advertising service-->

While distortion effect units are most associated with electric and bass guitar, they are also commonly used on keyboard instruments (i.e. [[synthesizer]]s, [[Combo organ|combo]] and [[tonewheel organ]]s, [[electric piano]]), as well as drums and vocals.

===Dynamics===
[[File:Comp. rack (Supernatural).jpg|thumb|upright|A rack of [[rackmount]] audio compressors in a recording studio. From top to bottom: Retro Instruments/Gates STA level; Spectra Sonic; [[Dbx (noise reduction)|Dbx]] 162; Dbx 165; [[Empirical Labs Distressor]]; Smart Research C2; Chandler Limited TG1; Daking FET (91579); and [[Altec Lansing|Altec]] 436c.]]

Also called volume and [[amplitude]] effects, dynamics effects modify the volume of an instrument. Dynamics effects were among the first effects introduced to guitarists.<ref name="art" />

''Boost/volume pedal'': When activated, a ''boost'' or ''clean boost'' pedal amplifies the volume of an instrument by increasing the [[amplitude]] of its [[audio signal]]. These units are generally used for ''boosting'' volume during solos and preventing signal loss in long effects chains. A guitarist switching from rhythm guitar to lead guitar for a [[guitar solo]] may use a boost to increase the volume of their solo.<ref>Hunter, Dave (2004). [https://books.google.com/books?id=7DjYrk7Vap4C ''Guitar Effects Pedals: The Practical Handbook'']. Hal Leonard. p. 23.</ref>

Volume effects: [[Electro-Harmonix]] LPB-1, Fender Volume Pedal, [[MXR Micro Amp]], [[Ernie Ball Inc.|Ernie Ball]] Volume Pedal.<!--This article has often been used to advertise. Add only list products that 1.) have Wikipedia articles and 2. ) have been very known for a number of years and used by influential musicians--> [[Treadle]]-based volume pedals are used by electric instrument players (guitar, bass, keyboards) to adjust the volume of their instrument with one foot while their hands are being used to play their instrument. Treadle-style volume pedals are often also used to create swelling effects by removing the attack of a note or chord, as popularised by [[pedal steel guitar]] players. This enables electric guitar and pedal steel players to imitate the soft swelling sound that an orchestra [[string section]] can produce, in which a note or chord starts very softly and then grows in volume. Treadle-based volume pedals do not usually have batteries or require external power.

''[[Dynamic range compression|Compressor]]'': Compressors make loud sounds quieter and quiet sounds louder by decreasing or ''compressing'' the [[dynamic range compression|dynamic range]] of an [[audio signal]].<ref name="Reese">{{Cite book|last1=Reese|first1=David|last2=Gross|first2=Lynne|last3=Gross|first3=Brian|title=Audio Production Worktext: Concepts, Techniques, and Equipment|publisher=Focal Press|year=2009|page=[https://archive.org/details/audioproductionw0000rees/page/149 149]|url=https://archive.org/details/audioproductionw0000rees|url-access=registration|isbn=978-0-240-81098-0}}</ref> A compressor is often used to stabilize volume and alter the sound of a note's ''attack''. With extreme settings of its controls, a compressor can function as a [[limiter]].<ref name="google23">Hunter, D (2004). [https://books.google.com/books?id=7DjYrk7Vap4C ''Guitar Effects Pedals: The Practical Handbook'']. Hal Leonard. p. 23.</ref>

Compressor effects: [[Robert Keeley (instrument maker)|Keeley Compressor]], [[MXR Dyna Comp]], [[Boss Corporation|Boss CS-3 Compression Sustainer]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2.) have been well known for a number of years and used by influential musicians-->

''[[Noise gate]]'': Noise gates [[attenuate]] hum, hiss, and static in the signal by greatly diminishing the volume when the signal falls below a set threshold. Noise gates are [[Dynamic range compression#Types|expanders]]—meaning that, unlike compressors, they increase the [[dynamic range compression|dynamic range]] of an [[audio signal]] to make quiet sounds even quieter.<ref name="Reese" /> If used with extreme settings and combined with reverb, they can create unusual sounds, such as the [[gated reverb|gated drum effect]] used in 1980s pop songs, a style popularized by the [[Phil Collins]] song ''[[In the Air Tonight]]''.<ref>Louie, Gary J.; White, Glenn D. (2005). [https://books.google.com/books?id=DulVm8t88QkC ''The Audio Dictionary''], University of Washington Press. p. 171.</ref><ref>{{cite magazine |last=Flans |first=Robyn |url=http://mixonline.com/mag/audio_phil_collins_air/ |title=Classic Tracks: Phil Collins' "In the Air Tonight" |archive-url=https://web.archive.org/web/20110303210034/http://mixonline.com/mag/audio_phil_collins_air/ |archive-date=3 March 2011 |magazine=Mix |date=1 May 2005}}</ref>

Noise gate effects: [[Boss Corporation|Boss NS-2 Noise Suppressor]].

===Filter===
Filter effects alter the [[frequency]] content of an [[audio signal]] that passes through them by either boosting or weakening specific frequencies or frequency regions.

''[[Equalization (audio)|Equalizer]]'': An equalizer is a set of [[linear filter]]s that strengthen (''boost'') or weaken (''cut'') specific [[frequency]] regions. While basic [[Hifi|home stereos]] often have equalizers for two bands, to adjust bass and treble, professional [[graphic equalizer]]s offer much more targeted control over the audio frequency spectrum.<ref>Rudolph, Thomas; Leonard, Vincent (2001) [https://books.google.com/books?id=MFSilO_OEPAC ''Recording in the Digital World: Complete Guide to Studio Gear and Software''], Hal Leonard . p. 192.</ref> [[Audio engineers]] use highly sophisticated equalizers to eliminate unwanted sounds, make an instrument or voice more prominent, and enhance particular aspects of an instrument's tone.<ref>{{Cite book|last=Strong|first=Jeff|title=PC Recording Studios for Dummies|url=https://books.google.com/books?id=4-2SfnghnYwC&q=pc+recording+studios+for+dummies|publisher=For Dummies|year=2005|page=25|isbn=9780764577079}}</ref>

Equalizer effects: [[Boss Corporation|Boss GE-7 Equalizer]], [[MXR]] 10-band EQ Pedal.

