Instrument amplifier

An instrument amplifier is an electronic device that converts the often barely audible or purely electronic signal of a musical instrument into a larger electronic signal to feed to a loudspeaker. An instrument amplifier is used with musical instruments such as an electric guitar, an electric bass, electric organ, synthesizers and drum machine to convert the signal from the pickup (with guitars and other string instruments and some keyboards) or other sound source (e.g, a synthesizer's signal) into an electronic signal that has enough power, due to being routed through a power amplifier, capable of driving one or more loudspeaker that can be heard by the performers and audience.

Combination ("combo") amplifiers include a preamplifier, a power amplifier, tone controls, and one or more speakers in a cabinet, a housing or box usually made of hardwood, plywood or particleboard (or, less commonly, moulded plastic). Instrument amplifiers for some instruments are also available without an internal speaker; these amplifiers, called heads, must plug into one or more external speaker cabinets. Instrument amplifiers also have features that let the performer modify the signal's tone, such as changing the equalization (adjusting bass and treble tone) or adding electronic effects such as intentional distortion/overdrive, reverb or chorus effect.

A Fender "combo" amplifier. The combination amplifier is a preamplifier, power amplifier and tone controls and one or more loudspeakers or drivers mounted in a portable wooden cabinet. This amp's sound is being picked up with a microphone in a recording studio.

Instrument amplifiers are available for specific instruments, including the electric guitar, electric bass, electric/electronic keyboards, and acoustic instruments such as the mandolin and banjo. Some amplifiers are designed for specific styles of music, such as the "traditional"-style "tweed" guitar amplifiers, such as the Fender Bassman used by blues and country music musicians, and the Marshall amplifiers used by hard rock and heavy metal bands.

Unlike home "hi-fi" amplifiers or public address systems, which are designed to accurately reproduce the source sound signals with as little harmonic distortion as possible and without changing the tone or equalization (at least not unless the hi-fi owner adjusts it themselves with a graphic equalizer), instrument amplifiers are often designed to add additional tonal coloration to the original signal, emphasize (or de-emphasize) certain frequencies (most electric guitar amps roll off the very high frequencies), and, in the case of guitar amplifiers designed for electric guitar or Hammond organ, offer the capability to intentionally add some degree of "overdrive" or distortion to the tone. The two exceptions are keyboard amplifiers designed for use with digital pianos and synthesizers and "acoustic" instrument amplifiers for use with acoustic guitar or fiddle in a folk music setting, which typically aim for a relatively flat frequency response (i.e., no added colouration of the sound) and little or no distortion of the signal.


Guitar amplifiers

A guitar amplifier amplifies the electrical signal of an electric guitar (or, less commonly, with acoustic amplifiers, an acoustic guitar) so that it can drive a loudspeaker at sufficient volume for the performer and audience to hear. Most guitar amplifiers can also modify the instrument's with controls that emphasize or de-emphasize certain frequencies and add electronic effects. String vibrations are sensed by a suitable microphone or pickup, depending on the type of guitar. For electric guitars, strings are almost always made of metal, and the pickup works by electro-magnetic induction (these are called magnetic pickups; they are the most widely used type of pickup on electric guitars). Acoustic guitars do not usually have a built-in pickup or microphone, at least with entry-level and beginner instruments. Some acoustic guitars have a small condenser microphone mounted inside the body, which designed to convert acoustic vibrations into an electrical signal, but usually they do so from direct contact with the strings (replacing the guitar's bridge) or with the guitar's body, rather than having a membrane like general-purpose microphones. Acoustic guitars may also use a piezoelectric pickup, which converts the vibrations of the instrument into an electronic signal. More rarely, a magnetic pickup may be mounted in the sound hole of an acoustic guitar; while magnetic pickups do not have the same acoustic tone that microphones and piezo pickups can produce, magnetic pickups are more resistant to acoustic feedback.

Gibson 1
A small Gibson "combo" amplifier.

