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An electronic keyboard or digital keyboard is an electronic musical instrument, an electronic or digital derivative of keyboard instruments. Broadly speaking, in a popular music context, the term electronic keyboard or just a keyboard mostly refers to any type of digital or electronic keyboard instrument. These include synthesizers, digital pianos, stage pianos, electronic organs and digital audio workstations. However, in true musical terminology, an electronic keyboard is an inexpensive synthesizer equipped with built-in power amplifier and small loudspeakers.
Electronic keyboards are capable of recreating a wide range of instrument sounds (piano, electric piano, Hammond organ, pipe organ, violin, etc.) with less complex sound synthesis. Electronic keyboards are usually dedicated for home users, beginners and other non-professional users. They typically have unweighted keys. The least expensive models do not have velocity-sensitive keys; but mid- to high-priced models do have these feature. Home keyboards typically have little if any sound editing capacity. The user typically selects from a range of preset "voices" or sounds, which include imitations of many instruments and some electronic synthesizer sounds. Home keyboards have a much lower cost than professional synthesizers. Casio and Yamaha are among the leading manufacturers of home keyboards.
An electronic keyboard may also called a digital keyboard, portable keyboard, or home keyboard, referring their digital-based sound generation and light-weight, portable build. In China, Japan, India, and Southeast Asia (particularly Indonesia, Vietnam, and Thailand), electronic keyboards were often mistakenly referred to as an organ, due to popularity of home electronic organs in those countries and keyboards/synthesizers are considered as a similar instrument.
In Russia, most kinds of keyboards (including digital pianos and stage pianos) were simply often referred to as a synthesizer (Russian, sintezator), usually with no other term to distinguish them from actual digital synthesizers.
The term electronic keyboard may also be used to refer to synthesizer or digital piano on colloquial usage.
The major components of a typical modern electronic keyboard are:
Keyboard instruments can be found as far back as the hydraulis (a water organ) 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 (tangent-struck strings) and harpsichord (quill-plucked strings), 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 such as a pipe organ or harpsichord could only produce sounds of one particular volume. In the 18th century, the pianoforte was invented. The pianoforte had metal strings which were struck by hammers which were activated by pressing or striking the keys. Depending on whether the keys were pressed lightly or forcefully, the pianoforte would produce a softer or louder sound.
The next step was to develop electric sound technology. The first electric musical instrument was the 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 the clavecin électrique. This was a keyboard instrument incorporated with plectra and activated by electricity. But both instruments were not using electricity to produce sound. Elisha Gray invented an electric musical instrument called the 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, exploiting previous limited production efforts like the Robb Wave Organ from 1923. It was capable of producing polyphonic sounds by virtue of a spinning shaft with many magnetic 'lobes' which would cycle past an electromagnetic pickup at a rate that would produce each desired tone. "Tone Wheel Organ" is the general name for this technology. The Hammond organ was connected to a power amplifier and a speaker cabinet. In 1929, the electric piano was invented. In 1939, Hammond introduced the Novachord which used about 170 vacuum tubes, coils, capacitors and resistors largely to create an upper octave of notes and then divide them in half using 'flip flop' circuits to create successively lower octaves from each note. But the instrument also has many features like envelopes for filter and amplifiers so that sounds can be contoured at the user's discretion, making it the first production analog synthesizer.
In 1941 Georges Jenny's previously prototyped Ondioline became the first truly portable synthesizer keyboard (the Novachord weighed over 500 pounds (230 kg)). More developments were made with the Chamberlin Music Maker in late 1940s and the Mellotron in the early 1950s, which employed mechanisms to play back recordings at speeds that would produce the desired tone for the key being struck. Other technologies improved on this idea over the years. Machines like the Optigan used photo-emulsion to create disks that had images whose density would covert to waveforms when spun in front of a beam/sensor assembly. In 1981 the E-mu Emulator was marketed to digitally store samples and play them back.
The first step towards the electric piano was by Harold Rhodes who developed various prototypes using parts from B-17 aircraft that were being scrapped. Harold received a medal since the resulting keyboard was used as therapy for people rehabilitating from injuries from WW2. (It is small enough to set on a stand over a patient's bed in a hospital, looking something like a miniature grand piano in shape.) Instructions were made and people built this "pre-piano" which amplifies the signals generated in a pickup from the vibration of Stainless Steel rods tapered near the steel base they are driven into holes in. Piano type wooden hammers are used to strike them. It was a three octave (E to F for 38 notes) instrument. A tube amplifier drove a speaker pointing out the bottom.
