- May 10, 2017 -
Power amplifier Referred to as "amplifier", refers to the given distortion rate conditions, can produce the maximum power output to drive a load (such as speakers) amplifier. Power amplifier in the entire sound system has played a "organization, coordination," the role of the hub, to some extent, dominate the whole system can provide a good sound output.
Power amplifier working principle
Power amplifier The power of the power supply is converted to a current that varies according to the input signal by using the current control function of the transistor or the voltage control of the field effect transistor. Because the sound is different amplitude and different frequency of the wave, that is, AC signal current, the transistor collector current is always the base current β times, β is the transistor AC magnification, the application of this point, if the small signal into the base, The current flowing through the collector will be equal to β of the base current, and then the signal is isolated from the DC blocking capacitor to obtain the current (or voltage) is the original β times the large signal, this phenomenon becomes the transistor amplification effect. After constant current amplification, to complete the power amplifier.
Power amplifier Basic composition
Power amplifier is usually composed of three parts: preamplifier, drive amplifier, the final power amplifier.
1, the pre-amplifier from the match, the input impedance is high (not less than 10kΩ), you can absorb the majority of the previous signal in the past, the output impedance is low (tens of Ω or less), the signal can be sent out of most of the wind. At the same time, it itself is a current amplifier, the input voltage signal into a current signal, and give the appropriate amplification.
2, the drive amplifier from the role of the bridge, it will be sent to the preamplifier current signal for further amplification, to amplify into a medium power signal to drive the final power amplifier to work properly. If there is no drive amplifier, the final power amplifier can not send high-power sound signal.
3, the final power amplifier plays a key role. It will drive the amplifier to send the current signal to form a high-power signal, driving the speaker sound, its technical indicators determine the technical indicators of the entire power amplifier.