What are the characteristics of power amplifiers?

Power amplifier is one of the common devices in our life, but do you really know about power amplifier? In order to enhance our understanding of power amplifier, this paper introduces the definition, application, characteristics and functions of power amplifier.
 

 
Definition of power amplifier + purpose. Class ab amplifier characteristics

Power amplifier, referred to as power amplifier, is the comprehensive voltage and current amplification of audio signals to obtain power amplification. The position of the power amplifier in the system diagram is in front of the loudspeaker system, and its output is sent directly to the loudspeaker system to drive the loudspeaker system. Since the output sensitivity of the power amplifier is generally around 0dB, the input signal added to the power amplifier is generally taken from the 0dB output signal of the mixing table or peripheral equipment. For the low level output signal such as microphone, the power amplifier can only be driven after voltage amplification by the preamplifier or the mixer. Preamplifier, mixer or peripheral devices are voltage signal output, only minimal output current, is not a power signal, so they cannot be used to drive the speaker system, must pass a power amplifier will be voltage amplifier, audio signal further finally carried out on the current and power amplifier, has the enough power output, just enough to drive a speaker system, sound radiation, promote speakers to work properly.
 

 
Characteristics of power amplifier

1.can output a large power, the power here usually refers to more than 1W power;
 
2,.has the high power conversion efficiency, power amplifier is a kind of energy conversion circuit, so the efficiency is one of the important indexes of power amplifier, assuming that the Po is the output power of the road, Ps is to provide power dc power supply, Pc is consumption, the conversion efficiency is defined as Ƞ = Po/Ps * 100%;
 
3. With small nonlinear distortion, the total harmonic distortion coefficient (THD) is expressed by the percentage of the RMS of the total harmonic component of the output signal and the effective value of the fundamental component. The harmonic distortion is caused by the incomplete linearity of the system;
 
4.power tube heat dissipation problem: power tube is the most easily damaged device in the circuit, the main reason is because the pipe actual dissipation power over the rated value, the dissipation power of power tube depends on tube inside the collector junction temperature, when the temperature exceeds tube can withstand the highest temperature, the tube current increases sharply and make the transistor burn out (silicon tube temperature 120 ℃ ~ 200 ℃, germanium tube temperature about 85 ℃.