In recent years, with the popularity of 4K large-size LCD TV, we can experience the visual experience close to the cinema at home. But it is said that the film is an audio-visual feast. With the visual experience, the auditory experience can not be left behind. Therefore, a popular product in recent years has come into our attention. It is the echo wall. However, many people say that after using the echo wall, the echo wall is just like that. It sounds like an ordinary Bluetooth speaker. It does not have the claimed surround sound effect, and the sound quality is just like that. < / P > < p > in order to get a cinema like hearing experience, we first think of a set of home theater. In the traditional home theater system, take a 5.1 channel home theater as an example, there will be a total of 6 speakers, including the main speaker at the front left and the front right, a bass speaker for bass, a center speaker for human voice dialogue in the front, and a surround speaker at the right rear and left rear. At the same time, there is an AV power amplifier responsible for audio decoding. A set of home theater has higher requirements on the environment and takes up space. It is better to bury wire in advance when decorating. In short, it is very troublesome. The echo wall, also known as soundbar, is a cheaper and less difficult solution for traditional home theater. The echo wall integrates the speaker functions of multiple channels into a strip-shaped box, and the AV power amplifier responsible for audio decoding is also integrated into it. According to different principles, the echo wall can be divided into two types, one is the real reflection echo wall, the other is the virtual surround echo wall. The real reflection echo wall is to send sound to different parts of the room by controlling multiple loudspeakers in the speaker box. Through the reflection of the wall, you can feel the sound coming from all directions and realize the effect of surround sound. The virtual surround echo wall uses software algorithm to control the time difference between each speaker’s voice and the time difference between the sound to the human ear, so as to realize the virtual surround sound effect. Of course, the effect of real reflection is better than that of virtual surround. < / P > < p > in the market, many speakers with the same shape as the echo wall. Manufacturers also like to call themselves the echo wall in the publicity. In fact, these speakers are ordinary speakers in the shape of a bar, which can not be called the echo wall. So how to distinguish the echo wall from the ordinary bar speaker? Among them, Dolby Digital, Dolby Digital plus and DTS digital surround are lossy audio compression technologies that support 5.1 channel audio coding and decoding (Dolby Digital + and dtsvirtual: X support 7.1 channels). It is mainly applied to streaming media video websites, so these impact certification are mostly applicable to the low-end echo wall of the entry-level, and it is sufficient for daily watching of online TV programs. However, Dolby atmos, Dolby truehd and DTS-HD, DTS: X are lossless audio compression technologies, supporting 7.1 channels. Take Dolby atmos as an example, the traditional audio system can only flow sound from a few speakers with fixed position, while full scene sound can free the sound from the fixed speaker, so that it can flow freely in the whole three-dimensional space above your head and around. Therefore, these lossless formats of panoramic sound technology are mostly used on Blu ray disc, and these technologies are mostly used in high-end echo wall. Dtsvirtual: X also has Dolby Virtual Speaker technology, which can transform 2.0-channel audio into virtual 5.1 surround channel. Dtsvirtual: X can even simulate 7.1.4 panoramic sound, but the sound quality will be lost in the conversion process, and the effect is not as good as that of real multi-channel surround sound. < / P > < p > therefore, when purchasing, you only need to check whether the speaker has the above mentioned sound effect certification to determine whether it is a true echo wall. Of course, the simpler way is to look at the price. Generally, the echo wall below 1000 yuan is not the real echo wall. 1000-2000 price to buy an entry and echo wall. < / P > < p > I believe that we all have a certain understanding of the vocal tract. Usually, we can only hear 2.0 and 2.1 channels. But when purchasing echo wall, there are often 5.1 channels, 7.1 channels, and even 5.1.2, 7.1.4 channels. What is the difference between these channels? < / P > < p > among them, 2.0 channel is the left and right dual channel output stereo, like the mobile phone dual stereo dual speaker, is 2.0 channel. For 2.1 channel, a subwoofer is added on the basis of 2.0 channel to enhance the bass effect. 3.1 channel is to add a central channel in charge of the voice on the basis of channel 2.1 to make the dialogue clearer. 5.1 channel I have already introduced, that is, on the basis of 3.1 channel, add surround channel at the right rear and left rear. 7.1 channel has two more left and right surround channels than 5.1 channel. < / P > < p > and channel 5.1.2 is to add two sky channels to the ceiling on the basis of the original 5.1 channel, which is used to realize the effect of the aircraft flying over your head. < / P > < p > there are many ways to connect audio equipment. Among them, the most familiar one is the 3.5mm audio interface and Bluetooth. In addition to these audio transmission modes, there are optical fiber, coaxial and HDMI. < / P > < p > 3.5mm audio interface is mostly used on mobile devices such as mobile phones, MP3 players, laptops, etc., and can only transmit 2.0 channels. Bluetooth, too, can only transmit 2.0 channels, and Bluetooth transmission will lose part of the sound quality. Fiber and coaxial can support up to 5.1 channel of uncompressed, and fiber can achieve longer distance transmission than coaxial. HDMI has a huge bandwidth, hdmi1.4 bandwidth is 10.2gbps, hdmi2.0 bandwidth is 18gbps, and hdmi2.1 bandwidth is 48Gbps. Therefore, to achieve high bit rate lossless full scene sound transmission, we need to use HDMI interface, such as Dolby atmos and DTS: X both need hdmi2.0. So when you buy an echo wall, you need to see if there is an HDMI interface. In the beginning, it is mentioned that some people use the echo wall to listen to music and feel that the sound quality is not good. In fact, sound quality is a very metaphysical thing. Many people’s intuitive feeling of sound quality is “Oh, this bass is good, this sound quality is good”. To talk about the performance of high frequency and intermediate frequency, as well as the analysis, dynamic range and other messy things, different people will have different feelings, so it is really a very subjective thing to evaluate the sound quality of an audio product. < p > < p > then I will answer the question that the sound quality of the echo wall is general according to my personal subjective feeling. My answer is, yes! The sound quality of echo wall is not as good as hifi speakers at the same price. Normally speaking, the sound quality is directly proportional to the power, volume and price. That is to say, the higher the power, the larger the unit size, the better the sound performance. This is why the sound quality of TV speakers is better than that of mobile phones. The echo wall needs to plug multiple loudspeakers into one cavity. Limited by the volume, the volume of each speaker will be affected accordingly. Compared with the hifi speaker with larger size, the sound quality of the speaker is definitely unable to beat. In addition, ordinary music is basically 2.0 or 2.1 channels, which are played on the echo wall of 5.1 channel. In fact, only two main speakers and a bass speaker are used to make sound, and the rest speakers are silent. Therefore, the technology has its own specialty. The echo wall is used to replace the home theater to achieve surround sound effect, which is impossible for ordinary 2.0 and 2.1 channel hifi speakers. < / P > < p > of course, as long as you can pay for it, the high-end echo wall has good sound quality, but film is different from music and has so many rich melodies. Therefore, under the limited budget, we should consider the connection ability, decoding ability and channel number of echo walls. < / P > < p > this article is a relatively simple science popularization. I hope it can help those who are ready to buy back the sound wall. Finally, in order to give some suggestions, that is, when purchasing the echo wall, you can choose to go to the offline physical store for on-the-spot audition, which is more useful than watching the evaluation at night. Chinese version of K-car: reading a10e design drawing exposure