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39-511: The Six-Trak was an analogue synthesizer manufactured by Sequential Circuits in San Jose, California and released in January 1984. It is notable for being one of the first multi-timbral synthesizers, equipped with MIDI and an on-board six-track digital sequencer , hence the name. It was designed as an inexpensive and easily portable 'scratch-pad' machine for trying out arrangements. It

78-613: A "synthetic harmoniser" using electricity appears to be in 1906, created by the Scottish physicist James Robert Milne FRSE (d.1961). The earliest synthesizers used a variety of thermionic-valve ( vacuum tube ) and electro-mechanical technologies. While some electric instruments were produced in bulk, such as Georges Jenny 's Ondioline , the Hammond organ , and the Trautonium , many of these would not be considered synthesizers by

117-464: A VCO can be used for frequency modulation (FM) or phase modulation (PM) by applying a modulating signal to the control input. A VCO is also an integral part of a phase-locked loop . VCOs are used in synthesizers to generate a waveform whose pitch can be adjusted by a voltage determined by a musical keyboard or other input. A voltage-to-frequency converter ( VFC ) is a special type of VCO designed to be very linear in frequency control over

156-504: A control system, the Laplace transforms of the above signals are useful. Tuning range, tuning gain and phase noise are the important characteristics of a VCO. Generally, low phase noise is preferred in a VCO. Tuning gain and noise present in the control signal affect the phase noise; high noise or high tuning gain imply more phase noise. Other important elements that determine the phase noise are sources of flicker noise (1/ f noise) in

195-429: A control voltage applied to the diode. Special-purpose variable-capacitance varactor diodes are available with well-characterized wide-ranging values of capacitance. A varactor is used to change the capacitance (and hence the frequency) of an LC tank. A varactor can also change loading on a crystal resonator and pull its resonant frequency. For low-frequency VCOs, other methods of varying the frequency (such as altering

234-640: A modular design, normalization made the instrument more portable and easier to use. This first pre-patched synthesizer, the Minimoog , became highly popular, with over 12,000 units sold. The Minimoog also influenced the design of nearly all subsequent synthesizers, with integrated keyboard, pitch wheel and modulation wheel, and a VCO -> VCF -> VCA signal flow. In the 1970s, miniaturized solid-state components let manufacturers produce self-contained, portable instruments, which musicians soon began to use in live performances. Electronic synthesizers quickly become

273-859: A number of independent electronic modules connected by patch cables into a patchbay that resembled the jackfields used by 1940s-era telephone operators. Synthesizer modules in early analog synthesizers included voltage-controlled oscillators (VCOs), voltage-controlled filters (VCFs), and voltage-controlled amplifiers (VCAs). The control voltage varied frequency in VCOs and VCFs, and attenuation (gain) in VCAs. Additionally, they used envelope generators , low-frequency oscillators , and ring modulators . Some synthesizers also had effects devices, such as reverb units, or tools such as sequencers or sound mixers . Because many of these modules took input sound signals and processed them, an analog synthesizer could be used both as

312-433: A sound-generating and sound-processing system. Famous modular synthesizer manufacturers included Moog Music , ARP Instruments, Inc. , Serge Modular Music Systems , and Electronic Music Studios . Moog established standards recognized worldwide for control interfacing on analog synthesizers, using an exponential 1-volt-per-octave pitch control and a separate pulse triggering signal. These control signals were routed using

351-733: A stable single-frequency clock. A digitally controlled oscillator based on a frequency synthesizer may serve as a digital alternative to analog voltage controlled oscillator circuits. VCOs are used in function generators , phase-locked loops including frequency synthesizers used in communication equipment and the production of electronic music , to generate variable tones in synthesizers . Function generators are low-frequency oscillators which feature multiple waveforms, typically sine, square, and triangle waves. Monolithic function generators are voltage-controlled. Analog phase-locked loops typically contain VCOs. High-frequency VCOs are usually used in phase-locked loops for radio receivers. Phase noise

390-466: A standard part of the popular-music repertoire. The first movie to use music made with a (Moog) synthesizer was the James Bond film On Her Majesty's Secret Service in 1969. After the release of the film, composers produced a large number of movie soundtracks that featured synthesizers. Notable makers of all-in-one analog synthesizers included Moog, ARP, Roland , Korg and Yamaha . Because of

429-462: A timing signal to synchronize operations in digital circuits. VCXO clock generators are used in many areas such as digital TV, modems, transmitters and computers. Design parameters for a VCXO clock generator are tuning voltage range, center frequency, frequency tuning range and the timing jitter of the output signal. Jitter is a form of phase noise that must be minimised in applications such as radio receivers, transmitters and measuring equipment. When

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468-415: A voltage input for fine control. The temperature is selected to be the turnover temperature : the temperature where small changes do not affect the resonance. The control voltage can be used to occasionally adjust the reference frequency to a NIST source. Sophisticated designs may also adjust the control voltage over time to compensate for crystal aging. A clock generator is an oscillator that provides

