An electronic keyboard or digital keyboard is a type of keyboard instrument. Its sound is generated or amplified by one or more electronic devices.
Modern usage of the term "electronic keyboard" typically describes a type of inexpensive sampler marketed to amateurs and children. The term is occasionally used as an umbrella descriptor for any electronic musical instruments with a musical keyboard (including but not limited to electric pianos, digital pianos, synthesizers,mellotrons, samplers, electronic organs, and arranger keyboards) but professional musicians generally refer to these instruments by name or simply as "keyboards", reserving the term "electronic keyboard" for the inexpensive type noted above.
Such electronic keyboard instruments are typically inexpensive, smaller, with mediocre sound quality, and lack many features offered by professional instruments. They can generally be located in electronics stores side-by-side with stereos, video games and the like, or even in toy stores.
However, the line between "professional" and "amateur" instruments can often be blurred: professional musicians may use inexpensive keyboards for novelty or out of necessity (for example, reggae music in the '80s made frequent use of pre-programmed rhythm patterns on inexpensive digital keyboards), and due to advances in computer and electronics technology, many relatively inexpensive keyboards (under US$1000) have an array of features that would have been unavailable on even the most expensive synthesizers of past decades.
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[edit]Internal architecture
To facilitate the engineering processes of design and development of electronic keyboards, keyboards 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 MIDIcommands 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.
[edit]Pre-programmed features
- Auto accompaniment: Auto accompaniment is used on programmed styles to trigger specific chords that will sound on the style.
- Demonstration: Programmed demo songs loaded on the RAM of keyboards can help users for entertainment or add to their learned songs.
[edit]Concepts and definitions
- Touch response (also called Touch Sensitivity) : While the least expensive keyboards are simply "on-off" switches, mid-range and higher-range instruments incorporate simulating the process of sound generation in chordophones which are sensitive to the velocity of a key press. For implementation two sensors are installed for each key: a sensor detects whenever a key is beginning to be pressed and the other fired when the key is pressed completely. By a time reference a device can estimate the velocity of pressure. As the key mass is constant this velocity can also be considered as the strength of key press. Based on this value, the sound generator produces the appropriate 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 and electronic keyboard terminology, polyphony refers to the number of notes that can be played concurrently. Some of the least expensive toy electronic keyboards designed for children can only play one note at a time. Many low-priced keyboards can perform polyphonic parts, but they are often limited to four or five notes at a time. Better-quality keyboards can perform over ten notes at a time.
- 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.
- 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.
- Split point: The point where a keyboard is split to allow two instrument sounds to be played at once on a single keyboard. In the late1980s 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 on keyboards nowadays compose of two to four sections, so adding transistion effects, called syncs, can add that realistic effect that a listener and a player wants to have.
- Auto harmony: A feature of some keyboards that automatically adds secondary tones to a note based upon chording given by the accompaniment system, made to make harmony easier for those who lack the ability to make complex chording changes with their left hand.
- Wheels and knobs: Used in performances to add qualities to a sound that are not present by default, such as vibrato, panning, tremolo, pitch changes, and so on.
- Keyboard response: Weighted or spring loaded keys. "Weighted response" refers to keys with weights and springs in them, which give a "hammer action" response similar to a piano. Most electronic keyboards use "spring-loaded" keys that make some kinds of playing techniques, such as backhanded sweeps, impossible but also make the keyboards lighter and easier to transport. Pianists who are accustomed to standard weighted piano keys may find non-weighted spring-action keyboards uncomfortable and difficult to play effectively. Conversely, keyboard players who are used to the non-weighted action may encounter difficulty and discomfort playing on a piano or electronic piano with weighted keys.
[edit]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 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 centre — 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 subtlely. 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.
