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62-458: Rupert Neve formed Neve Electronics in 1961. The company specialised in producing professional audio equipment and mixing consoles. The products used high-quality components and utilized Class-A circuit designs. In 1964 the company moved to Cambridgeshire . That year Neve Electronics built one of the first transistor-based mixing consoles for Philips Records Studios in London. The company moved to

124-455: A transformer where one winding is used to control the saturation of a magnetic core and hence alter the impedance of the other winding. They have largely fallen out of use due to development in semiconductor amplifiers but are still useful in HVDC control, and in nuclear power control circuitry due to not being affected by radioactivity. Negative resistances can be used as amplifiers, such as

186-646: A transmission line at input and output, especially RF amplifiers , do not fit into this classification approach. Rather than dealing with voltage or current individually, they ideally couple with an input or output impedance matched to the transmission line impedance, that is, match ratios of voltage to current. Many real RF amplifiers come close to this ideal. Although, for a given appropriate source and load impedance, RF amplifiers can be characterized as amplifying voltage or current, they fundamentally are amplifying power. Amplifier properties are given by parameters that include: Amplifiers are described according to

248-406: A vacuum tube or transistor . Negative feedback is a technique used in most modern amplifiers to increase bandwidth, reduce distortion, and control gain. In a negative feedback amplifier part of the output is fed back and added to the input in the opposite phase, subtracting from the input. The main effect is to reduce the overall gain of the system. However, any unwanted signals introduced by

310-690: A bipolar junction transistor can realize common base , common collector or common emitter amplification; a MOSFET can realize common gate , common source or common drain amplification. Each configuration has different characteristics. Vacuum-tube amplifiers (also known as tube amplifiers or valve amplifiers) use a vacuum tube as the active device. While semiconductor amplifiers have largely displaced valve amplifiers for low-power applications, valve amplifiers can be much more cost effective in high power applications such as radar, countermeasures equipment, and communications equipment. Many microwave amplifiers are specially designed valve amplifiers, such as

372-795: A broad spectrum of frequencies; however, they are usually not as tunable as klystrons. Klystrons are specialized linear-beam vacuum-devices, designed to provide high power, widely tunable amplification of millimetre and sub-millimetre waves. Klystrons are designed for large scale operations and despite having a narrower bandwidth than TWTAs, they have the advantage of coherently amplifying a reference signal so its output may be precisely controlled in amplitude, frequency and phase. Solid-state devices such as silicon short channel MOSFETs like double-diffused metal–oxide–semiconductor (DMOS) FETs, GaAs FETs , SiGe and GaAs heterojunction bipolar transistors /HBTs, HEMTs , IMPATT diodes , and others, are used especially at lower microwave frequencies and power levels on

434-408: A higher bandwidth to be achieved than could otherwise be realised even with the same gain stage elements. These nonlinear amplifiers have much higher efficiencies than linear amps, and are used where the power saving justifies the extra complexity. Class-D amplifiers are the main example of this type of amplification. A negative resistance amplifier is a type of regenerative amplifier that can use

496-561: A large gain, and the output performance of the system (the "closed loop performance ") is defined entirely by the components in the feedback loop. This technique is used particularly with operational amplifiers (op-amps). Non-feedback amplifiers can achieve only about 1% distortion for audio-frequency signals. With negative feedback , distortion can typically be reduced to 0.001%. Noise, even crossover distortion, can be practically eliminated. Negative feedback also compensates for changing temperatures, and degrading or nonlinear components in

558-400: A later point, allowing the dubbing mixer to build a mix in stages and focus on the creative and artistic elements of a mix, rather than on managing the technology. For those working in television post production, this was seen as a major breakthrough. In 1979, the 8108 console was produced using both analog and digital technology. The console had assignable controls and memory mixing faders. In

620-402: A power amplifier is usually used after other amplifier stages to provide enough output power for the final use of the signal. The first practical electrical device which could amplify was the triode vacuum tube , invented in 1906 by Lee De Forest , which led to the first amplifiers around 1912. Today most amplifiers use transistors . The first practical prominent device that could amplify

682-683: A purpose-built factory in Melbourn , near Cambridge where in 1968 they designed the 2254 compressor limiter for ABC Weekend TV in the UK. It was also in 1968 that Neve Electronics began to distribute their products in North America. Vanguard Records , of New York City , was the first American recording studio to take possession of the Neve console in October, 1968. In 1970, Rupert Neve designed

