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Rational evaluation of car audio quality
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How to calculate a good car audio, in the IASCA standard, it includes good sound quality, safe circuit, complete installation, beautiful craftsmanship, unique creativity, accurate frequency response, bursting sound pressure.
It’s a pity that Chinese car owners are the busiest people in the world. They are eager for a CAR AUDTO SYSTEM that reflects their personal tastes regardless of their appearance. However, they don’t have enough time for the audio conversion shop to fulfill his requirements. The refit shop has to show its professional level, so the streets and alleys are filled with the results of the process and process. If the majority of car owners are unfamiliar with the appearance of the process requirements, a set of safe sound system with excellent sound quality is your favorite.
What is the good sound quality in car audio? Most audio revamped people and enthusiasts will use home audio as a reference. The sound field positioning music reproduction of home audio is indeed the goal pursued by car audio, but it is generated in car audio. The real-life sound effect is definitely not comparable to the average home audio, so it adds another reference object for the car audio - headphones, if you have used excellent headphones to enjoy the music, I believe you will remember that let you float too The feeling of imaginary. In the narrow, closed, and strong absorption environment of the car, the ultra-wideband and balanced frequency response of the earphone is the "Utopia" that the car audio is looking for.
How to evaluate the sound quality of a car audio? Let's share the review rules of the International Car Audio Contest.
1. The accuracy of the tone and the balance of the full frequency band
2. Sound field and hall sound
3. Audio and video positioning
4. Sound linearity
The accuracy of the tone and the balance of the full frequency band are the main parts. The accuracy of the tone is affected by six characteristics: 1. LOUNDESS It refers to the intensity of the auditory stimuli caused by the sound. She will be subject to EQ or The influence of the sound pressure matching of the horn; Second, the pitch (PITCH) determines the position of the sound on the sound spectrum, it is a subjective quality, excessive distortion and nonlinearity will affect the pitch; Third, the tone (T NB wang) It is the sound characteristic produced by the interaction of the pitch of a certain sound with the overtone. It is related to the essence of the equipment and the wire; 4. Modulation (MODULAT 0N) It ​​refers to the change of the sound in size, phase or frequency. Will be affected by the phase and frequency response of the system; 5, the length of the sound (DURATI0N) is the length of time of the sound. She will react to the state of the system or the influence of the baffle resonance; 6. The time required for the ATTACK AND DECAY sound to be small to large (the lyrics) and the time required for the big and small (attenuation) ), it will be adversely affected by poor system response, baffle resonance and excessive pre-reflection.
According to the above six points, we can divide the sound into four frequency bands for identification. Ultra-low frequency (18-60Hz) This band represents the lowest frequency of all large stringed instruments, bass drums, bass synthesis 9S, organ. The sound of this frequency band should be clearly and vividly recognized by the system, with real sense of volume and elasticity, good extension, and must not be distorted. The common defect in this band is that the ultra-low frequency appears to be muddy due to excessive decay time or blurred sound. The lowest frequency band of the organ is a good example. Medium-low frequency (60-200Hz) It represents medium-sized drums (Indian drums, big Latin drums), the middle of bass guitars and bass, the bass of piano and sound synthesizers, which requires a smooth reproduction of elastic and detailed sounds. The difficulty is the performance of the drum and bass guitar; the middle sound and the broken sound. This is a frequency band that makes all audio conversion shops extremely painful, because in the car body, there will be resonance or peaks in this frequency band, which will affect the accurate reproduction of sound.
The first part of the "California Hotel" drum test is to test the preferred music, a good system should show the drum skin tension, size and impact of the hand drum, the common flaw we have is the drum sound is an exaggerated low frequency synthesizer the sound of. IF (200-3000Hz) This is an important frequency band. It contains most of the music information. It is also the most sensitive frequency band of the human ear. The excellent speakers and ordinary speakers are in this frequency band, basically using vocals as reference objects. The vocals should sound real and full without unnatural feelings such as bleakness or distortion. High frequency (3000-20000Hz) is conducive to the normal operation of high frequency in the environment of strong reflection in the car. However, due to the influence of installation position and improper attenuation, the high frequency of most car audio will be too bright and exposed. Rough texture and excessive tongue and sound. After an independent evaluation of the four frequency bands, we must consider the balance of the full frequency band of the music, which indicates the pitch accuracy of the system within the entire audio bandwidth. The common balance defect in China is the ultra-low frequency infinite amplification, which also causes many owners who do not like to install the subwoofer!
Six elements of sensory identification of car audio quality:
1, clarity. The wonderful sound quality is very clear, the transparency is good, and every word can be heard clearly. 2, fullness. Medium and low bass, moderate treble, warm, comfortable and flexible. If the reverberation time is short, especially the reverberation time of the low frequency band is shorter than the middle frequency band, its fullness will not be too good; the output frequency characteristics of the audio system are poor, and the middle and low sounds are lacking, so the sound will appear dry. Powerless, but also not full. 3, intimacy. It is the kind of expressiveness that people usually say, that is, there is a sense of communication and confession in the voice heard. The general or very poor sound quality is not experienced, it will make you feel urgent and far away. 4, a sense of balance. Refers to the left and right speakers, the proportional coordination of the output power between the main and auxiliary speakers and the correct phase. The stereo left and right channels have good consistency and the sound image is normal. If the sound image is sometimes offset and not coordinated enough, it is not a good sound quality. 5. Environmental sense. The sound has a good sense of space, and the whole gives a realistic feeling. It is most appropriate to use immersiveness to describe good sound quality. 6, loudness. In terms of loudness, good sound quality sounds appropriate and comfortable. In particular, it is more advantageous to select an excellent sound source as the source of the audition when distinguishing the sound quality, and to select the content that you are familiar with for testing.