507-413: A voltage-controlled crystal oscillator can be varied a few tens of parts per million (ppm) over a control voltage range of typically 0 to 3 volts, because the high Q factor of the crystals allows frequency control over only a small range of frequencies. A temperature-compensated VCXO ( TCVCXO ) incorporates components that partially correct the dependence on temperature of the resonant frequency of

546-423: A wide range of input control voltages. VCOs can be generally categorized into two groups based on the type of waveform produced. A voltage-controlled capacitor is one method of making an LC oscillator vary its frequency in response to a control voltage. Any reverse-biased semiconductor diode displays a measure of voltage-dependent capacitance and can be used to change the frequency of an oscillator by varying

585-529: A wider selection of clock frequencies is needed the VCXO output can be passed through digital divider circuits to obtain lower frequencies or be fed to a phase-locked loop (PLL). ICs containing both a VCXO (for external crystal) and a PLL are available. A typical application is to provide clock frequencies in a range from 12 kHz to 96 kHz to an audio digital-to-analog converter . A frequency synthesizer generates precise and adjustable frequencies based on

624-446: Is a stub . You can help Misplaced Pages by expanding it . Analogue synthesizer The earliest analog synthesizers in the 1920s and 1930s, such as the Trautonium , were built with a variety of vacuum-tube (thermionic valve) and electro-mechanical technologies. After the 1960s, analog synthesizers were built using operational amplifier (op-amp) integrated circuits , and used potentiometers (pots, or variable resistors ) to adjust

663-425: Is possible to latch the arpeggiator and play along with sequences in real time. Also available is a unison mode which renders the keyboard monophonic but allows for very rich sounding timbres. The Six-Trak is prominently featured and can be heard on the 1998 minimalist space music CD release The Dream Garden , by musician/composer Dane Rochelle. More recently it has been used by composer Christopher de Groot for

702-407: Is the most important specification in this application. Audio-frequency VCOs are used in analog music synthesizers. For these, sweep range, linearity, and distortion are often the most important specifications. Audio-frequency VCOs for use in musical contexts were largely superseded in the 1980s by their digital counterparts, digitally controlled oscillators (DCOs), due to their output stability in

741-484: The Kawai K5 (waveforms constructed via additive synthesis). With the falling cost of microprocessors, this architecture became the standard architecture for high-end analog synthesizers. During the middle to late 1980s, digital synthesizers and samplers largely replaced analog synthesizers. By the early 1990s, however, musicians from the techno , rave and DJ scenes who wanted to produce electronic music but lacked

780-569: The Moog synthesizer transistor ladder filter, has spurred a return of DIY and kit synthesizer modules, as well as an increase in the number of commercial companies selling analog modules. Reverse engineering has also revealed the secrets of some synthesizer components, such as those from ARP Instruments, Inc. In addition, despite the widespread availability during the 2000s of relatively inexpensive digital synthesizers that offered complex synthesis algorithms and envelopes, some musicians are attracted to

819-404: The "hands-on", practical controls of analog synths – potentiometer knobs, faders, and other features – offering a strong appeal. Voltage-controlled oscillator A voltage-controlled oscillator ( VCO ) is an electronic oscillator whose oscillation frequency is controlled by a voltage input. The applied input voltage determines the instantaneous oscillation frequency. Consequently,

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858-685: The 2012 soundtrack to Australian feature film "Sororal". The Six-Trak's more famous sibling is the Prophet 5 , widely used in much of the 1970s progressive rock . A number of other synthesizers made by Sequential Circuits used similar electronics, including the Multi-Trak, Max, and Split-8 . the important parts on board of them was CEM3394 (a complete monophonic analog synth chip manufactured by Curtis Electromusic Specialties ). The Six-Trak used 6 chips for 6 voices of different timbre program. This article relating to electronic musical instruments

897-486: The advantages of having no off-chip components (expensive) or on-chip inductors (low yields on generic CMOS processes). Commonly used VCO circuits are the Clapp and Colpitts oscillators. The more widely used oscillator of the two is Colpitts and these oscillators are very similar in configuration. A voltage-controlled crystal oscillator ( VCXO ) is used for fine adjustment of the operating frequency. The frequency of

936-669: The budget for large digital systems created a market for the then cheap second hand analog equipment. This increased demand for analog synthesizers towards the mid-1990s, as larger numbers of musicians gradually rediscovered the analog qualities. As a result, sounds associated with analog synths became popular again. Over time, this increased demand for used units (such as the 1980 Roland TR-808 drum machine and Roland TB-303 bass synthesizer). Late 1970s-era drum machines used tuned resonance voice circuits for pitched drum sounds and shaped white noise for others. The TR-808 improves on these designs, by using detuned square wave oscillators (for

975-435: The charging rate of a capacitor by means of a voltage-controlled current source ) are used (see function generator ). The frequency of a ring oscillator is controlled by varying either the supply voltage, the current available to each inverter stage, or the capacitive loading on each stage. VCOs are used in analog applications such as frequency modulation and frequency-shift keying . The functional relationship between