Standard amps

Standard amplifiers, such as the Fender "tweed"-style amps (e.g., the Fender Bassman) and Gibson amps, are often used by traditional rock, blues, and country musicians who wish to create a "vintage" 1950s-style sound. They are used by electric guitarists, pedal steel guitar players, and blues harmonica ("harp") players. Combo amplifiers such as the Fender Super Reverb have powerful, loud tube amplifiers, four 10" speakers, and they often have built-in reverb and "vibrato" effects units. Smaller guitar amps are also available, which have fewer speakers (some have only one speaker) and lighter, less powerful amplifier units. Smaller guitar amps are easier to transport to gigs and sound recording sessions. Smaller amps are widely used in small venue shows (nightclubs) and in recordings, because players can obtain the tone they want without having to have an excessively loud volume. One of the challenge with the large, powerful 4x10 Fender Bassman-type amps is that to get the tone a player wants, they have to turn up the amp to a loud volume.

These amps are designed to produce a variety of sounds ranging from a clean, warm sound (when used in country and soft rock) to a growling, natural overdrive, when the volume is set near its maximum, (when used for blues, rockabilly, psychobilly, and roots rock). These amplifiers usually have a sharp treble roll-off at 5 kHz to reduce the extreme high frequencies, and a bass roll-off at 60–100 Hz to reduce unwanted boominess. The nickname "tweed" refers to the lacquered beige-light brown fabric covering used on these amplifiers.

The smallest "combo" amplifiers, which are mainly used for individual practice and warm-up purposes, may have only a single 8" or 10" speaker. Some harmonica players use these small combo amplifiers for concert performances, though, because it is easier to create natural overdrive with these lower-powered amplifiers. Larger combo amplifiers, with one 12 inch speaker or two or four 10 or 12 inch speakers are used for club performances and larger venues. For large concert venues such as stadiums, performers may also use an amplifier "head" with several separate speaker cabinets (which usually contain two or four 12" speakers).

Hard rock and heavy metal

MarshallStack Slayer
A 3×6 stack of mock Marshall guitar cabinets for Jeff Hanneman of Slayer

Electric guitar amplifiers designed for heavy metal are used to add an aggressive "drive", intensity, and "edge" to the guitar sound with distortion effects, preamplification boost controls (sometimes with multiple stages of preamps), and tone filters. While many of the most expensive, high-end models use 1950s-style tube amplifiers (even in the 2000s), there are also many models that use transistor amplifiers, or a mixture of the two technologies (i.e., a tube preamplifier with a transistor power amplifier). Amplifiers of this type, such as Marshall amplifiers, are used in a range of the louder, heavier genres of rock, including hard rock, heavy metal, and hardcore punk. This type of amplifier is available in a range of formats, ranging from small, self contained combo amplifiers for rehearsal and warm-ups to heavy "heads" that are used with separate speaker cabinets—colloquially referred to as a "stack."

In the late 1960s and early 1970s, public address systems at rock concerts were used mainly for the vocals. As a result, to get a loud electric guitar sound, early heavy metal and rock-blues bands often used "stacks" of 4x12" Marshall speaker cabinets on the stage. In 1969, Jimi Hendrix used four stacks to create a powerful lead sound, and in the early 1970s by the band Blue Öyster Cult used an entire wall of Marshall Amplifiers to create a roaring wall of sound that projected massive volume and sonic power. In the 1980s, metal bands such as Slayer and Yngwie Malmsteen also used "walls" of over 20 Marshall cabinets. However, by the 1980s and 1990s, most of the sound at live concerts was produced by the sound reinforcement system rather than the onstage guitar amplifiers, so most of these cabinets were not connected to an amplifier. Instead, walls of speaker cabinets were used for aesthetic reasons.

Amplifiers for harder, heavier genres often use valve amplifiers (known as "tube amplifiers" in North America) also. Valve amplifiers are perceived by musicians and fans to have a "warmer" tone than those of transistor amps, particularly when overdriven (turned up to the level that the amplifier starts to clip or shear off the wave forms). Instead of abruptly clipping off the signal at cut-off and saturation levels, the signal is rounded off more smoothly. Vacuum tubes also exhibit different harmonic effects than transistors. In contrast to the "tweed"-style amplifiers, which use speakers in an open-backed cabinet, companies such as Marshall tend to use 12" speakers in a closed-back cabinet. These amplifiers usually allow users to switch between "clean" and distorted tones (or a rhythm guitar-style "crunch" tone and a sustained "lead" tone) with a foot-operated switch.

A 2 x 10" bass speaker cabinet stacked on top of a 15" cabinet, with separate bass amplifier "head" unit


Bass amplifiers are designed for bass guitars or more rarely, for upright bass. They differ from amplifiers for the regular (and comparatively higher-pitched) electric guitar in several respects. They have extended low frequency response and tone controls optimised for bass instruments, which produce pitches of 41 Hz, in the case of a standard four-string electric bass or double bass, or even lower for five- or six-string electric basses.

