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A shunt regulated push-pull amplifier is a Class A amplifier whose output drivers (transistors or more commonly vacuum tubes) operate in antiphase. The key design element is the output stage also serves as the phase splitter.
The acronym SRPP is also used to describe a series regulated push-pull amplifier.
The earliest vacuum tubes based circuit reference is a patent by Henry Clough of the Marconi company filled in 1940. [1] It proposes its use as a modulator, but also mentions an audio amplifier use.
Other patents mention this circuit later in a slightly modified form, but it is not widely used until 1951, when Peterson and Sinclair finally adapted and patented the SRPP for audio use. [2] Variety of transistor based versions appeared after the 1960s.
Compactrons are a type of thermionic valve, or vacuum tube, which contain multiple electrode structures packed into a single enclosure. They were designed to compete with early transistor electronics and were used in televisions, radios, and similar roles.
An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal. It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude 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 is defined as a circuit that has a power gain greater than one.
A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits.
An audio power amplifier is an electronic amplifier that amplifies low-power electronic audio signals, such as the signal from a radio receiver or an electric guitar pickup, to a level that is high enough for driving loudspeakers or headphones. Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address, home audio systems and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers.
A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers in the 1960s and 1970s. Valve amplifiers can be used for applications such as guitar amplifiers, satellite transponders such as DirecTV and GPS, high quality stereo amplifiers, military applications and very high power radio and UHF television transmitters.
A differential amplifier is a type of electronic amplifier that amplifies the difference between two input voltages but suppresses any voltage common to the two inputs. It is an analog circuit with two inputs and and one output , in which the output is ideally proportional to the difference between the two voltages:
The Armstrong oscillator is an electronic oscillator circuit which uses an inductor and capacitor to generate an oscillation. It is the earliest oscillator circuit, invented by US engineer Edwin Armstrong in 1912 and independently by Austrian engineer Alexander Meissner in 1913, and was used in the first vacuum tube radio transmitters. It is sometimes called a tickler oscillator because its distinguishing feature is that the feedback signal needed to produce oscillations is magnetically coupled into the tank inductor in the input circuit by a "tickler coil" (L2, right) in the output circuit. Assuming the coupling is weak but sufficient to sustain oscillation, the oscillation frequency f is determined primarily by the LC circuit and is approximately given by
A push–pull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load. This kind of amplifier can enhance both the load capacity and switching speed.
A class-D amplifier or switching amplifier is an electronic amplifier in which the amplifying devices operate as electronic switches, and not as linear gain devices as in other amplifiers. They operate by rapidly switching back and forth between the supply rails, using pulse-width modulation, pulse-density modulation, or related techniques to produce a pulse train output. This passes through a simple low-pass filter which blocks the high-frequency pulses and provides analog output current and voltage. Because they are always either in fully on or fully off modes, little energy is dissipated in the transistors and efficiency can exceed 90%.
A linear amplifier is an electronic circuit whose output is proportional to its input, but capable of delivering more power into a load. The term usually refers to a type of radio-frequency (RF) power amplifier, some of which have output power measured in kilowatts, and are used in amateur radio. Other types of linear amplifier are used in audio and laboratory equipment. Linearity refers to the ability of the amplifier to produce signals that are accurate copies of the input. A linear amplifier responds to different frequency components independently, and tends not to generate harmonic distortion or intermodulation distortion. No amplifier can provide perfect linearity however, because the amplifying devices—transistors or vacuum tubes—follow nonlinear transfer function and rely on circuitry techniques to reduce those effects. There are a number of amplifier classes providing various trade-offs between implementation cost, efficiency, and signal accuracy.
Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its power rating.
In electronics, the Sziklai pair, also known as a complementary feedback pair, is a configuration of two bipolar transistors, similar to a Darlington pair. In contrast to the Darlington arrangement, the Sziklai pair has one NPN and one PNP transistor, and so it is sometimes also called the "complementary Darlington". The configuration is named for George C. Sziklai, thought to be its inventor.
A valve audio amplifier (UK) or vacuum tube audio amplifier (US) is a valve amplifier used for sound reinforcement, sound recording and reproduction.
A reflex radio receiver, occasionally called a reflectional receiver, is a radio receiver design in which the same amplifier is used to amplify the high-frequency radio signal (RF) and low-frequency audio (sound) signal (AF). It was first invented in 1914 by German scientists Wilhelm Schloemilch and Otto von Bronk, and rediscovered and extended to multiple tubes in 1917 by Marius Latour and William H. Priess. The radio signal from the antenna and tuned circuit passes through an amplifier, is demodulated in a detector which extracts the audio signal from the radio carrier, and the resulting audio signal passes again through the same amplifier for audio amplification before being applied to the earphone or loudspeaker. The reason for using the amplifier for "double duty" was to reduce the number of active devices, vacuum tubes or transistors, required in the circuit, to reduce the cost. The economical reflex circuit was used in inexpensive vacuum tube radios in the 1920s, and was revived again in simple portable tube radios in the 1930s.
A direct-coupled amplifier or DC amplifier is a type of amplifier in which the output of one stage of the amplifier is coupled to the input of the next stage in such a way as to permit signals with zero frequency, also referred to as direct current, to pass from input to output. This is an application of the more general direct coupling. It was invented by Harold J Paz and Francis P. Keiper Jr. in 1955. It displaced the triode vacuum tube amplifier designed by Lee de Forest. Almost all vacuum tube circuit designs are now replaced with direct coupled transistor circuit design. It is the first transistor amplifier design that did not include coupling capacitors. The direct-coupled amplifier allowed analog circuits to be built smaller with the elimination of coupling capacitors and removed the lower frequency limitation that is dependent on capacitors.
In electronics, biasing is the setting of DC operating conditions of an active device in an amplifier. Many electronic devices, such as diodes, transistors and vacuum tubes, whose function is processing time-varying (AC) signals, also require a steady (DC) current or voltage at their terminals to operate correctly. This current or voltage is called bias. The AC signal applied to them is superposed on this DC bias current or voltage.
Ultra-linear electronic circuits are those used to couple a tetrode or pentode vacuum-tube to a load.
A phase splitter is a device that separates a signal into multiple phases.
Tube sound is the characteristic sound associated with a vacuum tube amplifier, a vacuum tube-based audio amplifier. At first, the concept of tube sound did not exist, because practically all electronic amplification of audio signals was done with vacuum tubes and other comparable methods were not known or used. After introduction of solid state amplifiers, tube sound appeared as the logical complement of transistor sound, which had some negative connotations due to crossover distortion in early transistor amplifiers. However, solid state amplifiers have been developed to be flawless and the sound is later regarded neutral compared to tube amplifiers. Thus the tube sound now means 'euphonic distortion.' The audible significance of tube amplification on audio signals is a subject of continuing debate among audio enthusiasts.
In electronics, power amplifier classes are letter symbols applied to different power amplifier types. The class gives a broad indication of an amplifier's characteristics and performance. The classes are related to the time period that the active amplifier device is passing current, expressed as a fraction of the period of a signal waveform applied to the input. A class A amplifier is conducting through all the period of the signal; Class B only for one-half the input period, class C for much less than half the input period. A Class D amplifier operates its output device in a switching manner; the fraction of the time that the device is conducting is adjusted so a pulse-width modulation output is obtained from the stage.
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