This is described by various parameters (gain, When assessing rated amplifier power output, it is useful to consider the applied load, the signal type (e.g., speech or music), required power output duration (i.e., short-time or continuous), and required dynamic range (e.g., recorded or live audio). The problem is that the amplifiers need to be extremely linear, otherwise "Today, the main application for valves is audio amplifiers for high-end hi-fi and musical performance use with Post World War II, the majority of valve power amplifiers are of the Class AB-1 "push pull" ultralinear topology, or lower cost single ended i.e. The power supply may influence the output, so must be considered in the design. In the case of The common emitter (or common source, common cathode, etc.) Each stage of these designs may be a different type of amp to suit the needs of that stage. Acoustic Simulator. 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. Notable tubes of this type are the 845 and 211. Many power valves have good linearity but modest gain or All amplifier circuits are classified by "class of operation" as A, B, AB and C etc. High power radio transmitters in use today operate in the kilovolt range, where there is still no other comparable technology available. Amplifiers for direct current signals are vulnerable to minor variations in the properties of components with time. The common-collector circuit is, therefore, better known as an emitter follower, source follower, or cathode follower.

Amplifiers are described according to the properties of their inputs, their outputs, and how they relate.Most amplifiers are designed to be linear. Different types of these include: Today, radio transmitters are overwhelmingly silicon based, even at microwave frequencies. They argue that tube amplifiers produce a "warmer" or more "natural" Many professional guitar players use 'tube amps' because of their renowned 'tone'. These functional descriptions usually apply to complete amplifier systems or sub-systems and rarely to individual stages. See The high output impedance of tube plate circuits is not well matched to low-impedance loads such as loudspeakers or antennas. RF circuits by contrast are typically required to operate at high frequencies but often over a very narrow frequency range. Le terme abrégé « ampli » désigne communément le couple constitué par l'amplificateur électronique et le haut-parleur. Negative Resistance Amplifier is a type of Regenerative Amplifier Video amplifiers are designed to process video signals and have varying bandwidths depending on whether the video signal is for SDTV, EDTV, HDTV 720p or 1080i/p etc.. An amplifier can either be a separate piece of equipment or an The first practical device that could amplify was the The development of audio communication technology in form of the The amplifying vacuum tube revolutionized electrical technology, creating the new field of The vacuum tube was virtually the only amplifying device, other than specialized power devices such as the The replacement of bulky electron tubes with transistors during the 1960s and 1970s created a revolution in electronics, making possible a large class of portable electronic devices, such as the Beginning in the 1970s, more and more transistors were connected on a single chip thereby creating higher scales of integration (such as small-scale, medium-scale and For special purposes, other active elements have been used. As soon as any connection within the circuit gets longer than perhaps 1% of the wavelength of the highest specified frequency (e.g., at 100 MHz the wavelength is 3 m, so the critical connection length is approx. For example, a specified length and width of a The frequency range handled by an amplifier might be specified in terms of Power amplifier circuits (output stages) are classified as A, B, AB and C for The practical amplifier circuit shown above could be the basis for a moderate-power audio amplifier. With Another advantage of negative feedback is that it extends the Negative feedback can be applied at each stage of an amplifier to stabilize the Some feedback, positive or negative, is unavoidable and often undesirable—introduced, for example, by All amplifiers include some form of active device: this is the device that does the actual amplification. The first practical device that could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. For example, in the early days of the 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 the output is proportional to the current through the port. ([power = voltage * amperage], so high power requires high voltage, high amperage, or both) Further circuit elements would probably be found in a real design that would A common solution to help stabilise the output devices is to include some emitter resistors, typically one ohm or so.