Higher-cost bass amplifiers sometimes include built-in bass effects, which are electronic effects units designed for electric bass or more rarely, for upright bass. Common built-in effects include audio compressor or limiter features, which help to keep the amplifier from doing unwanted distorting at high volume levels and potentially damaging the speakers; equalizers; and in some amps from the 1980s and more commonly in the 2000s, bass overdrive. Bass amps may provide an XLR DI output for plugging the bass amp signal directly into a mixing board or PA system. Larger, more powerful bass amplifiers (300 or more watts) are often provided with internal or external metal heat sinks and/or fans to help keep the amplifier cool.

Speaker cabinets designed for bass usually use larger loudspeakers (or more loudspeakers, in the case of the popular 4x10" cabinets, which contain four 10" speakers) than the cabinets used for other instruments, so that they can move the larger amounts of air needed to reproduce low frequencies. Bass players have to use more powerful amplifiers than the electric guitarists, because deep bass frequencies take more power to amplify. As such, in a band in which the electric guitar player uses a 50 watt guitar amp, the bass player typically uses a 200 watt to 300 watt bass amp. While the largest speakers commonly used for regular electric guitar are 12" speakers, electric bass speaker cabinets often use 15" speakers. Bass players who play styles of music that require an extended low-range response, such as death metal, sometimes use speaker cabinets with 18" speakers or add a large subwoofer cabinet to their rig.

Speakers for bass instrument amplification tend to be heavier-duty than those for regular electric guitar, and the speaker cabinets are typically more rigidly constructed and heavily braced, to prevent unwanted buzzes and rattles. Bass cabinets often include bass reflex ports, vents or openings in the cabinet, which improve the bass response and low-end, especially at high volumes.

A small keyboard amplifier suitable for at-home practice capable of mixing the inputs from two keyboards.


A keyboard amplifier, used for the stage piano, synthesizer, clonewheel organs and similar instruments, is distinct from other types of amplification systems due to the particular challenges associated with keyboards; namely, to provide solid low-frequency sound reproduction and crisp high-frequency sound reproduction. It is typically a combination amplifier that contains a two, three, or four-channel mixer, a pre-amplifier for each channel, equalization controls, a power amplifier, a speaker, and a horn, all in a single cabinet.

Notable exceptions include keyboard amplifiers for specific keyboard types. The vintage Leslie speaker cabinet and modern recreations, which are generally used for Hammond organs, use a tube amplifier that is often turned up to add a warm, "growling" overdrive. Some electric pianos have built-in amplifiers and speakers, in addition to outputs for external amplification.

Acoustic amplifiers

These amplifiers are intended for acoustic instruments such as violin ("fiddle"), mandolin, and acoustic guitar—especially for the way musicians play these instruments in quieter genres such as folk and bluegrass. They are similar to keyboard amplifiers, in that they have a relatively flat frequency response and avoid tonal coloration.

To produce this relatively "clean" sound, these amplifiers often have very powerful amplifiers (up to 800 watts RMS), to provide additional "headroom" and prevent unwanted distortion. Since an 800 watt amplifier built with standard Class AB technology would be heavy, some acoustic amplifier manufacturers use lightweight Class D, "switching amplifiers."

Acoustic amplifier designs strive to produce a clean, transparent, "acoustic" sound that does not—except for reverb and other effects—alter the natural instrument sound, other than to make it louder. Amplifiers often come with a simple mixer to blend signals from a pickup and microphone. Since the early 2000s, it is increasingly common for acoustic amplifiers to provided digital effects, such as reverb and compression. Some also contain feedback-suppressing devices, such as notch filters or parametric equalizers.[1]


Instrument amplifiers have a different purpose than 'Hi-Fi' (high fidelity) stereo amplifiers in radios and home stereo systems. Hi-fi home stereo amplifiers strive to accurately reproduce signals from pre-recorded music, with as little harmonic distortion as possible. In contrast, instrument amplifiers are add additional tonal coloration to the original signal or emphasize certain frequencies. For electric instruments such as electric guitar, the amplifier helps to create the instrument's tone by boosting the input signal gain and distorting the signal, and by emphasizing frequencies deemed desirable (e.g., low frequencies) and de-emphasizing frequencies deemed undesirable (e.g., very high frequencies).

