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A guitar amplifier (or amp) is an electronic device or system that strengthens the weak electrical signal from a pickup on an electric guitar, bass guitar, or acoustic guitar so that it can produce sound through one or more loudspeakers, which are typically housed in a wooden cabinet. A guitar amplifier may be a standalone wood or metal cabinet that contains only the power amplifier (and preamplifier) circuits, requiring the use of a separate speaker cabinet–or it may be a "combo" amplifier, which contains both the amplifier and one or more speakers in a wooden cabinet. There is a wide range of sizes and power ratings for guitar amplifiers, from small, lightweight "practice amplifiers" with a single 6" speaker and a 10 watt amp to heavy combo amps with four 10” or four 12" speakers and a powerful 100 watt amplifier, which are loud enough to use in a nightclub or bar performance.
Guitar amplifiers can also modify the instrument's tone by emphasizing or de-emphasizing certain frequencies, using equalizer controls, which function the same way as the bass and treble knobs on a home hi-fi stereo, and by adding electronic effects; distortion (also called "overdrive") and reverb are commonly available as built-in features. The input of modern guitar amplifiers is a 1/4" jack, which is fed a signal from an electro-magnetic pickup (from an electric guitar) or a piezoelectric pickup (usually from an acoustic guitar) using a patch cord, or a wireless transmitter. For electric guitar players, their choice of guitar amp and the settings they use on the amplifier are a key part of their signature tone or sound. Some guitar players are longtime users of a specific amp brand or model. Guitarists may also use external effects pedals to alter the sound of their tone before the signal reaches the amplifier.
In the 1920s, it was very hard for a musician playing a pickup-equipped guitar to find an amplifier and speaker to make their instrument louder as the only speakers that could be bought were "radio horns of limited frequency range and low acoustic output". The cone speaker, widely used in 2000s-era amp cabinets, was not offered for sale until 1995. The first amplifiers and speakers could only be powered with large batteries, which made them heavy and hard to carry around. When engineers developed the first AC mains-powered amplifiers, they were soon used to make musical instruments louder.
Engineers invented the first loud, powerful amplifier and speaker systems for public address systems and movie theaters. These large PA systems and movie theatre sound systems were very large and very expensive, and so they could not be used by most touring musicians. After 1927, smaller, portable AC mains-powered PA systems that could be plugged into a regular wall socket "quickly became popular with musicians"; indeed, "...Leon McAuliffe (with Bob Wills) still used a carbon mic and a portable PA as late as 1935." During the late 1920s to mid-1930s, small portable PA systems and guitar combo amplifiers were fairly similar. These early amps had a "single volume control and one or two input jacks, field coil speakers" and thin wooden cabinets; remarkably, these early amps did not have tone controls or even an on-off switch.
In 1928, the Stromberg-Voisinet firm was the first company to sell an electric stringed instrument and amplifier package. However, musicians found that the amps had an "unsatisfactory tone and volume, [and] dependability problems", so the product did not sell well. Even though the Stromberg-Voisinet amp did not sell well, it still launched a new idea: a portable electric instrument amp with a speaker, all in an easily transported wooden cabinet. In 1929, Vega electrics launched a portable banjo amplifier. In 1932, Electro String Instruments and amplifier (this is not the same company as Stromberg Electro Instruments) introduced a guitar amp with "high output" and a "string driven magnetic pickup". Electro set out the standard template for combo amps: a wooden cabinet with the electronic amplifier mounted inside, and a convenient carrying handle to facilitate transporting the cabinet. In 1933, Vivi-Tone amp set-ups were used for live performances and radio shows. In 1934, Rickenbacker launched a similar combo amp that added metal corner protectors to keep the corners in good condition during transportation.
In 1933, Dobro released an electric guitar and amp package. The combo amp had "two 8″ Lansing speakers and a five-tube chassis. Dobro made a two speaker combo amp that was on the market over 12 years before Fender launched its two-speaker "Dual Professional/Super" combo amp. In 1933, Audio-Vox was founded by Paul Tutmarc, the inventor of the first electric bass (Tutmarc's instrument did not achieve market success until Leo Fender's launched the Precision Bass). In 1933, Vega sold a pickup and amplifier set for musicians to use with existing guitars.
