Features of digital power amplifier
Release Time:
2023-06-26
Because the working method of digital power amplifier is completely different from that of traditional analog power amplifier, it overcomes some inherent shortcomings of analog power amplifier and has some unique characteristics.
1. Overload capability and power reserve
The overload capacity of the digital power amplifier circuit is much higher than that of the analog power amplifier. The analog power amplifier circuit is divided into Class A, Class A or Class AB power amplifier circuit. The power amplifier tube works in the linear region during normal operation; when overloaded, the power amplifier tube works in saturation. Harmonic distortion occurs in the area, the degree of distortion increases exponentially, and the sound quality deteriorates rapidly. However, the digital power amplifier is always in the saturation area and cut-off area when the power is amplified. As long as the power amplifier tube is not damaged, the degree of distortion will not increase rapidly.
Since the digital power amplifier adopts a switching amplifier circuit, the efficiency is extremely high, up to 75[%]~90[%] (the efficiency of the analog power amplifier is only 30[%]~50[%]), and it basically does not generate heat during work. Therefore, it does not have The quiescent current consumption of the analog power amplifier, almost all the energy is reserved for audio output, plus there is no analog amplification before and after, and no negative feedback restraint, so it has better "dynamic" characteristics, good transient response, and extremely "explosive feeling" powerful.
2. Crossover Distortion and Mismatch Distortion
Analog Class B amplifiers have zero-crossing distortion, which is caused by the nonlinear characteristics of transistors at small currents at the positive and negative intersections of the output waveform. Severe distortion). And the digital power amplifier only works in the switch state, and will not produce crossover distortion.
The analog power amplifier has the inconsistency of the characteristics of the push-pull pair of tubes, which causes the output waveform to be asymmetrical and mismatched. Basically, it can be used without strict selection.
3. Matching of power amplifier and speaker
Since the internal resistance of the power amplifier tube in the analog power amplifier is relatively large, when matching speakers with different resistance values, the working state of the analog power amplifier circuit will be affected by the size of the load (speaker). The internal resistance of the digital power amplifier does not exceed 0.2 (the internal resistance of the switch tube Resistance plus filter internal resistance), relative to the load (speaker) resistance (4~8), it is completely negligible, so there is no matching problem with the speaker.
4. Transient Intermodulation Distortion
Almost all analog power amplifiers use negative feedback circuits to ensure their electroacoustic indicators. In negative feedback circuits, in order to suppress parasitic oscillations, phase compensation circuits are used, which will cause transient intermodulation distortion. Digital power amplifiers do not use any power conversion Analog amplifier feedback circuit, thus avoiding transient intermodulation distortion.
5. Sound image localization
For analog power amplifiers, there is generally a phase difference between the output signal and the input signal, and when the output power is different, the phase distortion is also different. The digital power amplifier uses digital signal amplification to make the phase of the output signal and the input signal exactly the same. The phase shift is zero, so the sound image positioning is accurate.
6. Upgrading
The digital power amplifier can obtain high power by simply replacing the switching amplifier module. The cost of the high-power switching amplifier module is relatively low, and it has broad development prospects in the professional field.
7. Production commissioning
Analog power amplifiers have debugging problems at all levels of working points, which is not conducive to mass production. Most of the digital power amplifiers are digital circuits, which can work normally without debugging, and are especially suitable for mass production.
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