Size and power rating

In the 1960s and 1970s, large, heavy, high output power amplifiers were preferred for instrument amplifiers, especially for large concerts, because public address systems were generally only used to amplify the vocals. Moreover, in the 1960s, PA systems typically did not use monitor speaker systems to amplify the music for the onstage musicians. Instead, the musicians were expected to have instrument amplifiers that were powerful enough to provide amplification for the stage and audience. In late 1960s and early 1970s rock concerts, bands often used large stacks of speaker cabinets powered by heavy tube amplifiers such as the Super Valve Technology (SVT) amplifier, which was often used with eight 10" speakers.

However, over subsequent decades, PA systems substantially improved, and used different approaches, such as horn-loaded "bass bins" (in the 1980s) and subwoofers (1990s and 2000s) to amplify bass frequencies. As well, in the 1980s and 1990s, monitor systems substantially improved, which helped sound engineers provide onstage musicians with a better reproduction of their instruments' sound.

As a result of improvements to PA and monitor systems, musicians in the 2000s no longer need huge, powerful amplifier systems. A small combo amplifier patched into the PA suffices. In the 2000s, virtually all sound reaching the audience in large venues comes from the PA system. Onstage instrument amplifiers are more likely to be at a low volume, because high volume levels onstage make it harder for the sound engineer to control the sound mix.

As a result, in many large venues much of the onstage sound reaching the musicians now comes from in-ear monitors, not from the instrument amplifiers. While stacks of huge speaker cabinets and amplifiers are still used in concerts (especially in heavy metal), this is often mainly for aesthetics or to create a more authentic tone. The switch to smaller instrument amplifiers makes it easier for musicians to transport their equipment to performances. As well, it makes concert stage management easier at large clubs and festivals where several bands are performing in sequence, because the bands can be moved on and off the stage more quickly.

Amplifier technology

Instrument amplifiers may be based on thermionic ("tube" or "valve") or solid state (transistor) technology.

Tube amplifiers

Vacuum tubes were the dominant active electronic components in amplifiers from the 1930s through the early 1970s, and tube amplifiers remain preferred by many musicians and producers. Some musicians feel that tube amplifiers produce a "warmer" or more "natural" sound than solid state units, and a more pleasing overdrive sound when overdriven. However, these subjective assessments of the attributes of tube amplifiers' sound qualities are the subject of ongoing debate. Tube amps are more fragile, require more maintenance, and are usually more expensive than solid state amps.

Tube amplifiers produce more heat than solid state amplifiers, but few manufacturers of these units include cooling fans in the chassis. While tube amplifiers do need to attain a proper operating temperature, if the temperature goes above this operating temperature, it may shorten the tubes' lifespan and lead to tonal inconsistencies.[2]

Trace Elliot Bonneville rear view
A Trace Elliot "Bonneville" tube amplifier as seen from the rear view: note the vacuum tubes extending into the wooden cabinet.

Solid-state amplifiers

By the 1960s and 1970s, semiconductor transistor-based amplifiers began to become more popular because they are less expensive, more resistant to bumps during transportation, lighter-weight, and require less maintenance. In some cases, tube and solid-state technologies are used together in amplifiers. A common setup is the use of a tube preamplifier with a solid-state power amplifier. There are also an increasing range of products that use digital signal processing and digital modeling technology to simulate many different combinations of amp and cabinets.

The output transistors of solid-state amplifiers can be passively cooled by using metal fins called heatsinks to radiate away the heat. For high-wattage amplifiers (over 800 watts), a fan is often used to move air across internal heatsinks.[3]


The most common hybrid amp design is to use a tube preamp with a solid state power amplifier. This gives users the pleasing preamp and overdrive tone of a tube amp with the lowered cost, maintenance and weight of a solid state power amp.