In that same year, the Los Angeles-based Volu-Tone company also sold a pickup/amplifier set. Volu-Tone used "high voltage current" to sense the string vibration, a potentially dangerous approach that did not become popular. In 1934 Dobro released a guitar amp with a vacuum tube rectifier and two power tubes. By 1935, Dobro and National began selling combo amps for Hawaiian guitar. In 1934, Gibson had developed prototype combo amps, but never them. By 1935, Electro/Rickenbacher had sold more amps and electric guitars than all the amps and electrified or electric guitars that had been made from 1928 through the end of 1934.
The first electric instrument amplifiers were not intended for electric guitars, but were portable PA systems. These appeared in the early 1930s when the introduction of electrolytic capacitors and rectifier tubes enabled economical built-in power supplies that could plug into wall sockets. Previously, amplifiers required heavy multiple battery packs. People used these amplifiers to amplify acoustic guitar, but electronic amplification of guitar first became widely poplular in the 1930s and 1940s craze for Hawaiian music, which extensively used amplified lap steel guitars.
In the 1920s, the earliest combo amplifiers had no tone controls. The first tone controls were simple, mainly providing treble adjustment. The limited controls, the early loudspeakers, and the low amplifier power (typically 15 watts or less prior to the mid-1950s) gave poor high treble and bass output. Some models also provided effects such as an electronic tremolo unit. In confusion over nomenclature, Fender labeled early amplifier tremolo as "vibrato" and called the vibrato arm of the Stratocaster guitar a "tremolo bar" (see vibrato unit, electric guitar, and tremolo).
Some later amplifier models included an onboard spring reverb effect, one of the first being the Ampeg Reverberocket amp.
In the 1950s, several guitarists experimented with producing distortion by deliberately overdriving amplifiers. These included Goree Carter,Joe Hill Louis, Elmore James, Ike Turner, Willie Johnson, Pat Hare, Guitar Slim, Chuck Berry, Johnny Burnette, and Link Wray. In the early 1960s, surf rock guitarist Dick Dale worked closely with Fender to produce custom made amplifiers, including the first 100-watt guitar amplifier. He pushed the limits of electric amplification technology, helping to develop new equipment that was capable of producing "thick, clearly defined tones" at "previously undreamed-of volumes."
Distortion became more popular from the mid-1960s, when The Kinks guitarist Dave Davies produced distortion effects by connecting the already distorted output of one amplifier into the input of another. Later, most guitar amps were provided with preamplifier distortion controls, and "fuzz boxes" and other effects units were engineered to safely and reliably produce these sounds. In the 2000s, overdrive and distortion has become an integral part of many styles of electric guitar playing, ranging from blues rock to heavy metal and hardcore punk.
Guitar combo amplifiers were at first used with bass guitars and electric pianos, but these instruments produce a wider frequency range and need a full-range speaker system. Much more amplifier power is required to reproduce low-frequency sound, especially at high volume. Reproducing low frequencies also requires a suitable woofer or subwoofer speaker and enclosure, with bass cabinets often being larger in size than a cabinet for mid-range or high-range sounds. As well, the open-back cabinets used on many electric guitar amps, while effective for electric guitar, do not have good bass reproduction.
Woofer enclosures must be larger and more sturdily built than cabinets for mid-range or high-frequency (tweeter) speakers. As such, in the 1950s, when Ampeg introduced bass amplifier and speaker systems, bass guitarists began to use them. Similarly, Hammond organ players used a specialized keyboard combo amplifier, the Leslie speaker cabinet, which contains a woofer for the low frequencies and a horn for the high frequencies. The Leslie horns rotate and a baffle around the woofer rotates as well, producing a rich tremolo and chorus effect.
Typically, guitar amplifiers have two amplifying circuit stages and in addition frequently have tone-shaping electric circuits, which usually include at least bass and treble controls, which function similarly to the equivalent controls on a home hi-fi system. More expensive amplifiers typically have more controls for other frequency ranges, such as one or two "midrange" controls and a "presence" control for high frequencies. Some guitar amplifiers have a graphic equalizer, which uses vertical faders to control multiple frequency bands. Some more expensive bass amps have a parametric equalizer, which enables precise control of tone.
