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An electronic keyboard (also called digital keyboard, portable keyboard and home keyboard) is an electronic or digital keyboard instrument.
The major components of an electronic keyboard are:
- Musical keyboard: The plastic 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)
- Rhythm & chord generator: A software program which produces rhythms and chords by the means of MIDI electronic 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 definitionsEdit
- Auto accompaniment: 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. When the on-board rhythm track is turned on, the auto-chords will be played automatically in the tempo of the rhythm track.
- 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, 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 and 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 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 (e.g., pop, rock, jazz, country, reggae). The keyboard plays a chord voicing and rhythm which is appropriate for the selected genre. For example, if the "jazz" style is selected, the keyboard would play seventh and ninth chords in a characteristic jazz "comping" rhythm.
- 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. 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. 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 manufacturersEdit
- Kurzweil Music Systems
- Moog Music
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