What is a Power Amplifier? The role of the power amplifier

Power amplifier (English name: power amplifier), referred to as "power amplifier", refers to an amplifier that can generate maximum power output to drive a certain load (such as a speaker) under a given distortion rate. The power amplifier plays a pivotal role in "organizing and coordinating" the entire audio system, and to some extent determines whether the entire system can provide good sound quality output.

power amplifier

working principle

Use the current control function of the triode or the voltage control function of the field effect tube to convert the power of the power supply into a current that changes according to the input signal. Because the sound is a wave of different amplitude and frequency, that is, the AC signal current, the collector current of the triode is always β times the base current, and β is the AC magnification of the triode. Applying this point, if a small signal is injected into the base, Then the current flowing through the collector will be equal to β times the base current, and then the signal is isolated with a DC blocking capacitor, and a large signal with a current (or voltage) that is β times the original is obtained. This phenomenon becomes the amplification of the triode effect. After continuous current amplification, power amplification is completed.

The role of the power amplifier

Preamplifier

The main function of the front-stage power amplifier is to perform necessary processing and voltage amplification on the program signal transmitted from the signal source, and then output it to the rear-stage power amplifier. It is like a railway fork, controlling and switching which audio source signal is connected to the power amplifier, and which audio source signal is disconnected from the power amplifier.

Power amplifier

The post-stage power amplifier is the part that performs simple power amplification. Its function is to amplify the signal from the pre-stage as much as possible. Our requirement for the post-stage is that the amplification factor should be as high as possible, and the degree of distortion of the amplified signal should be as high as possible. probably low. In addition to the amplification circuit, various protection circuits are also designed, such as short circuit protection, overvoltage protection, overheat protection, overcurrent protection, etc.

Amplify the volume: The main function of the power amplifier is to amplify the volume, which is generally used in home audio and various audio equipment. The installation of the power amplifier is also relatively simple. Many audio equipment will come with some power amplifiers, but some people will install a power amplifier by themselves because they cannot meet the needs.

Improve sound quality: In addition to amplifying the volume, the power amplifier also has the function of improving sound quality. But it should be noted that only if the power amplifier is installed correctly, it can effectively improve the sound quality of our audio system.

for military use

A very important function of the power amplifier is to use it in the military, mainly to amplify the captured signal. Since the sound signal we capture is very small, it is difficult to obtain effective information. At this time, we can use a power amplifier to amplify the signal.

The role of audio power amplifiers

There are two types of audio amplifiers: one is an operational amplifier dedicated to audio amplification, which has better performance in the audio range (mainly frequency response characteristics and distortion characteristics, and a good audio amplifier has both characteristics very good), It is generally used in the pre-amplification stage of audio. The other is an audio power amplifier, that is, a power amplifier circuit, which is used in the driving stage of the audio system, and can drive a speaker or audio system with relatively high power to make it emit sound.

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