[[File:Peter Frampton's Talk Box-3-2.jpg|thumb|left|[[Peter Frampton]]'s [[Talk box]]]]
''[[Talk box]]'': A talk box directs the sound from an electric guitar or synthesizer into the mouth of a performer using a tube, allowing the sound to be shaped into [[vowel]]s and [[consonant]]s with movements of the mouth. The modified sound is then picked up by a microphone. In this way, the guitarist is able create the effect that the guitar is talking. Some famous uses of the talkbox include [[Bon Jovi]]'s "[[Livin' on a Prayer]]", [[Songs in the Key of Life|Stevie Wonder]]'s "[[Black Man (song)|Black Man]]", [[Mötley Crüe]]'s "[[Kickstart My Heart]]", [[Joe Walsh]]'s "[[Rocky Mountain Way]]", [[Alice in Chains]]'s "[[Man in the box]]" and [[Peter Frampton]]'s "[[Show Me the Way (Peter Frampton song)|Show Me the Way]]".<ref>{{cite web|last=Dyers|first=Jon|url=http://www.dyers.org/blog/archives/2008/03/21/the-talkbox-will-never-die-a-talkbox-playlist/|title=The Talkbox Will Never Die: A Talkbox Playlist|publisher=Dyers|date=21 March 2008|access-date=20 September 2010|archive-url=https://web.archive.org/web/20100617102921/http://www.dyers.org/blog/archives/2008/03/21/the-talkbox-will-never-die-a-talkbox-playlist/|archive-date=17 June 2010|url-status=dead}}</ref><ref>{{cite web|url=http://www.blamepro.com/talkbox.htm#top|title=The Talkbox FAQ|author=McCarron, Brett|access-date=10 September 2010}}</ref>

Talk boxes: [[Dunlop Manufacturing|Dunlop HT1 Heil Talk Box]], [[Bruce Egnater|Rocktron Banshee]].<!--This article has often been used to advertise. Please list only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

[[File:Thomas Organ Crybaby.jpg|thumb|right|Thomas Organ Cry Baby [[Wah-wah pedal]] (1970) manufactured by JEN]]
''[[Wah-wah pedal|Wah-wah]]'': A wah-wah pedal creates vowel-like sounds by altering the [[Audio spectrum|frequency spectrum]] produced by an instrument—i.e., how loud it is at each separate [[frequency]]—in what is known as a [[spectral glide]] or ''sweep''.<ref>{{Cite book|last1=Denton|first1=Dailey J.|title=Electronics for Guitarists|publisher=Springer|year=2011|page=183|isbn=9781441995360|url=https://books.google.com/books?id=PPg5_lPQJyMC&pg=PA185}}</ref> The device is operated by a foot treadle that manipulates a [[potentiometer]] or other electronic control. Wah-wah pedals are often used by [[funk]] and rock guitarists.<ref name="The Contemporary Guitar">Schneider, John (1985). [https://books.google.com/books?id=6-QE1jyJHgEC ''The Contemporary Guitar''], University of California Press. p. 202.</ref>

Wah effects: [[Dunlop Cry Baby]],<ref>{{Cite web |url=https://www.sweetwater.com/feature/dunlop/wah-pedals/ |title=Wah Comparison Chart | access-date= 17 August 2020 }}</ref> [[Morley Pedals|Morley Power Wah]], [[Vox (company)|Vox]].<ref>[https://voxamps.com/series/wah-pedal/ Vox V846 Wah]</ref><!--This article has often been used to advertise. Please list only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

''[[Auto-wah]]'' or, more generally, envelope filter effects: A filter effect that is controlled by the volume of the input signal.<ref name="The Boss Book">''The Boss Book: The Ultimate Guide to the World's Most Popular Compact Effects for Guitar'', 2002, Hal Leonard Corporation</ref>  The most common filter type used for this effect pedal is the low-pass filter, although many designs include a toggle for band-pass or high-pass filters as well.  Additionally, some designs can switch between a down filter mode and an up filter.  This effect is commonly used in funk, reggae and jam band music.

Envelope filter effects: [[Mu-tron|Musitronics Mu-Tron III]], Electro-Harmonix Q-Tron Plus,<ref>[https://www.ehx.com/products/q-tron-plus/ Electro-Harmonix Q-Tron Plus]</ref> DOD Envelope Filter 440.<ref>[https://www.digitech.com/discontinued-products/Envelope+Filter+440.html DOD Envelope Filter 440] {{Webarchive|url=https://web.archive.org/web/20210629054118/https://www.digitech.com/discontinued-products/Envelope+Filter+440.html |date=29 June 2021 }}</ref>

===Modulation===
{{listen
|filename =Demo chorus.ogg
|title  =Chorus effect
|description=Chorus effect on guitar, coming from an Electro-Harmonix Small Clone
|filename2=Flanging effect.ogg
|title2  =Flanging effect
|description2=A short synthesizer sample followed by two flanging versions
|filename3=Phasing_effect.ogg
|title3  =Phaser effect
|description3=Unprocessed organ followed by different phasing effects
|filename4=Ring_Modulation-with_2500Hz.ogg
|title4  =Ring modulation effect
|description4=Bell-like sound
|filename5=LFOtoVolume-Tremolo.ogg
|title5  =Tremolo effect
|description5=A low-frequency oscillator modulating a tremolo (synthesizer)
|filename6=LFOtoPitch-Vibrato.ogg
|title6  =Vibrato effect
|description6=A low-frequency oscillator modulating a vibrato (synthesizer)
}}
[[Modulation]], in general electronics, means the altering of one signal based on another. In audio effects, modulation is a control feature that varies the strength or other attribute of the effect over time to alter tonal properties. Some modulation effects modulate an instrument's [[audio signal]] with a signal generated by the effect called a [[carrier wave]].<ref name="Zolzer">{{Cite book|last1=Zölzer|last2=Amatriain|first1=Udo|first2=Xavier|url=https://books.google.com/books?id=h90HIV0uwVsC|title=DAFX: Digital Audio Effects|publisher=John Wiley and Sons|year=2002|page=76|isbn=9780471490784}}</ref> Other modulation effects split an instrument's audio signal in two, altering one portion of the signal and mixing it with the unaltered portion.<ref name="Coulter">{{cite book |last=Coulter |first=Doug |date=2000 |title=Digital Audio Processing |publisher=Taylor & Francis |page=271 |isbn=9780879305666}}<!--imperfectly recovered reference: previous indicated |url=https://books.google.com/books?id=_VIKe7n9R_8C (not found) |publisher=Focal Press |date=2001 possibly a different edition, page number may be incorrect--></ref>

