Great God teaches you to choose the power amplifier, to analyze the difference and characteristics between European and American power amplifiers and Japanese power amplifiers.

[Home Theater Network HDAV.com.cn] Amplifiers produced in different regions have different sound characteristics, especially in foreign excellent products. As the foreign-produced power amplifiers currently seen in the domestic audio market are basically produced in Europe and the United States and Japan. Because of this, understanding and mastering the (sound) characteristics of the power amplifiers produced in these areas will undoubtedly help the selection of power amplifiers (including AV amplifiers).

1, the characteristics of European and American amplifiers

In the history of power amplifiers, McIntosh and Marantz were once outstanding representatives of early American products. Due to the three major industrial standards of UC, NEMA and NEC, the power amplifiers produced in the United States have certain guarantees in quality. I don’t see some products produced by Mai Jingtu in the 1950s, but they still work normally. Marantz’s Mode7, Mode8(B) and Mode9 (Hi-Fi amplifiers) are still hot for fever. In the 1970s, due to the rise of Japanese products in the world audio market and the rising cost of processing in the United States, not only did some American companies advocating handcrafted and small-scale production fail or be merged, even Mai Jingtu, Fisher. And the famous manufacturers such as Marantz are also difficult to escape. Marantz is now acquired by Philips in Japan, Fisher is acquired by Sanyo Electric of Japan, and Mai Jingtu has to accept funds from Aiwa. However, with the economic upturn and the emergence of companies such as Jeff Rowland, Mark Levinson, and Krell, the American-produced amplifiers can basically maintain their original features.


In general, the high-end amplifiers produced in the United States are of the highest quality, and the sound performance is focused on the width and depth of the sound field. At the same time, they have sufficient energy to easily cope with all types of speakers produced around the world. In general, they are sold. The high price, large size, good quality, and good musicality of the sound are the distinguishing features of the power amplifiers produced in the United States.

European power amplifiers are represented by products from the United Kingdom, the Netherlands, Germany, France and other countries. The amplifiers produced in the UK are mostly influenced by their humanistic factors, and they tend to be good at interpreting classical music. This tendency makes it popular at the beginning of the digital sound, and some of them have the traditional LP turntable. The warm, supple sound of the power amplifier is deeply praised by fans and the media. No wonder some people say that if you want to buy a sound amplifier with a musical taste at a low price, then British goods may be the only choice. British brands that are more common in China and have certain influences include: Link, Quad, Naim, Musical Fidelity, Arcam, etc. In the middle and low price, music fax and Yajun are good reputations. s brand.

2. Features of Japanese-made power amplifiers

Due to the advanced technology and the advantages of mass production, the Japanese-made power amplifiers not only have a beautiful appearance, but also have certain advantages in performance and price ratio. In the past, Japanese-made power amplifiers, due to the influence of their traditional music "Yale", often emphasized too high and low frequencies, and the sounds were hard, so they were dubbed the drums and triangles. However, the excellent products produced by some famous Japanese companies have paid more and more attention to the balance of the sound of the power amplifier. The details are also very clear. In the high-end products, some products such as Accuphase are enough to make the products of Europe and America ashamed; Among the products, a large number of products such as Tianlong, Sony, Onkyo and Pioneer have shown an aggressive trend. Especially in AV amplifiers, Japan's advanced electronic technology is widely used. If compared with European and American products at the same price, Japanese products tend to be value-for-money.



In the collocation, if the mid-priced Japanese-made amplifiers and European and American speakers (such as Denon and Kef, Yamaha and B&W) match and complement each other, there will be satisfactory results in the tone.

As far as AV amplifiers are concerned, the sound characteristics of Japanese brands are as follows:

1. I like the huge fluffy sound of the theater, Marantz Marantz performed well;

2. Like the European and American style, strong enough to choose DENON Tianlong;

3. To enrich the details. The sense of envelop is strong, the first to push SONY Sony;

4. The performance and spatial transformation of surround sound is YAMAHA Yamaha;

5. The bass is not turbid, the midrange has thickness, the treble does not float, and the various bands are selected to be ONKYO Anqiao;

6. Like a clean sound, all frequency bands can be clearly heard is the pioneer of the pioneer.

In short, the European and American amplifiers are winning in the dynamic, sound field and sound quality! As for the Japanese power amplifier, it is easy to operate and respond to the speed. At the easy price, you can enjoy the latest sound technology and performance in the sound! So, if you pursue technology and Sound effects, Japanese amplifiers have been very good performance, if the sound is supreme, European and American amplifiers can give better enjoyment!

More fresh and fun home theater information, please pay attention to home theater network http:// (WeChat: cnhifi), the country's most influential home theater audio player interactive media website.