See also


  1. ^ Note: Acoustic amplifiers should not be confused with the amplifier brand name Acoustic, whose products are still available in the used equipment market.)
  2. ^ Cool it, man; Michael "Mac" McCullough.
  3. ^ Power Amplifiers - General Information: Yorkville Sound Archived 2010-10-07 at the Wayback Machine

External links

Audio crossover

Audio crossovers are a type of electronic filter circuitry used in a range of audio applications, to split up an audio signal into two or more frequency ranges, so that the signals can be sent to drivers that are designed for different frequency ranges. Crossovers are often described as "two-way" or "three-way", which indicate, respectively, that the crossover splits a given signal into two frequency ranges or three frequency ranges. Crossovers are used in loudspeaker cabinets, power amplifiers in consumer electronics (hi-fi, home cinema sound and car audio) and pro audio and musical instrument amplifier products. For the latter two markets, crossovers are used in bass amplifiers, keyboard amplifiers, bass and keyboard speaker enclosures and sound reinforcement system equipment (PA speakers, monitor speakers, subwoofer systems, etc.).

Crossovers are used because most individual loudspeaker drivers are incapable of covering the entire audio spectrum from low frequencies to high frequencies with acceptable relative volume and absence of distortion. Most hi-fi speaker systems and sound reinforcement system speaker cabinets use a combination of multiple loudspeaker drivers, each catering to a different frequency band. A standard simple example is in hi-fi and PA system cabinets that contain a woofer for low and mid frequencies and a tweeter for high frequencies. Since a sound signal source, be it recorded music from a CD player or a live band's mix from an audio console has all of the low, mid and high frequencies combined, a crossover circuit is used to split the audio signal into separate frequency bands that can be separately routed to loudspeakers, tweeters or horns optimized for those frequency bands.

Active crossovers are distinguished from passive crossovers in that whereas passive crossovers split up an amplified signal coming from one power amplifier so that it can be sent to two or more drivers (e.g., a woofer and a very low frequency subwoofer, or a woofer and a tweeter), an active crossover splits up audio signal prior to amplification, so that it can be sent to two or more power amplifiers, each of which is connected to a separate driver type. Home cinema 5.1 surround sound audio systems use a crossover which separates out the low-frequency signal, so that it can be sent to a subwoofer, and then sends the mid- and high-range frequencies to five speakers which are placed around the listener; in a typical application, the signals sent to the surround speaker cabinets are further split up with a passive crossover into a low/mid-range woofer and a high range tweeter. Active crossovers come in both digital and analog varieties.

Digital active crossovers often include additional signal processing, such as limiting, delay, and equalization. Signal crossovers allow the audio signal to be split into bands that are processed separately before they are mixed together again. Some examples are multiband dynamics (compression, limiting, de-essing), multiband distortion, bass enhancement, high frequency exciters, and noise reduction such as Dolby A noise reduction.

Audio power amplifier

An audio power amplifier (or power amp) is an electronic amplifier that amplifies low-power electronic audio signals such as the signal from radio receiver or electric guitar pickup to a level that is high enough for driving loudspeakers or headphones. Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address and home audio systems and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers.

The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification of the signal (this is particularly associated with record turntable signals, microphone signals and electric instrument signals from pickups, such as the electric guitar and electric bass), equalization (e.g., adjusting the bass and treble), tone controls, mixing different input signals or adding electronic effects such as reverb. The inputs can also be any number of audio sources like record players, CD players, digital audio players and cassette players. Most audio power amplifiers require these low-level inputs, which are line level.

While the input signal to an audio power amplifier, such as the signal from an electric guitar, may measure only a few hundred microwatts, its output may be a few watts for small consumer electronics devices, such as clock radios, tens or hundreds of watts for a home stereo system, several thousand watts for a nightclub's sound system or tens of thousands of watts for a large rock concert sound reinforcement system. While power amplifiers are available in standalone units, typically aimed at the hi-fi audiophile market (a niche market) of audio enthusiasts and sound reinforcement system professionals, most consumer electronics sound products, such as clock radios, boom boxes and televisions have relatively small power amplifiers that are integrated inside the chassis of the main product.

Band-stop filter

In signal processing, a band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter. A notch filter is a band-stop filter with a narrow stopband (high Q factor).

Narrow notch filters (optical) are used in Raman spectroscopy, live sound reproduction (public address systems, or PA systems) and in instrument amplifiers (especially amplifiers or preamplifiers for acoustic instruments such as acoustic guitar, mandolin, bass instrument amplifier, etc.) to reduce or prevent audio feedback, while having little noticeable effect on the rest of the frequency spectrum (electronic or software filters). Other names include 'band limit filter', 'T-notch filter', 'band-elimination filter', and 'band-reject filter'.