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744-445: A signal chain (the output stage) and is the amplifier stage that requires attention to power efficiency. Efficiency considerations lead to the various classes of power amplifiers based on the biasing of the output transistors or tubes: see power amplifier classes below. Audio power amplifiers are typically used to drive loudspeakers . They will often have two output channels and deliver equal power to each. An RF power amplifier

806-409: A single chip thereby creating higher scales of integration (such as small-scale, medium-scale and large-scale integration ) in integrated circuits . Many amplifiers commercially available today are based on integrated circuits. For special purposes, other active elements have been used. For example, in the early days of the satellite communication , parametric amplifiers were used. The core circuit

868-411: Is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude (magnitude of the voltage or current) of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. The amount of amplification provided by an amplifier is measured by its gain : the ratio of output voltage, current, or power to input. An amplifier

930-416: Is a 19” rack mounted compressor limiter produced by Neve Electronics for broadcast and recording purposes. The unit can be linked for stereo and multi-channel operation. The compressor processes the audio signal before the output amplifier, meaning the output level can be raised after compression of the signal. The controls include compression attack and recovery times. There is also a bypass control to switch

992-428: Is also a passive third-order (18 dB/octave) high pass filter. Two switches were also fitted on the module's front panel for equaliser bypass and phase polarity. The 1073 module was designed to be part of the 80 series Neve console. It was never intended for use as a stand alone module. It is now regarded as a "desert island" preamp by many recording engineers, and has been used on a countless number of hit records over

1054-474: Is defined as a circuit that has a power gain greater than one. An amplifier can be either a separate piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are widely used in almost all electronic equipment. Amplifiers can be categorized in different ways. One is by the frequency of the electronic signal being amplified. For example, audio amplifiers amplify signals in

1116-514: Is found in radio transmitter final stages. A servo motor controller amplifies a control voltage to adjust the speed of a motor, or the position of a motorized system. An operational amplifier is an amplifier circuit which typically has very high open loop gain and differential inputs. Op amps have become very widely used as standardized "gain blocks" in circuits due to their versatility; their gain, bandwidth and other characteristics can be controlled by feedback through an external circuit. Though

1178-409: Is most often configured to provide amplification of a voltage applied between base and emitter, and the output signal taken between collector and emitter is inverted, relative to the input. The common collector arrangement applies the input voltage between base and collector, and to take the output voltage between emitter and collector. This causes negative feedback, and the output voltage tends to follow

1240-413: Is said to have a gain of 20 dB might have a voltage gain of 20 dB and an available power gain of much more than 20 dB (power ratio of 100)—yet actually deliver a much lower power gain if, for example, the input is from a 600 Ω microphone and the output connects to a 47  kΩ input socket for a power amplifier. In general, the power amplifier is the last 'amplifier' or actual circuit in

1302-402: Is the device that does the actual amplification. The active device can be a vacuum tube , discrete solid state component, such as a single transistor , or part of an integrated circuit , as in an op-amp . Transistor amplifiers (or solid state amplifiers) are the most common type of amplifier in use today. A transistor is used as the active element. The gain of the amplifier is determined by

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1364-430: Is useful. Certain signal processing applications use exponential gain amplifiers. Amplifiers are usually designed to function well in a specific application, for example: radio and television transmitters and receivers , high-fidelity ("hi-fi") stereo equipment, microcomputers and other digital equipment, and guitar and other instrument amplifiers . Every amplifier includes at least one active device , such as

1426-480: The Class-D amplifier . In principle, an amplifier is an electrical two-port network that produces a signal at the output port that is a replica of the signal applied to the input port, but increased in magnitude. The input port can be idealized as either being a voltage input, which takes no current, with the output proportional to the voltage across the port; or a current input, with no voltage across it, in which

1488-432: The audio (sound) range of less than 20 kHz, RF amplifiers amplify frequencies in the radio frequency range between 20 kHz and 300 GHz, and servo amplifiers and instrumentation amplifiers may work with very low frequencies down to direct current. Amplifiers can also be categorized by their physical placement in the signal chain ; a preamplifier may precede other signal processing stages, for example, while

1550-475: The bipolar junction transistor (BJT) in 1948. They were followed by the invention of the metal–oxide–semiconductor field-effect transistor (MOSFET) by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959. Due to MOSFET scaling , the ability to scale down to increasingly small sizes, the MOSFET has since become the most widely used amplifier. The replacement of bulky electron tubes with transistors during

1612-412: The klystron , gyrotron , traveling wave tube , and crossed-field amplifier , and these microwave valves provide much greater single-device power output at microwave frequencies than solid-state devices. Vacuum tubes remain in use in some high end audio equipment, as well as in musical instrument amplifiers , due to a preference for " tube sound ". Magnetic amplifiers are devices somewhat similar to