''[[chorus effect|Chorus]]'': Chorus pedals mimic the effect [[choir]]s and [[string orchestra]]s produce naturally, by mixing similar sounds with slight differences in [[timbre]] and [[pitch (music)|pitch]]. A chorus effect splits the [[audio signal]] and adds a slight delay and [[frequency]] variations or ''[[vibrato]]'' to one version while leaving the rest unaltered.<ref name="Coulter" /><ref>{{Cite book|last=Perkins|first=Chad|title=The After Effects Illusionist: All the Effects in One Complete Guide|publisher=Focal Press|year=2009|page=37|url=https://books.google.com/books?id=qsvgDeyrz-0C&q=chorus+signal+delay&pg=PA37|isbn=978-0-240-81145-1}}</ref> A well-known usage of chorus is the lead guitar in "[[Come as You Are (Nirvana song)|Come As You Are]]" by [[Nirvana (band)|Nirvana]].<ref name="google23"/>

Chorus effects: [[Boss Corporation|Boss]] CE-1 Chorus Ensemble, [[Electro-Harmonix]] Small Clone, [[TC Electronic]] Stereo Chorus.<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

''[[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 [[Reel-to-reel audio tape recording|tape decks]] and periodically slowing one tape by pressing the edge of its reel (the ''flange''). When the two tapes' [[audio signal]]s 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]].<ref>{{Cite book|last=Kurasaki|first=Kurt|title=Power Tools for Reason 3.0: Master the World's Most Popular Virtual Studio|publisher=Hal Leonard|year=2005|page=169|isbn=9780879308612|url=https://books.google.com/books?id=nPkBCZ1F7kAC&pg=PA169}}</ref><ref>Louie, G; White, G (2005). [https://books.google.com/books?id=DulVm8t88QkC ''The Audio Dictionary''], University of Washington Press. p. 153.</ref> 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 (song)|Barracuda]]" by [[Heart (band)|Heart]].<ref>{{cite web|url=http://www.igdb.co.uk/pages/reviews/effect/electro_harmonix/deluxe_electric_mistress.htm|title=Electro Harmonix Deluxe Electric Mistress Review|publisher=Internet Guitar Database|access-date=19 September 2001|archive-url=https://web.archive.org/web/20051030020829/http://www.igdb.co.uk/pages/reviews/effect/electro_harmonix/deluxe_electric_mistress.htm|archive-date=30 October 2005|url-status=dead}}</ref><ref>{{Citation|last=Brewster|first=David M.|title=Introduction to Guitar Tone and Effects: A Manual for Getting the Sounds from Electric Guitars, Amplifiers, Effects Pedals and Processors|publisher=Hal Leonard|url=https://books.google.com/books?id=q99-bY3cL8YC|year=2001|page=29|isbn=9780634060465}}</ref>

Flanger effects: [[Electro-Harmonix]] Electric Mistress, [[MXR]] Flanger, [[Boss Corporation|Boss]] BF-3 Flanger.<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

[[File:MXR M-101 Phase 90 modified.jpg|thumb|left|200px|An MXR-101 Phaser pedal]]
''[[Phaser (effect)|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 (waves)|phase]] of one portion. Three well-known examples of phaser are the [[two-handed tapping]] part on the Van Halen instrumental "[[Eruption (instrumental)|Eruption]]" and the keyboard parts on [[Billy Joel]]'s "[[Just the Way You Are (Billy Joel song)|Just the Way You Are]]" and [[Paul Simon]]'s "[[Slip Slidin' Away]]".<ref>Louie, G; White, G. (2005). [https://books.google.com/books?id=DulVm8t88QkC ''The Audio Dictionary''], University of Washington Press. p. 288.</ref>

Phase shift effects: [[Uni-Vibe]], [[Electro-Harmonix]] Small Stone, [[MXR Phase 90]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

''[[Ring modulator]]'': A ring modulator produces a resonant, metallic sound by [[frequency mixing]] an instrument's [[audio signal]] with a [[carrier wave]] generated by the device's internal [[Electronic oscillator|oscillator]]. The original sound wave is suppressed and replaced by a ''ring'' of [[inharmonic]] higher and lower [[pitch (music)|pitches]] or [[sideband]]s.<ref name="Zolzer" /><ref>{{Citation|last=Moog|first=Robert|author-link=Robert Moog|title=Synthesizer technique|publisher=Hal Leonard|series=Keyboard Synthesizer Library|volume=2|year=1984|chapter=Pitch Blending, Modulation, and Expression|page=52|chapter-url=https://books.google.com/books?id=IQrOFoWL0T4C&pg=PA53|isbn=0-88188-290-9}}</ref> A notable use of [[ring modulation]] is the guitar in the [[Black Sabbath]] song "[[Paranoid (Black Sabbath song)|Paranoid]]".<ref>McNamee, David [https://www.theguardian.com/music/2009/nov/09/ring-modulators "Hey, What's That Sound: Ring Modulators"], ''The Guardian'', London, 9 November 2009.</ref>

Ring modulator effects: [[Moogerfooger#MF-102|Moogerfooger MF-102 Ring Modulator]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