Typically, the width of the stopband is 1 to 2 decades (that is, the highest frequency attenuated is 10 to 100 times the lowest frequency attenuated). However, in the audio band, a notch filter has high and low frequencies that may be only semitones apart.

Bass amplifier

A bass amplifier or "bass amp" is a musical instrument electronic device that uses electrical power to make lower-pitched instruments such as the bass guitar or double bass loud enough to be heard by the performers and audience. Bass amps typically consist of a preamplifier, tone controls, a power amplifier and one or more loudspeakers ("drivers") in a cabinet. While bass amps share many features with the guitar amplifiers used for electric guitar, such as providing an amplifier with tone and volume controls and a carrying handle, they are distinct from other types of amplification systems, due to the particular challenges associated with low-frequency sound reproduction. This distinction affects the design of the loudspeakers, the size and design of the speaker cabinet and the design of the preamplifier and amplifier. Speaker cabinets for bass amps usually incorporate larger loudspeakers (e.g., 15" speakers are more common for bass than for electric guitar amps) or more speakers and larger cabinet sizes than those used for the amplification of other instruments. The loudspeakers themselves must also be sturdier to handle the higher power levels and they must be capable of reproducing very low pitches at high sound pressure levels.

Bass amp speaker cabinets are typically more rigidly constructed, with thicker wood and more heavy bracing than those for non-bass amplification. They usually include tuned bass reflex ports or vents cut into the cabinet, for increased efficiency at low frequencies and improved bass sound. Preamplifier sections have equalization controls that are designed for the deeper frequency range of bass instruments, which extend down to 41 Hz or below. Bass amplifiers are more likely to be designed with heat sinks and/or cooling fans than regular guitar amplifiers, due to the high power demands of bass amplification. They are also more commonly equipped with audio compression or limiter circuitry to prevent overloading the power amplifier and to protect the speakers from damage due to unintended clipping in the power amp.

A common format of bass amplifier–the "combo" amp–contains the amplifier electronics and one or more speakers in a single wooden cabinet. Combo amps have been used by musicians since the 1920s, as they are convenient for transporting to rehearsals and for performances at small to mid-size venues. Combo amps range from small, low-powered "practice amps" used for individual practice, to mid- and large-size and more powerful combo amps which produce enough volume for rehearsals and small to mid-size venues (e.g., nightclubs). For larger venues, such as stadiums, bassists may use the "bass stack" approach, in which one or more separate speaker cabinets, each with one or more speakers (but not containing an amplifier) and a separate "head" containing the amplifier electronics are used. With a large "bass stack", a bassist can obtain a much higher wattage and onstage volume than a "combo" amp could provide. As with an electric guitar amp, a bass amp is not used simply to make the instrument louder; performers use the preamplifier and equalizer controls and, particularly in amps from the 1980s and 1990s onward, the onboard electronic effects, to create their preferred tone.

In the 2000s, new developments in bass amplifier technology include the use of lightweight neodymium magnets in some higher-priced cabinets and the use of lightweight, powerful Class D amplifiers in some combo amps and amp heads; both of these innovations have made transporting amps and cabinets easier. As well, some 2010s-era bass amps and heads have digital effects units and modelling amplifier features which enable the recreation or simulation of the sound of numerous well-known bass amps, including vintage tube amplifiers by famous brands (e.g., Ampeg SVT-Pro amp heads) and a range of speaker cabinets. Digital amp and cabinet modelling also makes transporting bass amps and cabinets to gigs and recording sessions easier, because a bassist can emulate the sound of many different brands of very large, heavy vintage gear without having to bring the actual amps and cabinets. Another trend for higher-priced and higher-wattage amps and cabinets aimed at professionals is providing Speakon speaker jacks in addition to, or in place of traditional 1/4" speaker jacks. Speakon jacks are considered safer for high-wattage amps, since the bassist cannot accidentally touch the "live" parts of the cable end and they lock in, so there is less risk of accidental disconnection. As of 2017, a few digital amp and cabinet modelling amplifiers have a USB input or other computer input, to enable users to download new sounds and presets.

Boutique amplifier

Boutique amplifier is a catch-all descriptor for any type of instrument amplifier that is typically hand built with the intention of being much better than the mass-produced variety offered by large companies. In the majority of cases, this is reflected in the price. Sometimes they are clones of older designs, often with minor improvements or alterations in layout or circuit design; sometimes they are new designs altogether.


