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    Guitar Effects Schematics & Projects

    Guitar Effects Schematics & Projects

    Guitar Effects Background Information


    Guitar effects are electronic devices that modify the tone, pitch, or sound of an electric guitar.


    Effects units are electronic devices that affect the sound of an electric or electronic instrument or other audio source. Effects can be used in "real time", during a live performance (typically used with an electric guitar, electronic keyboard, or electric bass), or in post-production, with recorded vocals and instruments. To use an effect in a live performance, the effect is plugged in to the electrical signal path of the instrument. In a post-production setting, the source's auxiliary output is patched into the effect. Effects can also be used on other instruments or sound sources, like the Rhodes electric piano, acoustic instruments, or drums. While some effect units "color" the sound in a subtle way, others transform the sound in a dramatic fashion.

    An effects unit consists of analog or digital circuitry which processes audio signals. In some cases, effects processing circuitry is similar to that found in music synthesizers, as it may include active and passive filters, envelope followers or envelope modifiers, wave-shaping circuits, voltage-controlled oscillators, or digital delays.

    Effects units come in several formats, the most common of which are the stomp-box and the rack-mount unit. A "stomp box" (or "pedal") is a small metal or plastic box containing the circuitry which is placed on the floor in front of the musician and connected in line with the patch cord connected to the instrument. The box is typically controlled by one or more foot-pedal on-off switches and it typically contains only one or two effects.

    A rack-mount effects unit may contain the identical electronic circuit, but is mounted in a standard 19" equipment rack. Usually, however, rack-mount effects units contain several different types of effects. They are typically controlled by knobs or switches on the front panel, and often by a MIDI digital control interface. "Guitar pedalboards" are used by musicians who use multiple stomp-boxes; these may be a DIY project made with plywood or a commercial pedalboard.

    Modern desktop and notebook computers often have sound processing capabilities that rival commercially available effects boxes. Some can process sound through VST or similar plugins, such as LADSPA, RTAS or Direct X. With a decent sound card, musicians can play any instrument through a computer, emulating effects units or amplifiers. Many VST-plugins are can be downloaded for little or no cost.



    Clean boost or any other "booster"
    Amplifies some aspect of the instrument's signal output. Generally used for preventing signal loss through long chains of effects units (pedals) and boosting volume for solos. On stage, guitarists who are switching between rhythm guitar and lead guitar may use a clean boost device to boost the volume of their guitar solos. Most clean boost pedals have an on-off switch that can be operated with the foot and a potentiometer to set the gain level. In cases where guitarists use a booster to get overdrive tones out of a tube amp, the booster can be considered to have a tone-modifying function.
    Mic pre-amp
    A mic preamp accomplishes a similar result for microphones that the "clean booster" does for guitar, except that a mic preamp is designed for use with a microphone. It increases a microphone's low output voltage to a stronger, more usable level. Some mic pre-amps also provide phantom power for condensor mics and equalization pre-sets for different tonal effects. The least expensive single-channel mic preamps cost less than $100 USD; the most expensive tube preamps cost several thousand dollars.
    This effect reduces the gain of the signal in high-frequency bandwidths when it contains heavy emphasis of high frequencies. De-essers are usually used to reduce or eliminate excess sibilant 's' or 't' sounds in recordings of the human voice. These unwanted sounds are typically in frequencies between 2 kHz-10 kHz.
    This effect automatically varies the gain of an audio signal to reduce the dynamic range of the signal. In effect, a compressor is an automatic volume control which reduces loud sounds over a certain threshold. A compressor can also function as a limiter if with an extreme setting of the controls (in some cases, a compressor may be marketed as a limiter).
    Tremolo produces a periodic variation in the amplitude (volume) of the note or chord, which creates a "shuddering" effect. A sine wave applied as input to a voltage-controlled amplifier produces this effect. Tremolo effects normally have a "rate" knob which allows a performer to change the speed of the variation. Some tremolo effects also have a "depth" knob (see Guyatone VT2 above). The "tremolo" effect described here should not be confused with the mis-named "tremolo bar", a device on a guitar bridge which allows the player to create a vibrato or pitch-bending effect.
    Noise gate
    This pedal attempts to remove hum, hiss and static by gating out sounds below a certain gain threshold. The entire signal is reduced in amplitude when the signal amplitude of the entire signal falls below a certain adjustable level. This significantly reduces noise as well as any other sounds coming into the pedal. (In some rare cases, musicians will use a pedal that does the exact opposite-the "lo-fi" pedal, which adds noise, hiss, and static; see below in the Tone section). As is the case with a number of pedals, even though the noise gate was intended to be a "transparent" effect, if it is used with extreme settings along with reverb, it can create unusual sounds, such as the gated drum effect used in 1980s pop songs, a style popularized by the Phil Collins song In the Air Tonight.