''[[Tremolo]]'': A tremolo effect produces a variation in the volume of a signal. 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 electronic effects, a tremolo is produced by modulating an instrument's audio signal with a [[Subaudible tone|sub-audible]] carrier wave in such a way that generates amplitude variations in the sound wave.<ref>{{Citation|last=Hartman|first=W. M.|date=19 March 1979|title=The Electronic Music Synthesizer and the Physics of Music|publisher=American Association of Physics Teachers|url=http://www.pa.msu.edu/acoustics/ajpsynth.pdf|access-date=2021-10-10|archive-date=5 March 2016|archive-url=https://web.archive.org/web/20160305034409/http://www.pa.msu.edu/acoustics/ajpsynth.pdf|url-status=dead}}</ref><ref name="Holmes">{{Citation|last=Holmes|first=Thomas|title=Electronic and Experimental Music: Technology, Music, and Culture|url=https://books.google.com/books?id=hCthQ-bec-QC&q=vibrato+%22carrier+wave%22+%22carrier+signal%22&pg=PA198|year=2008|publisher=Taylor & Francis|isbn=978-0-415-95781-6|page=198}}</ref> Tremolo effects are built-in effects in some vintage [[guitar amplifiers]]. The guitar intro in the [[Rolling Stones]]' "[[Gimme Shelter]]" features a tremolo effect.<ref>{{cite web|url=http://www.guitaretab.com/r/rolling-stones/16342.html|title=Rolling Stones – Gimme Shelter tab|author=Trolet, Jean-Pierre|access-date=9 September 2010}}</ref>

Tremolo effects: Demeter TRM-1 Tremulator, [[Fender Tremolux]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

''[[Slicer (guitar effect)|Slicer]]'': Combines a [[modulation]] sequence with a [[noise gate]] or [[envelope filter]] to create a percussive and rhythmic effect like a helicopter.<ref>{{cite web |url=https://rolandcorp.com.au/blog/guitar-fx-101-guide-guitar-effects-pedals#FXS |title=Guitar FX-101: Your Guide to Guitar Effects Pedals |date=6 August 2016 |publisher=[[Roland Corporation]] |access-date=2020-03-14}}</ref>

''[[Vibrato]]'': Vibrato effects produce slight, rapid variations in [[Pitch (music)|pitch]], mimicking the fractional [[semitone]] variations produced naturally by [[opera singer]]s 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 (''depth''). A vibrato with an extreme ''depth'' setting (e.g., half a semitone or more) will produce a dramatic, [[ululating]] sound. In [[transistor]]ized effects, vibrato is produced by mixing an instrument's [[audio signal]] with a [[carrier wave]] in such a way that generates frequency variations in the sound wave.<ref name="Holmes" /> Guitarists often use the terms ''[[vibrato]]'' and ''[[tremolo]]'' misleadingly. A so-called ''vibrato unit'' in a guitar amplifier may actually produces tremolo, while a ''[[tremolo arm]]'' or ''whammy bar'' on a guitar produces vibrato.<ref>Mangum, E; Stubbs, D (2000). [https://books.google.com/books?id=pp6xpWAgjFcC ''Dod Presents 100 Superstar Guitar Sounds on a Stompbox Budget'']. Hal Leonard. p. 94.</ref><ref>Fischer, Peter (2000), [https://books.google.com/books?id=fFSEYzW5SAAC ''Rock Guitar Secrets''], Mel Bay. p. 164.</ref>

Vibrato effects: [[Boss Corporation|Boss VB-2 Vibrato]].

===Pitch and frequency===
{{Main article|Pitch shifter}}
[[File:EH POG-2.jpg|thumb|right|An [[Electro-Harmonix]] Polyphonic Octaver Generator (POG)]]

A pitch shifter (also called an ''octaver'' for effects that shift pitch by an [[octave]]) raises or lowers (i.e. [[Transposition (music)|transposes]]) each note a performer plays by a pre-set [[Interval (music)|interval]]. For example, a pitch shifter set to increase the pitch by a fourth will raise each note four [[diatonic]] intervals above the notes actually played. Simple, less expensive pitch shifters raise or lower the pitch by one or two [[octave]]s, while more sophisticated devices offer a range of interval alterations. A pitch shifter can be used by an electric guitarist to play notes that would normally only be available on an electric bass. As well, a bass player with a four string electric bass can use an octave pedal to obtain low notes that would normally only be obtainable with a five-string bass with a low B string.

A harmonizer is a type of sophisticated pitch shifter that combines the altered pitch with the original pitch to create a two or three note [[harmony]] based on the original pitch. Some hamonizers are able to create chorus-like effects by modulating of small shifts in pitch.<ref>Izhaki, Roey (2007). [https://books.google.com/books?id=tIi4HQ2kWRoC ''Mixing Audio: Concepts, Practices and Tools''], Focal Press. p. 470.</ref>

