Car power amplifier profile
The car power amplifier is the audio power amplifier in the car audio and video system. Its function is to select and input the audio input signal, perform power amplification, and make the electric signal have the ability to push the speaker.
Car power amplifiers are slightly different from those in ordinary home theaters. Because many car hosts integrate power amplifier functions to perform pre-amplifier functions, car amplifiers are sometimes called post-amplifiers, which means that they can be connected to already amplified High level input.
Amplifier is an indispensable component of a good sound system. The power amplifier on the main unit often cannot really amplify the sound current, so if you want to have a good music experience, you must install a power amplifier. In general, the power of the power amplifier is greater than the power of the speaker. Many car owners believe that the addition of a bass amplifier is just for shocking effect. In fact, this ignores the characteristics of the car. Even high-end cars will have noise. The bass part of the music released during driving will be affected to varying degrees. Attenuation, and the addition of a bass amplifier can increase the reserve power, supplement the loss of bass, and reduce distortion.
Because the car power amplifier is connected to the host and the speaker, you must consider the cooperation between the host and the speaker when purchasing the power amplifier. It directly affects the effect of music playback and the life of the equipment. The matching of vehicle power amplifier mainly includes impedance matching and power matching. Amplifiers have a great impact on sound quality. Generally speaking, the same brand of amplifiers and speakers are better matched, and should be considered first; if you choose a brand-name car speaker and amplifier, you can generally match them according to their technical parameters; It is best to actually mix with audition.
Car audio and video matching
Many people think that to modify the car audio is to remove the equipment of the original car and replace it with a professional product with more ideal performance. In fact, most people do the same. It ca n’t be said that this modification method is wrong, only It can be said that this is only suitable for those who do not have high requirements for sound quality. To obtain a more beautiful sound enjoyment involves the installation of power amplifiers, subwoofers and other equipment, and also involves the coordination of various products.
Power amplifier
In many cases, the rated output power of the host is not competent to drive the entire audio system. At this time, a power amplifier must be installed between the host and the playback device to supplement the required power gap, and the power amplifier plays a role in the entire audio system. The pivotal role of "organization and coordination" dominates to a certain extent whether the entire system can provide good sound quality output.
There are many types of automotive power amplifiers on the market, and the classification method is relatively complicated. The most common is divided into A-type, B-type and AB-type according to working methods. Class A means that the amplifier collects the audio signal transmitted from the host at a certain time and amplifies it and transmits it to the speaker. The "buffering effect" in this process ensures that the system can output a gentle and smooth sound signal. The point is that the energy consumed is larger. Class B power amplifiers have cancelled the aforementioned "buffering effect", and the work of the amplifier has been in a timely state, but the sound quality is worse than the former. Class AB amplifiers are actually a combination of Class A and Class B. The turn-on time of each device is between 50% and 100%, which can be regarded as the current ideal power amplifier.
When choosing a power amplifier, you must first pay attention to some of its technical indicators: 1, input impedance: usually indicates the size of the power amplifier's anti-interference ability, usually in the range of 5 000 ~ 15 000 Ω, the larger the value, the stronger the anti-interference ability ; 2. Distortion: refers to the degree of distortion of the output signal compared to the input signal, the smaller the value, the better the quality, generally below 0.05%; 3. Signal to noise ratio: refers to the output signal between the music signal and the noise signal Ratio, the larger the value, the cleaner the sound.
In addition, when purchasing a power amplifier, you should also be clear about your purchase intention. If you want to install a subwoofer, it is best to buy a 5-channel power amplifier. Usually 2-channel and 4-channel speakers can only drive front and rear speakers, and The subwoofer can only be equipped with a power amplifier, and the 5-channel power amplifier can solve this problem. The output power of the power amplifier should also be greater than the rated power of the speaker.
bass
Compared with the audio equipment introduced earlier, the use of subwoofers seems to be the lowest, and it often appears near young people who like metallic music. It is a must-have for car owners who like pop music and rock music. In principle, the working methods of the subwoofer and the speaker are exactly the same, except that the diameter of the diaphragm is larger, generally 8 to 10 inches, and a speaker for resonance is added.
In terms of evaluation indicators, the subwoofer is basically the same as the speaker. The specific content is not described here. Only the numerical requirements are mentioned. The frequency response is generally below 200 Hz, the rated impedance is also about 4Ω, and the sensitivity is generally greater than 90 dB / W / m.
At present, subwoofers can be roughly divided into active subwoofers and passive subwoofers. Active subwoofer refers to the subwoofer with its own built-in power amplifier, no additional power amplifier is needed when it is used, and the shape is usually a barrel type. The disadvantage of this subwoofer is that the heat dissipation is not ideal and the power will not be very large, and the barrel shape usually produces unnecessary resonance, which reduces the controllability of the subwoofer. In contrast, passive subwoofers require an external power amplifier when working. The shape and power selection of this subwoofer can be more flexible, and the effect is naturally more ideal. In addition, active speakers can be further divided into sealed boxes and perforated boxes, the former is more suitable for deep symphony, the latter is more suitable for popular music.
Product Matching
So far, the common car audio equipment has been introduced, and the rest is another important problem: how to reasonably match each equipment to get the ideal sound effect. The following points introduce the problems that need to be paid attention to in the process of matching car audio:
The main device that reflects the music style is the speaker, and compared with the first selection of the host, after the speaker is selected, the matching amplifier and other devices have more flexibility. So the first step in purchasing is to choose the speaker that suits you, and the first step in matching is the problem between the speaker and the input device.
