Supply Of High Quality Power Amplifier

    In audio equipment audio output power amplifier, from a variety of audio processing and amplification without distortion, by pushing the speaker sound to achieve a specific power. How to achieve audio signal power amplifier, high power and high efficiency In this regard, distortion power amplifier is the main problem to solve.
Power amplifier basic requirements
Output Power. We need to get enough output power, working voltage and current amplifier tube close to the limit parameters. In order to improve the cooling conditions of the power amplifier, the maximum allowable power amplifier tube to enlarge the tube collector cooling conditions can increase the maximum allowable power. For practical use, the power amplifier radiator must be installed correctly.
high efficiency. To obtain power and power, the efficiency of the power amplifier is called the power of the loudspeaker. As the power amplifier tube has a certain internal resistance, so there is some power consumption, power amplifier output is DC. Maximize PA efficiency as much as possible.
Non-linear distortion is small. In the case where the dynamic range of the power amplifier signal is large, the power amplifier must minimize the linear range of the non-linear distortion over the operating characteristic curve near the saturation cutoff frequency.
The basic components of a power amplifier
In high fidelity circuits, the amplifier circuit is usually composed of two or more audio channel configurations. Each channel is divided into two main parts: a preamplifier and a power amplifier. The circuit can be integrated in the same chassis, can be divided into two parts in two chassis, which is called integrated amplifier.
Since the same left and right channels describe the dual channel circuit, the only way is the circuit block in the figure below. The image preamplifier is reserved for the power amplifier on the right side.
The composition of the preamplifier. Various Tone Control It has a dual function: to beautify the sound by selecting the desired audio signal to zoom in to the nominal level. This function has been amplified by the equalizer, source selection, amplification and tone control input circuit.
(1) Select source. The source selection circuit turns off the other audio channels and selects the desired audio signal in the next stage. Output different sound sources are usually different, divided into high and low. Moving coil moving magnet record player Tuner, tape drive, CD player, VCD / DVD player and other audio The output signal level from 50 to 500 mV (high level source) can be fed directly to the source selection circuit. 0.5 ~ 5mV output level source selection circuit is called to provide the target equalization to the amplified bass. The line has not yet increased the availability and flexibility of the auxiliary input preamplifier, and the other inputs that connect the high television signal to the source.
(2) input amplifier. Amplify the input audio signal, usually amplified to about 1V nominal level. The input amplifier can be designed as an isolation amplifier. Can be amplified on the desired pitch control circuit.
(3) Tone control. According to the taste of the audience and the taste of the landscaping, the quality control of the desired frequency characteristics of the sound system is able to control to achieve high fidelity sound quality. Occasionally you can insert another equalizer to make the sound more beautiful. Tone controls include volume control, volume control, and low-frequency and high-frequency noise suppression.
2 sets of power amplifier. Many circuit mode power amplifiers are basically exciting, but the output stage and the protection circuit.
(1) driver stage. In order to provide a sufficient voltage gain, the electrons need to provide sufficient power to enable the gain amplifier to implement the amplifier output stage, which can be divided into driver stage and input stage.
(2) output stage. The output stage is used to generate enough power output without distortion. In order to obtain good frequency characteristics, harmonic distortion and SNR performance, we can introduce negative feedback between the output stage and the driver stage.
(3) protection circuit. Protects the circuit, protects the output stage of the power transistor and the loudspeaker, to prevent damage caused by overload.
In addition, a complete high-fidelity power amplifier, the DC power supply must be equipped with an organic level display circuit.