Guitar amplifiers guitar amplifier used by
The Beatles A guitar amplifier amplifies the electrical signal of an
electric 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 sound with controls that emphasize or de-emphasize certain frequencies and add
electronic effects. String vibrations are sensed by a
pickup. For electric guitars, strings are made of metal, and the pickup works by
electromagnetic induction.
Standard amps Standard amplifiers, such as the Fender
tweed-style amps (e.g., the
Fender Bassman) 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 players. These amps are designed to produce a variety of sounds ranging from a clean, warm sound to a growling, natural overdrive. 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. Combo amplifiers such as the
Fender Super Reverb have powerful
tube amplifiers, 10- or 12-inch speakers, and they often have built-in
reverb and
vibrato effects units. These larger combo amplifiers 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. Smaller, lighter guitar amps are also available, which have less powerful amplifier units and as few as one speaker. Smaller guitar amps are easier to transport to gigs and
sound recording sessions. Smaller amps are widely used in small venue shows, because players can obtain the tone they want without having to have an excessively loud volume. The smallest combo amplifiers, which are mainly used for individual practice and warm-up purposes, may have only a single 8 or 10-inch speaker. Some players use these small combo amplifiers for concert performances, though, because it is easier to create natural overdrive with these lower-powered amplifiers.
Hard rock and heavy metal guitar cabinets for
Jeff Hanneman of
Slayer Powerful electric guitar amplifiers, such as
Marshall amplifiers, are used in a range of louder, heavier genres of rock, including hard rock,
heavy metal, and
hardcore punk. These amplifiers can add an aggressive
drive, intensity, and
edge to the guitar sound with distortion effects, preamplification boost controls, and tone filters. 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 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. While many of the most expensive, high-end models use 1950s-style
tube amplifiers, there are also many models that use transistor amplifiers, or a combination of the two technologies (e.g., a tube preamplifier with a transistor
power amplifier). 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, rock and
electric blues bands often used stacks of " 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. 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 tube amplifiers. Tube amplifiers are perceived to have a warmer tone than transistor amps, particularly when overdriven to produce intentional distortion. 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.
Bass Bass amplifiers are designed for
bass guitars or more rarely, for
upright bass. They differ from amplifiers for the electric guitar in several respects, with extended low-frequency response, and tone controls optimized for the needs of bass players. Amplifiers may include built-in
bass effects units, such as
audio compressor or
limiter features, to avoid unwanted distortion at high volume levels and potential damage to speakers; equalizers; and
bass overdrive. Bass amps may provide an
XLR DI output for routing the bass amp signal directly into a
mixing board or
PA system. Larger, more powerful bass amplifiers are often include internal or external metal
heat sinks or fans to help keep the components cool. Speaker cabinets designed for bass usually use larger
loudspeakers 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 human hearing is
less sensitive to bass frequencies. While the largest speakers commonly used for regular electric guitar have twelve-inch cones, electric bass speaker cabinets often use 15-inch 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-inch 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.
Keyboard A
keyboard amplifier, used for
stage piano,
synthesizer,
clonewheel organ 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. Other variations 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,
mandolin,
harp, 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, to provide additional
headroom and prevent unwanted distortion. 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 provide digital effects, such as
reverb and
compression. Some also contain
feedback-suppressing devices, such as
notch filters or
parametric equalizers. Acoustic guitars do not usually have a built-in pickup or microphone. Some acoustic guitars have a microphone mounted inside the body, which is designed to convert acoustic vibrations into an electrical signal, but may do so from direct contact with the guitar's body. 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. ==Roles==