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Guitar effects - Wikipedia, the free encyclopedia

Guitar effects

From Wikipedia, the free encyclopedia

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Guitar effects are electronic devices that modify the tone, pitch, or sound of an electric guitar. Effects can be housed in effects pedals, guitar amplifiers, guitar amplifier simulation software, and rackmount preamplifiers or processors. Electronic effects and signal processing form an important part of the electric guitar tone used in many genres, such as rock, pop, blues, and metal.

Guitar effects are also used with other instruments in rock, pop, blues, and metal, such as electronic keyboards and synthesizers. Electric bass players use bass effects, which are designed to work with low-frequency tones of the bass.

The TS9 Tubescreamer from Ibanez, a popular[citation needed] pedal adding vacuum tube-like distortion (via transistors) to the output signal from electric instruments.
The TS9 Tubescreamer from Ibanez, a popular[citation needed] pedal adding vacuum tube-like distortion (via transistors) to the output signal from electric instruments.

Contents

[edit] Distortion-related effects

Main article: Distortion (guitar)

Distortion is an important part of an electric guitar's sound in many genres, particularly for rock, hard rock, and metal. A distortion pedal takes a normal electric guitar signal and distorts the signal's waveform by "clipping" the signal. There are several different types of distortion effects, each with distinct sonic characteristics. These include overdrive/distortion (or vacuum tube-style distortion), overdrive/crunch, fuzz, and hi-gain.

[edit] Overdrive Distortion

Main article: Overdrive

Overdrive distortion is a well-known distortion. While the general purpose is to emulate classic "warm-tube" sounds, distortion pedals such as the ones in this list can be distinguished from overdrive pedals in that the intent is to provide players with instant access to the sound of a high-gain Marshall amplifier such as the JCM800 pushed past the point of tonal breakup and into the range of tonal distortion known to electric guitarists as "saturated gain." Although most distortion devices use solid-state circuitry, some "tube distortion" pedals are designed with preamplifier vacuum tubes. In some cases, tube distortion pedals use power tubes or a preamp tube used as a power tube driving a built-in "dummy load." Pedals designed specifically for bass guitar are also available. Some distortion pedals include:

[edit] Overdrive/Crunch

Some distortion effects provide an "overdrive" effect. Either by using a vacuum tube, or by using simulated tube modeling techniques, the top of the wave form is compressed, thus giving a smoother distorted signal than regular distortion effects. When an overdrive effect is used at a high setting, the sound's waveform can become clipped, which imparts a gritty or "dirty" tone, which sounds like a tube amplifier "driven" to its limit. Used in conjunction with an amplifier, especially a tube amplifier, driven to the point of mild tonal breakup, short of what would be generally considered distortion or overdrive, these pedals can produce extremely thick distortion sounds much like those used by Carlos Santana or Eddie Van Halen. Today there is a huge variety of overdrive pedals, and some of them are:

[edit] Fuzz

Main article: Fuzzbox

Fuzz was originally intended to recreate the classic 1960's tone of an overdriven tube amp combined with torn speaker cones. Oldschool guitar players (like Link Wray) would use a screwdriver to poke several holes through the paperboard part of the guitar amp speaker to achieve a similar sound. Since the original designs, more extreme fuzz pedals have been designed and produced, incorporating octave-up effects, oscillation, gating, and greater amounts of distortion.

Some fuzzbox pedals include:

[edit] Hi-Gain

Hi-Gain (descended from the more generic electric guitar amplification term high-gain) is the sound most used in Heavy Metal. High gain in normal electric guitar playing simply references a thick sound produced by heavily overdriven amplifier tubes, a distortion pedal, or some combination of both--the essential component is the typically loud, thick, harmonically rich, and sustaining quality of the tone. However, the Hi-Gain sound of modern pedals is somewhat distinct from, although descended from, this sound. The distortion often produces sounds not possible any other way. Many extreme distortions are either hi-gain or the descendents of such. The Mesa Boogie Triple Rectifier Series of amps are an example.

Some Hi-Gain Pedals Include:

[edit] Power-tube pedal

A Power-Tube pedal contains a power tube and optional dummy load, or a preamp tube used as a power tube. This allows the device to produce power-tube distortion independently of volume; therefore, power-tube distortion can be used as an effects module in an effects chain. Some examples are:

[edit] Power attenuator

Main article: Power attenuator (guitar)

A power Attenuator enables a player to obtain power-tube distortion independently of listening volume. A power attenuator is a dummy load placed between the guitar amplifier's power tubes and the guitar speaker, or a power-supply based circuit to reduce the plate voltage on the power tubes. Examples of power attenuators are the Marshall PowerBrake and THD HotPlate.