The first amplifier stage is a preamplifier. It amplifies the audio signal to a level that can drive the power stage. The preamplifier also changes the tone of the signal; high preamp settings add overdrive. The power amplifier produces a high current signal to drive a loudspeaker and produce sound.
Various types of tone stages may affect the guitar signal:
Tone stages may also provide electronic effects—such as equalization, compression, distortion, chorus, or reverb. Amplifiers may use vacuum tubes (called valves in Britain), solid-state (transistor) devices, or both.
The two common guitar amplifier configurations are: a combination ("combo") amplifier that includes an amplifier and one or more speakers in a single cabinet, and a standalone amplifier (often called a "head" or "amp head"), which passes the amplified signal via a speaker cable to one or more external speaker cabinets. A wide range of speaker configurations are available in guitar cabinets—from cabinets with a single speaker (e.g., 1×10" or 1×12") or multiple speakers (e.g., 2×10", 4×10" or 8x10").
Guitar amplifiers vary widely in price and quality. Many music equipment companies import small, low-powered practice amplifiers for students and beginners that sell for less than $50 USD. Other companies produce expensive custom-made amplifiers for professional musicians, which can cost hundreds or even thousands of dollars (USD). Most combo amplifiers have a carrying handle, and many combo amplifiers and cabinets have metal or plastic-reinforced corners to protect the amp during transportation.
Control knobs and buttons are typically on the front of the cabinet or chassis, though in some cases, the knobs are on a recessed panel at the back of the top of the amplifier. The most basic amps only have a few knobs, which typically control volume, bass and treble. More expensive amps may have a number of knobs that control pre-amp volume (or "gain"), distortion or overdrive, volume, bass, mid and treble, and reverb. Some older amps (and their re-issued versions) have a knob that controls a vibrato or tremolo effect. The 1/4" input jack is typically mounted on the front of the amplifier. In the simplest, least expensive amplifiers, this 1/4" jack is the only jack on the amplifier.
More expensive amplifiers may have a patch bay for multiple inputs and outputs, such as a pre-amp out (for sending to another guitar amplifier), a second low gain input, to use with active basses, an in jack to create an effects loop (when used with the pre-amp out jack), an external speaker output (for powering an additional speaker cabinet), and stereo RCA jacks or an 1/8" jack, for connecting a CD player or MP3 player so that a player can practice along with recorded music. Some amps have a 1/4" jack for connecting a pedal to turn the amp's onboard overdrive and reverb on and off or to switch between channels. Some amps have an XLR jack for a microphone, either for the guitar amp to be used for singing (in effect as a mini-PA system), or, for acoustic guitar, to mix a mic signal with a pickup signal.
The vast majority of guitar amps can only be powered by AC mains power (plugging into a wall outlet); however, a small number of practice amps designed for buskers also have battery power so they can be used for street performances.
A combo amp contains the amplifier and one or more speakers in a single cabinet. In a "head and speaker cabinet" configuration, the amplifier and speaker each have their own cabinet. The amplifier (head) may drive one or more speaker cabinets.
In the 1920s, guitarists played through public address amplifiers, but by the 1940s this was uncommon.
Besides instrument inputs and speaker outputs (typically via 1/4" jacks), an amp may have other inputs and outputs. These can include an auxiliary input jack (sometimes with its own level control, for a drum machine), "send" and "return" jacks to create an effects loop,[ further explanation needed ] a “line out” jack and an extension speaker jack. Practice amps sometimes have a 1/4" headphone jack, or stereo RCA or mini jacks for connecting a CD player, portable media player or other sound source. Some guitar amps have an XLR input so that a microphone can be plugged in for singing. Guitar amps that include a mic input are in effect small, portable PA systems. Some amps, typically bass amps, have an XLR connector to provide a balanced output from the preamp section to a PA system or recording input.
Instrument amplifiers are available in a wide range of price, quality, and performance levels. Some are designed for beginners, such as small, low-wattage practice amps, which typically have a single 8" speaker and about 10 watts, or smaller "combo" amps with relatively low wattage (15 to 20 watts) and a single 10" speaker. Mid- to large-size "combo" amps with 30 to 50 watts and one 12" speaker or four 10" speakers are best for high-volume situations, such as band rehearsals and onstage performances. For large venues, such as outdoor music festivals, guitarists may use one or more 100 watt (or several hundred watt) heads with one or more 8x10” cabinets.
