Guitar amplifier
Guitar amplifier (guitar amp) is an electronic amplifier designed to make the signal of an electric or acoustic guitar 
louder so that it will produce sound through a loudspeaker and modify the tone by emphasizing or de-emphasizing certain frequencies and adding electronic effects.
The amplifier comprises a preamplifier stage, which amplifies the voltage of the signal from the guitar, and a power amplifier stage which delivers a higher current to the speaker to produce sound. The preamplifier stage may also have electronic effects such as distortion, chorus, or reverb and additional controls such as a graphic equalizer. Amplifiers may use vacuum tubes (in Britain they are called valves), or solid state (transistor) devices, or a mixture of both.
There are two configurations of guitar amplifiers: combination ("combo") amplifiers, which include an amplifier and one, two, or four speakers in a wooden cabinet; and the standalone amplifier (often called a "head" or "amp head"), which does not include a speaker.
A wide range of instrument amplifiers is available, some for general purposes and others designed for specific instruments or particular sounds. These include:
* "Traditional" guitar amplifiers, with a clean, warm sound, a sharp treble roll-off at 5 kHz or less and bass roll-off at 60–100 Hz, and often built-in reverb and tremolo ("vibrato") units. These amplifiers, such as the Fender "Tweed"-style amps, are often used by traditional rock, blues, and country musicians.Traditional amps have more recently become popular with musicians in indie and alternative bands
* Hard rock-style guitar amplifiers, which often include preamplification controls, tone filters, and distortion effects that provide the amplifier's characteristic tone. Users of these amplifiers use the amplifier's tone to add "drive", intensity, and "edge" to their guitar sound. Amplifiers of this type, such as Marshall amplifiers, are used in a range of genres, including hard rock, metal, and punk.
* Bass amplifiers, with extended bass response and tone controls optimized for bass guitars (or more rarely, for upright bass). Higher-end bass amplifiers sometimes include compressor or limiter features, which help to keep the amplifier from distorting at high volume levels, and an XLR DI output for patching the bass signal directly into a mixing board. Bass amplifiers are often provided with external metal heat sinks or fans to help keep the amplifier cool.
* Keyboard amplifiers, with very low distortion and extended, flat frequency response in both directions. Keyboard amplifiers often have a simple onboard mixer, so that keyboardists can control the tone and level of several keyboards.
* Acoustic amplifiers, similar in many ways to keyboard amplifiers but designed specifically to produce a "clean," transparent, "acoustic" sound when used with acoustic instruments with built-in transducer pickups and/or microphones.
Guitar Amplifiers brands
Marshall, Fender, Peavey, Vox, Rocktron, Krank, Soldano, Ibanez, Epiphone, PRS, Yamaha and etc
louder so that it will produce sound through a loudspeaker and modify the tone by emphasizing or de-emphasizing certain frequencies and adding electronic effects.The amplifier comprises a preamplifier stage, which amplifies the voltage of the signal from the guitar, and a power amplifier stage which delivers a higher current to the speaker to produce sound. The preamplifier stage may also have electronic effects such as distortion, chorus, or reverb and additional controls such as a graphic equalizer. Amplifiers may use vacuum tubes (in Britain they are called valves), or solid state (transistor) devices, or a mixture of both.
There are two configurations of guitar amplifiers: combination ("combo") amplifiers, which include an amplifier and one, two, or four speakers in a wooden cabinet; and the standalone amplifier (often called a "head" or "amp head"), which does not include a speaker.
A wide range of instrument amplifiers is available, some for general purposes and others designed for specific instruments or particular sounds. These include:
* "Traditional" guitar amplifiers, with a clean, warm sound, a sharp treble roll-off at 5 kHz or less and bass roll-off at 60–100 Hz, and often built-in reverb and tremolo ("vibrato") units. These amplifiers, such as the Fender "Tweed"-style amps, are often used by traditional rock, blues, and country musicians.Traditional amps have more recently become popular with musicians in indie and alternative bands
* Hard rock-style guitar amplifiers, which often include preamplification controls, tone filters, and distortion effects that provide the amplifier's characteristic tone. Users of these amplifiers use the amplifier's tone to add "drive", intensity, and "edge" to their guitar sound. Amplifiers of this type, such as Marshall amplifiers, are used in a range of genres, including hard rock, metal, and punk.
* Bass amplifiers, with extended bass response and tone controls optimized for bass guitars (or more rarely, for upright bass). Higher-end bass amplifiers sometimes include compressor or limiter features, which help to keep the amplifier from distorting at high volume levels, and an XLR DI output for patching the bass signal directly into a mixing board. Bass amplifiers are often provided with external metal heat sinks or fans to help keep the amplifier cool.
* Keyboard amplifiers, with very low distortion and extended, flat frequency response in both directions. Keyboard amplifiers often have a simple onboard mixer, so that keyboardists can control the tone and level of several keyboards.
* Acoustic amplifiers, similar in many ways to keyboard amplifiers but designed specifically to produce a "clean," transparent, "acoustic" sound when used with acoustic instruments with built-in transducer pickups and/or microphones.
Guitar Amplifiers brands
Marshall, Fender, Peavey, Vox, Rocktron, Krank, Soldano, Ibanez, Epiphone, PRS, Yamaha and etc