Effects unit

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/overdrive, often used with electric guitar in electric blues and rock music; dynamic effects such as volume pedals and compressors, which affect loudness; filters such as wah-wah pedals and graphic equalizers, which modify frequency ranges; modulation effects such as chorus, flangers and phasers; pitch effects such as pitch shifters; and time effects such as reverb and delay, which create echoing sounds and emulate the sound of different spaces.^[1]^[2]

Most modern effects use solid-state electronics or digital signal processors. Some effects, particularly older ones such as Leslie speakers and spring reverbs, use mechanical components or vacuum tubes. Effects are often used as stompboxes, typically placed on the floor and controlled with footswitches. They may also be built into guitar amplifiers, instruments (such as the Hammond B-3 organ), tabletop units designed for DJs and record producers, and rackmounts, and are widely used as audio plug-ins in such common formats as VST, AAX, and AU.

Musicians, audio engineers, 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 electric or electronic instruments, they can be used with any audio source, such as acoustic instruments, drums, and vocals.^[3]^[4]

Terminology

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.^[5]

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 mounted road case, this case may be called an effects rack or rig. When rack-mounted effects are mounted in a road case, 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.^[6]^{[failed verification]} An effects unit can consist of 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 auxiliary output of a mixer or a DAW — is patched into the effect.^[7]^[8] Whatever the form factor, effects units are part of a studio or musician's outboard gear.^[9]

Stompboxes

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 is 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").^[6]^[10]

An 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.^[11] 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.^[12]

It is common to put compression, wah and overdrive pedals at the start of the chain; modulation (chorus, flanger, phase shifter) in the middle; and time-based units (delay/echo, reverb at the end.^[13] When using many effects, unwanted noise and hum can be introduced into the sound. Some performers use a noise gate pedal at the end of a chain to reduce unwanted noise and hum introduced by overdrive units or vintage gear.^[14]

Rackmounts

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 industry. Rackmount effects have a standardized 19-inch width, and height of 1 or more rack unit(s). Devices that are less than 19 inches wide can sometimes be made rackmount-compatible via special rackmount adapters.^[15]

A rackmount effects unit may contain electronic circuitry identical to a stompbox's, although its circuits are typically more complex. Unlike stompboxes, rackmounts usually have several different types of effects.^[16] 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.^[17]

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

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.^[18] 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 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.^[19]

Built-in units

Effects are often incorporated into instrument amplifiers and even some types of instruments. Electric guitar amplifiers often have built-in reverb, chorus and distortion, while acoustic guitar and keyboard amplifiers 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 amplifiers, the only control on the 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 compressor/limiter or fuzz bass effect.^[20]^{[better source needed]}

Instruments with built-in effects include Hammond organs, electronic organs, electronic pianos and digital synthesizers.^[21] Built-in effects for keyboards typically include reverb, chorus and, for Hammond organ, vibrato. Many clonewheel organs include an overdrive effect. Occasionally, acoustic-electric and electric guitars will have built-in effects, such as a preamp or equalizer.^[22]^[23]

History

Studio effects and early stand-alone units

The earliest sound effects were strictly used in studio productions. Microphones placed in echo chambers with specially designed acoustic properties simulated the sound of live performances in different environments. In the mid to late 1940s, recording engineers and experimental musicians such as Les Paul began manipulating reel-to-reel recording tape to create echo effects and unusual, futuristic sounds.^[24]^[25] In 1941, DeArmond released the Model 601 Tremolo Control,^[26] 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.^[27] 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 transformers and high voltages. 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 tape echo effect made famous by the British band, The Shadows.^[28]^[29]

Amplifiers

Effects built into tube-powered guitar amplifiers were the first effects that musicians used regularly outside the studio. From the late 1940s onward, the Gibson began including vibrato circuits in combo amplifiers that incorporated one or more speakers with the amp. The 1950 Ray Butts EchoSonic amp was the first to feature a tape echo,^[30] which quickly became popular with guitarists such as Chet Atkins, Carl Perkins, Scotty Moore, Luther Perkins, and Roy Orbison.^[31] Both Premier and Gibson built amplifiers with spring reverb. Fender began manufacturing the tremolo amps Tremolux in 1955 and Vibrolux in 1956.^[32]

Distortion was not an effect originally intended by amplifier manufacturers, but could often easily be achieved by overdriving the power supply in early tube amplifiers. In the 1950s, guitarists began deliberately increasing gain beyond its intended levels to achieve warm distorted sounds.^[33] Among the first musicians to experiment with distortion were Willie Johnson of Howlin' Wolf,^[33] Goree Carter,^[34] Joe Hill Louis,^[35]^[36] Ike Turner,^[37] Guitar Slim,^[38] and Chuck Berry.^[39]

In 1954, Pat Hare produced heavily distorted power chords for several recordings (including James Cotton's "Cotton Crop Blues"), creating "a grittier, nastier, more ferocious electric guitar sound,"^[40] accomplished by turning the volume knob on his amplifier "all the way to the right until the speaker was screaming."^[41] Link Wray's 1958 recording "Rumble" inspired young musicians such as Pete Townshend of The Who, Jimmy Page of Led Zeppelin, Jeff Beck, Dave Davies of The Kinks, and Neil Young to explore distortion by various means.^[42] 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.^[43]^[44]

Stompboxes

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".^[45]^[46]

Warwick Electronics manufactured the first wah-wah pedal,^[47] The Clyde McCoy, in 1967 and that same year Roger Mayer developed the first octave effect, which Jimi Hendrix named "Octavio".^[48] 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".^[49] 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 effects of the Leslie rotating speakers used in Hammond organs. The pedals soon became favorite effects of guitarists Jimi Hendrix and Robin Trower. In 1976, 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.^[50] By the mid-1970s a variety of solid-state effects pedals including flangers, chorus pedals, ring modulators and phase shifters were available.^[51]^[52]

In the 1980s, digital 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]} The success of 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.^[53] Throughout the 1990s, musicians committed to a lo-fi aesthetic such as J Mascis of Dinosaur Jr., Stephen Malkmus of Pavement and Robert Pollard of Guided by Voices continued to use analog effects pedals.^[54]

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,^[55] is commemorated by the Depeche Mode song "Big Muff" and the Mudhoney 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.^[56]

Techniques

Distortion

Distortion effect

Electric guitar played first clean (no effects), then with distortion pedal.

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Distortion, overdrive, and fuzz effects units add a warm, gritty, or fuzzy character to an audio signal by re-shaping or 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 effects, as distorted guitar sounds were first achieved by increasing the gain of tube amplifiers.^[57]^[58]^[59]

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.^[60]^[61]

Notable

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