GUITARS
An electric guitar is a type of guitar that uses pickups to convert the vibration of its steel-cored strings (sometimes nickel) into an electrical current, which is made louder with an instrument amplifier and a speaker. The signal that comes from the guitar is sometimes electronically altered with guitar effects such as reverb or distortion. While most electric guitars have six strings, seven-string instruments are used by some jazz guitarists and metal guitarists (especially in nu metal), and 12-string electric guitars (with six pairs of strings, four of which are tuned in octaves) are used in genres such as jangle pop and rock.

The electric guitar was first used by jazz guitarists, who used amplified hollow-bodied instruments to get a louder sound in Swing-era big bands. The earliest electric guitars were hollow bodied acoustic instruments with tungsten steel pickups made by the Rickenbacker company in 1931. While one of the first solid-body guitars was invented by Les Paul, the first commercially successful solid-body electric guitar was the Fender Esquire (1950). The electric guitar was a key instrument in the development of many musical styles that emerged since the late 1940s, such as Chicago blues, early rock and roll and rockabilly, and 1960s blues rock. It is also used in a range of other genres, including country music, Ambient (or New Age), and in some contemporary classical music. the natural sound of the acoustic instrument fairly accurately, without adding coloration or overdrive.



AMPS
A guitar amplifier is an electronic amplifier designed to make the signal of an electric 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 not come with a speaker. The amplifier components in combo amplifiers and amp heads include both a 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, or reverb 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 12" 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 12" 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 12" 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.

EFFECTS & PEDALS
Guitar effects are electronic devices that modify the tone, pitch, or sound of an electric guitar, or condition or reroute the signal in some fashion. Effects can be housed in small effects pedals ("stomp boxes"), guitar amplifiers, guitar amplifier simulation software, and in rackmount preamplifiers or processors. Electronic effects and signal processing form an important part of the electric guitar tone used in many genres, such as rock, pop, blues, and metal. Guitar effects are also used with other instruments in these genres, such as electronic keyboards and synthesizers. Electric bass players use bass effects, which are designed to work with low-frequency tones of the bass.
The overdriven sound of distortion, which alters a signal's waveform by "clipping" the signal, is an important part of an electric guitar's sound in many genres, particularly for rock, hard rock, and metal. Filtering-related effects such as equalizers are used to adjust the frequency response in a number of different frequency bands, either for subtle sound shaping, to notch out unwanted resonance, or to enhance certain frequencies. Some filtering effects are used for creating more pronounced effects such as the "crying" sound of the wah pedal, the funky tone of the auto-wah, or the vocal-like sounds of the talk box. Volume-related effects such as volume pedals are used to adjust the volume of an instrument, make notes or chords fade in and out, or create a tremolo effect by rapidly increasing and decreasing the volume. A more complex volume-related effect is the compressor, which acts as an automatic volume control and smoothes out the peaks and valleys in the signal.

Time-based effects such as delay or echo pedals create a copy of an incoming sound which can be used for reverb effects; very long delay times can be used as a looping pedal. Modulation-related effects include the swirling sound of rotary speakers such as the Leslie speaker, the "whooshing" sound of the electronic phase shifter, the psychedelic rock-style flanger, or the shimmering sound of a chorus effect. Pitch-related effects includes octave effects (different effects are able to create octaves above or below the initial pitch) and pitch shifting pedals which can be used with an expression pedal to give a smooth bend-like effect or to add a parallel harmony part to a melody. Other pedals include switcher pedals (used to route a signal between different effects, or to select different guitars or amplifiers); noise gates (for filtering out hum); and multi-effect pedals, which contain many different effects in a single chassis.

An effect pedas is an electronic effects unit housed in a small metal or plastic chassis used by musicians, usually electric guitar players, to modify their instrument sound. Musicians playing electronic keyboards, electromechanical organs, the electric bass, or electric violin also use effects pedals. These devices alter the sound quality or timbre of the input signal, adding effects such as distortion, fuzz, overdrive, chorus, reverberation, wah-wah, flanging, phaser or pitch shifting. The sound of a guitar or other instrument that is played without an effects pedal is described as "clean", "straight" or "dry."

The TS9 Tubescreamer from Ibanez, a widely-imitated pedal adding a vacuum tube-like overdrive sound using op-amps.Users refer to them as pedals because they sit on the floor and have large on/off switches on top that are activated using the foot. Some pedals, such as wah-wah or volume pedals, employ what is known as an expression pedal. Expression pedals are manipulated while in operation by rocking a large foot-activated potentiometer (pot) back and forth. The relative position of the expression pedal changes some parameter of the effect, such as a filter response in a wah pedal.Effects pedals permit the musician to activate and deactivate effects while playing an instrument. Some musicians use rack-mounted effects processors controlled using MIDI instead of or in addition to effects pedals, since the greater size of the rack form factor usually allows more flexibility and processing power. Others prefer only using a few analog effects pedals, to avoid sending the instrument signal through multiple stages of analog-to-digital conversion, as occurs in more complicated and powerful digital effects processors.