Classification of power amplifiers: classified according to the equipment used in the circuit. Tube amplifiers: commonly known as "tube amplifiers". The main advantages of using vacuum tubes as amplification stages are: large dynamic range, good linearity, sweet, pleasant and gentle tone. The transmission characteristics of electron tubes and transistors are different, and there is a certain difference between the two. For example, when the signal is too large to be excited (the signal stimulation exceeds the tolerance range), the waveform of the electron tube changes more gently, while the waveform of the transistor is not very smooth, which directly affects the sound quality. Another example is that of an electron tube. The amplification of transistor amplifiers mostly excites "even harmonics", which are harmless to the sound quality, while the transistor amplifiers mostly excite "odd harmonics", which can cause listening discomfort. Filtered Advertisements However, there are two problems with tube power amplifiers. First, the large internal resistance leads to a small damping coefficient of the amplifier, which affects the transient characteristics. Second, the tubes require high-voltage power supply and cannot be separated from the transformer. The transformer not only consumes a lot of power, but also causes distortion. , and large in size. Due to the harsh usage environment in cars (high temperature, vibration, power supply, etc.), which greatly limits the use of amplifiers in car audio systems, their circulation rate in the market is not high. Transistor amplifier: It overcomes two shortcomings of tube power amplifiers. First, the damping coefficient can be made very high, and it has good transient characteristics. The rhythm and intensity of the sound are brighter, heartier, and more powerful than tube amplifiers; second, the There is no need for a transformer, which not only saves costs and reduces the size, but also avoids distortion caused by the transformer. Transistor amplifiers are the mainstream products of car audio power amplifiers on the market today. They come in various varieties and grades and are the main products chosen by car owners. The last one is the integrated circuit amplifier. Its most prominent advantages are high reliability, simple peripheral circuits, and easy assembly. Its shortcomings are that the electroacoustic indicators (power, frequency response, distortion, signal-to-noise ratio, etc.) and sound quality are inferior. Amplifiers composed of discrete components are mainly used in the power amplifier stage of the host computer. Class A amplifiers are classified according to the working state of the circuit. The working principle of this kind of power amplifier is that the output device (transistor or electron tube) always works in the linear part of the transmission characteristic curve. There is always a continuous flow of current in the output device during the entire cycle of the input signal. This kind of power amplifier The amplifier has small distortion, but low efficiency, about 50%, and large power loss. It is generally used in high-end machines at home. In a Class B amplifier, two transistors work alternately. Each transistor is turned on during half the signal cycle and turned off during the other half cycle. The efficiency of this machine is relatively high, about 78%, but the disadvantage is that it is prone to crossover distortion (distortion that occurs when two transistors are turned on separately). Class A and B amplifiers have the advantages of good sound quality of Class A amplifiers and high amplification efficiency of Class B. They are widely used in home, professional and car audio systems.