Vacuum tubes (called "valves" in British English) were by far the dominant active electronic components in most instrument amplifier applications until the 1970s, when solid-state semiconductors (transistors) started taking over. Transistor amplifiers are less expensive to build and maintain, reduce the weight and heat of an amplifier, and tend to be more reliable and more shock-resistant. Tubes are fragile and they must be replaced and maintained periodically. As well, serious problems with the tubes can render an amplifier inoperable until the issue is resolved.
While tube-based circuitry is technologically outdated, tube amps remain popular since many guitarists prefer their sound.Tube enthusiasts believe that tube amps produce a "warmer" sound and a more natural "overdrive" sound.
Most inexpensive and mid-priced guitar amplifiers are based on transistor or semiconductor (solid-state) circuits, which are cheaper to produce and more reliable, and usually much lighter than tube amplifiers.Solid-state amps are less fragile than tube amps.
High-end solid-state amplifiers are less common, since many professional guitarists favor vacuum tubes.[ citation needed ] Some[ who? ] jazz guitarists favor the "cleaner" sound of solid-state amplifiers. Only a few solid-state amps have enduring attraction, such as the Roland Jazz Chorus. Solid-state amplifiers vary in output power, functionality, size, price, and sound quality in a wide range, from practice amplifiers to combos suitable for gigging to professional models intended for session musicians who do studio recording work.
A hybrid amplifier involves one of two combinations of tube and solid-state amplification. It may have a tube power amp fed by a solid-state pre-amp circuit, as in most of the original MusicMan amplifiers.
Alternatively, a tube preamplifier can feed a solid-state output stage, as in models from Kustom, Hartke, SWR and Vox. This approach dispenses with the need for an output transformer and easily achieves modern power levels.
Microprocessor technology allows the use of digital onboard effects in guitar amps to create numerous different sounds and tones that simulate the sound of a range of tube amplifiers and different sized speaker cabinets, all using the same amplifier and speaker. These are known as modeling amplifiers, and can be programmed with simulated characteristic tones of different existing amplifier models (and speaker cabinets—even microphone type or placement), or dialed in to the user's taste. Many amps of this type are also programmable by way of USB connection to a home computer or laptop.Line 6 is generally credited with bringing modeling amplification to the market. Modeling amplifiers and stompbox pedals, rackmount units, and software that models specific amplifiers, speakers cabinets, and microphones can provide a large number of sounds and tones. Players can get a reasonable facsimile of the sound of tube amplifiers, vintage combo amplifiers, and huge 8x10” speaker stacks without bringing all that heavy equipment to the studio or stage.
The use of "full range, flat response" (FRFR) amplification systems by electric guitarists has received an extra impetus from modeling amplifiers. Before widespread availability of modeling, guitarists did not commonly plug electric guitars straight into PA systems or powered speakers, because most genres relied on the tonal coloration of a regular guitar amplifier setup—from the preamplifier, equalization filters, power amp, guitar speakers, and cabinet design. The FRFR approach assumes the tone is shaped by sound processors in the signal chain before the amplifier and speaker stage, so it strives to not add further colorationor dedicated combo-style amplifiers with a broad frequency range. Such processors can be traditional guitar effects, a modeling amplifier (without power amplifier), or a computer running tone-shaping software. Using a modeling amp or a multi effects pedal used with line level output, a guitarist can plug in the guitar into a flat response mic input or into a keyboard amplifier.
Acoustic amplifiers are intended for acoustic guitars and other acoustic instruments, especially for the way these instruments are used in relatively quiet genres such as folk and bluegrass. They are similar to keyboard amplifiers, in that they have a relatively flat frequency response with minimal coloration. To produce this relatively "clean" sound, these amplifiers often have powerful amplifiers (providing up to 800 watts RMS), to provide additional "Headroom" and prevent unwanted distortion. Since an 800 watt amplifier built with standard Class AB technology is heavy, some acoustic amplifier manufacturers use lightweight Class D amplifiers, which are also called "switching amplifiers."
