The function of the power amplifier is to amplify the weak signal from the sound source or the preamplifier and push the speaker to sound. The function of a good sound system amplifier is indispensable.
Power amplifiers are the largest family of various types of audio equipment. Their main function is to amplify relatively weak signals input from audio equipment and generate enough current to push loudspeakers for sound reproduction. Due to the consideration of power, impedance, distortion, dynamics, and different use ranges and control and adjustment functions, the signal processing, circuit design, and production process of different amplifiers are also different.
Power amplifiers play an important role in public broadcasting systems. Inferior power amplifiers are not only prone to failure but also affect broadcast effects. Therefore, it is imperative to avoid the use of inferior power amplifiers. The following Xiao Bian talks about how to identify inferior power amplifiers and how to select power amplifiers.
1, the protection function is not perfect
Although poor quality machines have boot protection against impact, most of them eliminate the necessary over-current, over-voltage, and output DC protection functions. This can cause poor performance of the whole machine. Once a problem occurs, it is very likely that the expensive speaker unit will be burned. For the identification of such fake craftsmanship, the first is to check whether the design has a perfect protection function by looking at the circuit diagram. The second is short-circuit short-circuit output, if the amplifier does not appear protection action. It is very likely that these protection circuits are omitted, or at least poorly tuned.
How to tell:
The simplest method is a short-circuit short-circuit output. If the amplifier that you want to start has no protection action, it may cause damage to your horn. If there is no physical object, you can use the circuit diagram to determine if there is a protection function, but if you want to do this, you should still find someone who knows what to do.
2, ignore important circuit design
This point also proves that the profiteers had a good grasp of the consumer psychology, that is, a tall appearance design is very attractive to consumers, and then there is basically no special design at all, and it can be understood as a high appearance. , And cover up the shortcomings of its internal circuit design. It is also a common method to use Class B to fill Class A. This must be taken care of.
How to tell:
This point if your friends are not very familiar with amplifier products, the easiest way is to buy some of the big manufacturers' products, reliable and assured, a penny and a piece of goods. Or find a knowledgeable fan, let him go with you to choose to buy.
3, the weight of the amplifier (really not the more Shen better)
For many people think that the power amplifier "dawn better," the idea of ​​low-quality power amplifiers have adopted a toroidal transformer, and many use a fever of double-ring cattle. However, the quality of the silicon steel sheet of this type of bovine cattle is very poor, and the winding process is still not closed. The result is low efficiency and low actual power. It is easy to hear the ring cows buzzing when it is quiet.
How to tell:
In fact, this is very easy, that is, at home or in a relatively quiet environment such as a shop, carefully listening to the ring cow is not a squeaky voice, if any, you have to pay attention, is not your Toroidal transformers are inferior products.
4, the size of the capacitor (capacitance is not the bigger the better)
This means that if you do not open the box of the amplifier, it is difficult to find, and many unscrupulous traders like to use larger domestic capacitors to impersonate small and heavy imported capacitors, and the capacitor will also choose some capacitors that are eliminated. , shoddy, with a large volume gives a feeling of calm, in fact, pressure and capacity are not up to standard.
How to tell:
Distinguishing the capacitance is actually very simple, because many of the counterfeit capacitors will be lighter than the high-capacity capacitors of the same size.
5, no dedicated decoding circuit
Although it is a poor quality amplifier, in order to hide its eyes, many profiteers still design their inferior amplifier products into 5-channel and 7-channel outputs. However, this is mainly due to the left and right channel series resistors. Many poor quality amplifiers are not designed independently. The amplifier circuit has no dedicated decoding circuit and sound field processing circuit. Although marked with Dolby Oriented Processing, there are no noise tests and so on.
How to tell:
The easiest way to distinguish this aspect is to see if its surround and center can adjust the volume individually. If a power amplifier with SRS technology is specified, it is easy to distinguish between true and false by turning on different surround modes. If it is a Dolby decoding chip with M69032, but there is no Dolby label, it may be a counterfeit product, so it must be pay attention.