3G 4G LTE/5G Antenna

  • The Description of 3G 4G LTE/5G Antenna
  • 2G base station: GSM: 900/1800MHz; CDMA: 800 MHZ;
    3G base station: CDMA2000&WCDMA: 2100MHz; Td-scdma: 1880-1920201 0 0-2025232-2370 MHZ;
    4G base station: TDD-LTE: 2320-2370,2570-2620MHz;
  • This paper discusses the key technologies in 3G/4G/5G (third generation/fourth generation/fifth generation) communication systems, and then discusses the differences in the antenna technologies adopted by them. After reading and studying a large number of papers on the key technologies of 3G/4G/5G communication system, here I make some analysis and summary of my own. With the rapid development of science and technology, mobile communication technology has undergone profound changes, from 1G to 2G, to 3G, and then to 4G and 5G. On December 4, 2013, the fourth generation of mobile communication 4G technology was officially operated in the Chinese market, which means that China's mobile communication industry has entered the 4G era. At this time, research institutes in various countries and world-renowned enterprises engaged in communication technology research have entered the research and development of the new generation of mobile communications, namely 5G (fifth generation mobile communication system). No matter which generation of communication system, the research technology is to analyze the characteristics of wireless communication channel to overcome the noise interference. A lot of researchers are now looking at Massive MIMO technology. How is it different from the antenna technology used in 3G/4G communication systems? Will it become the core technology of the next generation of wireless communications? 1 Key technologies of 3G/4G/5G Communication System 1.1 Key technologies of 3G Communication System Since the early 1990s, the mobile communication industry began to actively study the standards and technologies of the third generation of mobile communication. In January 2009, China's Ministry of Industry and Information Technology issued 3G licenses to China Mobile, China Telecom and China Unicom, indicating that China entered the ERA of 3G mobile communications. The third generation mobile communication system mainly includes WCDMA, CD-MA2000 and TD-SCDMA. Its key technologies include: A. Rake receiving technology; B. Channel coding and decoding technology; C. Power control technology; D. Multi-user detection technology; E. Smart antenna; F. Software radio. 1.2 Key technologies of 4G Communication System In December 2013, China officially entered the era of 4G (fourth generation mobile communication system) communication network. In 4G mobile communication system, OFDM(Orthogonal frequency Division multiplexing) technology is adopted. OFDM technology is due to its spectrum utilization
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    It is widely regarded as high rate of 2 and good anti-multipath fading performance. In the future, RESEARCH related to OFDM technology will also be carried out in 5G communication networks. The main key technologies of 4G communication system include: a. OFDM technology; B. MIMO technology; C. Multi-user detection technology; D. Software radio; E. Smart antenna technology; F. IPv6 technology. China's Ministry of Industry and Information Technology has just issued 4G licenses to the three major operators, and they are still deploying their networks on a large scale with a small number of users. At this time, China Mobile said it will start the RESEARCH and development of 5G communication system. Analysts pointed out that the three major operators are participating in THE RESEARCH and development of 5G, one is to keep up with the changes of The Times, and the other is that the demand is faster than the technology development. Li Zhengmao, vice-president of China Mobile, said at the 2014 MWC in Barcelona: "China Mobile will fully support the development of 5G projects, hoping to lead the industry in THE development of 5G technology and the setting of technical standards." With the deepening of mobile communication technology research, the key support technologies of 5G will be gradually defined and enter the substantive standardization research and formulation stage in the next few years. The jury is still out on what core technologies will be used in the future. However, I have compiled a list of nine key technologies that have been the focus of discussion in various high-end mobile forums. A. Large-scale MIMO technology; B. Filter bank based multi-carrier technology; C. Full duplex technology; D. Ultra-dense heterogeneous network technology; E. Self-organizing network technology; F. Use of high frequency band; G. Software-defined wireless networks; H. Wireless access technology: (1) BDMA (Beam Split multiple Access technology)
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    3 (2) NOMA (Non-orthogonal multiple Access technology) i. D2D (device-to-device) communication. Figure 1 is the layout of Massive MIMO antennas in 5G communication networks. I am studying Massive MIMO technology in my lab. Figure 1 shows users communicating with each other centered on a large-scale antenna. The performance of wireless communication systems is mainly restricted by mobile wireless channels. Wireless channel is very complex, and its modeling has always been a difficult point in system design. Generally, statistics are made according to the measured values of communication systems in specific frequency bands. Wireless fading channel is divided into large scale fading channel model and small scale fading channel model. The so-called large-scale fading model describes the field intensity variation over a long distance (hundreds or thousands of meters) between the transmitter and receiver, and reflects the rule that the received signal power changes with the distance caused by path loss and shadow effect. A small scale fading model describes the rapid fluctuations of the received field intensity over a short distance or time. The large scale fading channel model is caused by the influence of the surface contour (such as mountains, forests, buildings, etc.) between the receiver and the source. The small-scale fading channel model is caused by the multipath effect and doppler effect. If there are a large number of reflected paths but no LOS (direct signal) signal component, the small-scale fading is called Rayleigh fading, and the envelope of the received signal is described statistically by the Rayleigh probability density function. If LOS is present, the envelope is subject to Rician distribution. Multipath effect phenomena cause flat fading and frequency selective fading.

The Picture of 3G 4G LTE/5G Antenna

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