Chorus (or chorusing, choruser or chorused effect) is an audio effect that occurs when individual sounds with approximately the same time, and very similar pitches, converge. While similar sounds coming from multiple sources can occur naturally, as in the case of a choir or string orchestra, it can also be simulated using an electronic effects unit or signal processing device.
When the effect is produced successfully, none of the constituent sounds are perceived as being out of tune. It is characteristic of sounds with a rich, shimmering quality that would be absent if the sound came from a single source. The shimmer occurs because of beating. The effect is more apparent when listening to sounds that sustain for longer periods of time.
The chorus effect is especially easy to hear when listening to a choir or string ensemble. A choir has multiple people singing each part (alto, tenor, etc.). A string ensemble has multiple violinists and possibly multiples of other stringed instruments.
Acoustically created
Although most acoustic instruments cannot produce a chorus effect by themselves, some instruments (particularly, chordophones with multiple courses of strings) can produce it as part of their own design. The effect can make these acoustic instruments sound fuller and louder than by using a single tone generator (b.e.: a single vibrating string or a reed). Some examples:
Piano – Each of the hammers strikes a course of multiple strings tuned to nearly the same pitch (for all notes except the bass notes). Professional piano tuners carefully control the mistuning of each string to add movement without losing clarity. However, in some poorly-cared instruments (like the honky-tonk pianos), the effect is more prominent.
Santur (and similar coursed-hammered dulcimers) – As well as on the piano, the player can strike (by using a pair of manual hammers instead) a course of multiple strings tuned to nearly the same pitch. As the instrument is frequently tuned by the musicians themselves (rather than by professional tuners), the chorus effect is more easily heard than on the piano.
12-string guitar, bajo sexto and Greek bouzouki – Courses with pairs of strings, tuned in octaves and unisons, create a distinctive complex shimmer. In the 12-string guitar, this effect is often accentuated by the use of open and modal tunings, such as open-G and DADGAD.
Mandolin, lute and oud – Courses with pairs of identically-tuned strings, as opposed to octaves and unisons on the 12-string guitar.
Accordion – two or three reed blocks tuned to nearly the same pitch, but with one a bit sharp, produce a unique and distinctive "musette" sound exclusive to the accordion, colloquially called a "wet" sound.
Pipe organ – The voix céleste [Fr.] (heavenly voice) is an organ stop consisting of either one or two ranks of pipes slightly out of tune. The term celeste refers to a rank of pipes detuned slightly so as to produce a beating effect when combined with a normally tuned rank. It is also used to refer to a compound stop of two or more ranks in which at the ranks are detuned relative to each other.[1]
However, while the open strings of a standard-tuned guitar (or any single-stringed instrument like ukuleles, banjos, etc.) can't produce any chorus effect, it can also be obtained by the use of alternative tunings (such as the unisons-and-octaves-only "ostrich tuning" by Lou Reed); by playing chords or fingerings with "redundant" notes (like playing the open high E string and the same "E" note on the 5th fret of the B string); and/or by using extended techniques like bending while playing a note (like playing the 5th fret on the 2nd string and, simultaneously, playing a full-tone bending in the 7th fret on the 3rd string).
Ensembles of instruments and voices can produce a natural chorus effect, such as with a string orchestra or choir.
The chorus effect can be simulated by a range of electronic and digital effects units and signal processing equipment, including software effects. The signal processor may be software running on a computer, software running in a digital effect processor, or an analog effect processor. If the processor is hardware-based, it may be packaged as a pedal, a rack-mount module, a table-top device, built into an instrument amplifier (often an acoustic guitar amplifier or an electric guitar amplifier), or even built into some electronic instruments, such as synthesizers, electronic pianos and Hammond organs.
The effect is achieved by taking an audio signal and mixing it with one or more delayed copies of itself. The pitch of the added voices is typically modulated by an LFO, which is implemented similarly to a flanger, except with longer delays and without feedback. In the case of the synthesizer, the effect can be achieved by using multiple, slightly detuned oscillators for each note, or by passing all the notes played through a separate electronic chorus circuit.
Stereo chorus effect processors produce the same effect, but it is varied between the left and right channels by offsetting the delay or phase of the LFO. The effect is thereby enhanced because sounds are produced from multiple locations in the stereo field. Used on instruments like "clean" (undistorted) electric guitar and keyboards, it can yield very dreamy or ambient sounds. Commercial chorus effect devices often include controls that enable them to be used to also produce delay, reverberation, or other related effects that use similar hardware, rather than exclusively as chorus effects.
In spite of the name, most electronic chorus effects do not accurately emulate the acoustic ensemble effect. Instead, they create a constantly moving electronic shimmer. Some pitch shift pedals create a slightly detuned unison effect which is more similar to the acoustic chorus sound.
Notable electronic chorus devices
Although the electronic chorus effect can be obtained by the multiple ways mentioned above, some devices have acquired a high status among musicians, especially in the "effect pedal" form.
A modded BOSS CE-3 chorus pedal from 1984.
Boss CE-1 – Released in 1976, it was one of the first chorus effect pedals commercially available, based on the same circuit from the Roland Jazz Chorus amplifier. It was originally conceived for keyboard and synthesizer players, but guitarists have utilized it as well, like John Frusciante (Red Hot Chili Peppers).
Boss CE-2 – A smaller pedal (in the standard Boss enclosure) than the CE-1, and a popular choice for guitarists during the 1980s.
Some examples of the use of "obviously chorused guitar tracks" include Red Hot Chili Peppers' "Soul to Squeeze" (0:00), Fripp & Eno's "Evensong" (0:37), Nirvana's "Come As You Are" (0:00, clearest at 0:48), Mike Stern's "Swunk" (0:00), and Satellite Party's "Mr. Sunshine" (0:19, right channel).[2] The chorus effect was also a prominent hallmark of guitarist Andy Summers ("The Police"; Tracks: "Don't Stand so Close to Me", "Walking on The Moon", "Every Breath You Take").