    Overdrive and distortion
    Overdrive is a gain (amplification) and distortion obtained by pushing vacuum valves (called "tubes" in the US) to their limits, which creates warm, rich-sounding "soft clipping". If the valve is driven harder, the compression becomes more extreme and the peaks of the waveforms are clipped. This adds additional odd-order harmonics, creating a "dirty" or "gritty" tone. A number of overdrive-style effects do not contain tubes (valves), and thus the effect is simulated by transistors or a computer chip. Distortion created using transistor "clipping" stages behaves far more linearly within their operating regions; when the input voltage falls outside its operating region of the amplifier, the signal is clipped without compression, known as "hard clipping", a sound which has more odd-order harmonics (see Fuzzbox). The number of controls on overdrive style pedals ranges from two knobs and an on-off switch on a relatively simple pedal like the FuzzFace to seven knobs, four tone-shaping switches, and two footswitches on a complex pedal such as the Radial Tonebone Classic TriMode distortion pedal.
    Wah-wah pedal 
    An effect which mimics the human voice by sweeping the peak response of a filter up and down in frequency to create a spectral glide. The device is operated by a foot treadle that opens and closes a potentiometer. Examples include: Eric Clapton's guitar sound in "White Room" by Cream. It is also popular in funk and psychedelic rock, i.e. Jimi Hendrix and Pink Floyd. A variant form of this effect is the auto-wah, a device that automatically creates the same effect. Some wah pedals come with other effects combined into the unit, typically fuzz or overdrive. When a wah pedal comes with an additional effect (e.g., fuzz), the player may be provided with a side-mounted foot-switch for toggling the fuzz effect on and off.
    Ring modulation 
    An effect that multiplies two signals, where one is typically a sine-wave or another simple waveform. It and outputs the sum and difference of the two pitches, creating a signal rich in overtones, with an unusual bell-like or metallic sound. A notable example is the guitar in the Black Sabbath song "Paranoid".
    Adjusts the frequency response in a number of different bands of equalization. The effect, which is often referred to as an "EQ" has variants including the parametric EQ which instead of flatly boosting and cutting frequencies, curves the frequency response to include changes in adjacent frequencies. As well the paragraphic EQ, which combines the visual interface of the graphic EQ with the flexibility of the parametric EQ, giving each band its own adjustable "Q" ("Q" refers to the width of the band). Setting a very narrow "Q" allows a performer to make very precise adjustments (such as reducing a single note which is overly resonant), without adversely affecting the tone of the instrument.
    Talk box 
    An effects device that allows a musician to modify the sound of a musical instrument by lip syncing, or by changing the shape of their mouth.The device contains a speaker attached with an airtight connection to a plastic tube with connectors for the connection to the speaker output of an instrument amplifier. The other end of the tube is taped to the side of a microphone, extending enough to direct the reproduced sound in or near the performer's mouth. The shape of the mouth filters the sound, with the modified sound being picked up by the microphone. The effect is manipulated by vocal technique. Notable uses include Rufus's "Tell Me Something Good", Peter Frampton's "Show Me the Way", Aerosmith's "Sweet Emotion" and by Slash in many songs and solos. Also used in many Bon Jovi songs. One of the most prominent and consistent talk box users was Roger Troutman, Zapp frontman and solo artist.
    Filter and synthesizer effects
    Pedals such as the Moog MF-105 Moogerfooger MURF provide multiple filters and envelope control knobs to control modulation. The MF-107 FreqBox uses the input signal to modulate an internal VCO oscillator.
    Lo-fi effects
    These effects emulate the hiss, static, and poor tone quality of vintage analog electronic equipment. The "Radio Havana" pedal uses ceramic capacitors "to supply grit, and a distortion circuit" to " downgrade ... tone quality" and adds a Voltage Starve circuit to "further brea[k] down your tone" . The Ibanez LF7 creates lo-fi "transistor radio and megaphone type sounds" by using "voltage controlled analog high and low pass filters". One of the more extreme lo-fi effects is the Z-Vex Lo-Fi Loop Junky, which adds "hiss, moan, distortion and...strangeness" that converts guitar tone to a "smashed,...shimmering/warbling" of a "warped, damaged 45-rpm record".