1014-671: The circuit, the output power level, and the loaded Q factor of the resonator. (see Leeson's equation ). The low frequency flicker noise affects the phase noise because the flicker noise is heterodyned to the oscillator output frequency due to the non-linear transfer function of active devices. The effect of flicker noise can be reduced with negative feedback that linearizes the transfer function (for example, emitter degeneration ). VCOs generally have lower Q factor compared to similar fixed-frequency oscillators, and so suffer more jitter . The jitter can be made low enough for many applications (such as driving an ASIC), in which case VCOs enjoy

1053-406: The complexity of generating even a single note using analog synthesis, most synthesizers remained monophonic . Polyphonic analog synthesizers featured limited polyphony, typically supporting four voices. Oberheim was a notable manufacturer of analog polyphonic synthesizers. The Polymoog was an attempt to create a truly polyphonic analog synthesizer, with sound generation circuitry for every key on

1092-504: The control voltage and the output frequency for a VCO (especially those used at radio frequency ) may not be linear, but over small ranges, the relationship is approximately linear, and linear control theory can be used. A voltage-to-frequency converter (VFC) is a special type of VCO designed to be very linear over a wide range of input voltages. Modeling for VCOs is often not concerned with the amplitude or shape (sinewave, triangle wave, sawtooth) but rather its instantaneous phase. In effect,

1131-576: The cow bell and cymbal sounds) and analogue reverberation (for the handclap sound). The demand for the analog synth sound led to development of a variety of analog modeling synthesizers —which emulate analog VCOs and VCFs using samples, software, or specialized digital circuitry, and the construction of new analog keyboard synths such as the Alesis Andromeda , Prophet '08 , and Moog's Little Phatty , as well as semi-modular and modular units. The lapse of patents in recent years, such as for

1170-423: The crystal. A smaller range of voltage control then suffices to stabilize the oscillator frequency in applications where temperature varies, such as heat buildup inside a transmitter . Placing the oscillator in a crystal oven at a constant but higher-than-ambient temperature is another way to stabilize oscillator frequency. High stability crystal oscillator references often place the crystal in an oven and use

1209-400: The face of temperature changes during operation. Since the 1990s, musical software has become the dominant sound-generating method. Voltage-to-frequency converters are voltage-controlled oscillators with a highly linear relation between applied voltage and frequency. They are used to convert a slow analog signal (such as from a temperature transducer) to a signal suitable for transmission over

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1248-413: The focus is not on the time-domain signal A sin( ωt + θ 0 ) but rather the argument of the sine function (the phase). Consequently, modeling is often done in the phase domain. The instantaneous frequency of a VCO is often modeled as a linear relationship with its instantaneous control voltage. The output phase of the oscillator is the integral of the instantaneous frequency. For analyzing

1287-520: The keyboard. However, its architecture resembled an electronic organ more than a traditional analog synthesizer, and the Polymoog was not widely imitated. In 1978, the first microprocessor -controlled analog synthesizers were created by Sequential Circuits . These used microprocessors for system control and control voltage generation, including envelope trigger generation, but the main sound generating path remained analog. The MIDI interface standard

1326-436: The same building blocks, but integrated them into single units, eliminating patch cords in favour of integrated signal routing systems. The most popular of these was the Minimoog . In 1970, Moog designed an innovative synthesizer with a built-in keyboard and without modular design—the analog circuits were retained, but made interconnectable with switches in a simplified arrangement called "normalization". Though less flexible than

1365-500: The same types of connectors and cables that were used for routing the synthesized sound signals. A specialized form of analog synthesizer is the analog vocoder , based on equipment developed for speech synthesis. Vocoders are often used to make a sound that resembles a musical instrument talking or singing. Patch cords could be damaged by use (creating hard-to-find intermittent faults) and made complex patches difficult and time-consuming to recreate. Thus, later analog synthesizers used

1404-428: The sound parameters. Analog synthesizers also use low-pass filters and high-pass filters to modify the sound. While 1960s-era analog synthesizers such as the Moog used a number of independent electronic modules connected by patch cables , later analog synthesizers such as the Minimoog integrated them into single units, eliminating patch cords in favour of integrated signal routing systems. The earliest mention of

1443-443: The sounds of monophonic and polyphonic analog synths. While some musicians embrace analog synthesizers as preferable, others counter that analog and digital synthesis simply represent different sonic generation processes that both reproduce characteristics the other misses. Another factor considered to have increased use of analog synths since the 1990s is weariness with the complex screen-based navigation systems of digital synths, with

1482-666: The standards of later instruments. However, some of these synthesizers achieved a high level of sophistication, such as the Trautonium of Oskar Sala , the Electronium of Raymond Scott , and the ANS synthesizer of Evgeny Murzin . Another notable early instrument is the Hammond Novachord , first produced in 1938. Early analog synthesizers used technology from electronic analog computers and laboratory test equipment. They were generally "modular" synthesizers, consisting of

1521-466: Was developed for these systems. This generation of synthesizers often featured six or eight voice polyphony. Also during this period, a number of analog/digital hybrid synthesizers were introduced, which replaced certain sound-producing functions with digital equivalents, for example the digital oscillators in synthesizers like the Korg DW-8000 (which played back PCM samples of various waveforms) and

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