[edit] Filtering-related effects

[edit] Equalizer

Main article: Equalization

An equalizer adjusts the frequency response in a number of different frequency bands. A graphic equalizer (or "graphic EQ") provides slider controls for a number of frequency region. Each of these bands has a fixed width (Q) and a fixed center-frequency, and as such, the slider changes only the level of the frequency band. The tone controls on guitars, guitar amps, and most pedals are similarly fixed-Q and fixed-frequency, but unlike a graphic EQ, rotary controls are used rather than sliders.

Most parametric EQ pedals (such as the [1] Boss PQ-4) provide semi-parametric EQ. That is, in addition to level control, each band provides either a center frequency or Q width control. Parametric EQs have rotating controls rather than sliders.

Placement of EQ in a distortion signal processing chain affects the basic guitar amp tone. Using a guitar's rotary tone control potentiometer is a form of pre-distortion EQ. Placing an EQ pedal before a distortion pedal or before a guitar amp's built-in preamp distortion provides preliminary control of the preamp distortion voicing.

For more complete control of preamp distortion voicing, an additional EQ pedal can be placed after a distortion pedal; or, equivalently, the guitar amp's tone controls, after the built-in preamp distortion, can be used. An EQ pedal in the amp's effects loop, or the amp's tone controls placed after preamp distortion, constitutes post-distortion EQ, which finishes shaping the preamp distortion and sets up the power-tube distortion voicing.

As an example of pre-distortion EQ, Eddie Van Halen places a 6-band MXR EQ pedal before the Marshall amplifier head (pre-distortion EQ). Slash places a Boss GE-7, a 7-band EQ pedal, before his Marshall amp. This technique is similar to placing a Wah pedal before the amp's preamp distortion and leaving the Wah pedal positioned part-way down, sometimes mentioned as "fixed wah," (pre-distortion EQ), along with adjusting the amp's tone controls (post-distortion EQ).

If a dummy load guitar-amp configuration is used, an additional EQ position becomes available, between the dummy load and the final amplifier that drives the guitar speaker. Van Halen used an additional EQ in this position. This configuration is commonly used with rackmount systems.

Finally, an EQ pedal such as a 10-band graphic EQ pedal can be placed in the Insert jack of a mixer to replace the mixer channel's EQ controls, providing graphical control over the miked guitar speaker signal.

Equalization-related effects pedals include Wah, Auto-Wah, and Phase Shifter. Most EQ pedals also have an overall Level control distinct from the frequency-specific controls, thus enabling an EQ pedal to act as a configurable level-boost pedal. Some EQ pedals include:

  • MXR M-108 10-band Equalizer
  • Boss GE-7 Equalizer

[edit] Wah pedal

Main article: Wah-wah pedal

A wah-wah pedal is a foot-operated pedal, technically a kind of band-pass filter, which allows only a small portion of the incoming signal's frequencies to pass. Rocking the pedal back and forth alternately allows lower and higher frequencies to pass through, the effect being similar to a person saying "wah". The wah pedal, used with guitar, is most associated with 1960s psychedelic rock and 1970s funk. During this period wah-wah pedals often incorporated a fuzzbox to process the sound before the wah-wah circuit, the combination producing a dramatic effect known as fuzz-wah.

Some wah-wah pedals include:

[edit] Auto-Wah / Envelope Filter

Main article: Auto-wah

An auto-wah is a wah-wah pedal without a rocker pedal, controlled instead by the dynamic envelope of the signal. An auto-wah, also called more technically an envelope filter, uses the level of the guitar signal to control the wah filter position, so that as a note is played, it automatically starts with the sound of a wah-wah pedal pulled back, and then quickly changes to the sound of a wah-wah pedal pushed forward, or the reverse movement depending on the settings. Controls include wah-wah pedal direction and input level sensitivity. This is an EQ-related effect and can be placed before preamp distortion or before power-tube distortion with natural sounding results. Auto-Wah pedals include:


[edit] Talk Box

Main article: Talk box

Early forms of the talk box, such as the Heil Talk Box, first appeared in Country Music circles in Nashville in the 1940',s 1950's, and 1960's, by artist like swing band pedal steel player Alvino Rey, Link Wray ("Rumble"), Bill West, a Country Music steel guitar player and husband of Dottie West, and Pete Drake, a Nashville mainstay on the pedal steel guitar and friend of Bill West. Drake used it on his 1964 album Forever, in what came to be called his "talking steel guitar." The device used the guitar amplifier's output to drive a speaker horn that pushed air into a tube held in the player's mouth, which filters and thereby shapes the sound leading to a unique effect. The singer and guitarist Peter Frampton made this effect famous with hit songs such as "Do You Feel Like We Do" and "Show Me the Way," as did Joe Walsh on "Rocky Mountain Way." On Van Halen's cover of "You Really Got Me" Eddie Van Halen uses a talk box after the guitar solo to make a sound similar to a person having sex. Newer devices, such as Danelectro's Free Speech pedal, use a microphone and vocoder-like circuit to modulate the frequency response of the guitar signal. Some Talk Boxes include: The Dunlop Heil Talk Box, Rocktron Banshee, and Peter Frampton's own company,Framptone.

[edit] Volume-related effects

[edit] Volume pedal

A volume pedal is a volume potentiometer that is tilted forward or back by foot. A volume pedal enables a musician to adjust the volume of their instrument while they are performing. Volume pedals can also be used to make the guitar's notes or chords fade in and out. This allows the percussive plucking of the strings to be softened or eliminated entirely, imparting a human-vocal sound. Volume pedals are also widely used with pedal steel guitars in country music. It has also been used to great effect in rock music; the Pat McGee Band's live version of "Can't Miss What You Never Had" on General Admission illustrates what the pedal is capable of. Some volume pedals are:

[edit] Auto-Volume/Envelope Volume

Just as an Auto-Wah is a version of a Wah pedal controlled by the signal's dynamic envelope, there is an envelope-controlled version of a volume pedal. This is generally used to mimic automatically the sound of picking a note while the guitar's volume knob is turned down, then smoothly turning the knob up, for a violin-like muted attack. An example is:

  • Boss SG-1 Slow Gear

[edit] Tremolo

Main article: Tremolo

Tremolo is a regular and repetitive variation in gain for the duration of a single note, which works like an auto-volume knob. This is a volume-related effects pedal. This effect is based on one of the earliest effects that were built into guitar amplifiers. Examples include:

[edit] Compressor

Main article: Audio level compression

A compressor acts as an automatic volume control, progressively decreasing the output level as the incoming signal gets louder, and vice versa. It preserves the note's attack rather than silencing it as with an Envelope Volume pedal. This adjustment of the volume for the attack and tail of a note evens out the overall volume of an instrument. Compressors can also change the behaviour of other effects, especially distortion. When applied toward the guitar, it can provide a uniformed sustained note; when applied to instruments with a normally short attack, such as drums or harpsichord, compression can drastically change the resulting sound.

Another kind of compressor is the optical compressor which uses a light source (LED or lamp) to compress the signal.

Some compressor pedals are:

[edit] Time-based effects

[edit] Delay/Echo

Main article: Delay (audio effect)

A delay or echo pedal creates a copy of an incoming sound and slightly time-delays it, creating either a "slap" (single repetition) or an echo (multiple repetitions) effect. Delay pedals may use either analog or digital technology. Analog delays often are less flexible and not as "perfect" sounding as digital delays, but some guitarists argue that analog effects produce "warmer" tones. Early delay devices actually used magnetic tape to produce the time delay effect. U2's guitarist, The Edge, is known for his extensive use of delay effects. Some common Delay pedals are:

Another technology that is used in Delay units is a feedback circuit, consisting of a tracking oscillator circuit to hold a note of the last interval, and after amplifying the signal, send it back to the input side of the delay. While it was first associated with Boss DF-2 Super Feedbacker & Distortion, currently, the signal feedback circuit is employed by Delay pedals, and if used under "hold" mode (As in Boss DD-3) it will provide a sustain effect instead of simply a delay effect.

[edit] Looping

Extremely long delay times form a looping pedal, which allows performers to record a phrase or passage and play along with it. This allows a solo performer to record an accompaniment or ostinato passage and then, with the looping pedal playing back this passage, perform solo improvisations over the accompaniment. The guitarist creates the loop either on the spot or it is held in storage for later use (as in playback) when needed. Some examples of loops effects are:

[edit] Reverb

Main article: Reverb

Reverbration, or "reverb", is the persistence of sound in a particular space after the original sound is removed. When sound is produced in a space, a large number of echoes build up and then slowly decay as the sound is absorbed by the walls and air, creating reverberation, or reverb. A plate reverb system uses an electromechanical transducer, similar to the driver in a loudspeaker, to create vibration in a plate of sheet metal. A pickup captures the vibrations as they bounce across the plate, and the result is output as an audio signal. A spring reverb system uses a transducer at one end of a spring and a pickup at the other, similar to those used in plate reverbs, to create and capture vibrations within a metal spring. Guitar amplifiers frequently incorporate spring reverbs due to their compact construction. Spring reverberators were once widely used in semi-professional recording due to their modest cost and small size. Due to quality problems and improved digital reverb units, spring reverberators are declining rapidly in use. Digital reverb units use various signal processing algorithms in order to create the reverb effect. Since reverberation is essentially caused by a very large number of echoes, simple DSPs use multiple feedback delay circuits to create a large, decaying series of echoes that die out over time.

Examples of reverb pedals include:

[edit] Modulation-related effects

[edit] Rotary Speaker

Before such effects are available electronically, these are accomplished by the use of Rotary speakers, by spinning the speakers and/or place a rotating baffle in front of it. This creates a doppler effect, and depend on the speed of the rotation, translate into phasing, flanging, chorus, vibrato, or even tremolo.

  • Lesile Speakers: This is a unit that contains a bass speaker that blare into a rotating baffle, and a horn speaker that rotate like a siren. Originally designed for Hammond organs, they are also favored by guitarist; some say that no electronic effects can duplicate its sounds.
  • Fender Vibratone: This is a simplified version of Leslie Speaker, containing only a 10" speaker that blare into a rotating baffle.

All the electronic-based effects can duplicate the sound of a rotating speakers, as all the following effects differ based on speed, volume, and modulation. In fact, it is not uncommon for a pedal to be capable of doing two or more of modulation effects.

[edit] Phase Shifter

Main article: Phase shifter

A phase shifter creates a complex frequency response containing many regularly-spaced "notches" in an incoming signal by combining it with a copy of itself out of phase, and shifting the phase relationship cyclically. The phasing effect creates a "whooshing" sound that is reminiscent of the sound of a flying jet. This effect dominates the sound in the song Star Guitar by Chemical Brothers. The song was not played with any guitars but one can hear the phasing effect. The instrument being phased was actually a synthesizer. Some electronic "rotating speaker simulators" are actually phase shifters. Phase shifters were popular in the 1970s, particularly used with electric piano and funk bass guitar. The number of stages in a phase shifter is the number of moving dips in the frequency response curve. From a sonic perspective, this effect is equalization-oriented. However, it may be derived through moderate time-based processing. Some phaser pedals include:

[edit] Vibrato

A Vibe or vibrato pedal reproduces the sound of a rotating speaker by synchronizing volume oscillation, frequency-specific volume oscillation, vibrato (pitch wavering), phase shifting, and chorusing in relation to a non-rotating speaker. The modulation speed can be ramped up or down, with separate speeds for the bass and treble frequencies, to simulate the sound of a rotating bass speaker and a rotating horn. This effect is simultaneously a volume-oriented effect, an equalization-oriented effect, and a time-based effect. Furthermore, this effect is typically related to chorus. Some vibe pedals also include an overdrive effect, which allows the performer to add "tube"-style distortion. Some Vibe pedals include:

  • BBE Soul Vibe
  • Voodoo Lab Microvibe

Some vibe-chorus pedals include

[edit] Flanger

Main article: Flanging

A flanger simulates the sound effect originally created by momentarily slowing the tape during recording by holding something against the flange, or edge of the tape reel, and then allowing it to speed up again. This effect was used to simulate passing into "warp speed," in scifi films, and also in psychedelic rock music of the 1960s. Flanging has a sound similar to an auto-wah, but weaker, yet is closely related to the production of chorus.

The first pedal-operated flanger designed for use as a guitar effect was designed by Jim Gamble of Tycobrahe Sound Company in Hermosa Beach, CA, during the mid 1970s. Last made in 1977, the existing "Pedalflangers" appear occasionally on eBay and sell for several hundred dollars. A modern "clone" of the Tycobrahe Pedalflanger is sold by Chicago Iron.Famous users of this Flanger effect include Randy Rhoads and Eddie Van Halen, coincidentally they both used the MXR M-117R flanger and Eddie Van Halen even has his own signature model now.

