Guitar amplifier

Guitar amplifiers can also modify an 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 stereo, and by adding electronic effects; distortion (also called overdrive) and reverb are commonly available as built-in features.

For electric guitar players, their choice of amp and the settings they use on the amplifier are a key part of their signature tone or sound.

Guitarists may also use external effects pedals to alter the sound of their tone before the signal reaches the amplifier.

During the late 1920s to mid-1930s, small portable PA systems and guitar combo amplifiers were fairly similar.

Stromberg-Voisinet still launched a new idea: a portable electric instrument amp with a speaker, all in a transportable wooden cabinet.

Volu-Tone used high voltage current to sense the string vibration, a potentially dangerous approach that did not become popular.

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.

The limited controls, the early loudspeakers, and the low amplifier power (typically 15 watts or less before the mid-1950s) gave poor high treble and bass output.

These included Goree Carter,[3] Joe Hill Louis,[4][5] Elmore James,[6] Ike Turner,[7] Willie Johnson,[8] Pat Hare,[9] Guitar Slim,[10] Chuck Berry,[11] Johnny Burnette,[8] and Link Wray.

[14] 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.

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.

Overdrive and distortion have become integral parts of many styles of electric guitar playing, ranging from blues rock to heavy metal and hardcore punk.

Some guitar amplifiers have a graphic equalizer, which uses vertical faders to control multiple frequency bands.

Many music equipment companies import small, low-powered practice amplifiers for students and beginners that sell for less than $50.

Other companies produce expensive custom-made amplifiers for professional musicians, which can cost hundreds or even thousands of dollars (USD).

Guitar amps that include a mic input are in effect small, portable PA systems.

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.

While tube-based circuitry is technologically outdated, tube amps remain popular since many guitarists prefer their sound.

[15][16][17] 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.

Alternatively, a tube preamplifier can feed a solid-state output stage, as in models from Kustom, Hartke, SWR, and Vox.

The use of full range, flat response (FRFR) amplification systems by electric guitarists has received an extra impetus from modeling amplifiers.

[20] 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.

Since the early 2000s, it has become increasingly common for acoustic amplifiers to provide a range of digital effects, such as reverb and compression.

Some touring metal and rock bands have used a large array of guitar speaker cabinets for their impressive appearance.

Speakers wired in parallel slightly dampen[s] and restrain[s] them, giving what some describe as tighter response and smoother breakup.

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.

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.

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.

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.

As a consequence of the film, real bands and musicians started buying equipment whose knobs went up to eleven.