Most consumers, when choosing amplifiers, first pay attention to the numerical value of output power. Indeed, the value of using a power amplifier lies in providing power to the audio system, so there is no improper way to categorize the motivation for purchasing an amplifier as "purchasing power". However, when purchasing an amplifier (in order to obtain power supply), we should also understand that the numerical value of output power is not the only selection criterion that needs to be considered.
Firstly, we should pay attention to the design type of the amplifier. According to different circuit design principles, power amplifiers can be divided into design types such as Class A, Class B, Class AB, and Class D. Among them, Class A power amplifiers have ideal sound quality but low conversion efficiency, while Class B power amplifiers have outstanding conversion efficiency but relatively rough sound quality. Therefore, automotive power amplifiers rarely use these two types of designs, mainly using Class AB and Class D.
The AB class amplifier combines the design methods of Class A and Class B, achieving a good balance between sound quality and efficiency. The output current to the speaker can be maintained above 70% of the input current, and the signal is still linear with low distortion, ensuring playback quality. In addition, due to the mature design of Class AB, it can provide good power and sound quality effects at a controllable cost.
D-class power amplifiers use nonlinear PWM pulse width modulation signals, which have advantages such as high conversion efficiency, low heat generation, low power consumption, and small size compared to traditional linear output designs. They can provide larger output power at a lower cost. However, due to the drawbacks of easy distortion and narrow dynamic range in D-class design, which directly affect sound quality performance, if one wishes to further achieve outstanding sound quality on the basis of high-power output in D-class, specialized sound quality optimization processing is required in circuit design, resulting in higher technical requirements and research and development costs.
From this, it can be seen that both AB class amplifiers and D class amplifiers can provide power to the audio system, but there are certain differences between the two in terms of output quality and price. If the power level is solely used as the standard, under the premise of the same price, Class D power amplifiers can often provide much greater output power than Class AB power amplifiers, and are also smaller and more controllable in size. However, if sound quality is used as the standard, Class AB power amplifiers can achieve good results at lower cost.
Therefore, when choosing an amplifier, consumers should first determine their usage needs, and then decide whether to first consider an AB class amplifier or a D class amplifier based on their budget. For example, if they want to find a high-power, small-sized amplifier to promote a subwoofer, and do not have high requirements for detail resolution, a D class mono amplifier is naturally an ideal choice. However, if they are considering sound quality and cost-effectiveness, common AB class amplifiers should be given priority.
Secondly, the control power of the power amplifier often has a more significant impact on the playback effect than the power size. We know that in daily work, power amplifiers often do not reach their marked output power values. However, the quality of their control power always directly affects the playback effect. Specifically, at the research and development level, the design of the power supply, the design of the amplification circuit, and the selection of components are all determining factors of the power amplifier's control power. If we only understand the power amplifier's control power through the data on the parameter table, we often cannot clearly understand its quality.
As a result, we will all find that amplifiers with a rated output power of 100W per circuit are not only entry-level products with very low prices, but also high-end models with high prices. The factor that determines their price is not the power size, but also the circuit design and materials that determine their control power.
Since it is not possible to understand the control force of a power amplifier from parameters such as power size, what method is there to determine the quality of the control force? For friends who have a certain understanding of amplifier design, by observing its circuit design, analyzing its layout and materials, they can roughly determine the advantages and disadvantages. However, the most effective method is to directly conduct a trial listening. If conditions permit, it is best to use several pairs of speakers with different styles and slightly different qualities for comparative testing, so as to more comprehensively identify the characteristics of the amplifier in terms of control power.
From the above analysis, we can understand that when choosing a car amplifier, power size is indeed an important indicator, but simply focusing on power size is not comprehensive. It is necessary to consider factors such as power type and output control force comprehensively in order to truly choose a satisfactory set of amplifier products.