1674-514: The tunnel diode amplifier. A power amplifier is an amplifier designed primarily to increase the power available to a load . In practice, amplifier power gain depends on the source and load impedances , as well as the inherent voltage and current gain. A radio frequency (RF) amplifier design typically optimizes impedances for power transfer, while audio and instrumentation amplifier designs normally optimize input and output impedance for least loading and highest signal integrity. An amplifier that

1736-485: The '1073' and '1081' microphone preamps are still among the most popular and expensive in the recording world. Neve was the first company to develop computer-controlled moving fader automation , NECAM, in the mid-1970s. In 1985 Neve Electronics was acquired by the Siemens group; in 1992 the Siemens group combined Neve Electronics with another newly acquired company, Advanced Music Systems to form AMS Neve. Today,

1798-622: The 1073 module for the new A88 mixing console; this console was designed for Wessex Studios . During the seventies Neve Electronics produced a whole series of mixing consoles for both broadcast and recording studios. In 1973, the 8048 console was produced; this included the newer 1081 microphone/line preamplifier and equaliser. In the same year Rupert Neve sold Neve Electronics to the Bonochord Group . He continued working alongside Neve Electronics until 1975 when he left altogether. In 1977, Neve Electronics began using digital technology with

1860-415: The 1960s and 1970s created a revolution in electronics, making possible a large class of portable electronic devices, such as the transistor radio developed in 1954. Today, use of vacuum tubes is limited to some high power applications, such as radio transmitters , as well as some musical instrument and high-end audiophile amplifiers. Beginning in the 1970s, more and more transistors were connected on

1922-514: The 1980s, there were concerns about Neve Electronics' financial situation. This was partly due to their ambitious investment into research and development of projects such as the DSP console and the Necam system. Another product that was included in the company's research and development programme was a digitally controlled routing system; very few of these were sold. In 1985, Neve Electronics was acquired by

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1984-508: The Siemens group; then in 1992 the Siemens group combined Neve Electronics with another newly acquired company, Advanced Music Systems to form AMS Neve which continues to produce products under both the Neve and AMS Neve brands. The 1073 is a Class-A design microphone/line preamplifier with three equaliser bands. The equaliser has a fixed 12kHz high frequency band and switchable low and mid range bands with cut and boost controls. There

2046-451: The amplifier specifications and size requirements microwave amplifiers can be realised as monolithically integrated, integrated as modules or based on discrete parts or any combination of those. The maser is a non-electronic microwave amplifier. Instrument amplifiers are a range of audio power amplifiers used to increase the sound level of musical instruments, for example guitars, during performances. An amplifier's tone mainly comes from

2108-447: The amplifier, such as distortion are also fed back. Since they are not part of the original input, they are added to the input in opposite phase, subtracting them from the input. In this way, negative feedback also reduces nonlinearity, distortion and other errors introduced by the amplifier. Large amounts of negative feedback can reduce errors to the point that the response of the amplifier itself becomes almost irrelevant as long as it has

2170-669: The components in the feedback loop. Negative feedback can be applied at each stage of an amplifier to stabilize the operating point of active devices against minor changes in power-supply voltage or device characteristics. Some feedback, positive or negative, is unavoidable and often undesirable—introduced, for example, by parasitic elements , such as inherent capacitance between input and output of devices such as transistors, and capacitive coupling of external wiring. Excessive frequency-dependent positive feedback can produce parasitic oscillation and turn an amplifier into an oscillator . All amplifiers include some form of active device: this

2232-409: The distortion levels to be greatly reduced, at the cost of lower gain. Other advances in the theory of amplification were made by Harry Nyquist and Hendrik Wade Bode . The vacuum tube was virtually the only amplifying device, other than specialized power devices such as the magnetic amplifier and amplidyne , for 40 years. Power control circuitry used magnetic amplifiers until the latter half of

2294-442: The effect in or out of the circuit. Other configurations were available at the time of the product's release. The Neve 33609 compressor limiter was re-designed around 2009 by AMS Neve and labelled as the 33609JD stereo compressor. Electronic amplifier An amplifier , electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current ). It

2356-449: The feedback between the transistor's source and gate to transform a capacitive impedance on the transistor's source to a negative resistance on its gate. Compared to other types of amplifiers, a negative resistance amplifier will require only a tiny amount of power to achieve very high gain, maintaining a good noise figure at the same time. Video amplifiers are designed to process video signals and have varying bandwidths depending on whether

