【 Weak current College 】 buy AV amplifier will see a few parameters

At present, has become a popular element in HD, HDTV, HD movies, HD camera, HD camera, HD, DV, etc has been unknowingly into our daily lives. Power amplifier, as an important part of home theater, and of course also have to upgrade to the HD. If this is the line, then the product on the market at present is mainly divided into two levels, one is to support high-definition of the next generation of power amplifier, one is a DVD times normal power amplifier. Of course, such a classification is not a very scientific and complete, because a wide variety of power amplifier, and the non-class are only suitable for AV amplifier. Up in accordance with the purposes, we can generally be divided into three main categories: professional power amplifier, civilian power amplifier, a special amplifier. Professional amplifier is typically used for meetings, the performance of the PA Office. While the civil power amplifier breakdown and HI-FI amplifier, AV amplifier, KALAOK amplifier and a variety of common feature set in one of the so-called integrated amplifier. HI-FI amplifier and "split" (the former level amplifier independent out), and "merge" (to the fore and back machine into one).
Light is the face of so much power amplifier category, even the enthusiasts are headache, let alone ordinary consumers. And each watershed product has ten well-known brand manufacturers of dozens of hundreds of products, the unknown becomes even more numerous, are facing so many cohabitation as a product, if you do not understand, want to buy or do not know how to start. What's more, to understand their parameters, properties, targets, and so on, it's really difficult, because each product has its own standards, and each manufacturer has its own standards. As with output power of this parameter, the Japanese Department of the power amplifier are generally around 100-200W, but more of Europe and is around 60-100W, 150W is the Japanese power amplifier is definitely better than 80W of Europe and the United States Department of the amplifier output to? maybe on the surface, but this in reality is not necessarily, because Japanese PA more exist xubiao, light parameters. So how should I select? mainly look at those indicators? how? Let's take home cinema in the most common AV amplifier, for example to give hope to start, by analogy to members.
AV amplifier, as its name suggests A (audio), audio, Hi-Fi, V (video), audio, images, AV amplifier is a collection of audio and video of two signal processing, mainly for audio amplifier and image source compatible, produces audiovisual effects, combining to create a sound field as the primary design goal, specialized for home theater use. Through its internal delay, reverb processing circuit to control playback when the delay between channels, by adjusting the length of the delay time to simulate various listening environments of sound field. High-fidelity Hi-Fi amplifier specifications have output power, THD, Snr, frequency range, rated impedance and damping coefficients, etc, in particular harmonic distortion and signal to noise ratio, etc; and AV amplifier while also have these specifications, but also highlighted channel isolation, the delay time range, various sound field pattern (DSP systems, home THX system, Dolby AC-3 system) and other parameters.
1) decoding format
Home theater system's core is a surround sound system. With surround sound system, you can reach the cinema in the family. Surround sound system is a multichannel playback system, there are many kinds of format, different formats have different characteristics and current amplifier of number of channels increasing, not only 5.1, 6.1, 7.1, 8.2, etc. We all know, 5.1 channel generally refers to DolbyDigital5.1 and DTS5.1 two digital multichannel surround sound audio format. While 6.1 channel generally refers to DolbyDigitalEX and DTSES two digital multichannel surround sound audio format. This is in 5.1 basis, in order for the left and right surround sound better connection between the increase in the Middle after all, it will surround a 6.1 channel format.
As regards 7.1 channel means THXSurroundEX system, Dolby company also owns DolbyProLogicIIx technology, which can pass complex matrix calculation to 2-channel audio into 7.1 channel restored. THX is Lucas companies on the cinema a certification standard, not the audio format. When 6.1 channel of the DTSES after DolbyDigitalEX and, THX to further evolution into THXSurroundEX system. For compatibility with the original two-way voice and again strengthened side-channel surround sound sense, surrounded by original side-channel on the basis of the two rear channels, this constitutes 7.1 channel. Finally, 8.2 channel currently used products, it is for the purpose of enhancing surround sound field effect in DolbyDigitalEX and DTSES 6.1 channel, on the basis of increased YAMAHA exclusive front surround (speaker box placed in the main channel after above), then adding a subwoofer output, after the middle of surround sound from single expansion into two road (similar with 7.1 channel).