The first mass-market digital pitch shifter was the [[DigiTech Whammy]], introduced in 1989.<ref name="Lynham-20192">{{Cite web |last=Lynham |first=Alex |date=2019-08-02 |title=The FX files: DigiTech Whammy |url=https://www.musicradar.com/news/the-fx-files-digitech-whammy |access-date=2024-07-27 |website=[[MusicRadar]] |language=en}}</ref> It creates a "strange and artificial" sound, with distinctive "wobbly" [[Artifact (error)|artifacts]].<ref name=":0">{{Cite web |last=Greeves |first=David |date=April 2013 |title=Digitech Whammy (5th Gen) |url=https://www.soundonsound.com/reviews/digitech-whammy-5th-gen |access-date=2021-09-16 |website=[[Sound on Sound]]}}</ref><ref name="Lynham-20193">{{Cite web |last=Lynham |first=Alex |date=2019-08-02 |title=The FX files: DigiTech Whammy |url=https://www.musicradar.com/news/the-fx-files-digitech-whammy |access-date=2024-07-27 |website=[[MusicRadar]] |language=en}}</ref> Its users include [[Jonny Greenwood]] and [[Ed O'Brien]] of [[Radiohead]],<ref>{{Cite journal |date=19 October 2018 |title=Iron man |url=https://www.pressreader.com/australia/total-guitar/20181019/283016875682882 |journal=[[Total Guitar]] |publisher=[[Future plc]] |via=[[PressReader]]}}</ref><ref>{{cite web |author=Astley-Brown |first1=Michael |last2=Laing |first2=Rob |date=14 November 2017 |title=Radiohead's Ed O'Brien: 'I was always drawn to sounds that didn't sound like the guitar' |url=http://www.musicradar.com/news/radioheads-ed-obrien-i-was-always-drawn-to-sounds-that-didnt-sound-like-the-guitar |access-date=19 November 2017 |website=[[MusicRadar]] |publisher=}}</ref> [[Matt Bellamy]] of [[Muse (band)|Muse]],<ref name="Charupakorn-2022">{{Cite web |last=Charupakorn |first=Joe |date=11 August 2022 |title=Muse's Matt Bellamy: Natural-Born Disruptor |url=https://www.premierguitar.com/artists/guitarists/muse |website=[[Premier Guitar]]}}</ref> [[Tom Morello]] of [[Rage Against the Machine]] and [[Audioslave]],<ref name="Lynham-20193" /> [[David Gilmour]] of [[Pink Floyd]]<ref>{{Cite web |last=Tolinski |first=Brad |date=September 1994 |title=David Gilmour discusses guitars, blues and ''The Division Bell'' in 1994 ''Guitar World'' interview |url=https://www.guitarworld.com/gw-archive/david-gilmour-discusses-guitars-blues-and-division-bell-1994-guitar-world-interview |access-date=2024-07-27 |website=[[Guitar World]] |language=en}}</ref> and [[Jack White]] of the [[White Stripes]].<ref>{{Cite web |last=Gill |first=Chris |date=2020-07-09 |title=The secrets behind Jack White's guitar tone on the White Stripes' Seven Nation Army |url=https://www.guitarworld.com/features/the-secrets-behind-jack-whites-guitar-tone-on-the-white-stripes-seven-nation-army |access-date=2024-07-27 |website=[[Guitar World]] |language=en}}</ref> ''[[Guitar World]]'' described the Whammy as one of the most iconic guitar pedals.<ref name="Vallese-20122">{{Cite web |last=Vallese |first=Nick |date=2012-06-05 |title=Digitech releases new Whammy with chord shifting |url=https://www.guitarworld.com/uncategorized/digitech-releases-new-whammy-chord-shifting |access-date=2021-09-16 |website=[[Guitar World]] |language=en}}</ref><!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

===Time-based===
[[File:Maestro Echoplex EP-2.jpg|right|thumb|A vintage [[Echoplex]] EP-2 delay effect]]
{{listen
|filename=flute-delay.ogg
|title=Delay effect
|description=A flute before and after delay|format=[[Ogg]]
|filename2=Reverberation_effect.ogg
|title2=Reverberation effect
|description2=Reverb with increasingly longer delay
}}
Time-based effects delay the sound signal, add reverb or echos, or enable musicians to record and play back [[Loop (music)|loops]].

''[[Delay (audio effect)|Delay/echo]]'': Delay/echo units produce an echo effect by adding a duplicate to the original signal at a slight time delay. The effect can either be a single echo (called a ''slap'' or ''slapback''), or multiple echos. A well-known use of delay is the lead guitar in the [[U2]] song "[[Where the Streets Have No Name]]", and also the opening riff of "[[Welcome to the Jungle]]" by [[Guns N' Roses]].<ref>Hubner, David; Runstein, Robert (2009). [https://books.google.com/books?id=W9U7A-rSXtEC ''Modern Recording Techniques''], Focal Press. p. 508.</ref>

Delay effects: [[Boss Corporation|Boss]] DD-3 Digital Delay, [[MXR]] Carbon Copy, [[Electro-Harmonix]] Deluxe Memory Man, [[Line 6 DL4]], [[Roland RE-201]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians-->

''Looper pedal'': A looper pedal or ''phrase looper'' allows a performer to record and later replay a phrase, [[riff]] or passage from a song. [[Loop (music)|Loops]] can be created on the spot during a performance ([[live looping]]) or they can be pre-recorded. By using a looper pedal, a singer-guitarist in a [[one person band]] can play the backing chords to a song, loop them with the pedal, and then sing and do a [[guitar solo]] over the chords. Some units allow a performer to layer multiple loops, enabling the performer to create the effect of a full band.<ref>{{cite web|title = Starting Point|url = http://loopermusic.com/starting-point|website = LooperMusic.com|access-date = 28 December 2015}}</ref> The first loop effects were created with [[reel-to-reel tape]] using a [[tape loop]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians--><!--[[User:Kvng/RTH]]-->

[[File:Reverb-4-2.jpg|thumb|left|Folded line spring reverberation]]
''[[Reverb effect|Reverb]]'': Reverb units simulate the spacious sounds produced naturally in a huge stone cathedral (or other [[acoustic space]] such as a hall or room). This is done by creating a large number of echoes that gradually fade away in volume or "decay". One early technique for creating a reverb effect was to send an amplified signal of the music via a speaker to another room with reflective surfaces, such as a tile bathroom, and then record the natural reverberations that were produced. A plate reverb system uses an electromechanical [[transducer]] to create vibrations in a plate of metal. [[Spring reverb]] systems, which are often used in guitar amplifiers, use a transducer to create vibrations in a spring. Digital reverb effects use various [[Digital signal processing|signal processing]] [[algorithm]]s to create the reverb effect, often by using multiple feedback [[Delay (audio effect)|delay circuits]]. [[Rockabilly]] and [[surf guitar]] are two genres that make heavy use of reverb.<ref>Hubner, D; Runstein, R (2009). [https://books.google.com/books?id=W9U7A-rSXtEC ''Modern Recording Techniques''], Focal Press. p. 508.</ref>

Reverb effects: [[Electro-Harmonix]] Holy Grail, [[Fender Reverb Unit]].<!--This article has often been used to advertise. List only products that 1.) have Wikipedia articles and 2. ) have been well known for a number of years and used by influential musicians and which have WP articles-->