    First used by Les Paul, e.g. I'm Forever Blowing Bubbles. Paul achieved time delay by stretching audiotape between two reel-to-reel tape decks spaced several feet apart. The first modern digital delay was the Eventide Harmonizer, which involved sound waves being converted from analog to digital signals, and clocked through large banks of RAM memory. The Edge of U2 is a notable user of this effect in his music. A well-known example of this is the song "Where the Streets Have No Name".
    Uses short, effected delays to simulate an echo. Early echo effects such as the 1959 Echoplex used a tape loop. The length of delay was adjusted by changing the distance between the tape record and playback heads. By the 1970s, many echo units used solid state circuitry. In the 1990s and 2000s, digital echo effects were widely used in mixers and effect pedals.
    Simulates the persistence of sound in a hall or room after the original sound is removed The first reverb effects created for recordings were created by piping the recorded sound into a real physical space such as a tiled bathroom, thus creating a natural echo chamber. In the 1950s and 1960s, portable reverb effects were created, such as the plate and spring reverb systems. A plate reverb system uses an electromechanical transducer to create vibration in a large plate of sheet metal. Spring reverb systems, which are often used in guitar amplifiers, use a transducer at one end of a spring and a pickup at the other. Some tape echo effects from the 1950s and 1960s could also produce a reverb effect. Digital reverb effects use various signal processing algorithms in order to create the reverb effect, often by using multiple feedback delay circuits.
    Uses very short variable delays to cause a changing comb filter effect. First notable uses were in "Itchycoo Park" by Small Faces, and "Sky Pilot" by The Animals. It creates a "sweeping" effect that is similar to the sound of a plane coming in for a landing or the swirling sound of water going down a drain. The flanger was a studio effect at first created by slowing one of the tape flanges in a reel-to-reel tape in regular time.
    Phase shifting (or phasing) 
    Modulates the phase of the signal. Popular during the 1970s; one example includes keyboard part of Paul Simon's "Slip-Slidin' Away". High phasing speeds produce an "underwater" effect, as used by Jimi Hendrix in "1983... (A Merman I Should Turn to Be)".
    Looper pedal
    Also called a "phrase looper", this pedal stores and plays back short loops or phrases, which allows a single performer to solo or "jam" over a backing part. As with the delay effect, the first forms of loop effects were created with reel-to-reel tape using a tape loop. High-end boutique tape loop effects are still used by some studios who want the vintage sound. Digital loop effects recreate this effect using an electronic memory. In the 1990s, digital effects could typically only store a few seconds; by the mid-2000s, some loop effects such as the Gibson Echoplex Digital Pro could store several minutes of sound, and flash memory-based effects such as the Electro-Harmonix 2880 could store nearly an hour of music in one or multiple loops. The DigiTech JamMan Looper Pedal can store up to 6.5 hours of samples, audio clips, or backing tracks .


    Pitch shifter 
    An effect which enables a user to transpose the pitch of the input signal. The simplest pitch shift effects can add octaves above or below the input pitch. More sophisticated pitch shifters can add fourths or fifths. Some 2000s-era pitch shifters can harmonize an input pitch in thirds or sixths, based on the key that is set by the user. This allows a performer to play a melody and have it harmonized like a duo. Pitch shift devices often allow the user to mix the input signal with the effected signal, thus creating a thicker, richer sound (e.g., parallel octaves or fifths). Some pitch shifters can also add very tiny shifts in pitch, thus creating a chorus-like effect. The Harmonizer brand pedal can change the input pitch up or down any interval. Some pitch shifters, such as the Digitech Whammy have a treadle-style footpedal which allows users to create "whammy bar" note-bending effects. The Electro-Harmonix Polyphonic Octave Generator can produce pitches an octave below the note being played, or one or two octaves above the note being played.
    To produce the effect, individual sounds with roughly the same timbre and nearly (but never exactly) the same pitch converge and are perceived as one, an effect which is created naturally in a choir of singers or a string orchestra. The effect creates this sound by splitting the signal into a vibrato effect and a clean path, so that the output is the sum of these inputs. A good quality chorus effect creates a rich, shimmering quality or a double-tracking effect when it is used subtly. It creates a "spacey" sound if it is used in a more pronounced fashion. Better-quality stompbox chorus pedals and almost all rackmount chorus units have stereo outputs, because the chorus effect is more effective when it is heard in stereo.
    Vibrato refers to a variation in frequency of a note. This is done naturally when an opera singer or violin player holding one note for a long time varies the frequency up and down using a fraction of a semitone. Most vibrato effects have a "rate" knob which allows the performer to set how fast the variation will occur. Some vibrato effects also have a "depth" knob that controls the pitch difference in the variation. A vibrato with a very shallow depth (e.g., a fraction of a semitone) can be a subtle effect. A vibrato with an exaggerated "depth" setting (e.g., half of a semitone or more) will produce a more dramatic, ululating sound. Electronically, the vibrato effect is created by taking a sine wave applied as input to a voltage-controlled oscillator.

    Guitarists often use the terms "vibrato" and "tremolo" inconsistently. A so-called vibrato unit in a guitar amplifier actually produces tremolo, while a tremolo arm on a guitar produces vibrato. However, finger vibrato is genuine vibrato. See Electric guitar, tremolo, vibrato.