These are the times of various DVD surround decoding format system, it is clear, select the number of channels, the more out of wrapping the more coherent sense of the siege. The next generation of HD today, modern power amplifier will have new features and requirements. With Blu-ray and the listing, a new generation of HD-DVD multi-channel surround sound formats are also out, including DolbyDigitalplus, DolbyTrueHD and DTSHD.
DolbyDigitalPlus (DD +) is the starting point in 7.1 channel, sampling rate from the original 96-640kbps DolbyDigital extended to 32kbps-6Mbps and facing the greatest 13.1 channel digital surround. And MLP Lossless technology based DolbyTrueHD, contains a higher bitrate, additional channels, enhanced stereo mixing support and extensive metadata functions (such as dynamic range controlAnd on Standardization). As for the same DTSHD 7.1 channel as a starting point, the support of more than $ 1.5Mbps ratios, sampling of high frequency from 8-192kHz (16/24bit), now a normal DVD discs by 768kbps etc. compression technology, the sound quality will DTSHD increased significantly. DTSHD data traffic can be according to the requirements of sound quality and flexible conversion, exclusive of lossless compression techniques, DTS compression ratio smaller details, providing higher quality sound records, maximum 32-channel surround output.
Finally, we often say that analog sound field, whether it is advocated in the YAMAHA DSP simulates sound field, or a SONY exclusive DigitalCinemaSound are simulation cinema and concert hall space characteristics of surround sound processing. If you want to sensory approach to compare different, most people think that SONY DCs focused sound sense, while surrounded by YAMAHA focused sense of open space, both of which can be said to be their own strength.
(2) power matching
AV amplifier's focus is with Visual effects to create the ideal listening environments to create realistic sense of orientation, Telepresence and awesome. Therefore, AV amplifier design focus more care in the performance with clarity and audiovisual environment of large dynamic "bursting" effect, restore or analog out art-in-one of the sound field positioning to create various acoustic atmosphere. In this way, not only requires AV amplifier frequency range as wide, distortion is small, the signal to noise ratio is high, the transient characteristics of a good, sound, tone, sweetly and pay more attention to the sound pressure level: that is, low distortion, ensure sufficient output power.
Amplifier output power units of Watts (W), because the manufacturers of measuring methods, so there are some names different name. For example the rated output power, Max output power, output power music, peak output power music, etc. High-grade AV amplifier front main channel of the rated power is generally more than 80W to meet cinema 107dB sound pressure level requirement. However, some import AV amplifier, 5-7-channel, per-channel chief Mark 100 W, W total power of thousands, but power transformer is so great, I really don't know what's the power of standard worked out, the most notable Japanese AV, total to 6 euro to bluffing, really worked out by 8 European have totally 100W (each channel is good). Used AV amplifier knows, large dynamic often seem soft feet. It is recommended to buy AV amplifier, the best selection of mid-range above, otherwise rendered chicken.
In General, the amplifier's power is better. But the amplifier's main role is to promote the speaker, so it must be determined by the power amplifier and speakers. But the amplifier and speaker configuration aspects involved, such as amplifier brand, power tube type choice and loudspeakers low sensitivity should configure what kind of power amplifier, it is difficult to find a unified standard. But it is worth noting that the universal enthusiasts are of the view that the amplifier's speakers selected must be decided, should not have "power reserve" concept to configure power amplifier. Amplifier and speaker power configuration of specific standards should be: under certain conditions, the impedance of the amplifier power should be greater than speaker power, but not too big. In General applies the place amplifiers not distortion rate should be the speakers rated power of 1.2-1.5 times; in large dynamic applications you should be 1.5-2 times.
(3) interface
Traditional home theater on the signal transmission through the optical fibre would not, coaxial and RCA analog interfaces, such as previous DTS, Dolby offers a variety of encodings with fiber and coax connector to transmit digital compression and coding to AV amplifier decoding. As of the latest generation digital interface that HDMI has been widely used in a variety of digital products, along with HDMI interface begins in the use of audio-visual products and technology matures, more and more power amplifier have started using it theoretically is no loss in transmission mode. But HDMI itself after three versions of HDMI earliest interface specification HDMI1.0 in December 2002, the current highest version was released in June of this year's HDMI1.3 specification. Greater attention should be clear, their differences and application. For example, DolbyDIGITALplus, DolbyTrueHD DTSHD these technologies as well as to transfer by HDMI1.3 interface, so we buy time to note that only with this interface amplifier to enjoy the next generation of music. HDMI audio signals do not consume extra channels, instead of using and other auxiliary information together to form a packet, the use of the 3 TMDS channel in video signal transmission of blanking period to island data transfers. You can provide the highest 8-channel, per-channel sampling frequency 192kHz of high-quality audio signals, by contrast, CD audio system with two-channel signal 44.1kHz, as well as the latest DVD-Audio audio format 96kHz 6-channel signal is inferior to many.