Acoustic amplifiers produce an uncolored, "acoustic" sound when used with acoustic instruments with built-in transducer pickups or microphones. The amplifiers often come with a simple mixer, so that the signals from a pickup and condenser microphone can be blended. Since the early 2000s, it has become increasingly common for acoustic amplifiers to provide a range of digital effects, such as reverb and compression. As well, these amplifiers often contain feedback-suppressing devices, such as notch filters or parametric equalizers.
An amplifier stack consists of an amplifier head atop a speaker cabinet—a head on top of one cabinet is commonly called a half stack, a head atop two cabinets a full stack. The cabinet that the head sits on often has an angled top in front, while the lower cabinet of a full stack has a straight front. The first version of the Marshall stack was an amp head on an 8×12 cabinet, meaning a single speaker cabinet containing eight 12" guitar speakers. After six of these cabinets were made, the cabinet arrangement was changed to an amp head on two 4×12 (four 12" speakers) cabinets to make the cabinets more transportable. Some touring metal and rock bands have used a large array of guitar speaker cabinets for their impressive appearance. Some of these arrangements include only the fronts of speaker cabinets mounted on a large frame.
There are many varieties of speaker combinations used in guitar speaker cabinets, including one 12" speaker, one 15" speaker (this is more common for bass amplifiers than for electric guitar cabinets), two 10" speakers, four 10" speakers, four 12" speakers, or eight 10" speakers. Less commonly, guitar cabinets may contain different sizes of speaker in the same cabinet. Cabinets with eight 10" speakers are large and heavy, and they are often equipped with wheels and a "towel bar"-style handle for transport. Some cabinets use mixed speaker types, such as one 15" speaker and two 10" speakers.
Combo guitar amplifier cabinets and guitar speaker cabinets use several different designs, including the "open back" cabinet, the closed back cabinet (a sealed box), and, less commonly, bass reflex designs, which use a closed back with a vent or port cut into the cabinet.With guitar amps, most "open back" amp cabinets are not fully open; part of the back is enclosed with panels. Combo guitar amp cabinets and standalone speaker cabinets are often made of plywood. Some are made of MDF or particle board—especially in low-budget models. Cabinet size and depth, material types, assembly methods, type and thickness of the baffle material (the wood panel that holds the speaker), and the way the baffle attaches to the cabinet all affect tone.
When two or more speakers are used in the same cabinet, or when two cabinets are used together, the speakers can be wired in parallel or in series, or in a combination of the two (e.g., two 2x10" cabinets, with the two speakers wired in series, can be connected together in parallel). Whether speakers are wired in parallel or in series affects the impedance of the system. Two 8 ohm speakers wired in parallel have 4 ohm impedance. Guitarists who connect multiple cabinets to an amplifier must consider the amp's minimum impedance. Parallel vs. series also affects tone and sound. Speakers wired in parallel slightly dampen[s] and restrain[s] them, giving what some describe as "tighter response" and "smoother breakup". Some describe speakers wired in series (usually no more than two) as sounding "...looser, giving a slightly more raw, open and edgy sound."
The relationship between power output in watts and perceived volume is not immediately obvious. The human ear perceives a 5-watt amplifier as half as loud as a 50-watt amplifier (a tenfold increase in power), and a half-watt amplifier is a quarter as loud as a 50-watt amp. Doubling the output power of an amplifier results in a "just noticeable" increase in volume, so a 100-watt amplifier is only just noticeably louder than a 50-watt amplifier. Such generalizations are also subject to the human ear's tendency to behave as a natural compressor at high volumes.
For electric guitar amplifiers, there is often[ vague ] a distinction between "practice" or "recording studio" guitar amps, with output power ratings of less than one watt to 20 watts, and "performance" or "stage" amps of 30 watts or higher.[ citation needed ] Traditionally,[ according to whom? ] these have been fixed-power amplifiers,[ jargon ] with some models having a half-power switch to slightly reduce the listening volume while preserving power-tube distortion.
Power attenuation can be used with either low-power or high-power amplifiers, resulting in variable-power amplifiers. A high-power amplifier with power attenuation can produce power-tube distortion through a range of listening volumes, but with a decrease in high power distortion. Other technologies, such as dual rectifiers and the sag circuit[ jargon ]—which should not be confused with attenuation—allow high power amplifiers to produce low power volume while preserving high power distortion.