In 1955, the Wurlitzer Company released the company's first electric piano, the model 100. The wurlitzer strikes flat tines whose vibration is amplified from a surrounding electrostatic charged 'comb'. In '59 the Fender company bought the Rhodes name and produced the piano bass and then in the mid '60s began producing the famous Fender Rhodes series which used rod shaped tines mounted on a steel piece that runs parallel above them, with a coil pickup on each individual tine. The invention of the transistor in 1959 spawned the production of progressively more compact keyboards. Many home organs maintained the appearance but lost some weight due to the lower power consumption needs of transistor circuitry. Also in this era 'combo organs' found a lot of use like the famous Vox Continental used by the Beatles and others, the Gibson G101 used by the doors, and others by Farfisa, Wurlitzer, Acetone (Roland) and others. These were usually built using 12 oscillators and transistor pair 'divider' circuits to produce all the frequencies like all non- 'tone wheel' electronic organs of the era. They were just more compact and thus suited for 'combo' use.
The exploration 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. The rapid accumulation of momentum began in 1964 when Bob Moog produced his Moog synthesizer. It used a remote keyboard and was 'modular' in design. (i.e. it was a rack that held boxes which each had a function. At least one to create a tone controlled in pitch by a voltage input. And usually a host of other modules including Filter(s), Amplifier(s), Envelope Generator(s) etc. ) His next generation was equipped with a built-in keyboard in 1970; the Mini-Moog. These keyboards were monophonic, along with semi-modulars like the ARP2600, and were only able to respond to one note at a time. (Though 3 oscillators could be layered together in response to the 'control voltage' produced by that note.)
In 1972, instruments such as the EML 101, ARP Odyssey, and Moog Sonic six were duo-phonic meaning they could produce two different tones at once when two different keys were pressed. And in 1974 Oberheim produced the first polyphonic synthesizer using their SEM Modules (which were originally designed to allow musicians to just layer more complex sounds together in a monophonic 'stack'. ) They produced a key assigner circuit that would assign a note to one of several SEM modules. (They came in 2, 4 and 8 voice racks eventually.) When more notes got hit than the number of racks available the latest note would have to 'steal' one of the SEM modules from the note it had been assigned to. These polyphonic synthesizers were very popular eventually and Yamaha produced the CS-50 in 1976 which had four voices that didn't have to be individually programmed in order for them to sound the same. And a sea of other entries followed.
In 1970, Ken Freeman demonstrated the first 'string machine' which was essentially combo-organ like in size and how it generated tones. It had simple controls though centered around creating an ensemble effect where vibrato is happening at slightly different rates on different notes like in a real orchestra. Ken used 6 discrete LFO's (low frequency oscillator circuits) to modulate atypically hit together note combinations (diminished fifth combinations like C and F?). It had two 'ranks' of 12 oscillators plus a single oscillator driving a chip that develops the top octave of notes in the version that hit market in 1974. In November 1974 the British patent 1,509,530 lists an electronic digital musical arranger by Nicholas Kenneth Kirk. This patent was sold to Waddington' House of Games as Compute-a-Tune. This product was marketed in the early 1980s and sold a few thousand or so in the £15 range. The ARP Solina String Ensemble and Crumar Stringman used a much less expensive approach using digitally clocked chips called BBD's. Only a few hundred were made.
In 1973, the Yamaha GX-1 was manufactured. It was early polyphonic synthesizer, featuring eight voices. In 1974, Roland Corporation released the EP-30, the first touch-sensitive keyboard. Roland also released early polyphonic string synthesizers, the RS-101 in 1975 and the RS-202 in 1976.
In 1975, the turn towards building a synthesizer of sorts over an organ came to fruition in Moog's Polymoog. Many patents exist from this keyboard. It incorporated velocity sensitivity for one thing. Each note had its own circuit board with a VCF/VCA chip so that it was truly fully polyphonic. Many were disappointed that the filter lacked the facilities of the more flexible moog filter used in other keyboards. And that there were so many connectors and they were not all that reliable. Also in 1975 Crumar of Italy produced the "Multiman" which also was an organ with synthesizer facilities. It had a bass option, a brass with filter controls and simple envelope, a piano and clavi preset, and a couple string tabs with decay control and vibrato control. The first of what we might call the 'Swiss army knife' synthesizer. In 1976 the ARP Omni combined a more limited synthesizer with a string machine and bass also and became ARP's biggest seller. Also in 1976 the Korg PE-1000 used an individual saw oscillator for each note.
