An electronic keyboard (also called digital keyboard, portable keyboard, or home keyboard) is an electronic or digital keyboard instrument.
The major components of a typical modern electronic keyboard are:
- Musical keyboard: The white and black piano-style keys which the player presses, thus connecting the switches, which triggers the electronic note or other sound. Most keyboards use a keyboard matrix circuit to reduce the amount of wiring that is needed.
- User interface software: A program (usually embedded in a computer chip) which handles user interaction with control keys and menus, which allows the user to select tones (e.g., piano, organ, flute, drum kit), effects (reverb, echo, telephones or sustain), and other features (e.g., transposition, an electronic drum machine)
- Computerized musical arranger: A software program which produces rhythms and chords by the means of computerized commands, typically MIDI.
- Sound generator/sound chip: An electronic sound module or a musical synthesizer typically contained within an integrated circuit or chip, which is capable of accepting MIDI commands and producing sounds.
- Amplifier and speaker: a low to middle-powered audio amplifier and speakers that amplify the sounds so that the listener can hear them.
Keyboard instruments can be found as far back as the hydraulis in the 3rd century BCE, which developed into the pipe organ, and small portable instruments such as the portative and positive organ. Additional keyboard instruments, the clavichord and harpsichord, were developed in the 14th century CE. As technology improved, more sophisticated keyboards were developed, including the 12-tone keyboard still in use today. Initially, the keyboard of an instrument could only produce sounds of one particular volume. In the 18th century, the pianoforte was invented, which allowed a new way of controlling volume by varying the force of the keypress.
The next step was to develop electronic sound technology. The first musical instrument was Denis d'or which was built by Vaclav Prokop Dovis in 1753. It was incorporated with 700 strings temporarily electrified to enhance their sonic qualities. In 1760 Jean Baptiste Thillaie de Laborde developed clavecin electrique. This was keyboard instrument incorporated with plectra and activated by electricity.
But both instruments were not using electricity to produce sound. Elisha Gray invented a electric musical instrument called musical telegraph. It made sound from an electromagnetic circuit's vibration. He incorporated a basic single note oscillator. Next he added a loudspeaker consisting of diaphragm to make data audible.
In 1906, Lee de Forest invented the triode electronic valve. In 1915 he invented the first vacuum tube instrument, the audio piano. Then, until the invention of the transistor, the vacuum tube was an essential component in electric instruments.
In 1935, the Hammond organ was introduced. It was capable of producing polyphonic sounds. More developments were made with the Chamberlin Music Maker in late 1940s and the Mellotron in the early 1950s.
The first step towards the electronic piano was by Rhodes with the pre-piano. It was a three and a half octave instrument. The next generation was capable of doing self-amplification. In 1955, the Wurlitzer Company released the first electric piano, the 100.
The invention of musical synthesizers in the 1960s was a step towards the modern keyboard. As technology became more developed, huge synthesizers evolved into portable instruments that could be used in live shows.
This began in 1964 when Bob Moog produced his Moog synthesizer. It did not have its own keyboard, but its next generation was equipped with a built-in keyboard. The keyboard was monophonic, only able to produce one tone at a time. Some instruments such as the EML 101, ARP Odyssey, and the Moog Sonic six were polyphonic, meaning they could produce two different tones at once when two or more keys were pressed. The next number of electronic keyboards produced were combinations of organ circuits and synthesizers. These were Moog’s Polymoog, Opus 3, and the ARP Omni.
The invention of the musical instrumental digital interface(MIDI) as a standard for digital code transmission digital technology development spurred great development in keyboard technology.
Some manufacturers and retailers divide their keyboard products into the following categories:
- Digital piano - Electronic keyboards designed to sound and feel like an acoustic piano.
- Stage piano - A type of digital piano designed for stage or live band use.
- Synthesizer - Electronic keyboards that uses various sound synthesis to produce a wide variety of sounds.
- Arranger - Electronic keyboards that can produce a range of sounds as well as backing accompaniments accompany the performer, and is usually played by the left hand. An arranger keyboard player is usually called one-man bands.
Compared to digital pianos or stage pianos, digital keyboards are usually much lower in cost, have unweighted keys but have a great many ancillary controls and usually feature on-board loudspeakers. Unlike synthesisers, the primary focus is not on detailed control of sound synthesis parameters.