Speaker efficiency is also a major factor affecting a tube amplifier's maximum volume.
For bass instruments, higher-power amplifiers are needed to reproduce low-frequency sounds. While an electric guitarist would be able to play at a small club with a 50-watt amplifier, a bass player performing in the same venue would probably need an amplifier with 200 or more watts.
Distortion is a feature available on many guitar amplifiers that is not typically found on keyboard or bass guitar amplifiers. Tube guitar amplifiers can produce distortion through pre-distortion equalization, preamp tube distortion, post-distortion EQ, power-tube distortion, tube rectifier compression, output transformer distortion, guitar speaker distortion, and guitar speaker and cabinet frequency response. Because many factors beyond preamp distortion contribute to a particular guitarist's sound, recording engineers and PA system techs typically put a microphone in front of the guitar speaker, rather than only use the guitar amp's pre-amp out signal. A sound engineer or music producer may send the DI out signal from the pickups to a separate track at the same time, so they can re-amp the signal later. In contrast, it is fairly common to use a DI box with electric bass.
Distortion sound or "texture" from guitar amplifiers is further shaped or processed through the frequency response and distortion factors in the microphones (their response, placement, and multi-microphone comb filtering effects), microphone preamps, mixer channel equalization, and compression. Additionally, the basic sound produced by the guitar amplifier can be changed and shaped by adding distortion and/or equalization effect pedals before the amp's input jack, in the effects loop just before the tube power amp, or after the power tubes.
Power-tube distortion is required for amp sounds in some genres. In a standard master-volume guitar amp, as the amp's final or master volume is increased beyond the full power of the amplifier, power tube distortion is produced. The "power soak" approach places the attenuation between the power tubes and the guitar speaker. In the re-amped or "dummy load" approach, the tube power amp drives a mostly resistive dummy load while an additional low power amp drives the guitar speaker. In the isolation box approach, the guitar amplifier is used with a guitar speaker in a separate cabinet. A soundproofed isolation cabinet, isolation box, isolation booth, or isolation room can be used.
A variety of labels are used for level attenuation potentiometers (knobs) in a guitar amplifier and other guitar equipment. Electric guitars and basses have a volume control on the instrument that attenuates the signal from selected pickups. There may be two volume controls on an electric guitar or bass, wired in parallel to mix the signal levels from the neck and bridge pickups. Rolling back the guitar's volume control also changes the pickup's equalization or frequency response, which can provide pre-distortion equalization.
The simplest guitar amplifiers, such as some vintage amps and modern practice amps, have only a single volume control. Most have two volume controls: a first volume control called "preamplifier" or "gain" and a master volume control. The preamp or gain control works differently on different guitar amp designs. On an amp designed for acoustic guitar, turning up the preamp knob pre-amplifies the signal—but even at its maximum setting, the preamp control is unlikely to produce much overdrive. However, with amps designed for electric guitarists playing blues, hard rock and heavy metal music, turning up the preamp or gain knob usually produces overdrive distortion. Some electric guitar amps have three controls in the volume section: pre-amplifier, distortion and master control. Turning up the preamp and distortion knobs in varying combinations can create a range of overdrive tones, from a gentle, warm growling overdrive suitable for a traditional blues show or a rockabilly band to the extreme distortion used in hardcore punk and death metal. On some electric guitar amps, the "gain" knob is equivalent to the distortion control on a distortion pedal, and similarly may have a side-effect of changing the proportion of bass and treble sent to the next stage.
A simple, inexpensive amplifier may have only two tone controls, a passive bass and treble control. In some better quality amps, one or more midrange controls are provided. On the most expensive amps, there may be shelving equalizers for bass and treble, a number of mid-range controls (e.g., low mid, mid and high mid), and a graphic equalizer or parametric equalizer. The amplifier's master volume control restricts the amount of signal permitted through to the driver stage and the power amplifier. When using a power attenuator with a tube amplifier, the master volume no longer acts as the master volume control. Instead, the power attenuator's attenuation control controls the power delivered to the speaker, and the amplifier's master volume control determines the amount of power-tube distortion. Power-supply based power reduction is controlled by a knob on the tube power amp, variously labeled "wattage", "power", "scale", "power scale", or "power dampening".