    Harmonic Exciter
    This effect, which is also known as a "psychoacoustic exciter", adds upper harmonic content and a subtle amount of controlled harmonic distortion to a sound source, which creates a richer tone colour in the upper mid and treble part of the spectrum. Unlike many effects, the Aural Exciter is not usually used in "real time" during the recording. It is usually added to the vocals or the entire track in the post-production stage. The effect was developed in the mid-1970s to add "brightness" to reel-to-reel tape mixes that had lost clarity due to repeated overdubs. Aphex, the company that invented the first "Aural Exciter" effect, claims that the effect provides increased presence and clarity, restored natural brightness, greater perceived loudness, and improved detail and intelligibility.


    While audio feedback in general is undesirable due to the high frequency overtone, when controlled properly, it can provide true sustain of the sound (instead of using a distortion/compressor to make quiet notes louder, or a feedback of a signal in a circuit as in a delay unit). Several approaches have been used to produce guitar feedback effects, which sustain the sound from the guitar. The most primitive form, as used by for example Jimi Hendrix, is to use the feedback created when the guitar is played in front of an instrument amplifier's loudspeaker when it is set to a high volume.

    The neck pickup can be replaced by a magnetic string driver to push the strings based on the bridge pickup, such as the Sustainiac Sustainer and Fernandes Sustainer. A string driver can be mounted on a stand as in the Guitar Resonator. Feedback start, stop and harmonics can be controlled here by positioning the drivers distance to the strings and the position along the guitar neck while playing. A signal amplifier can be used to power the headstock transducer, which in turn sends feedback vibration down the string, as in Sustainiac's Model C. A handheld string driver can contain a pickup and driver, as in the EBow, which uses a small inductor coil to vibrate the string, creating a bow-like sustained sound. A dedicated high-gain guitar amplifier can be used in the control room, without a microphone, as a footswitch-controlled string feedback driver. The microphone is placed on the speaker cabinet of the main guitar amp in the isolation booth or live room. Many compressor pedals are also marketed as "sustainer pedals" as well. Compressor pedals accomplish a limited amount of sustain by compressing the low end signals of the guitar. As a note is sustained, it loses energy and volume because there is less vibration in the string. As the input volume gets lower, the compressor pedal boosts its signal to the specified dynamic range, giving a slightly longer sustain.

    Other specific effects

    In the 2000s, several simulator effects were introduced that make a guitar sound like a different stringed instrument or like a different model. The defretter effect simulates the sound of a fretless bass guitar with a fretted bass. The effect creates a fretless sound through the use of an envelope-controlled filter and voltage controlled amplifier, whose parameters are controlled with an ADSR envelope. This creates a sound in which the note's attack is softened, both in volume and timbre. As well, some fretless simulators add a portamento effect so that one note glides up or down to the next note (a review of the BOSS GT-8 states that the defretter on this unit "slurs between the notes sliding up or down depending on which way you go"). The acoustic guitar simulator makes an electric guitar sound like an acoustic guitar. A bass simulator effect makes an electric guitar sound like an electric bass. a pickup simulator can make a guitar with a single-coil pickup sound like a humbucker or vice-versa. A rarer simulator effect is the sitar simulator, which makes an electric guitar sound like an Indian sitar.
    Rotary speaker simulator
    An electronic effect which simulates the doppler effect sound of a rotating Leslie speaker system. One such pedal, the Uni-Vibe, was made famous by Jimi Hendrix when he used it with electric guitar. The most expensive rotary speaker simulators recreate the amplitude modulation, frequency modulation, and phase shift created by the two rotating speakers, along with the overdrive created by the Leslie's tube amplifier.
    Envelope Follower 
    Uses the signal amplitude envelope to control one or more effects. The envelope follower takes an audio input and converts it into a "control voltage" which rises and falls with the volume of the input signal. The standard controls are threshold, filter, and volume. One effect which uses an envelope follower is the "auto-wah", which automatically produces a "wah" effect based on the dynamics of the notes being played.
    Guitar amplifier modelling 
    Uses digital signal processing to model or recreate the instrument tone produced by various amplifiers, especially to attain the valve sound with solid-state equipment. Some sophisticated modelling effects can simulate the effect of using different vintage tube amplifiers, speaker cabinets, and miking techniques (e.g., miking in front of the cabinet versus behind the cabinet). These types of effects are usually digital, and can therefore be found as features of effect processors such as the Boss ME series and Vox multieffects. Some 2000s-era guitar amplifiers have modelling processors built in.

    Intended use

    Many effects devices are not designed for a specific type of end user, and as such they are used by electric guitarists, bassists, singers, and other performers (e.g., rackmount compressors, reverb units, etc.). Some effects units are designed for and marketed to specific end users, typically electric guitarists, keyboard players, and bass players. In the 2000s, several new target markets for effects units developed, such as vocalists and acoustic instrument users.

