guitar amplifier

A guitar amplifier (or guitar amp) is an electronic amplifier designed to make the signal of anelectric guitar or an acoustic guitar louder and modify the tone by emphasizing or de-emphasizing certain frequencies and/or by adding electronic effects. There are two types 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 notcome with a speaker. The amplifier components in combo amplifiers and amp heads include both preamplifier, which boosts the signal coming out of the guitar to prepare it for the next amplifier stage, and a power amplifier, which provides the higher current which causes the speaker to produce sound. The simplest guitar amplifiers have only a power switch, a volume knob, and one or two tone control knobs. Guitar amplifiers may also have one or more electronic effects such as distortion, chorus, and additional controls such as a graphic equalizer. There are two main classes of amplifiers used with electric guitars: tube (or valve) amplifiers, which use vacuum tubes; and solid state(transistor) amplifiers.

Combo amplifiers range from small practice amplifiers with one 6" or 8" speaker and a 10 to 15 watt amplifier, to mid-sized combo amps with a 12" speaker and a 50 watt amplifier (suitable for rehearsals or performances in small venues), to large combo amplifiers with four 10" speakers and 100 or more watts of power, which can be used for shows in large clubs or halls. Amp heads are used with one or more speaker cabinets, creating what is nicknamed a "stack". Some guitarists who use amp heads and separate speaker cabinets use a single 4 X 10" speaker cabinet with the amp head. In some styles of music, such as heavy metal and blues rock, guitarists may connect the guitar amp head to a number of 4 X 10" cabinets. Guitar amplifiers range in price and quality from small, low-powered practice amplifier designed for students which sell for less than $50 USD to expensive "boutique" amplifiers which are custom made for professional musicians, and which can cost thousands of dollars.

Bass guitars, which are a type of guitar that can play notes an octave or more below a regular guitar, are typically amplified with a bass amplifier which is designed to handle the low frequency range. Acoustic guitar amplifiers differ from electric guitar amplifiers in that while electric guitar amplifiers are typically designed to modify the tone of the instrument--either by "rolling off" high frequencies or adding the warmth of tube overdrive--acoustic guitar amplifiers are generally designed to reproduce the natural sound of the acoustic instrument fairly accurately, without adding coloration or overdrive.