Concepts and definitions
- Auto accompaniment / chord recognition: Auto accompaniment is used on programmed styles to trigger specific chords that will sound when a single key is pressed on the keyboard. For example, when the auto accompaniment feature is on, and the performer presses a "C" note in the low range of the keyboard, the auto accompaniment feature will play a C Major chord. In many keyboards, the auto accompaniment feature will play the automatic chords in a rhythm and style that is appropriate for the musical style (e.g., rock, pop, hip-hop) selected by the performer (see the Accompaniment styles section for more). When the on-board rhythm track is turned on, the auto-chords will be played automatically in the tempo of the rhythm track. Many keyboards have an option to form on-bass chords, as well as many other complex chords.
- Demonstration: Most keyboards have pre-programmed demo songs. As the name "demo" implies, one usage of these pre-programmed songs is for a salesperson to use to demonstrate the capabilities of the keyboard, in terms of its different voices and effects. The demo songs can also be used for entertainment and learning. Some keyboards have a teaching feature that will indicate the notes to be played on the display and wait for the player to press the right one.
- Touch sensitivity (also found under the keyword velocity in some manuals): While the least expensive keyboards are simply "on-off" switches, mid-range and higher-range instruments simulate the process of sound generation in chordophones (string instruments) which are sensitive to the pressure (or "hardness") of a key press. Mid-range instruments may only have two or three levels of sensitivity (e.g., soft-medium-loud). More expensive models may have a broader range of sensitivity. For implementation, two sensors are installed for each key: the first sensor detects when a key is beginning to be pressed and the other triggers when the key is pressed completely. On some higher-end electronic keyboards or digital pianos, a third sensor is installed. This third sensor allows the player to strike a key and still sound a note even when the key has not yet come to its full resting position, allowing for faster (and more accurate) playing of repeated notes. The time between the two (or three) signals allows a keyboard to determine the velocity with which the key was struck. As the key weight is constant this velocity can be considered as the strength of the press. Based on this value the sound generator produces a correspondingly loud or soft sound. The least sophisticated types of touch sensitivity cause the keyboard to change the volume of the instrument voice. The most sophisticated, expensive types will trigger both a change in volume and a change in timbre, which simulates the way that very hard strikes of a piano or electric piano cause a difference in tone—as well as an increase in volume. Some sophisticated touch-sensitivity systems accomplish this by having several samples of an acoustic instrument note per key (e.g., a soft strike, a mid-level strike, and a hard strike). Alternatively, a similar effect can be accomplished using synthesis-modelling of the ASDR envelope or digital modelling (e.g., for the hard strike, the keyboard would add the timbres associated with a hard strike—in the case of a Fender Rhodes voice, this would be a biting, "bark" sound).
- After-touch: A feature brought in the late 1980s (although synthesizers like the CS-80 extensively used by artists like Vangelis featured after-touch as early as 1977) whereby dynamics are added after the key is hit, allowing the sound to be modulated in some way (such as fade away or return), based upon the amount of pressure applied to the keyboard. For example, in some synth voices, if the key continues to be pressed hard after the initial note has been sounded, the keyboard will add an effect such as vibrato or sustain. After-touch is found on many mid-range and high-range synthesizers, and is an important modulation source on modern keyboards. After-touch is most prevalent in music of the mid to late 1980s, such as the opening string-pad on Cock Robin's When Your Heart Is Weak, which is only possible with the use of after-touch (or one hand on the volume control). After-touch is not normally found on inexpensive, beginner-level home keyboards.
- Polyphony: In digital music terminology, polyphony refers to the maximum number of notes that can be produced by the sound generator at once. Polyphony allows significantly smoother and more natural transitions between notes. Inexpensive toy electronic keyboards designed for children can usually only play one note at a time. Many low priced keyboards can perform four or five notes at a time. Better-quality keyboards can perform over ten notes at a time with 32 or 64 notes being common.
- Multi-timbre: The ability to play more than one kind of instrument sound at the same time. Such as with the Roland MT-32's ability to play up to eight different instruments at once.
- Split point: The point on a keyboard where the choice of instrument can be split to allow two instruments to be played at once. In the late 1980s it was common to use a MIDI controller to control more than one keyboard from a single device. The MIDI controller had no sound of its own, but was designed for the sole purpose of allowing access to more sound controls for performance purposes. MIDI controllers allowed one to split the keyboard into two or more sections and assign each section to a MIDI channel, to send note data to an external keyboard. Many consumer keyboards offer at least one split to separate bass or auto-accompaniment chording instruments from the melody instrument.