    Electric guitar

    Many effects, and the majority of stomp-box pedals, are designed and marketed for use with an electric guitar (e.g., heavy metal distortion pedals; wah-wah pedals, etc). Some pedals are designed for a specific genre of electric guitar player. For example, Barber Electronic's Dirty Bomb, the DigiTech XMM Metal Master, the Boss MT-2 Metal Zone pedal and the MXR M116 Fullbore Metal pedal(all are distortion pedals) are designed to produce extreme distortion for metal guitarists. Other pedals, such as the Seymour Duncan SFX-11 Twin Tube Blues Distortion guitar pedal and the Boss Blues Driver are designed to produce the warm tube-amp overdrive sound used by blues electric guitar players. As well, many electric guitar effects are used by performers of other instruments. Keyboardists use wah-wah pedals and overdrive pedals, and some electric bass players use fuzzboxes or guitar overdrive pedals.


    One of the most notable effects designed specifically for keyboard players is the rotary speaker simulator effect. This effect was designed so that Hammond organists could reproduce the chorus-type effect of a large Leslie rotating speaker without having to transport the heavy speaker cabinet around. Even though rotating speaker pedals are marketed to organ players, some models such as the Uni-Vibe pedal are also used by electric guitar players (e.g., Jimi Hendrix). Many electric guitar effects can be used successfully with keyboard instruments, and there are some combinations which have become well-known (e.g., a guitar phaser pedal used with a Fender Rhodes electric piano). Some effects pedal companies have taken note of this, and in the 2000s, a number of standard guitar pedals are cross-marketed to electronic keyboardists in advertisements (e.g., the Boss Blues Driver).


    Most effects marketed for use with the bass guitar are the same, or almost the same as the similar effects sold for use with the electric guitar. In some cases, though, bass effects do have unique features designed for the electric bass or the double bass. Bass preamplifiers for double basses are designed to match the impedance of piezoelectric pickups with the input impedance of bass amplifiers. Some double bass preamplifiers may also provide phantom power for powering condenser microphones and anti-feedback features such as a notch filter. Makers of bass distortion (or "fuzz bass") effects claim that bass-specific distortion pedal maintain the low-range bass signal better than distortion pedals designed for electric guitar. Paul McCartney of The Beatles used fuzz bass on "Think for Yourself" in the 1965 album Rubber Soul and Hugh Hopper from the jazz rock band Soft Machine in 1968 and 1969. Hopper's use of the fuzz bass sound allowed the bass to be forefronted more in the band, and take on more of a melodic, lead instrument role. Fuzz bass went out of fashion for much of the 1970s, as the desired sound of the era was a clean "hi-fi" tone. In the 1980s and subsequent decades, bass distortion came back, but mostly in the metal and hardcore punk styles.

    Some manufacturers sell bass equalizers, which, while similar in operation and design to an electric guitar graphic equalizer, have a lower frequency range that goes down to 40 Hz or even below. Bass-specific wah pedals and bass chorus effects are also available. Bass wah pedals optimize the frequency of the sweep so that it will work better with the lower range of the electric bass. Some bass chorus effects devices only apply the swirling chorus effect to the higher parts of the bass tone, leaving the instrument's low fundamental untouched. Multi-effects devices designed specifically for electric bass reconfigure the effects so that they are compatible with the electric bass' low range and include electric bass-oriented effects such as a fretless bass simulator effect or a bass synthesizer. Some multi-FX pedals for bass contain modelled versions of well-known bass effects pedals, bass amplifiers, and bass speaker cabinets. Just as some electric guitar pedals are cross-marketed to keyboard players, some electric guitar pedals are cross-marketed to bass players. Some BOSS electric guitar pedals have an alternate 1/4" jack input for an electric bass which has circuitry which optimizes the effect for the lower range of the bass.


    Some floor-based effects units are designed for use by singers, such as harmonizer pedals (which add a harmony part to a vocal melody) and pitch correction pedals or rack-mount units. Examples include the TC Helicon VoiceLive 2 Floor-Based Vocal Processor (which vocal backup group); the Electro-Harmonix Voice Box Harmony Machine/Vocoder; the TC Helicon VoiceTone Correct Vocal Pedal; and the DigiTech Vocalist Live Pro Vocal Harmony Processor. Although of these portable, floor-based pedals were introduced in the 2000s, the innovation was largely the way that the technology was packaged into a rugged, road-ready chassis; many of these effects were only previously available in larger, heavier studio rack-mount units. As well, vocalists also use generic effects devices, such as compressors and reverb units. An example of a rack unit designed for vocalists is the Antares AVP Vocal Producer, which includes mic modeling technology, electronic pitch correction, tube pre-amp modellers, a de-esser, and parametric EQ, all of which is designed for use by a singer. More rarely, vocalists might route their microphone through a guitar pedal such as distortion pedal or a flanger to create an unusual effect.