2418-525: The first computers . For 50 years virtually all consumer electronic devices used vacuum tubes. Early tube amplifiers often had positive feedback ( regeneration ), which could increase gain but also make the amplifier unstable and prone to oscillation. Much of the mathematical theory of amplifiers was developed at Bell Telephone Laboratories during the 1920s to 1940s. Distortion levels in early amplifiers were high, usually around 5%, until 1934, when Harold Black developed negative feedback ; this allowed

2480-469: The four types of dependent source used in linear analysis, as shown in the figure, namely: Each type of amplifier in its ideal form has an ideal input and output resistance that is the same as that of the corresponding dependent source: In real amplifiers the ideal impedances are not possible to achieve, but these ideal elements can be used to construct equivalent circuits of real amplifiers by adding impedances (resistance, capacitance and inductance) to

2542-446: The gain stage, but any change or nonlinearity in the components in the feedback loop will affect the output. Indeed, the ability of the feedback loop to define the output is used to make active filter circuits . Another advantage of negative feedback is that it extends the bandwidth of the amplifier. The concept of feedback is used in operational amplifiers to precisely define gain, bandwidth, and other parameters entirely based on

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2604-427: The input and output. For any particular circuit, a small-signal analysis is often used to find the actual impedance. A small-signal AC test current I x is applied to the input or output node, all external sources are set to AC zero, and the corresponding alternating voltage V x across the test current source determines the impedance seen at that node as R = V x / I x . Amplifiers designed to attach to

2666-489: The input voltage. This arrangement is also used as the input presents a high impedance and does not load the signal source, though the voltage amplification is less than one. The common-collector circuit is, therefore, better known as an emitter follower, source follower, or cathode follower. AMS Neve AMS Neve Ltd is a privately owned audio engineering company who specialise in digital and analogue music consoles, outboard equipment and post production consoles. AMS Neve

2728-550: The introduction of their Necam system. Necam stood for Neve Computer Assisted Mixdown. The first Necam system was installed at AIR Studios in London . Necam also gained popularity in television post production facilities, including the BBC. Before the introduction of Necam, all fader mixing had to be done as live, a considerably skilled and stressful task for any dubbing mixer. Necam allowed for fader movements to be stored and recalled at

2790-560: The need to increase the amplitude of electrical signals to extend the transmission of signals over increasingly long distances. In telegraphy , this problem had been solved with intermediate devices at stations that replenished the dissipated energy by operating a signal recorder and transmitter back-to-back, forming a relay , so that a local energy source at each intermediate station powered the next leg of transmission. For duplex transmission, i.e. sending and receiving in both directions, bi-directional relay repeaters were developed starting with

2852-554: The order and amount in which it applies EQ and distortion. One set of classifications for amplifiers is based on which device terminal is common to both the input and the output circuit. In the case of bipolar junction transistors , the three classes are common emitter, common base, and common collector. For field-effect transistors , the corresponding configurations are common source, common gate, and common drain; for vacuum tubes , common cathode, common grid, and common plate. The common emitter (or common source, common cathode, etc.)

2914-512: The order of watts specifically in applications like portable RF terminals/ cell phones and access points where size and efficiency are the drivers. New materials like gallium nitride ( GaN ) or GaN on silicon or on silicon carbide /SiC are emerging in HEMT transistors and applications where improved efficiency, wide bandwidth, operation roughly from few to few tens of GHz with output power of few watts to few hundred of watts are needed. Depending on

2976-447: The output is proportional to the current through the port. The output port can be idealized as being either a dependent voltage source , with zero source resistance and its output voltage dependent on the input; or a dependent current source , with infinite source resistance and the output current dependent on the input. Combinations of these choices lead to four types of ideal amplifiers. In idealized form they are represented by each of

3038-414: The outputs of which are summed by the same transmission line. The transmission line is a balanced type with the input at one end and on one side only of the balanced transmission line and the output at the opposite end is also the opposite side of the balanced transmission line. The gain of each stage adds linearly to the output rather than multiplies one on the other as in a cascade configuration. This allows

3100-435: The past 30 years from Rock, Rap, Hip-hop, to Classical. The sound is described as very big, fat, and colored. The factor contributing to the larger than life sound is greatly attributed to the design of the transformer which seems to add subharmonics to the signal. The Equalizer section of the 1073 is regarded as very "musical" and practical and has become the favorite choice of many engineers for recording and mixing. The 33609

