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An electronic keyboard.

An electronic keyboard or digital keyboard is a keyboard instrument whose sound is generated or amplified by one or more electronic devices.

Electronic keyboards perhaps were most popular in the 1980s, and are closely related to 1980s pop and New Wave music, but they have remained popular since.

Contents

Internal architecture

To facilitate the engineering processes of design and development of electronic keyboards, they are divided into major components:

  • Musical keyboard: An electro-mechanical component connects the switches when the key is depressed, which triggers the 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 chip) which handles user interaction with control keys and menus, which allows the user to select tones (e.g., piano, organ, flute), effects (echo or sustain), and other features (e.g., transposition)
  • Rhythm & chord generator: This part which is again in the form of software program produces rhythms and chords by the mean of MIDI commands.
  • Sound generator: An electronic sound module, typically contained within an integrated circuit or chip, which is capable of accepting MIDI commands and producing sounds.
  • Amplifier and speaker: a low-powered audio amplifier and a small speaker that amplify the sounds so that the listener can hear them.

Concepts and definitions

Playing an electronic keyboard.
  • Auto accompaniment: Auto accompaniment is used on programmed styles to trigger specific chords that will sound on the style.
  • Demonstration: Most keyboards have pre-programmed demo songs 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 of a key press. 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. The time between the two 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.
  • After-touch: A feature brought in in the late 1980s, 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. After-touch is found on many 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).
  • Polyphony: In digital music terminology, polyphony refers to the 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.
  • Style: Pre-programmed "styles", usually depend on the chord given by the player, consist of a variety of genres for the player to use.
  • Synchronization: Usually, styles compose of two to four sections, so adding transition effects, called syncs, smooth the transition between sections and improve the rhythm of the effect.
  • 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 spring-loaded.
  • Keyboard response: Weighted or spring-loaded keys. "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.

MIDI controls

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 signals 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. These are often called "sustain pedals" by keyboardists, as their most common function is to simulate the sustain pedal 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.

A partial list of manufacturers

See also

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