(1) Speaker and input device
The input devices that can be matched with the speaker are the power amplifier and the host. Only the maximum power of the product is marked on the technical nameplate of the general host, and the actual work can only provide about 50% of this number. In many cases, it is wrong to judge that the speaker can be driven by looking at the nameplate. If you use a power amplifier to drive the speaker, it is best to choose a product with an effective output of more than 50 W, because the rated power of the general speaker is between 40 and 50 W.
(2) Amplifier and host
The most common problem in the matching of car audio systems occurs between the power amplifier and the host. The first is the signal output problem. Not all hosts can be connected to the power amplifier. To connect an external power amplifier host, there must be at least one group of front outputs, and a better host will have more than three groups. Secondly, the output signal voltage of the host must be above 2 V, and the high-fidelity host can reach above 4 V, so as to ensure that the amplifier has good "raw materials" for processing. Since the energy source of the power amplifier is independent of the host, there is generally no problem in matching the power between the host and the power amplifier.
(3) Host and car
The match between the host and the car should first pay attention to whether the battery can provide sufficient and stable power. If the battery encounters "turn on the headlights" and the current fluctuates greatly, it will affect the service life of the host. Secondly, when purchasing the main unit, try to achieve the panel style and lighting equivalent to the interior of the vehicle to achieve harmony and unity and consistent color tone. If you install the CD host again, it is best to recheck the vehicle wiring. If you cannot withstand excessive current, it is best to rewire.
The specific problems related to the matching of car audio can be summarized as the following aspects. First, try to achieve a balanced balance between various accessories. This balance covers many aspects such as music style, power, current, etc., and clarify your own budget. Tailor-made, there is no need to excessively demand the high performance of a component; Secondly, in terms of power, it is necessary to ensure that the output power of the host and the power amplifier can be greater than the rated power of the speaker, so that the control is handy.
Car host
The in-vehicle host is the core part of the in-vehicle audio and video system. Its main function is to play the audio source, which is equivalent to a DVD player in a home theater. However, in order to be more suitable for the narrow space in the car, the car host often has a certain power amplifier capacity. If the speaker requirements are not too high, there is no need for an external power amplifier. It is easier to form an audio-visual system. In addition, many hosts also have a display screen, which is a screen. Such a host can form an audio-visual system by simply connecting speakers. Of course, the car host with a screen is usually larger, generally 2DIN.
The main unit of the car audio is usually placed on the control panel of the car, which is convenient for the driver to touch and manipulate. In the whole car audio system, the host as the final signal source can be regarded as the most basic and important one among all components. To get the ideal sound quality, the host must first be able to ensure the output of high-quality signals. The host should choose a product with better quality, strong anti-vibration ability, higher sound quality purity, and beautiful style. The output power is slightly larger. After the modification, you can get a refreshing feeling.
Specifically, the role of the host includes: 1, tone adjustment, unified coordination of high, medium and low frequency range signals to make it more coordinated. 2. Loudness adjustment. For some signals with insufficient loudness, the host is responsible for moderately supplementing to make the sound fuller; 3. Built-in equalization, setting different frequency gain supplements for different styles of music, for example, if you press "ROCK" on the panel "Key, then the host will strengthen the bass and treble to highlight the feeling of rock.
There are various classification methods for car audio mainframes, and the most common method at present is to classify according to signal sources. The main signal sources of the host are: radio (FM / AM), magnetic tape, CD, VCD, DVD and MP3. The combination of these sound sources can produce different types of audio hosts. The most common is the three-in-one model of radio, tape and CD. Of course, there are MP3, tape and radio combination methods, but it is relatively rare. .
Car speakers
SPEAKER, commonly known as speaker, is an indispensable important equipment in a sound system. All music is sounded through speakers for people to listen and enjoy. As the only device that transforms electrical energy into "sound energy", the quality and characteristics of the speakers play a decisive role in the sound quality of the entire sound system. Due to the particularity of the car, it is not possible to install universal speakers like a home theater in the car, but to directly install each car speaker on the car, a high-end car can even install more than ten speakers.
The speakers mainly include double cone, two-way, three-way, independent component type, subwoofer and so on. The independent component type includes an independent tweeter unit, an independent midrange unit and a crossover network, and is generally installed at the front door of the car. In general, the larger the caliber of the speaker, the better the low frequency, so if you like to listen to bass, it is best to match a larger caliber speaker.
The importance of speakers in car audio systems is more prominent. To make car speakers show excellent sound and positioning, compared with home audio, the technical requirements and difficulties are much higher. The unfavorable factors of car speakers are numerous and complicated, because there are some unfavorable factors in the interior of the car that are not available in the house: narrow spaces, irregular objects, complex environments (noise, vibration, vehicle materials, etc.) and The installation position of the speaker (limited by the shape of the car's inside and outside); more importantly, the listening position is not good, left and right; and because the speaker's pointing is not positively symmetrical on the front, resulting in complex frequencies, phase differences and peak , Troughs, standing waves, reflective jet lag, reverberation time is too long (resonance), etc., is not conducive to listening problems. Nonetheless, we can correctly handle the installation position of speakers of different bandwidths and maintain their good orientation by understanding the properties, uses, categories, compatibility and speaker characteristics of sound system equipment, plus the correct installation experience and skills It is technically calibrated with compatible power amplifiers to achieve good results.
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