Examples:

[edit] Chorus

Main article: Chorus effect

Chorus splits your guitar's signal in two, modulating the second signal's pitch and mixing back in with the "dry" original signal. The effect sounds like several guitarists playing the same thing at the same time, resulting in a wide swelling sound. Some common chorus pedals are:


[edit] Rotary Speaker Simulator

Despite the numerous different analog devices, it is very rare for them to be able to duplicate all aspect of a Leslie speaker. Thus, Rotary Speaker Simulator are always going to be digital, utilizing modelling algorithms to model the relations between the rotating horns and bass baffle, and how the sound bounce around the cabinet. As Leslie also have an amplifier section, most of these typically have overdrives to simulate that aspect. Some of these pedals can even accept keyboard's input.

  • Boss RT-20 Rotary Ensemble Pedal: This is one of the few pedals that is capable of modelling all aspect of a Lesile Speaker.
  • Line 6 Rotomachine: Also a modelling pedal, it is available in a compact pedal size.
  • DLS Roto-Sim: Hybrid of analog with DSP modelling.


[edit] Pitch-related effects

[edit] Octaver

Main article: Octave effect

An octaver mixes the input signal with a synthesised signal whose musical pitch is an octave lower or higher than the original. Effects that synthesize intervals besides octaves are referred to as harmonizers or pitch shifters, shown below. These are frequently used in bands without a bassist.

Octave Up pedals include:

Octave Down pedals include:

[edit] Pitch Shifter

Main article: Pitch shifting

A pitch shifter is a device that alters the pitch of the instruments. They are generally used with an expression pedal to give a smooth bend-like effect. Pitch shifters can also be used to electronically "detune" the instrument. Some examples are:

[edit] Other effects

[edit] Feedbacker/Sustainer

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 Jimi Hendrix, is to use the feedback created when the guitar is played in front of a loudspeaker.
  • The neck pickup is used as a driver to push the strings based on the bridge pickup, such as the Sustainiac Sustainer and Fernandes Sustainer.
  • A signal amplifier that powers a headstock transducer, which in turn send 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.
  • A dedicated high-gain guitar amp 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.

[edit] Switcher/Mixer (or "A/B" pedal)

A switcher pedal (also called an "A/B" pedal) enables players to run two effects or two effects chains in parallel, or switch between two effects with a single press of the pedal.

Some switcher pedals also incorporate a simple mixer, which allows mixing the dry guitar signal to be mixed with an effected signal. This is useful to make overly processed effects more mild and natural sounding. Examples of the use of the mixer function include:

  • A wah can be mixed with dry guitar to make it more mild and full-bandwidth, with less volume swing.
  • A compressor can be mixed with dry guitar to preserve the natural attack of the dry signal as well as the sustain of the compressor.
  • Two overdrive pedals can be blended together.
  • A strong phaser effect can be mixed with dry guitar to make it more subtle and musical.

Some examples of switcher pedals include:

  • Dunlop A/B pedal
  • Loop Master

Some examples of Switcher/mixer pedals include:

  • Boss LS-2 Line Selector

[edit] Noise Gate

Main article: Noise gate

A noise gate allows a signal to pass through only when the signal's intensity is above a set threshold, which opens the gate. If the signal falls below the threshold, the gate closes, and no signal is allowed to pass. A noise gate can be used to control noise. When the level of the 'signal' is above the level of the 'noise', the threshold is set above the level of the 'noise' so that the gate is closed when there is no 'signal'. A noise gate does not remove noise from the signal: when the gate is open, both the signal and the noise will pass through.

Noise gates are also used as an effect to modify the envelope of signals, removing gradual attacks and decays.

Examples of noise gate pedals include:

  • Boss NS-2 Noise Suppressor
  • MXR M-135 Smart Gate

[edit] Multi-Effects Pedals

A multi-FX pedal is a single effects device that can perform several guitar effects simultaneously. Such devices generally use digital processing to simulate many of the above-mentioned effects without the need to carry several single-purpose units. In addition to the classic effects, most have amplifier/speaker simulations not found in analog units. This allows a guitarist to play directly into a recording device while simulating an amplifier and speaker of his choice.

A typical digital multi-effects pedal is programmed, with several memory locations available to save custom user settings. Many lack the front-panel knobs of analog devices, using buttons instead to program various effect parameters. Multi-effects devices continue to evolve, some gaining MIDI or USB interfaces to aid in programming. Examples include:

[edit] Samples

Fuzzed guitar

Several power chords, played clean, then with different settings of a Big Muff Pi.
Problems listening to the file? See media help.

Pro Co RAT Distortion Pedal Sound Samples.

Boss BD-2 (Blues Driver) modified to be a Fuzz.

Proco Rat distortion pedal modified by Indyguitarist.

[edit] Further reading

Wikimedia Commons has media related to:
Portal:Guitar

[edit] See also

[edit] External links


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