The role and classification of amplifiers

The power amplifier is referred to as the power amplifier. It generally refers to one of the most basic equipment in the audio system, commonly known as "amplifier". Drive the speaker to produce sound. It can also refer to other devices that perform power amplification.

Amplifier function

The function of the power amplifier is to amplify the weak signal from the audio source or the pre-amplifier to push the speaker to play. A good set of sound system power amplifiers is indispensable.

Amplifiers
The power amplifier is the largest family of all kinds of audio equipment. Its main function is to amplify the weaker signal input by the audio equipment, and then generate a large enough current to drive the speaker to reproduce the sound. Due to the consideration of power, impedance, distortion, dynamics, and different use ranges and control adjustment functions, different power amplifiers are also different in internal signal processing, circuit design and production technology.

Classification of Amplifier

mobile megaphone

In addition to the function of amplifying the signal of the ordinary power amplifier to drive the loudspeaker, the frequency-shifting power amplifier can also effectively suppress the on-site howling and ensure the quality of voice transmission. Protect audio equipment from being burned out due to howling.

Frequency-shifting power amplifiers are widely used in high-end multimedia classrooms, training rooms, small meeting rooms or other simple sound reinforcement occasions. The microphone can be directly connected to the frequency-shifting power amplifier, which can effectively suppress the howling from the microphone to the speakers, and supports background music connection. input for sound amplification.

By conduction method

According to the different conduction methods of the power amplifier tubes in the power amplifier, it can be divided into Class A power amplifier (also known as Class A), Class B power amplifier (also known as Class B), Class A and B power amplifier (also known as Class AB) and Class D power amplifier (also known as Class D) kind).

Class A power amplifier refers to a type of amplifier in which any power output element of the amplifier will not have a current cutoff (that is, stop output) during the entire period of the signal (positive and negative two and a half cycles of the sine wave). Class A amplifiers generate high heat and have low efficiency when operating, but have the inherent advantage of no crossover distortion. Single-ended amplifiers all work in Class A mode, and push-pull amplifiers can be Class A, Class B or Class A and B.

Class B power amplifier refers to a type of amplifier in which the positive and negative two half cycles of the sinusoidal signal are amplified and output by the two "arms" of the push-pull output stage in turn, and the conduction time of each "arm" is half a cycle of the signal. The advantage of Class B amplifiers is high efficiency, but the disadvantage is that it will produce crossover distortion.

Class A and B power amplifiers are between Class A and Class B, and the conduction time of each "arm" of push-pull amplification is greater than half a cycle of the signal and less than one cycle. Class A and B amplification effectively solves the crossover distortion problem of Class B amplifiers, and its efficiency is higher than that of Class A amplifiers, so it has been widely used.

Class D power amplifiers are also called digital amplifiers, which use extremely high-frequency switching circuits to amplify audio signals, and have the advantages of high efficiency and small size. Many Class D amplifiers with power up to 1000W are only about the size of a VHS tape. This type of amplifier is not suitable for use as a broadband amplifier, but it has more applications in active subwoofer speakers.

By amplifier tube type

According to the different types of power amplifier tubes in the power amplifier, it can be divided into tube amplifier and stone amplifier.

A tube amplifier is a power amplifier that uses electronic tubes.

Stone machine is a power amplifier using transistors

By function

According to different functions, it can be a preamplifier (also known as the front stage), a power amplifier (also known as the rear stage) and a combined amplifier.

Power amplifier, referred to as power amplifier, is an electronic device used to enhance signal power to drive speakers to sound. A power amplifier without auxiliary functions such as signal source selection and volume control is called a post-stage.
The pre-amplifier is the pre-amplification and control part before the power amplifier, which is used to enhance the voltage range of the signal, provide input signal selection, tone adjustment and volume control and other functions. A preamplifier is also called a preamplifier.

The amplifier that installs the preamplifier and the power amplifier in the same chassis is called an integrated amplifier, and the common power amplifiers in our homes are generally integrated.

By purpose

According to different purposes, it can be divided into AV power amplifier and Hi-Fi power amplifier.

AV power amplifier is an amplifier specially designed for home theater use, generally has more than 4 channels and surround sound decoding function, and has a display screen. The main purpose of this type of power amplifier is to truly create the ambient sound effect of the film and let the audience experience the theater effect.

Hi-Fi power amplifier is an amplifier designed to reproduce the true nature of music with high fidelity. It is generally designed for two channels and has no display screen.

According to the components used

According to the different components used, the power amplifier has "tube amplifier" (tube power amplifier), "stone machine" (transistor power amplifier), and "IC power amplifier" (integrated circuit power amplifier). Due to the new technology and the use of new concepts in tube amplifiers, the electronic tube, an ancient vacuum device, shines again. Its beautiful sound has attracted many enthusiasts. Almost every serious audiophile has one. "IC power amplifier" is rarely seen in HI-FI power amplifiers because its timbre is not as good as the two power amplifiers.

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