【 Weak current College 】 what is BBE is the sound quality of the King? (2)---Power By 【 China power house network 】

Use MP processing technology extended MP3 MP3 file contains the frequency range to acceptable quality copy sound required minimum signal, only 1/20 of acoustic information, the remaining signal is lost. Compressed file size of another strategy is to reduce the frequency range. Obviously, the MP3 music CD of high frequency signal ratio. 　　The digital compression of audio signals (including WMA) all have this problem. 　　Frequency response: MP3 MP3 frequency response to Sudden Cut-off at relatively low frequencies (cut-off frequency varies): frequency relatively low at the time of the sudden closing (closing rate is not fixed, unchanging) BBE MP treatment could restore the harmonic band; and, as shown in the following figure, with 48 KHz and 96 KHz sampling frequency of too technical, it also can be high-frequency bandwidth up to 24 KHz or 48 KHz. MP3 frequency expansion process: used by MP MP processing technology extended MP3 frequency
Generated harmonics by MP process: MP technology produces harmonics
High frequency expanded by MP process: MP technology extended high-frequency band after
The following figure shows the Diana · Clar singing "I remember you" part of the spectrum, where you can see the BBE MP processing technology. The first picture indicates that 16 KHz frequency in the following test audio, 32 kHz sampling frequency down original CD you can clear the high frequency components. If the second picture shows, you can use BBE MP processing technology to reproduce frequencies restricted test audio 16KHz more harmonic (each beat the beginning of the effect is obvious). The second picture of the central part is 6 KHz band generated KHz-8 harmonic, harmonic frequency number 16KHz, subordination.
Diana · Clar singing "I remember you"
32 KHz sampling frequency down to 48 KHz frequency resampling, 128KMP3
Diana · Clar singing "I remember you"
32 KHz to 48 KHz sampling frequency processing technology with BBE MP, 128KMP3
Diana · Clar singing "I remember you" CD
32 KHz to 48 KHz sampling frequency resampling, 128KMP3
Diana · Clar singing "I remember you"
32 KHz to 48 KHz sampling frequency, BBE MP technical processing, 128KMP3
Diana · Clar singing "I remember you"
48 KHz frequency resampling, soundtrack CD
And the picture corresponding to the following three pictures represent the same point in time frequency analysis. The first picture represents the frequency of up to 22 kHz frequency response to acoustic CD, a second picture represents the audio frequency are 16KHz following, frequency limitations of test material.
Diana · Clar singing "I remember you" soundtrack CD
48 KHz sampling frequency point
Diana · Clar singing "I remember you" CD
32 KHz to 48 KHz sampling frequency resampling can be seen from the following diagram BE MP processing results: MP processing regeneration frequency in 16 KHz and above all signals, resulting in high frequency extension to 24 KHz (this frequency and even raise in the acoustic CD 22 KHz frequency cap). From the diagram also shows that the frequency response of the soundtrack CD is copied exactly.
Diana · Clar singing "I remember you"
32 KHz to 48 KHz sampling frequency BBE MP technology processing effects, this kind of technology and similar MP3 PRO decoding technology. The difference is: MP3 PRO decoder only encoded audio, MP processing technology to MP3 and MP3 PRO Audio. In addition, MP technology also applies to all types of digital audio formats such as WMA and AAC.
As noted above, BBE technology is United States BBESound company launched in 1985 to significantly improve the sound quality of a sound-enhanced processing technology. 　　This technology in Europe, the United States and Japan have already successfully applied to the radio and television, sound recording industry, professional audio engineering and household, car audio, and other fields, and is widely recognized. 　　That's why this technology will gradually enter into the field to MP3?, there is only one reason: the fierce market competition. You can see a characteristic is, now use BBE sound effects are all SigmaTel chip MP3 solutions.
　　
Why use Philips chip products does not use BBE? Giants not better?
　　
The reason is: integrated DSP/DAC, Philips Philips > > Telchips Sigmatel and don't care about, since he is already a sound first programme, why can't they get a set of audio technology. This is not like some of the domestic manufacturers of various broadcasters, as a veteran audio manufacturer, manufacture chip itself, if you want to make this kind of thing, the choice is Philips.
　　
Philips in MP3 on hand, the combined application of Philips chip best IRIVER, Xtreme3D sound technology has been developed.COWON can rely on our own precision of style to counteract SigmaTel chip, but SigmaTel did not develop your own sound technology, COWON what reversal to such disadvantages, the answer is simple: BBE sound! before CW100, COWON CW200, work is already a very CW300 do feature works, but the effect is really good, when Korea largest brand MPIO, IAUDIO, IRIVER tripod, two are Philips. Only the COWON is to SigmaTel a path through. However the majority of users, top like still aircraft huashanzhi, IRIVER has come up with new sound effects. In this case, the IAudio finally took out BBE unlocks the secrets--! BBE Sonic Maximizer plug-in software effects are meant to sound signal for various effects processing programs, such as reverb, chorus, distortion, chrome, etc. Current music production software available soft effects plug-ins, there are two types, one for DirectX plug-ins, to almost all the audio processing software is called, but the live performance is not satisfactory; VST plug-in, only a few audio processing software can be used, but the excellent performance of the former. All software effects plug-in for VST plug-ins in the majority.