===Feedback/sustain===

''[[Audio feedback]]'': Audio feedback is an effect produced when amplified sound is picked up by a microphone or guitar pickup and played back through a [[guitar amplifier]], initiating a "feedback loop", which usually consists of high-pitched sound. Feedback that occurs from a vocal mic into a [[PA system]] is almost always avoided. However, in some styles of rock music, electric guitar players intentionally create feedback by playing their instrument directly in front of a heavily amplified, [[distortion (music)|distorted]] [[guitar amplifier]]'s [[speaker enclosure]]. The creative use of feedback effects was pioneered by guitarists such as [[Jimi Hendrix]] in the 1960s. This technique creates sustained, high-pitched [[overtone]]s and unusual sounds not possible through regular playing techniques. Guitar feedback effects can be difficult to perform, because it is difficult to determine the sound volume and guitar position relative to a guitar amp's loudspeaker necessary for achieving the desired feedback sound.<ref>Wright, Ed (2007). [https://books.google.com/books?id=ysmj8vITtzcC ''Left-Handed History of the World''], Murdoch Books. p. 209.</ref><ref>Amelar, Chris (1997). [https://books.google.com/books?id=KsV_l0FeKlwC ''The Guitar F/X Cookbook''], Hal Leonard. p. 41.</ref> Guitar feedback effects are used in a number of rock genres, including [[psychedelic rock]], [[heavy metal music]] and [[punk rock]].
[[File:EBow.jpg|thumb|left|upright|An [[EBow]] guitar string resonator]]

[[EBow]] is a [[brand name]] of Heet Sound Products, of Los Angeles, California, for a small, handheld, battery-powered resonator. The Ebow was invented by Greg Heet, as a way to make a note on an electric guitar string resonate continuously, creating an effect that sounds similar to a bowed violin note or a sustained [[pipe organ]] note. The resonator uses a [[Pickup (music technology)|pickup]] – inductive string driver – feedback circuit, including a sensor coil, driver coil, and amplifier, to induce forced string resonance. The Ebow brand resonator is monophonic, and drives only one string at a time.

Other handheld and mounted guitar and bass resonators have been on the market since the early 1990s, produced in Germany under the SRG brand, which ceased production in 2016, and were available in both monophonic (one string at a time) and polyphonic (multiple strings at a time) models, which included multiple onboard trigger switch effects, such as HPF (high pass filter) for enhancing harmonics and producing feedback effects, and LPF (low pass filter), producing a bass boost with a cello sound on heavy gauge strings.<ref>{{Cite web |url=http://www.effectsdatabase.com/model/srg/d1 |title=Archived copy |access-date=4 May 2020 |archive-date=20 January 2022 |archive-url=https://web.archive.org/web/20220120202528/https://www.effectsdatabase.com/model/srg/d1 |url-status=dead }}</ref> Later EBow models, such as the plus Ebow, contain a mode slide switch on the back, which allows the player to either produce just sustain or [[overtone]] feedback in addition to sustain.<ref name="The Contemporary Guitar"/> Pedals such as the Boss DF-2 and FB-2 use an internally generated signal matched to the pitch of the guitar that can be sustained indefinitely by depressing the pedal. Many [[#Dynamics|compressor pedals]] are often also marketed as "sustainer pedals". As a note is sustained, it loses energy and volume due to diminishing vibration in the string. The compressor pedal boosts its electrical signal to the specified [[dynamic range]], slightly prolonging the duration of the note.<ref>Hunter, Dave (2004). [https://books.google.com/books?id=7DjYrk7Vap4C ''Guitar Effects Pedals: The Practical Handbook'']. Hal Leonard. p. 25.</ref> This, combined with heavy distortion and the close proximity of the guitar and the speaker cabinet, can lead to infinite sustain at higher volumes.

===Other effects===
''Envelope follower'': An envelope follower activates an effect once a designated volume is reached. One effect that uses an envelope follower is the ''[[auto-wah]]'', which produces a "wah" effect depending on how loud or soft the notes are being played.<ref>{{Cite book|last=White, G|first=Louie, G|title=The Audio Dictionary Instruments|url=https://books.google.com/books?id=DulVm8t88QkC&q=flanger+jet+plane|year=2005|publisher=University of Washington Press|page=138|isbn=9780295984988}}</ref><ref>{{Cite book|last=Hopper|first=J|title=The Girl's Guide to Rocking Out|url=https://books.google.com/books?id=RwzQe_h-OjQC|year=2009|publisher=Workman Publishing|page=33|isbn=9780761151418}}</ref>
[[File:Line 6 Flextone III Plus control panel.jpg|thumb|right|A Line 6 modeling amplifier shown from above. Note the various amplifier and speaker emulations selectable via the rotary knob on the left.]]
''[[Guitar amplifier]] modeling'': [[Amplifier modeling]] is a [[Digital data|digital]] effect that replicates the sound of various amplifiers, most often vintage [[tube amplifier]]s and famous brands of speaker cabinets (e.g., the [[Ampeg SVT]] 8x10" bass cabinet). Sophisticated modeling effects can simulate different types of [[speaker cabinet]]s (e.g., the sound of an 8x10" cabinet) and [[miking]] techniques. A rotary speaker simulator mimics the [[doppler]] and [[chorus effect]] sound of a vintage [[Leslie speaker]] system by replicating its volume and pitch modulations, [[overdrive (music)|overdrive]] capacity and [[phase shift]]s.<ref>Bartlett, B; Bartlett, J (2008). [https://books.google.com/books?id=E0uy8adetQoC ''Practical Recording Techniques: The Step-by-step Approach to Professional Audio Recording'']. Focal Press. p. 226.</ref>

''[[Pitch correction]]/vocal effects'': Pitch correction effects use signal-processing algorithms to re-tune faulty intonation in a vocalist's performance <ref>Brice, Richard (2001). [https://books.google.com/books?id=ufVVgLwkcQwC ''Music Engineering''], Newnes. p. 413.</ref> or create unusual [[vocoder]]-type vocal effects. One of the best known examples of this is [[Autotune]], a software program and effect unit which can be used to both correct pitch (it moves a pitch to the nearest semitone), and add vocal effects. Some stompbox-style vocal pedals contain multiple effects, such as reverb and pitch correction.