The key to improving the sound quality of car audio:
When establishing the sound system, the matching of each equipment should be kept in the same style, otherwise it may cause disharmony in appearance, function, use and indicators. 1, to CD, MD do not VCD, MP3: If only used to play sound, the host still chooses CD, MD or DVD. VCD sound quality is poor, it is best not to use; MP3 is a compression format, although the sound quality processing circuit is added, but the sound quality is still not as good as CD; the sound quality of DVD is close to CD, but the overall comparison is still not as good as CD; the sound quality of MD is not much different from CD But the sound is a bit harder. The CD record should be genuine, and the best is the "DDD" printed on the disk. The sound quality of the CD record is good. 2. It should be "original". Do not equalizer: the host should use the machine without any modification to the signal. type. After the signal is modified, its waveform is distorted, so the music played is not ideal. The "original" host is best not equipped with equalizers and field effects (eg theater, plaza, studio, etc.). After modifying the field effect, the original signal will change and lose the original sound quality. 3, to 24bit not 1bit: Select the model to see the frequency response indicator, without any additional modified sound quality. 20bit and 24bit are indicated on the CD label of the audio store. 20bit and 24bit high resolution to make the music fully displayed. The average audio is mostly 1 bit, and the enthusiast audio is mostly high bit. Only when played on such a machine will it show its delicateness. 4, to high power do not distortion: If you use the host to directly push the speaker, you must choose a high output power. Now the host output power is generally 4 × 50W, mainly to reduce distortion. If you use the host's pre-output, you should choose a high output level, in order to improve the signal-to-noise ratio, the output level is generally 2V, preferably 4V output. In a sound system, the greater the output power of the main unit or amplifier, the greater the linear range of audio they can control, and the stronger the ability to drive the speakers. The low-power amplifier not only causes distortion in the sound, but also causes the amplifier or the horn to burn out. In the end, it takes a lot of effort to get the desired music effect. 5, the natural reproduction principle of sound quality: the so-called replay means that the played music and the original music change little. An important indicator in the evaluation of sound quality is the smoothness of the frequency response curve. The smoothness of the curve refers to the sound intensity of each range, the sound of each range is the same, the smoothness of the curve is good, the smoother the better, the better the audio-visual effect.
Effective shaping of car audio sound field:
The most important thing is the position and orientation of the speakers! The first thing to be clear is that since the directionality of the sound depends mainly on the high frequency part, the installation of the tweeter is crucial. The ideal location is: the left and right sides of the car dashboard. When the tweeter is installed here, the sound field can be effectively improved, and the sound field can be easily formed in front of the listener. However, it is very difficult to install in this way. How to find a suitable mounting position on the top of the instrument panel, how to fix the speaker, etc. requires better installation process support. In addition, when the tweeter is mounted to the instrument panel, it is inevitably separated from the intermediate frequency speaker by a long distance, which is not conducive to the accuracy of the sound field. Therefore, as far as practicable, the tweeter and the midrange speakers should not be more than 30 cm apart. Moreover, the direction of the tweeter and the midrange speaker should be as close as possible to the listener's position.
Let the sound field appear in front of the listener! Usually, when the car audio is modified, a sound-filling speaker is installed at the rear door or the tailgate position, so that the listener in the back seat also has the right to enjoy music. However, if the latter speakers are not properly adjusted, it will often cause the listener in the front seat to feel the sound coming out from behind the head. There are two ways to avoid this situation. The first is the simplest. It only needs to reduce the gain of the rear sound field speaker a little, but the sound pressure of the rear seat will be smaller. The second complicating point is that the rear sound field speaker needs to be set to band pass (that is, the combination of low pass and high pass, the Alpine MRV-F540 has this function). For example, set Qualcomm to 80 Hz and low pass to 3 kHz. Only the sound of 80-3kHz is transmitted from the rear sound field, which guarantees that low frequency distortion will not be generated and the high frequency sound will be pulled to the back of the sound field, and the rear seat listener also feels that the volume is large enough.
The last thing to consider is the low frequency part of the whole car. The subwoofer is usually installed in the trunk of the car. Although the theoretical subwoofer is theoretically non-directional, if the subwoofer's frequency band and the rear sound field speaker's frequency band have too many overlapping parts, it will make people feel that the bass part of the rear sound field speaker is part of the subwoofer bass. The entire subwoofer sound field is "locked" behind. So remember that the high-pass frequency setting of the rear sound field speaker should not be too low. When the frequency of the current sound field speaker and the subwoofer are properly connected, the fundamental frequency of the drum sound in the music is emitted by the subwoofer, and the higher harmonic part of the drum (still belonging to the low frequency sound) is emitted by the front sound field speaker. In this way, it sounds like the drum sound is emitted from the sound field!
No way to install is always the right law. Because of different models, different equipment performances, and even different people's appreciation habits, an excellent sound field environment needs to be experimented on the basis of theory, and your ears and feelings are the criteria for judging. Practice is the only condition for testing truth, and it is no exception during car audio installation.
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