In 1977, the Yamaha CS-60 and CS-80 polyphonic synthesizers began to implement synthesizer 'memory'. However it was merely an alternate set of sliders that hid under a hatch. In 1978, however the OB-1 from Oberheim gave actual electronic storage of the sound settings. The Sequential Circuits Prophet-5 the same year offered this feature in a five voice polyphonic synthesizer. Dave Smith's company developed some other firsts. But the ARP engineers were acquired by Fender when they bought the mismanaged company in 1979. And they completed the Fender Rhodes Chroma, the first computer controlled keyboard. Released in 1981, an Apple computer could be used to run sequencing software that allowed the user to easily program which notes were being hit at particular instants in the song production. The 'Chroma' port only appeared on the successor though, the Chroma Polaris in 1984.
Dave Smith's company found interest in a cooperative effort with Roland. In 1983, the invention of the musical instrumental digital interface (MIDI) as a standard for digital code transmission digital technology development spurred on more great development in keyboard technology. As now keyboards from totally different manufacturers could communicate through an inexpensive cable. The Sequential Circuits Prophet 600 and the Roland Jupiter 6 communicated at the NAMM trade show and Yamaha soon had the standard implemented into their DX synthesizers which would outsell all previous keyboards.
The Yamaha DX7, the most well known synth of the 1980s, used entirely digital circuitry leaving it free from the need of calibration, and vast numbers of parameters that could be accessed. The "FM" (frequency modulation) synthesis method was something that had not been explored to near this depth. Most synthesizers before this were subtractive i.e.: You start with a very harmonic-laden sound and you selectively subtract from them using low, high or bandpass filters, or some other methods that tended to result in stranger sounds like ring modulation. Also in 1983 Dave Smith's company SCI marketed the first polyphonic synthesizer keyboard that could play more than one sound at a time called the 'Six-Trak'. It had a six track sequencer and each track could access a different sound. The same year the SCI Prophet T8 with optical key sensing became the first piano action emulating midi keyboard.
But the remaining companies after ARP's demise that had produced analog synthesizers rapidly began to feel the stress. Roland and Korg also of Japan maintained with some innovations of their own and each had 'hit' keyboards: the D50 from Roland and M1 from Korg in the late 1980s. The total unit sales for the Yamaha DX series reached over 1 million with the others from Roland and Korg over 250,000. The success of the D50 and M1 was riding on the back of the Kurzweil K250 which first really applied this technology well in 1984. This machine was the first full digital workstation with facilities to sample acoustic sounds with a microphone and play them back with a rate that is proportioned for the note being struck. Many great samples were included in the unit including a piano sound that is still used in the 2000s. And the samples can be routed through a synthesizer architecture of some kind.
Initially some companies steered away from emulating the subtractive synthesis in the digital realm because it was difficult to model how a filter would respond to these complex signals. By the early '90s some fairly good implementations were beginning to appear. The Peavey DPM series also touted as the first keyboards that could import samples which were not 'sampling keyboards'. They also were the first to use off the shelf DSP chips, which emulated the response of analog filters. This sample playback technology also spawned a vast number of inexpensive consumer units called home keyboards in electronics stores. As the price of memory began to plummet every company was making keyboards of this type. Casio and Yamaha have led sales in these types of units which feature built in speaker systems, usually can run from batteries or power adapters, and have a library of samples with very limited editing if any. They often use cheap plastic strips of keys to keep cost down.
On a different note, the Kurzweil K150 and the Kawai K5 explored additive synthesis where harmonics can be proportioned to make different tones while enveloping groups of them differently in the mid '80s. RMI had explored this to a limited extent in 1974 with the harmonic synthesizer they produced. It should also be mentioned that they were producing the earliest electric piano machines in 1970. This less common synthesis method is also used in Kawai's last synthesizer product series, the K5000's from 1996. Organs like the Hammond B3 use drawbars to control harmonic content of the tone. But the K5000 has an envelope for each harmonic in the entire audio spectrum and dynamic filter control over that for vast possibilities in sound creation.
Apart from conventional home keyboards, electronic keyboards are divided into various types:
Compared to digital pianos or stage pianos, digital keyboards are usually much lower in cost, as they have unweighted keys. Like digital pianos, they usually feature on-board amplifiers and loudspeakers. Stage pianos, however, typically do not have integrated amplifiers and speakers, as these instruments are normally plugged into a keyboard amplifier in a professional concert setting. Unlike synthesizers, the primary focus of home electronic keyboards is not on detailed control of sound synthesis parameters. Most home electronic keyboards offer little or no control or editing of the sounds (although a selection of 128 or more preset sounds is typically provided).
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.
In live performances, multiple electronic keyboards could be played together at one time, each by one musician, forming a keyboard ensemble. Keyboard ensembles are mostly performed within a band on an elaborate stage, with some can even serve as a simpler substitute to the more conventional orchestra, replacing stringed and wind instruments.