The clavinet is an electrically amplified clavichord that was invented by Ernst Zacharias and manufactured by the Hohner company of Trossingen, West Germany from 1964 to the early 1980s. Hohner produced seven models over the years, designated I, II, L, C, D6, E7 and Duo. Its distinctive bright staccato sound has featured most prominently in funk, jazz-funk, reggae, rock, and soul songs.

Electric instrument

An electric musical instrument is one in which the use of electric devices determines or affects the sound produced by an instrument. Electric musical instruments are an example of electric music technology. It is also known as an amplified musical instrument due to the common utilization of an electronic instrument amplifier to project the intended sound as determined by electric signals from the instrument. Two common types of instrument amplifiers are the guitar amplifier and the bass amplifier. This is not the same as an electronic musical instrument, like a synthesizer, which uses entirely electronic means to both create and control sound.

Most electric or amplified musical instruments are electric versions of chordophones (including pianos, guitars and violins). Some of the most commonly used electric instruments are electric guitar, electric bass and electric piano. Other electric instruments include the varitone, an amplified saxophone (part of the aerophone family) that was first introduced by The Selmer Company in 1965; and the Hammond organ which uses tonewheels to generate electric sound.

Electric piano

An electric piano is an electric musical instrument which produces sounds when a performer presses the keys of the piano-style musical keyboard. Pressing keys causes mechanical hammers to strike metal strings, metal reeds or wire tines, leading to vibrations which are converted into electrical signals by magnetic pickups, which are then connected to an instrument amplifier and loudspeaker to make a sound loud enough for the performer and audience to hear. Unlike a synthesizer, the electric piano is not an electronic instrument. Instead, it is an electro-mechanical instrument. Some early electric pianos used lengths of wire to produce the tone, like a traditional piano. Smaller electric pianos used short slivers of steel to produce the tone. The earliest electric pianos were invented in the late 1920s; the 1929 Neo-Bechstein electric grand piano was among the first. Probably the earliest stringless model was Lloyd Loar's Vivi-Tone Clavier. A few other noteworthy producers of electric pianos include Baldwin Piano and Organ Company and the Wurlitzer Company.

Early electric piano recordings include Duke Ellington's in 1955 and Sun Ra's India as well as other tracks from the 1956 sessions included on his second album Super Sonic Jazz (a.k.a. Super Sonic Sounds). The popularity of the electric piano began to grow in the late 1950s after Ray Charles's 1959 hit record "What'd I Say", reaching its height during the 1970s, after which they were progressively displaced by more lightweight electronic pianos capable of piano-like sounds without the disadvantages of electric pianos' heavy weight and moving mechanical parts. Another factor driving their development and acceptance was the progressive electrification of popular music and the need for a portable keyboard instrument capable of high-volume amplification. Musicians adopted a number of types of domestic electric pianos for rock and pop use. This encouraged their manufacturers to modify them for stage use and then develop models primarily intended for stage use.

Digital pianos that provide an emulated electric piano sound have largely supplanted the actual electro-mechanical instruments in the 2010s, due to the small size, low weight and versatility of digital instruments, which can produce a huge range of tones besides piano tones (e.g., emulations of Hammond organ sounds, synthesizer sounds, etc.). However, some performers still perform and record with vintage electric pianos. In 2009, Rhodes produced a new line of electro-mechanical pianos, known as the Rhodes Mark 7, followed by an offering from Vintage Vibe.

Fender Bandmaster

The Fender Bandmaster was a musical instrument amplifier made by Fender. It was introduced in 1953 and discontinued in 1974. Some early models had both a microphone input and instrument inputs. Beginning in 1960, Bandmaster amps were equipped with a vibrato effect. In the 2000s, vintage Bandmaster amps remain in use by blues, Americana and rock and roll bands.

Fender Pro

The Fender Pro was an instrument amplifier manufactured by Fender Electric Instruments from 1946 to 1965. It was characterized by its dual 6L6-family power tubes and single 15" speaker, with output power increasing from 18 watts up to 40 watts over its production run. The Pro was replaced in the Fender lineup by its offspring the Pro Reverb.