- Accompaniment styles: Pre-programmed musical accompaniment styles (also called rhythm, backing or pattern by some manufacturers), consist of a variety of genres for the player to use (e.g., pop, rock, jazz, country, reggae). The keyboard plays a chord voicing and rhythm which is appropriate for the selected genre. In general, accompaniment styles usually imitates the sound of a full band or an orchestra. Certain keyboards may include a feature that allows the performer to create, compose and customize their own accompaniments. This feature is usually called a pattern sequencer, rhythm composer, or a style creator.
- Accompaniment sections and synchronization: Usually, styles compose of two to four sections, as well as fill-in patterns, introduction/ending patterns, and various synchronizations to improve the effects of the accompaniment.
- Tempo: A parameter that determines the speed of rhythms, chords and other auto-generated content on electronic keyboards. The unit of this parameter is beats per minute. Many keyboards feature audio or visual metronomes (using graphics on a portion of the display) to help players keep time.
- Auto harmony: A feature of some keyboards that automatically adds secondary tones to a note based upon chords given by the accompaniment system, to make harmony easier for players who lack the ability to make complex chord changes with their left hand.
- Wheels and knobs: Used to add effects to a sound that are not present by default, such as vibrato, panning, tremolo, pitch bending, and so on. A common wheel on contemporary keyboards is the pitch bend, adjusting the pitch of a note usually in the range of ±1 tone. The pitch bend wheel is usually on the left of the keyboard and is a spring-loaded potentiometer.
- Keyboard response: Weighted or spring-loaded keys. The least expensive home keyboards have no keyboard response, and they use plastic keys that are mounted on soft rubber or plastic pads. This set-up, called "synthesizer action" is also used in synthesizers. "Weighted response" refers to keys with weights and springs in them, which give a "hammer action" feel similar to an acoustic piano. Most electronic keyboards use spring-loaded keys that make some kinds of playing techniques, such as backhanded sweeps, impossible, but make the keyboards lighter and easier to transport. Players accustomed to standard weighted piano keys may find non-weighted spring-action keyboards uncomfortable and difficult to play effectively. Conversely, keyboard players accustomed to the non-weighted action may encounter difficulty and discomfort playing on a piano with weighted keys.
Electronic keyboards typically use MIDI signals to send and receive data, a standard format now universally used across most digital electronic musical instruments. On the simplest example of an electronic keyboard, MIDI messages would be sent when a note is pressed on the keyboard, and would determine which note is pressed and for how long. Additionally, most electronic keyboards now have a "touch sensitivity", or "touch response" function which operates by an extra sensor in each key, which estimates the pressure of each note being pressed by the difference in time between when the key begins to be pressed and when it is pressed completely. The values calculated by these sensors are then converted into MIDI data which gives a velocity value for each note, which is usually directly proportional to amplitude of the note when played.
MIDI data can also be used to add digital effects to the sounds played, such as reverb, chorus, delay and tremolo. These effects are usually mapped to three of the 127 MIDI controls within the keyboard's infrastructure — one for reverb, one for chorus and one for other effects — and are generally configurable through the keyboard's graphical interface. Additionally, many keyboards have "auto-harmony" effects which will complement each note played with one or more notes of higher or lower pitch, to create an interval or chord.
DSP effects can also be controlled on the fly by physical controllers. Electronic keyboards often have two wheels on the left hand side, generally known as a pitch bend and a modulation wheel. The difference between these is that the pitch bend wheel always flicks back to its default position — the center — while the modulation wheel can be placed freely. By default, the pitch bend wheel controls the pitch of the note in small values, allowing the simulation of slides and other techniques which control the pitch more subtly. The modulation wheel is usually set to control a tremolo effect by default. However, on most electronic keyboards, the user will be able to map any MIDI control to these wheels. Professional MIDI controller keyboards often also have an array of knobs and sliders to modulate various MIDI controls, which are often used to control DSP effects.
Most electronic keyboards also have a socket at the back, into which a foot switch can be plugged. The most common function is to simulate the sustain on a piano by turning on and off the MIDI control which adds sustain to a note. However, since they are also simple MIDI devices, foot switches can usually be configured to turn on and off any MIDI control, such as turning of one of the DSP effects, or the auto-harmony.
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