1, see if the interface is complete
The basic input/output interface that an AV amplifier should have should include the following: coaxial, fiber optic, and RCA multi-channel input interfaces for inputting digital or analog audio signals; and speaker output interfaces for outputting signals to the audio.
2, see if the surround sound format is complete
Popular surround sound formats include DD and DTS, both of which are 5.1 channels. Now these two formats have been developed to DD EX and DTS ES, both are 6.1 channels.
3, see all channel power is individually adjustable
Some cheap amplifiers are divided into two channels into five channels, the channel should be a big one, to a small one small, and truly qualified AV amplifier can be adjusted individually for each channel.
4. Power is the most important parameter in the sound system, indicating the ability of the sound system to carry loads. This is also the place we should pay attention to when purchasing. However, if all manufacturers use different measurement benchmarks to identify product performance, it is often difficult to make objective comparisons without adequate knowledge. The same is true for amplifiers. When looking at the power amplifier logo, the following three points should be noted:
First, the battery voltage.
The voltage of the car battery is constantly changing. For two commonly used tags: 14.4V/100W and 12V/100W amplifiers are completely different power specifications. Since the voltage of the car during driving is basically around 12V, the measured power value under the condition of 12V voltage is closer to the real situation. In addition, the power that identifies the power based on the continuous voltage of 12V can achieve greater power when it reaches 12V or more.
Second, harmonic distortion rate THD.
When comparing the amplifier's continuous output power, it needs to be performed at the same (or closer) THD value. The difference in sound quality measured under different THD values ​​is quite obvious. Sometimes the maximum power of its logo is high, but it is very likely that its distortion and noise are equally high. Therefore, when checking the maximum power, you should also pay attention to the THD value it identifies.
Third, the frequency range.
The amplifier's continuous power output should be tested within its actual frequency range of use. For the power of the amplifier, the complete detection range should be marked, and only the power value at a certain frequency has no meaning. After determining the same benchmark, we can compare the amplifier power. In general, the principle of high power output is generally followed in the purchase of audio systems. The greater the power output of the amplifiers, the stronger their ability to drive the speakers. The power of the amplifier should be greater than the indicated power of the horn. If the selected power is too small, it will burn out easily when the power output is used for a long time, and it will also lead to poor sound quality and distortion.
Of course, the introduction of high-powered text alone is not a good way to understand whether power amplifiers are good or bad. The high-quality amplifier must also be able to quickly reflect the peaks of the music signal, and at the same time be able to correspond to a powerful subwoofer and provide a smooth output in a low distortion/low noise state. To meet these requirements, you must have the following:
First of all, it is an excellent power supply. This is the key to the sound quality of the left and right amplifiers. Its power supply and amplifier should be designed separately to reduce noise. Large-scale step-down transformers are used to increase the supply of stable currents, and large-capacity capacitors can react more quickly to supply the current needed for amplification.
Second, the built-in parameter equalizer. There is a big difference between a car stereo and a home stereo. The installation position of the speaker is very limited and the sound adjustment is very important.
In addition, due to the sound insulation of the headrest and the window, as well as the chaos of the sound waves caused by the installation angle of the subwoofer, the sound effects of the car audio system will be achieved. The parametric equalizer that works at this time is that it can compensate for the peaks and troughs of sound waves caused by the above reasons and adjust the smooth sound field.
In addition, it is a built-in frequency divider. No matter how excellent the amplifier's own features are, when it is actually installed in a car, it will not be able to achieve the best results due to various acoustic problems and speaker configuration problems. To overcome this, a divider is used in addition to the parametric equalizer.
The built-in divider has two major advantages:
First, the system is expandable and it is free to combine power amplifiers and speakers.
Second, making adjustments simple and easy. In this way, the sound quality of the entire system can be improved. The use of an external frequency division system is complicated because wiring is complicated and noise is easily mixed. This requires a large space for installation and raises the price of the system. Therefore, we do not recommend it when selecting a vehicle power amplifier.
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