    Acoustic instruments

    Another newer target market is acoustic instrument players who perform on acoustic guitar, mandolin, violin, and similar instruments. These units are often designed to be "all-in-one" devices that will condition and equalize acoustic instrument signals so that they can be plugged directly into a mixer or PA system. Several companies such as Fishman, L.R. Baggs and Boss make stomp-box pedal style effects units for this market. These pedals typically contain a pre-amp, impedance-matching circuitry for piezoelectric pickups, equalization filters, and a DI output.

    Some of the more sophisticated pedals also include a compressor for smoothing out loud notes, a notch filter or feedback detector for preventing feedback howls (a common problem with acoustic instruments), and chorus or reverb effects. Many of these units have a microphone input and phantom power so that a condenser microphone can be mixed with the pickup sound. There is some variation in the format or housing. Many units are pedal-style units which have foot-operated switches for switching between pre-set sounds, activating reverb or chorus effects, etc. Units that are designed to be mounted on a belt clip or placed on a tabletop typically lack foot-operated switches.

    Boutique pedal manufacturers

    Boutique pedals are typically handmade or produced in small batches and designed by smaller, independent companies. Usually, they are mainly distributed online, through mail-order, or through a small number of music stores. In some cases, these products depend on "word-of-mouth" advertising. The prices of boutique pedals are too high to compete with mass-produced brands such as Boss or Digitech. Boutique manufacturers offer products and features for the more discriminating guitar player—features such as true-bypass switching, higher-quality components, and innovative designs. Other boutique companies focus on re-creating classic or vintage effects that are no longer available. The Dallas Arbiter Fuzz Face and Dallas Rangemaster are classic effects that are produced in many variations by the boutique industry. Some boutique pedal manufacturers add hand-painted artwork to each pedal chassis.

    Some boutique pedal manufacturers include:

    • AnalogMan
    • Pete Cornish
    • Lovetone
    • Metasonix
    • Moog Music
    • Robert Keeley
    • Z.Vex Effects
    • T-Rex Engineering

    Other boutique markets

    There is also a niche market for the modification (nicknamed "modding") of effects. Typically, vendors provide either custom modification services or they sell new effects pedals which have been modified. The Ibanez Tube Screamer, the Boss DS-1, the ProCo Rat and Digitech Whammy are some of the most commonly modified effects. Mods typically encompass value changes in capacitors or resistors, adding true bypass (when deselected, the effect's circuitry is no longer in the signal path), the substitution of higher-quality components, the replacement of the unit's original operational amplifiers (opamps) with different ones, or adding additional functions to the device (e.g., allowing additional control of some factor or adding an additional output jack).


    Effects units are available in a variety of formats, which provide for the needs of varying musical situations (recording, live performance) and budgets, and integrate with particular instrument setups. Stomp-box style pedals are usually the smallest and least expensive type of effect device for a typical effect purpose, and they are the most rugged format. Rackmount devices are larger, and they need to be protected in a rack case if they are taken on the road; at the same time, rackmount devices typically offer a wider range of functions and input-output jacks than the equivalent stomp box. As well, a rack-mount compressor or reverb unit designed for use in a studio will often have less noise than its stomp-box counterpart that is intended for use with an electric guitar.


    Stompboxes, or effects pedals, are effects units designed to sit on the floor or a pedalboard and be turned on and off with the user's feet. They typically house a single effect. An effects pedal is connected into a signal chain using two 2-conductor (conductor and shield) instrument cables with 1/4" jack plugs (or "phone plugs"). The input jack is usually on the right side, and output on the left; thus the signal path for a chain of pedals is usually right-to-left. Some effects pedals have stereo out via two mono out signals, and a few have stereo input jacks as well as stereo output jacks. Some effects pedals have expression pedal in-jack (e.g., some ZOOM multiFX stompboxes) or an additional pedal-in jack (e.g., some overdrive pedals can have an additional switch added for a "turbo" distortion boost effect).

    The simplest stompbox pedals have a single footswitch and one or two potentiometers for controlling the effect, gain, or tone, and a single LED to indicate the status of the effect to the player. The most complex stompbox pedals have multiple footswitches, eight to ten knobs, additional switches, and an alphanumeric display screen that can indicate the status of the effect with short acronyms (e.g.,DIST means "distortion").

    Several pedals can be linked together in a chain. An effects chain can be placed between the guitar and the guitar amplifier's preamp section, within the guitar amplifier's effects loop, after a guitar amplifier's DI (Direct Inject) line-level tap jack, after a "dummy load" attached to the guitar amplifier's output jack, or at the mixing board to process the miked guitar-speaker signal.

