The amplifier is commonly known as the "amplifier". His role is to amplify the weak signal from the sound source or preamplifier and push the speaker to sound. The function of a good sound system amplifier is indispensable. The amplifier is the most basic device in the audio system. Its task is to amplify the weak electric signal from the signal source (professional sound system is from the mixing console) to drive the speaker to produce sound. The power amplifier is abbreviated as power amplifier. It can be said that it is the largest family in all kinds of audio equipment. Its function is mainly to amplify the weaker signal input by the audio source equipment and generate enough current to push the speaker for sound reproduction. Due to the consideration of power, impedance, distortion, dynamics, and different use ranges and control adjustment functions, the signal processing, circuit design, and production process of different amplifiers are also different.
Classification: According to the different conductive modes of power amplifier tubes in power amplifiers, they can be divided into Class A power amplifiers (also called Class A), Class B power amplifiers (also called Class B), Class A and Class B power amplifiers (also called Class AB) and Class D. Power amplifiers ( Also known as Class D).
Class A power amplifier refers to a type of amplifier in which the current cutoff (ie, stop output) does not occur in any power output element of the amplifier during the entire cycle of the signal (positive and negative two and a half cycles of the sine wave). Class A amplifiers work with high heat and are inefficient, but the inherent advantage is that there is no crossover distortion. Single-ended amplifiers work in Class A. Push-pull amplifiers can be Class A or Class B or Class A and B.
Class B power amplifier refers to a type of amplifier in which the positive and negative phases of the sinusoidal signal are respectively amplified and output by the two “arms” of the push-pull output stage. The conduction time of each “arm” is half of the signal. Class B amplifiers have the advantage of high efficiency. The disadvantage is that crossover distortion will occur.
Class A and Class B amplifiers are between Class A and Class B. Each “arm” conduction time of push-pull amplification is greater than one-half cycle and less than one cycle of the signal. Class A and B amplifiers effectively solve the crossover distortion problem of Class B amplifiers, and their efficiency is higher than that of class A amplifiers. Therefore, they have been widely used.
Class D amplifiers, also known as digital amplifiers, use a very high frequency transfer switch circuit to amplify audio signals, which has the advantages of high efficiency and small size. Many Class D amplifiers with power up to 1000W are just as large as VHS tapes. This type of amplifier is not suitable for use as a wideband amplifier, but there are more applications in active subwoofers. According to the number of amplifier output stage amplifiers, they can be divided into single-ended amplifiers and push-pull amplifiers. The output stage of a single-ended amplifier consists of an amplifying element (or multiple elements but connected in parallel) that performs two and a half cycles of amplification of the signal. Single-ended amplification machines can only take Category A work. The output stage of the push-pull amplifier has two "arms" (two sets of amplifying elements). When the current of one "arm" increases, the current of the other "arm" decreases, and the states of the two switches alternately. For the load, it seems that an "arm" is pushing and an "arm" is pulling, and the current output task is completed together. Although Class A amplifiers can use push-pull amplification, it is more common to use push-pull amplification to form Class B or A and B amplifiers. According to the different types of power amplifier tubes in power amplifiers, they can be divided into tube amplifiers and stone machines. The amplifier is a power amplifier using a tube. Stone machines are amplifiers using transistors.
According to different functions, preamplifiers (also known as preamps), power amplifiers (also known as post-stages), and integrated amplifiers can be used. A power amplifier is referred to as a power amplifier and is an electronic device for enhancing signal power to drive a speaker to sound. Power amplifiers without ancillary functions such as signal source selection and volume control are called later stages.