(4) channel separation
Isolation degree refers to AV amplifier in surround sound decoder to audio encoded signal is restored to the capacity of each channel signals, but also represents the amplifier the signal between each channel of the degree of "isolation". Numerical decibels (dB), the larger the dB value their isolation between the greater degree, amplifier each restore out mono sound between mutual "crosstalk" small, sound better. Select AV amplifier, the greater the difference, the better, generally more than 60dB. Separation of poor power amplifier appears sound and image positioning no sound field not full, poor sound like coherence. The higher channel separation to ensure accurate positioning of the premise sounds phase. High isolation degree can make sound field expanded, resulting in a broader sense of space and makes it more precise and accurate sound positioning, high-channel separation makes music appreciation of musical instruments, voice positioning, game sound positioning and film wrapping, etc are to be strengthened. In short, the higher the degree of separation so that you can get some more ambitious sound field effect and more accurate positioning of sound.
(5) signal to noise ratioBR>
Signal to noise ratio (SignalNoiseRatio) hereinafter referred to as CyberLink noise ratio or Snr, unit is the dB, the amplifier output useful signal and useless noise ratio. Current amplifier SNR targets is fully able to cope with the normal music program, so we should be concerned about the background signal to noise ratio, you can try it out on the amplifier's volume to the maximum, to hear the noise of size, of course, is as small as possible. One amplifier such as have high appear noise ratio means that background calm, because of the noise level is low, a lot of noise exposure to weak tone details will appear, to increase air interested tone, dynamic range increase. Measuring amplifier before the noise ratio is good or bad there is no strict identification data, generally more than approximately 85dB, below this value it is possible in some large volume to hear cases heard in music clearance obvious noise.
(6) delay time range
Those who set up a home theater that you will be aware, when surround sound box put in place, the General need for AV amplifier surround delay adjustment so that the front and rear speaker sound seamless, perfectly, the satisfactory overall effect. This delay time range is adjustable speakers "delay" allows processor automatically compensate the room size. If the rear speakers than the front speakers is closer to the seats, not add short sound delay, before the front speakers to hear the sound of the rear speakers, so you want to set a delay, then you need to measure each speaker to the distance of the seat, and apply these values in the input amplifier or receiver of the "delay" in the settings section. Now most of the receiver and power amplifier provides meters or feet two choices to get accurate speaker delay calibration. However, some old equipment you will need your input in milliseconds delay value. To calculate these delays, you can use the following calculation methods: first, the measurement of the left front speaker to the distance of the seat. Then, the left rear speaker measurement to the distance of the seat. You will get two numbers. These two figures each within 30 cm, increase 1 millisecond latency. For example, 300 cm front speakers, rear speakers to 150 cm, that is, a difference of 150 cm, the delay is 5 Ms.
(7) frequency response
Frequency response indicates that the amplifier in the different frequency signal processing, to zoom in on each different frequency signal on a lot of consistency and agility, also called "frequency range." Its range is wide, the better "take care" more frequency components of a signal, the more good performance, it is of practical value. In General, one can hear the audio signal is about 20Hz ~ 20kHz between frequency and waveform, a different range of signals amplifier to properly complete audio signal amplification, the power amplifier frequency response at least achieve 20Hz ~ 20KHz. But the real musical sounds in a harmonic (overtone) is likely to exceed this range, in order to improve the performance of the transient response, and so on amplifier requires higher-frequency range, there should be an excellent power amplifier usually do 10Hz ~ 100kHz range. But the high-frequency amplifier, imports may start from 0Hz (DC), because the amplifier at full rated power is very rare, if amplifier works fine, frequency response to be very good, almost a straight line, often far beyond the audible tone range (20-20KHz).