    When a pedal is off or inactive, the signal coming in to the pedal is shunted onto a bypass, so that the "dry" or unaffected signal can go on to other effects down the chain, and thus any combination of effects on a chain can be created without having to reconnect boxes during a performance. "True Bypass" means the presence of an isolated wire passing straight through the effects pedal, as opposed to "buffered bypass," which uses active circuit elements to connect the input to the output. While these are 2 popular configurations, there are other bypass methods, such as input-only bypass which is semi-passive.

    The instrument signal can be routed through the stomp boxes in any combination, but to shape and preserve the clarity of the basic distortion tone, it is most common to put wah and overdrive pedals at the start of the chain; pedals which alter the pitch or color of the tone in the middle; and delay (echo) and reverb units at the end. When using many effects, unwanted noise and hum can be introduced into the sound. Some performers use a noise gate pedal at the end to reduce unwanted noise and hum introduced by overdrive units or vintage gear. Some performers make more complex signal chains by adding a loop selector pedal to switch between two effects loops. A guitarist might create a grungy rhythm guitar tone with an overdrive pedal, a lo-fi pedal, and a sub-octave pedal, and then use the loop selector pedal to switch to a shimmering, clear tone created with a reverb pedal, an acoustic guitar simulator pedal, and a chorus pedal. Another more complicated way of using multiple pedals is to use a line selector/mixer pedal to blend two effects loops together.


    Rackmounted effects are built into a case designed to integrate into the 19-inch rack standard also used by the telecommunication and computing industries. Rack effects are commonly used in recording studios and front of house settings. Rackmount effects can be one, two, or three rackspaces high. As well, some rackmount effects do not have the full width of a 19-inch rack, so special rack "ear" adapters are needed to mount these devices (e.g., the Alesis Nanocompressor and Nanoverb units). In some cases, when a user does not intend to transport effects units (e.g., when the effects are used in a studio), rackmountable effects may be placed on a shelf or tabletop. Rackmount cases range from soft-sided cases built around a frame, intended for easy carrying with a strap, to hard plastic cases intended for musicians who are transporting the effects in a van, to "shock mount" cases, which cushion the entire rack frame in foam. Shock mount racks are designed for musicians who are shipping gear on major tours.

    Tabletop units

    A tabletop unit is one which is meant to sit on a desk and be controlled primarily with hands rather than feet. The Pod guitar amplifier modeller is a rare exception in the world of guitar effects, because it is not intended to be operated with the feet like a stomp-box pedal. Some portable effects designed for small studios are also intended to be placed on a tabletop, such as some tube preamp effects which are not sold with rack "ears". Digital effects designed for DJs are often sold in tabletop models as well, as it is anticipated that the unit will be placed alongside a mixer, turntables and CD scratching gear.

    Built-in units

    Effects are often incorporated into amplifiers, mixers, and even some types of instruments. Guitar amplifiers often come with built-in reverb and distortion effects. Guitar amps from the 1950s and 1960s often had tremolo effects and a spring- or plate reverb. In the 2000s, some guitar amplifiers have built-in multiFX units of digital modelling effects, which give the user access to a wide range of sounds. Keyboard amplifiers and acoustic guitar amplifiers often have a built-in reverb effect. While bass amplifiers are less likely to have built-in effects, in some cases bass amplifiers have a built-in compressor/limiter or an overdrive effect (an example of the latter is the Roland D-500 amplifier). More rarely, a high-end bass amplifier may have a sub-octave effect (e.g., the Mo'Bass amp head).

    Even in the 1960s and 1970s, many mixers had simple built-in reverb or echo effects. Since the 2000s, many mixers have an onboard digital multi-effects unit which produces a variety of delay, reverb, and echo effects. Some instruments with built-in effects include Hammond organs (chorus and vibrato); electronic organs (chorus and reverb); and electronic pianos (reverb). In a few rare cases, effects are built into stringed instruments, as in the case of acoustic-electric guitars which have an on-board preamp and equalizer or electric guitars that have modelling effects built-in.

    Multi-effects devices

    A multi-effects device (also called a "multi-FX" device) is a single electronics effects pedal or rackmount device that contains many different electronic effects. In the late 1990s and throughout the 2000s, multi-FX manufacturers such as Zoom and Korg produced devices that were increasingly feature-laden. Multi-FX devices allow several of the effects to be used together, and most devices allow users to set "preset" combinations of different effects including distortion, chorus, reverb, compression, and so on. This allows musicians to have quick on-stage access to different effects combinations. Some multi-FX pedals for contain modelled versions of well-known effects pedals or amplifiers.