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.
The guitar is a stringed musical instrument that is usually fretted and typically has six or twelve strings. It is usually held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected strings against frets with the fingers of the opposite hand. A guitar pick may also be used to strike the strings. The sound of the guitar is projected either acoustically, by means of a resonant hollow chamber on the guitar, or amplified by an electronic pickup and an amplifier.
In music, there are two common meanings for tuning:
The piano is a keyboard instrument that produces sound when its keys are depressed, through engagement of an action whose hammers strike strings. Most pianos have a row of 88 black and white keys, representing each note of the chromatic scale as they repeat throughout the keyboard's span of seven and a quarter octaves. There are 52 white keys, known as “naturals”, and 36 black keys, known as “sharps”. The naturals repeat a pattern of whole steps and half steps unique to any given starting note. These patterns define a diatonic scale. The 36 sharps repeat a pattern of whole steps and minor thirds, which defines a pentatonic scale.
In physics, acoustics, and telecommunications, a harmonic is a sinusoidal wave with a frequency that is a positive integer multiple of the fundamental frequency of a periodic signal. The fundamental frequency is also called the 1st harmonic; the other harmonics are known as higher harmonics. As all harmonics are periodic at the fundamental frequency, the sum of harmonics is also periodic at that frequency. The set of harmonics forms a harmonic series.
In musical instrument classification, string instruments or chordophones, are musical instruments that produce sound from vibrating strings when a performer plays or sounds the strings in some manner.
In music, inharmonicity is the degree to which the frequencies of overtones depart from whole multiples of the fundamental frequency.
A twelve-string guitar is a steel-string guitar with 12 strings in six courses, which produces a thicker, more ringing tone than a standard six-string guitar. Typically, the strings of the lower four courses are tuned in octaves, with those of the upper two courses tuned in unison. The gap between the strings within each dual-string course is narrow, and the strings of each course are fretted and plucked as a single unit. The neck is wider, to accommodate the extra strings, and is similar to the width of a classical guitar neck. The sound, particularly on acoustic instruments, is fuller and more harmonically resonant than six-string instruments. The 12-string guitar can be played like a 6-string guitar as players still use the same notes, chords and guitar techniques like a standard 6-string guitar, but advanced techniques might be tough as players need to play or pluck two strings simultaneously.
An electronic keyboard, portable keyboard, or digital keyboard is an electronic musical instrument based on keyboard instruments. Electronic keyboards include synthesizers, digital pianos, stage pianos, electronic organs and digital audio workstations. In technical terms, an electronic keyboard is a rompler-based synthesizer with a low-wattage power amplifier and small loudspeakers.
An electric violin is a violin equipped with an electronic output of its sound. The term most properly refers to an instrument intentionally made to be electrified with built-in pickups, usually with a solid body. It can also refer to a violin fitted with an electric pickup of some type, although "amplified violin" or "electro-acoustic violin" are more accurate then.
Keyboard expression is the ability of a keyboard musical instrument to change tone or other qualities of the sound in response to velocity, pressure or other variations in how the performer depresses the keys of the musical keyboard. Expression types include:
A phaser is an electronic sound processor used to filter a signal by creating a series of peaks and troughs in the frequency spectrum. The position of the peaks and troughs of the waveform being affected is typically modulated by an internal low-frequency oscillator so that they vary over time, creating a sweeping effect.
Electro-Harmonix is a New York City-based company that makes electronic audio processors and sells rebranded vacuum tubes. The company was founded by Mike Matthews in 1968. It is best known for a series of guitar effects pedals introduced in the 1970s and 1990s. EHX also made a line of guitars in the 1970s.
The Korg DW-8000 is a polyphonic hybrid digital-analog synthesizer released in 1985. It blends digital waveforms with an analog filter and amplifier, followed by a digital delay for adding echo effects. It boasts eight-note polyphony and its keyboard is equipped with velocity sensitivity and aftertouch.
A course, on a stringed musical instrument, is either one string or two or more adjacent strings that are closely spaced relative to the other strings, and typically played as a single string. The strings in each multiple-string course are typically tuned in unison or an octave.
The following outline is provided as an overview of and topical guide to guitars:
A guitar technician is a member of a music ensemble's road crew who maintains and sets up the musical equipment for one or more guitarists. Depending on the type and size of band, the guitar tech may be responsible for stringing, tuning, and adjusting electric guitars and acoustic guitars, and maintaining and setting up guitar amplifiers and other related electronic equipment such as effect pedals.
Each bass guitar tuning assigns pitches to the strings of an electric bass. Because pitches are associated with notes, bass-guitar tunings assign open notes to open strings. There are several techniques for accurately tuning the strings of an electric bass. Bass method or lesson books introduce one or more tuning techniques, such as:
This is a glossary of jazz and popular music terms that are likely to be encountered in printed popular music songbooks, fake books and vocal scores, big band scores, jazz, and rock concert reviews, and album liner notes. This glossary includes terms for musical instruments, playing or singing techniques, amplifiers, effects units, sound reinforcement equipment, and recording gear and techniques which are widely used in jazz and popular music. Most of the terms are in English, but in some cases, terms from other languages are encountered.
A bass chorus is an electronic effect used with the electric bass. It creates the same "shimmering" sound as a chorus effect for electric guitar chorus pedals, which recreates the sound of having multiple instruments doubling the same musical line. The difference is that bass chorus pedals are modified in various ways to suit the low pitch register of the electric bass. While several bass chorus pedal manufacturers have modified the chorus circuit so that it does not affect the lower register, others have designed the effect so that it can have an effect on even very low pitches.
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