An effects unit or effectspedal is an electronic device that alters the sound of a musical instrument or other audio source.
An audio power amplifier 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.
Vox is a musical equipment manufacturer founded in 1957 by Thomas Walter Jennings in Dartford, Kent, England. The company is most famous for making the Vox AC30 guitar amplifier, used by The Beatles, The Rolling Stones, The Kinks, The Yardbirds, Queen, Dire Straits, U2 and Radiohead, the Vox Continental electric organ, the Vox wah-wah pedal used by Jimi Hendrix, and a series of innovative electric guitars and bass guitars. Since 1992, Vox has been owned by the Japanese electronics firm Korg.
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 or other sound source 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.
A DI unit is an electronic device typically used in recording studios and in sound reinforcement systems to connect a high-output impedance, line level, unbalanced output signal to a low-impedance, microphone level, balanced input, usually via an XLR connector and XLR cable. DIs are frequently used to connect an electric guitar or electric bass to a mixing console's microphone input jack. The DI performs level matching, balancing, and either active buffering or passive impedance matching/impedance bridging to minimize unwanted noise, distortion, and ground loops. DI units are typically metal boxes with input and output jacks and, for more expensive units, “ground lift” and attenuator switches.
Marshall Amplification is a British company that designs and manufactures music amplifiers, speaker cabinets, brands personal headphones and earphones, and, having acquired Natal Drums, drums and bongos. It was founded by drum shop owner and drummer Jim Marshall, and is now based in Bletchley, Milton Keynes, Buckinghamshire.
Scholz Research & Development, Inc. or SR&D is the name of the company founded by musician and engineer Tom Scholz to design and manufacture music technology products. Scholz was an MIT-trained engineer who developed many of his skills working on audio-production equipment as a product design engineer at Polaroid in the early 1970s. A musician in his off-time, he developed a recording studio in the basement of the apartment building where he lived, utilizing many home-built devices. Recordings made in his home studio later became the debut album of the band Boston, while the Scholz's proceeds from the success of his band were used to found the company to further develop and sell market versions of his inventions. Many of the devices were marketed under the Rockman brand.
A valve audio amplifier (UK) or vacuum tube audio amplifier is a valve amplifier used for sound reinforcement, sound recording and reproduction.
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.
Distortion and overdrive are forms of audio signal processing used to alter the sound of amplified electric musical instruments, usually by increasing their gain, producing a "fuzzy", "growling", or "gritty" tone. Distortion is most commonly used with the electric guitar, but may also be used with other electric instruments such as bass guitar, electric piano, and Hammond organ. Guitarists playing electric blues originally obtained an overdriven sound by turning up their vacuum tube-powered guitar amplifiers to high volumes, which caused the signal to distort. While overdriven tube amps are still used to obtain overdrive, especially in genres like blues and rockabilly, a number of other ways to produce distortion have been developed since the 1960s, such as distortion effect pedals. The growling tone of a distorted electric guitar is a key part of many genres, including blues and many rock music genres, notably hard rock, punk rock, hardcore punk, acid rock, and heavy metal music, while the use of distorted bass has been essential in a genre of hip hop music and alternative hip hop known as "SoundCloud rap".
A guitar speaker is a loudspeaker – specifically the driver (transducer) part – designed for use in a combination guitar amplifier of an electric guitar, or for use in a guitar speaker cabinet. Typically these drivers produce only the frequency range relevant to electric guitars, which is similar to a regular woofer type driver, which is approximately 75 Hz — 5 kHz, or for electric bass speakers, down to 41 Hz for regular four-string basses or down to about 30 Hz for five-string instruments.
A guitar speaker isolation cabinet is a sound-proof enclosure that surrounds the speaker and sound-capturing microphone and prevents sound leakage into the outside environment, enabling the amplifier to be turned up without excessive listening volume. An amplifier and speaker at full volume is extremely loud, posing a risk to hearing and an annoyance to neighbors, and will often drown out other instruments in a mix in live shows. In a recording studio, the sound of an amplifier at full volume may "leak" into the microphones for other instrumentalists.