''Simulators'': Simulators enable electric guitars to mimic the sound of other instruments such as [[Steel-string guitar|acoustic guitar]], electric bass and [[sitar]]. [[Pick up (music technology)|Pick up]] simulators used on guitars with [[single-coil]] pick ups replicate the sound of guitars with [[humbucker]] pick ups, or vice versa. A de-[[fret]]ter is a bass guitar effect that simulates the sound of a [[fretless bass]]. The effect uses an [[Voltage-controlled filter|envelope-controlled filter]] and [[voltage-controlled amplifier]] to "soften" a note's attack both in volume and [[timbre]].<ref>{{cite web|url=http://www.kellyindustries.com/guitars/boss_gt8.html|title=Boss GT-8 Floor Guitar Effects Processor|access-date=10 September 2010|archive-url=https://web.archive.org/web/20100207042056/http://www.kellyindustries.com/guitars/boss_gt8.html|archive-date=7 February 2010|url-status=dead}}</ref>

''[[Bitcrusher]] filters'': Bitcrushers rely on conversion of the audio signal into a digital format (ADC) and the reduction of sound fidelity by utilising bit (and sometimes sample) rates low enough to cause significant colouration and filtering within the audible frequency range.

[[File:Leslie Speaker.jpg|thumb|right|200px|A Leslie rotary speaker in a clear plastic cabinet. Typically, the Leslie is housed in a wooden cabinet.]]
''[[Leslie speaker|Rotary speakers]]'' are specially constructed [[amplifier]] and [[loudspeaker]]s used to create special audio effects by rotating the speakers or a sound-directing duct
to introduce the [[Doppler effect]] and other sound reflections. The rotating speaker baffle creates a chorus-type effect. Named after its inventor, [[Donald Leslie]], it is particularly associated with the [[Hammond organ]] but is used with a variety of instruments as well as vocals. The Hammond/Leslie combination has become an element in many genres of music. The Leslie Speaker and the Hammond Organ brands are currently owned by [[Suzuki Musical Instrument Corporation]].

The ''[[Korg Kaoss Pad]]'' is a small [[touchpad]] [[MIDI]] controller, [[sampler (musical instrument)|sampler]], and effects processor for audio and musical instruments, made by [[Korg]]. The Kaoss Pad's touchpad can be used to control its internal effects engine, which can be applied to a line-in signal or to samples recorded from the line-in. Effects types include pitch shifting, [[distortion]], filtering, [[wah-wah (music)|wah-wah]], [[tremolo]], [[flanging]], [[delay (audio effect)|delay]], [[reverberation]], auto-panning, gating, [[phasing]], and [[ring modulation]].
The Kaoss Pad can also be used as a [[MIDI controller]].

==Bass effects==
[[File:Bass effects - EH, fulltone, MXR, Demeter, AMT.jpg|thumb|right|250px|A selection of bass effect pedals at a music store]]
{{Main|Bass effects}}
[[Bass effects]] are electronic effects units that are designed for use with the low pitches created by an electric bass or for an [[upright bass]] used with a bass amp or [[PA system]]. Two examples of bass effects are [[fuzz bass]] and [[bass chorus]].  Some [[bass amplifier]]s have built-in effects, such as [[distortion (music)|overdrive]] or [[chorus effect|chorus]]. [[Upright bass]]ists in jazz, folk, blues and similar genres may use a bass [[preamplifier]], a small electronic device that matches the impedance between the [[piezoelectric pickup]] and the amp or PA system. Bass preamps also allow for the gain of the signal to be boosted or cut. Some models also offer equalization controls, a compressor, and a [[DI box]] connection.

==Boutique pedals==
[[File:T-Rex Mudhoney-2.jpg|thumb|left|upright|[[T-Rex Engineering|T-Rex]] brand "Mudhoney" overdrive pedal]]
Boutique pedals are designed by smaller, independent companies and are typically produced in limited quantities. Some may even be hand-made, with hand-soldered connections. These pedals are mainly distributed online or through mail-order, or sold in a few music stores.<ref>{{cite web|url=http://www.keithmcmillen.com/products/batt-o-meter/whereToBuy.php|title=Batt-O-Meter : Where to Buy|publisher=•Keith McMillen Instruments|access-date=18 September 2010}}</ref> They are often more expensive than mass-produced pedals<ref>{{cite book|last=Hunter|first=Dave|url=https://books.google.com/books?id=7DjYrk7Vap4C|title=Guitar Effects Pedals: The Practical Handbook|year=2004|publisher=Hal Leonard|page=204|isbn=9781617747021}}</ref> and offer higher-quality components, innovative designs, in-house-made knobs, and hand-painted artwork or etching. Some boutique companies focus on re-creating classic or vintage effects.<ref>{{cite web|url=http://www.jimdunlop.com/blog/?p=384 |title=What is True Bypass? |publisher=Dunlop News |access-date=18 September 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110824235134/http://www.jimdunlop.com/blog/?p=384 |archive-date=24 August 2011  }}</ref>{{better source needed|date=May 2018}}

Some boutique pedal manufacturers include: [[BJFE]], [[Pete Cornish]], [[Emlyn Crowther]], [[Death By Audio]], [[Robert Keeley (instrument maker)|Robert Keeley]], [[Roger Linn]], [[Roger Mayer (engineer)|Roger Mayer]], [[Strymon (company)|Strymon]], [[T-Rex Engineering]], ToadWorks, and [[Z.Vex Effects]].<!--Do not add any companies to this list who do not have Wikipedia articles. There are literally thousands of boutique pedal makers and we cannot have them all listed here. This section has continually been used to advertise and this is NOT tolerated on Wikipedia.-->