Gibson ES-150

The Gibson Guitar Corporation's ES-150 guitar is generally recognized as the world's first commercially successful Spanish-style electric guitar. The ES stands for Electric Spanish, and Gibson designated it "150" because they priced it (in an instrument/amplifier/cable bundle) at around $150. The particular sound of the instrument came from a combination of the specific bar-style pickup and its placement, and the guitar's overall construction. It became famous due in large part to its endorsement by notable guitar players including Charlie Christian. After Gibson introduced it in 1936, it immediately became popular in jazz orchestras. Unlike the usual acoustic guitars in jazz bands of the period, it was loud enough to take a more prominent position in ensembles. Gibson produced the guitar with minor variations until 1940, when the ES-150 designation (the "V2") denoted a model with a different construction and pickup.

Jazz violin

Jazz violin is the use of the violin or electric violin to improvise solo lines. Early jazz violinists included Eddie South, who played violin with Jimmy Wade's Dixielanders in Chicago; Stuff Smith; Claude "Fiddler" Williams, who played with Andy Kirk and his Twelve Clouds of Joy. Joe Venuti was best known for his work with guitarist Eddie Lang during the 1920s. Georgie Stoll was a jazz violinist who became an orchestra leader and film music director.

Improvising violinists include Stéphane Grappelli, Noel Pointer, Jean-Luc Ponty. While not primarily jazz violinists, Darol Anger and Mark O'Connor have spent significant parts of their careers playing jazz, while Sara Caswell, Scott Tixier, and Jeremy Kittel are equally fluent in both progressive and traditional styles of jazz. Violins appear in string ensembles or big bands supplying orchestral backgrounds to many jazz recordings.

The violin is a bowed string instrument with four strings usually tuned in perfect fifths. It is the smallest and highest-pitched member of the violin family of string instruments, which also includes the viola, cello, and double bass. A violinist produces sound by either drawing a bow (normally held in the right hand) across one or more strings (which may be stopped by the fingers of the other hand to produce a full range of pitches), plucking the strings (with either hand), or a variety of other techniques. In jazz fusion, violinists may use an electric violin plugged into an instrument amplifier with electronic effects.


Mute may refer to:

Muteness, a speech disorder in which a person lacks the ability to speak

Mute, a silent letter in phonology

Mute (2005 film), a short film by Melissa Joan Hart

Mute (2018 film), a science-fiction thriller directed by Duncan Jones

Mute (death customs), a professional mourner in Victorian and other European cultures

Mute (magazine), an online magazine of culture and politics

Mute (music), a device used to alter the sound of a musical instrument

Mute (food), a soup from Colombia

Mute Records, a record label in the United Kingdom

MUTE, a peer-to-peer file-sharing network

Mute (album), a 2000 compilation album from Hush Records featuring several indie rock acts

Muted (album), a 2003 album from hip hop artist Alias

"Mute" (The Twilight Zone), an episode of The Twilight Zone

"Mute" (short story), written by Stephen King

Pickup (music technology)

A pickup is a transducer that captures or senses mechanical vibrations produced by musical instruments, particularly stringed instruments such as the electric guitar, and converts these to an electrical signal that is amplified using an instrument amplifier to produce musical sounds through a loudspeaker in a speaker enclosure. The signal from a pickup can also be recorded directly.

Most electric guitars and electric basses use magnetic pickups. Acoustic guitars, upright basses and fiddles often use a piezoelectric pickup.


A preamplifier (preamp or "pre") is an electronic amplifier that converts a weak electrical signal into an output signal strong enough to be noise-tolerant and strong enough for further processing, or for sending to a power amplifier and a loudspeaker. Without this, the final signal would be noisy or distorted. They are typically used to amplify signals from analog sensors such as microphones and pickups. Because of this, the preamplifier is often placed close to the sensor to reduce the effects of noise and interference.


A pull-off is a stringed instrument plucking technique performed by "pulling" the finger off a string off the fingerboard of either a fretted or unfretted instrument.

White Amp

The White amplifier was an instrument amplifier made by the Fender company, named for Fender's production manager Forrest White and designed as a surprise by Leo Fender for his longtime associate. It was sold together with the matching steel guitar and was made from 1954 until 1962. Approximately 1,500 copies were made. The amp was nearly identical to the 5F2 Princeton circuit, but was made under the White production name, probably "to get more inexpensive amps and steels into the market without offending authorized Fender dealers." The amplifier was not in fact white, but had blue-gray linen tweed, dark blue grill cloth, and blue dyed leather handles.

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