The electric guitar is a stringed instrument which makes use of electrical signals and an amplifier to produce sound. Electric guitars were produced as early as the 1930s in addition to other electric instruments such as violins with telephone microphones installed. Since their popularization in the 1950s and 60s, electric guitars are now widespread in the music industry, especially amongst genres related to rhythm and blues such as rock 'n' roll.
In contrast to an acoustic guitar, an electric guitar typically does not feature a resonance chamber to amplify its sound. While this is not always the case, such as in the case of acoustic guitars with an internal microphone, most electric guitars instead use electro-magnetic pickups above the bridge. These pickups use magnetic capacitance to detect vibrations in the metal strings of an electric guitar.
While many techniques associated with acoustic guitars still apply to electric variants, the electric nature of the electric guitar creates some noticeable differences. This article will go over the differences in an electric guitar's design, sound, and application in relation to an acoustic guitar. It is advised to read the article on acoustic guitars before reading this article
Many of the same features on an acoustic guitar are found on an electric guitar, such as the guitar neck and guitar bridge. The main difference between an electric guitar and an acoustic are the pickups. Pickups are electro-magnetic coils; an electric current is created passively when the vibrating strings disturb the magnetic field within the pickup. This electric signal passes through the coil within the pickup, through the output jack, and into an amplifier.
Pickups typically present in two forms: single and double. Single pickups are single coils, in contrast to double, or humbucker, pickups which are essentially two single pickups placed next to each other. Single pickups typically have a brighter timbre and lower output compared to humbuckers; with distortion applied this translates to a fuller, grittier sound with a humbucker pickup. This makes single pickups more popular with classical applications of the electric guitar, while humbuckers are more popular with genres of the rock flavor.
The position of the pickup also plays a role in the timbre produced by an electric guitar. Pickups closer to the bridge create a brighter and twangier timbre, while pickups moved away from the bridge create a bass heavy hollow timbre. Pickups can be placed perpendicular to the strings, or at an angle. This angle can be positive or negative, with a positive (clockwise) angle being the most common. Although rare, humbucker pickups can be angled. Since moving a pickup closer or farther away from the bridge changes the timbre of the guitar, the goal with positively angled pickups is to create a brighter timbre towards the smaller higher pitched strings and a more bass heavy sound towards the heavier, lower pitched strings. Most applications of angled pickups, however, are based on personal preference.
Most electric guitars have more than one usable pickup because of the difference in timbre the positioning of a pickup can create. If the guitar has no or only one humbucker pickup, it will typically have three pickups arranged at varying distances from the bridge, with the humbucker typically being closest to the bridge. If the guitar has two humbuckers, there will typically be only those two pickups with no single pickups added. Electric guitars have a pickup switch which changes the pickup currently sending a signal out of the output jack, and can even combine the signals from two adjacent pickups with some settings.
Electric guitars, even without distortion or overdrive, have radically different timbres than acoustic guitars; adding effects only increases this difference.
Compared to an acoustic guitar, a clean, or non-distorted, electric guitar typically has a flatter sound. Notes do not carry as much of their signature twang found in acoustic guitars over to electric guitars. While the treble, or higher, strings of an electric guitar can recreate some of this twang, especially with pickups closer to the bridge, the lack of twang in electric guitars is very apparent in the bass, or lower, strings. This causes an electric guitar to have a timbre similar to a piano or stand-up bass. This also makes the pick attack less obvious; the lack of an obvious twang can make hearing when a pick plucks a string more difficult to hear, especially when distortion is added.
In application, the main purpose of an electric guitar is to be able to add effects that would otherwise not manifest well when applied to an acoustic guitar with a microphone. In specific, distortion, overdrive and other waveform modifying effects are applied to the signal sent from a guitar before it reaches the amplifier. Many amplifiers come with effects for overdrive, distortion, reverb, and equalization. Effects pedals expand on the list of common effects: wahwah pedals, talk boxes, and distortion pedals are some of the most common. Distortion and overdrive, however, are the most common by a wide margin.
Distortion and overdrive have similar effects and the words are often used interchangeably. Overdrive dramatically amplifies and clips the signal received from a guitar while adding overtones that are both in and out of harmony with the source signal. This gives an electric guitar a timbre which shrieks and buzzes. A small amount of overdrive is common in earlier rock 'n' roll genres. Bands such as Kansas, Creedence Clearwater Revival, and The Allman Brothers Band all use moderate to small amounts of overdrive. The more overdrive that is applied, the more distorted the signal becomes as a result of increased overloading, overtones and clipping.
An overdriven guitar is often applied more like a clean guitar with more energy rather than how fully distorted guitars are typically applied. It is not until a certain level of overdrive is reached that the signal crosses into being distorted and carries characteristics unique to the electric guitar specifically. These characteristics include: palm muted notes which have a characteristic chug to them, pinch harmonics which shriek to great effect, fuller sustained notes which buzz, compressed chords, and peculiarities such as feedback. Distorted guitars have a compressed feature to their timbre, which gives the feeling of having a heavier sound.
Distortion also has important effects on harmony. For example, major and minor thirds (two whole steps or one and a half respectively) whine, while minor firsts will vibrate. Since distortion can have a dramatic effect on harmony due to the presence of overtones in a distorted signal, many genres that have distorted electric guitars as a staple have different approaches to melody and chord theory as compared to those genres with acoustic guitars as a staple.
Electric guitars are also often easier to play from a finger strength point of view due to their strings typically being looser from the lack of a need to vibrate a whole instrument to produce sound. Since the strings are not as tense, things like hammer-ons, pull-offs, and tapping are made easier. This results in those techniques being more common.