===Modification===
There is also a [[niche market]] for modifying or "modding" effects.{{citation needed|date=May 2018}} Typically,{{according to whom|date=May 2018}} vendors provide either custom modification services or sell new effects pedals they have already modified.{{citation needed|date=May 2018}} The [[Ibanez Tube Screamer]], [[Boss DS-1]], [[Pro Co RAT]] and [[DigiTech Whammy]] are some of the most often-modified effects.<ref name="Moraga">{{cite web|last=Moraga|first=Christian|url=http://www.effectsbay.com/2009/11/mod-it-yourself-m-i-y-part-1/|title=Mod.It.Yourself (M.I.Y) Parts 1 – 3|date=19 November 2009|publisher=Effects Bay|access-date=18 September 2010}}</ref><ref>{{cite web|url=http://www.cubisteffects.com/category/modifications/|title=Modifications|publisher=cubisteffects|access-date=18 September 2010|archive-url=https://web.archive.org/web/20100830041804/http://www.cubisteffects.com/category/modifications/|archive-date=30 August 2010|url-status=dead}}</ref> Common modifications include value changes in capacitors or resistors, adding [[DI unit#Active units|true-bypass]] so that the effect's circuitry is no longer in the signal path, substituting higher-quality components, replacing the unit's original operational amplifiers (op-amps), or adding functions to the device, such as allowing additional control of some factor or adding another output jack.<ref name="Moraga"/><ref>{{cite web|url=http://www.diystompboxes.com/pedals/schematics.html|title=Selected Stompbox Schematics|publisher=DIY Stompbox|access-date=18 September 2010}}</ref><ref>{{cite magazine |last=Platt |first=Charles |url=http://makezine.com/15/stomp/ |title=Stompbox Basics: Tremolo and Fuzz |archive-url=https://web.archive.org/web/20100928121747/http://makezine.com/15/stomp/ |archive-date=28 September 2010 |magazine=MAKE Magazine |date=9 September 2008}}</ref>

==Other pedals and rackmount units==
[[File:Korg Pitchblack (tuned).jpg|thumb|left|120px|Some rock and pop guitarists and bassists use "[[stompbox]]" format electronic tuners.]] 
Not all stompboxes and rackmounted electronic devices designed for musicians are effects. [[Strobe tuner]] and regular [[electronic tuner]] pedals indicate whether a guitar string is too [[Sharp (music)|sharp]] or [[Flat (music)|flat]].<ref>Chappell, Jon; Phillips, Mark (2005). [https://books.google.com/books?id=jvNSyI6C3hEC ''Guitar for Dummies''], For Dummies. p. 291.</ref> Stompbox-format tuner pedals route the electric signal for the instrument through the unit via a 1/4" patch cable. These pedal-style tuners usually have an output so that the signal can be plugged into a [[guitar amp]] to produce sound. Rackmount [[power conditioner]] devices deliver a voltage of the proper level and characteristics to enable equipment to function properly (e.g., by providing transient impulse protection). A rackmounted wireless receiver unit is used to enable a guitarist or bassist to move around on stage without being connected to a cable. A footswitch pedal such as the "A/B" pedal routes a guitar signal to an amplifier or enables a performer to switch between two guitars, or between two amplifiers.

[[File:Fender 2-button 3-function Footswitch (Channel,Drive,More Drive).jpg|thumb|right|160px|This footswitch ''controls'' an effect (distortion), but it is not an effects pedal as the case does not contain effects circuitry; it is just a switch.]]
Guitar amplifiers and [[electronic keyboards]] may have switch pedals for turning built-in reverb and distortion effects on and off; the pedals contain only a switch, with the circuitry for the effect being housed in the amplifier chassis.<ref>Chappell, Jon; Phillips, Mark (2005). [https://books.google.com/books?id=jvNSyI6C3hEC ''Guitar for Dummies''], For Dummies. p. 187.</ref> Some musicians who use rackmounted effects or laptops employ a [[MIDI]] controller pedalboard or armband remote controls to trigger sound [[Sampling (music)|samples]], switch between different effects or control effect settings.<ref>{{Cite book|last=Delaney|first=Martin|url=https://books.google.com/books?id=3Sn4FaSVE-4C|title=Ableton Live 6 Tips and Tricks|year=2007|publisher=PC Publishing|page=5|isbn=9781906005023}}</ref><ref>{{citation|last=Kahn|first=Scott|title=Racks 201: MIDI Foot Controllers|url=https://musicplayers.com/2006/03/racks-201-midi-foot-controllers|periodical=Music Players|date=6 March 2006|access-date=18 September 2010}}</ref><ref>{{citation|url=http://www.effectsbay.com/2010/11/armband-controller-for-effects-chain/|title=Armband Controller for Effects Chain|date=23 October 2010|access-date=1 March 2011}}</ref> A [[pedal keyboard]] uses pedals, but it is not an effect unit; it is a foot-operated keyboard in which the pedals are typically used to play [[bassline]]s.

==Notable manufacturers==
*[[Dunlop Manufacturing]]/[[MXR]]
*[[Maxon Effects]]
*[[Electro-Harmonix]]
*[[Morley Pedals]]
*[[Eventide, Inc|Eventide Inc.]]
*[[Mu-Tron]]
*[[Roland Corporation|Roland]]/[[Boss Corporation]]
*[[TC Electronic]]/[[Behringer]]
*[[Seymour Duncan]]
*[[Zoom Corporation]]
*[[Tech 21]]
*[[Fulltone]]
*[[Z.Vex Effects]]
*[[Frantone Electronics]]
*[[T-Rex Engineering]]
*[[Universal Audio (company)|Universal Audio]]
*[[BJFE]]
*[[Keeley Electronics]]
*[[EarthQuaker Devices]]
*[[Strymon (company)|Strymon]]
*[[Source Audio]]
*[[JHS Pedals]]
*[[Wampler Pedals]]
*[[Darkglass|Darkglass Electronics]]
*[[Mooer Audio]]
*[[Supro]]
*[[DOD Electronics]]
*[[Chase Bliss Audio]]
*[[Meris (company)|Meris]]

==See also==
* {{slink|Acoustic wave|See also}} — a list of non-electronic audio effects
* [[:Category:Audio effects]]
* [[Frequency divider]]
* [[Frequency mixer]]
* [[Nonlinear filter]]
* [[Outboard gear]] — effects units used in the context of [[audio mixing]]
* [[Sound effect]]
* [[Vintage musical equipment]]

==References==
{{Reflist}}

{{Music production}}
{{Music technology}}

{{Portal bar|Music}}
{{Authority control}}

{{DEFAULTSORT:Effects Unit}}
[[Category:Effects units| ]]
[[Category:Electric guitars]]
[[Category:Guitars]]
[[Category:Sound recording]]
[[Category:Rock music]]
[[Category:Sound effects]]
[[Category:Pedals]]