3162-571: The properties of the transistor itself as well as the circuit it is contained within. Common active devices in transistor amplifiers include bipolar junction transistors (BJTs) and metal oxide semiconductor field-effect transistors (MOSFETs). Applications are numerous. Some common examples are audio amplifiers in a home stereo or public address system , RF high power generation for semiconductor equipment, to RF and microwave applications such as radio transmitters. Transistor-based amplification can be realized using various configurations: for example

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3224-422: The properties of their inputs, their outputs, and how they relate. All amplifiers have gain, a multiplication factor that relates the magnitude of some property of the output signal to a property of the input signal. The gain may be specified as the ratio of output voltage to input voltage ( voltage gain ), output power to input power ( power gain ), or some combination of current, voltage, and power. In many cases

3286-410: The property of the output that varies is dependent on the same property of the input, making the gain unitless (though often expressed in decibels (dB)). Most amplifiers are designed to be linear. That is, they provide constant gain for any normal input level and output signal. If an amplifier's gain is not linear, the output signal can become distorted . There are, however, cases where variable gain

3348-418: The term today commonly applies to integrated circuits, the original operational amplifier design used valves, and later designs used discrete transistor circuits. A fully differential amplifier is similar to the operational amplifier, but also has differential outputs. These are usually constructed using BJTs or FETs . These use balanced transmission lines to separate individual single stage amplifiers,

3410-508: The twentieth century when power semiconductor devices became more economical, with higher operating speeds. The old Shreeve electroacoustic carbon repeaters were used in adjustable amplifiers in telephone subscriber sets for the hearing impaired until the transistor provided smaller and higher quality amplifiers in the 1950s. The first working transistor was a point-contact transistor invented by John Bardeen and Walter Brattain in 1947 at Bell Labs , where William Shockley later invented

3472-462: The video signal is for SDTV, EDTV, HDTV 720p or 1080i/p etc. The specification of the bandwidth itself depends on what kind of filter is used—and at which point ( −1 dB or −3 dB for example) the bandwidth is measured. Certain requirements for step response and overshoot are necessary for an acceptable TV image. Traveling wave tube amplifiers (TWTAs) are used for high power amplification at low microwave frequencies. They typically can amplify across

3534-478: The work of C. F. Varley for telegraphic transmission. Duplex transmission was essential for telephony and the problem was not satisfactorily solved until 1904, when H. E. Shreeve of the American Telephone and Telegraph Company improved existing attempts at constructing a telephone repeater consisting of back-to-back carbon-granule transmitter and electrodynamic receiver pairs. The Shreeve repeater

3596-461: Was a diode whose capacitance was changed by an RF signal created locally. Under certain conditions, this RF signal provided energy that was modulated by the extremely weak satellite signal received at the earth station. Advances in digital electronics since the late 20th century provided new alternatives to the conventional linear-gain amplifiers by using digital switching to vary the pulse-shape of fixed amplitude signals, resulting in devices such as

3658-447: Was first tested on a line between Boston and Amesbury, MA, and more refined devices remained in service for some time. After the turn of the century it was found that negative resistance mercury lamps could amplify, and were also tried in repeaters, with little success. The development of thermionic valves which began around 1902, provided an entirely electronic method of amplifying signals. The first practical version of such devices

3720-851: Was the Audion triode , invented in 1906 by Lee De Forest , which led to the first amplifiers around 1912. Since the only previous device which was widely used to strengthen a signal was the relay used in telegraph systems, the amplifying vacuum tube was first called an electron relay . The terms amplifier and amplification , derived from the Latin amplificare , ( to enlarge or expand ), were first used for this new capability around 1915 when triodes became widespread. The amplifying vacuum tube revolutionized electrical technology. It made possible long-distance telephone lines, public address systems , radio broadcasting , talking motion pictures , practical audio recording , radar , television , and

3782-432: Was the triode vacuum tube , invented in 1906 by Lee De Forest , which led to the first amplifiers around 1912. Vacuum tubes were used in almost all amplifiers until the 1960s–1970s when transistors replaced them. Today, most amplifiers use transistors, but vacuum tubes continue to be used in some applications. The development of audio communication technology in form of the telephone , first patented in 1876, created

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3844-569: Was the result of the amalgamation in 1992 of AMS (Advanced Music Systems) with Neve Electronics . Neve Electronics was a British manufacturer of mixing consoles that originated in the work of Rupert Neve in the 1960s. Neve analogue consoles have been considered to be of such high quality that many of twenty or thirty years of age are still in use today at recording studios around the world—even as digital audio has taken over many aspects of recording technology. Studios with Neve equipment are often sought out by musicians. Models such as

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