The Fender Prosonic guitar amplifier was produced by Fender Musical Instruments from 1996 to 2002. Available in head and combo versions, the Prosonic featured several departures in design from traditional Fender amplifiers such as the Bassman, Twin Reverb, and Deluxe Reverb. Designed by Bruce Zinky as a project for the Fender Custom Shop, the amplifier later had a non-Custom Shop production run at the Fender facilities in Corona, California. It was initially priced to compete with buyers in the so-called boutique amplifier market who were seeking more distortion than any previous Fender had ever offered. It is believed that high list prices, and deviations from established Fender amplifier designs, swayed many buyers away from the Prosonic. It developed a cult following among serious guitarists, aided by the rise of musician-centric Internet communities.
The Fender Twin and Twin Reverb are guitar amplifiers made by Fender Musical Instruments Corporation. The Twin was introduced in 1952, two years before Fender began selling Stratocaster electric guitars. The amps are known for their characteristically clean tone.
Ahed was a Canadian company owned by Phil G. Anderson that produced guitar amplifiers, as well as guitars. Its main product line was the GBX amplifier, which could reach 180 watts with 4x10", 4x12" or 2x15" speakers. The GBX amplifier had a pre-amplifier that could change the gain, brilliance, depth, contour and response of the output.
The Fender Champ was a guitar amplifier made by Fender. It was introduced in 1948 and discontinued in 1982. An updated version was introduced in 2006 as part of the "Vintage Modified" line.
Blackstar Amplification is a producer of guitar amplifiers and effects units based in Northampton, England. The company was founded by a group of ex-Marshall employees, most notably Bruce Keir, current Technical Director at Blackstar and former Chief Design Engineer at Marshall and Ian Robinson. In 2009 they began operations in the United States. The majority of the research and development for Blackstar is carried out in the UK with production taking place in China, having previously been in Korea.
Jim Kelley Amplifiers is the trademark for the vacuum tube guitar amplifiers designed by Jim Kelley and manufactured by his company Active Guitar Electronics of Tustin, California between the years of 1978 and 1985. Approximately 600 of these amps were built during that time. The single-channel version of the amplifier employed modest gain in the preamp stages, Baxandall type bass and treble controls, a split load phase inverter, and four 6V6GT output tubes. The amplifiers produce 60 watts RMS at full power, and include a half power (30/60) switch.
Fuzz bass, also called "bass overdrive" or "bass distortion", is a style of playing the electric bass or modifying its signal that produces a buzzy, distorted, overdriven sound, which the name implies in an onomatopoetic fashion. Overdriving a bass signal significantly changes the timbre, adds higher overtones (harmonics), increases the sustain, and, if the gain is turned up high enough, creates a "breaking up" sound characterized by a growling, buzzy tone.
A keyboard amplifier is a powered electronic amplifier and loudspeaker in a wooden speaker cabinet used for amplification of electronic keyboard instruments. Keyboard amplifiers are distinct from other types of amplification systems such as guitar amplifiers due to the particular challenges associated with making keyboards sound louder on stage; namely, to provide solid low-frequency sound reproduction for the deep basslines which keyboards can play and crisp high-frequency sound for the high-register notes. Another difference between keyboard amplifiers and guitar/bass amplifiers is that keyboard amps are usually designed with a relatively flat frequency response and low distortion. In contrast, many guitar and bass amp designers purposely make their amplifiers modify the frequency response, typically to "roll off" very high frequencies, and most rock and blues guitar amps, and since the 1980s and 1990s, even many bass amps are designed to add distortion or overdrive to the instrument tone.
His first venture, the Phillips label, issued only one known release, and it was one of the loudest, most overdriven, and distorted guitar stomps ever recorded, "Boogie in the Park" by Memphis one-man-band Joe Hill Louis, who cranked his guitar while sitting and banging at a rudimentary drum kit.
Black country bluesmen made raw, heavily amplified boogie records of their own, especially in Memphis, where guitarists like Joe Hill Louis, Willie Johnson (with the early Howlin' Wolf band) and Pat Hare (with Little Junior Parker) played driving rhythms and scorching, distorted solos that might be counted the distant ancestors of heavy metal.
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