    Multi-effects devices have garnered a large share of the effects device market because they offer the user such a large variety of effects in a single package. A low-priced multi-effects pedal may provide 20 or more effects for the price of a regular single-effect pedal. More expensive multi-effect pedals may include 40 or more effects, amplifier modelling, and the ability to combine effects and/or modelled amp sounds in different combinations, as if the user was using multiple guitar amps. More expensive multi-effects pedals may also include more input and output jacks (e.g., an auxiliary input or a "dry" output), MIDI inputs and outputs, and an expression pedal, which can control volume or modify effect parameters (e.g., the rate of the simulated rotary speaker effect).

    Other formats

    Some effects units are housed in a unique fashion. The "reverb tanks" of the 1950s come in a rectangular box the size of a guitar amplifier "head". Some 1950s and 1960s tape echo machines were in similarly-sized housings. Perhaps the largest effect is the Leslie rotating speaker system. It consists of a cabinet with a tube amplifier, a bass speaker with a rotating, motor-driven baffle, and a rotating, motor-driven horn for the high frequencies. While the Leslie speaker was first marketed only to church organists who wanted to reproduce the natural chorus effect of an air-blown pipe organ with their electromechanical Hammond organs, by the 1960s and 1970s, the chorusing, rich sound of the Leslie speaker had become an integral part of organ playing in hard bop, soul jazz, psychedelic rock, and even the earliest forms of heavy metal (e.g., Deep Purple).

    Tributes by musicians

    Some effects units, particularly stomp-box style pedals, are celebrated by the music subculture, as can be seen in the references to these pedals in pop and rock songs and even in band names. In some cases, the mystique that is built up around a pedal comes from the notable use of a pedal by an influential musician (e.g., Jimi Hendrix's use of the FuzzFace pedal). In other cases, effects pedal manufacturers have created a cult following for some of their pedals, due to the unique features, tone, or styling of the units. Overdrive and distortion effects have been referred to in songs such as "Big Muff" (Depeche Mode); album and EP titles such as the Superfuzz Bigmuff EP (Mudhoney,1988) and in band names We've Got a Fuzzbox and We're Gonna Use It (an all-female British 1980s band) and The Fuzztones (a 1980s garage rock revival band). Other effects that have been referred to include the a vintage echo unit (in the Nine Inch Nails song "Echoplex"); the Harmonic Generator in a song by The Datsuns; pedals in general in the They Might Be Giants song "Stomp Box"; the Wah-wah pedal in George Harrison's 1970 song "All Things Must Pass" and in the Buffalo Tom song "Besides" (2002). The Super Furry Animals song 'Play It Cool' includes the lyric "The electric mistress always sounds so bold/She says I'm free to do anything I'm told", a reference to the Electric Mistress flanger pedal made by Electro-Harmonix.

    Other electric or electronic pedals and rackmount units

    Not all electric or electronic pedals used in music are effects pedals, in a pure sense. Switching pedals such as "A/B" pedals contain only a switch which can route a guitar signal to two different amplifiers or enable a performer to switch between two guitars onstage. As well, a tuning pedal, which indicates whether a guitar string is sharp or flat, is not an effects pedal. Guitar amplifiers that have on-board effects often come with a switch which turns the reverb or distortion on and off; since the switch pedal only contains on a latching switch, the pedal itself is not an effect (the effect is built into the chassis of the guitar amplifier).

    Electronic keyboards often have several pedals which are placed below the instrument on the floor; even though these pedals (such as the sustain pedal or the soft pedal) may trigger an effect, the pedals themselves do not contain any effects. Some guitarists who use a rack full of rack-mounted digital effects use a MIDI controller pedalboard to switch between different effects or control effect settings. The floor-based controller pedalboard controls effects, but it is not itself an effects device (indeed, a MIDI controller pedalboard can be used to control any device that accepts a MIDI signal, including stage lights). Bass pedal keyboards, which are sometimes called "bass pedals", are used with the Hammond organ or in standalone bass pedals such as the Moog Taurus are not effects pedals. Despite the name "bass pedal", a pedal keyboard is a foot-operated keyboard which triggers organ or other musical tones, not an effect pedal.

    As well, not every rack-mount electronic device used in a musical setting is an effects unit. Rack-mounted tuners, power conditioners, and power amplifiers may be placed in similar chassis' and rack-mountable housings, but they are not effects.

    Notable manufacturers

    • Analogman
    • Behringer
    • Boss Corporation
    • DigiTech
    • DOD
    • Jim Dunlop
    • Electro Harmonix
    • Fulltone
    • Ibanez
    • Korg
    • Lexicon
    • Line6
    • MXR
    • Roland Corporation
    • TC Electronic
    • Waves Audio
    • Vox
    • Zoom
    • Zvex

    Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License and Creative Commons Attribution-ShareAlike License.)

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