BBE Sound company not only provides the technology and hardware products to professional musicians, they also developed a reputable BBE Sonic Maximizer signal processor new plug-in for VST and Direct X, users do not need to directly capture a digital signal, you can directly use the BBE Sonic Maximizer plug-in. It uses the BBE's fourth-generation processors, and BBE
Hardware product in use of 482 and Sonic Maximizer processor same 882. This can be used for a variety of compatible Direct X and VST plug-ins for PC and Mac audio software. Whether it is a multi-track audio recording or sampling (or even mix), BBE Sonic Maximizer can do. BBE Sonic Maximizer plug-in can be used for a variety of host software did better compatibility, compared with
Name the enthusiasts there are some commonly used: Steinberg Cubase, VST and SL
Type: integrated music production platform Steinberg Cubase VST is a famous music production software, and domestic music widely adopted digital music platform Cakewalk compared to Cubase VST series of function appear. While Cubase VST is not on the use of Cakewalk so convenient, but because of the high-performance multitrack audio processing, real-time effects inserts, and numerous third-party software developers to provide compatibility with the standard soft VSTi audio sources, these are as many foreign music producer of second choice. In addition to ASIO, Steinberg also proposed raising the VSTi soft sound source performance standards and enable software audio effects to real-time VST plug-in specification work. 　　Because of these technical details are made public, so third-party software developers to Cubase VST platform provides a steady stream of new colors and new features. Bias Peak
Type: music production BIAS Peak-the world's top MAC music editing, processing, and mastering software. 　　From film, video or multimedia music production, to the broadcast of music making and music of rapid production release. Sonic Foundry Sound Forge, Acid, Sound Forge XP and CD Architect
Type: digital music production output is Sonic Foundry Sound Forge company developed an extremely powerful professional digital audio processing software. 　　It can be very easy and intuitive for audio files (wav files) as well as the video file (avi file) voice parts various processing to meet the most regular users to the most professional recording of all user's requirements, has been a multimedia developers preferred audio processing software. Acid is a set of background music production software, is to repeat play-based music production tools. It features unlimited cycling track (depending on system memory size), automatic control repeating the beat and rhythm sound tecnologies, real-time control, support 16-bit and 24-bit format of music, but also supports DirectX bolted and time music effect and cannot duplicate music and so on. Music can be in WAV or digital audio formats directly output, new versions or even directly including libraries and supports MP3, WMA, RealMedia G2 format output. 　　Acid also compatible CD Architect and direct-to-digital music format, which can be used as audio editing, producing and burning tool. Syntrillium Cool Edit Pro
Type: digital music editor and MP3 creation software this is probably the most music lovers love to use a software, website-related tutorials and more. Many people put Cool Edit described as audio "painting" program. You can use sound to "redraw" system: part of the pitch, songs, sounds, strings, vibrato, noise or adjust silence. But it also provides a variety of special effects to spice up your work: enlarge, reduce noise, compression, extension, ECHO, distortion, delay, etc. You can work on multiple files, easily in several files to cut, paste, merge, overlap sound operations. Use it to generate sound has: Noise, bass, mute, phone signal, etc. The software also includes a CD player. 　　Other features include: support for the optional plug-ins, crash recovery; support for multiple files; automatic silence detection and deletion; automatic beat find; recording, etc. Cakewalk SONAR
Type: powerful MIDI and digital music tools software Cakewalk family, is one of the most familiar of the sequencer software, hardware sequencer on the verge of elimination of edge largely because of its appearance. He is the MIDI music production in one easy software. Starting from version 4.0, Cakewalk joined the audio processing features, making it a simple sequencer software towards a professional MIDI and audio workstation. Oh, the family first is BBE effects tools! 1, Cakewalk BBE_Sonic_Maximizer woofer sound mixer
2, CakeWalk Groove Maker Super audio production masters
3, Cakewalk Guitar Studio v2.0 guitar music Studio
4, CAKEWALK Home Studio 2002 Home Music Studio
5, Cakewalk Home Studio XL Super Home Music Studio
6, CAKEWALK MUSIC CREATOR 2002 music production masters
7, CAKEWALK OVERTUNE sound editing master
8, CakeWalk Plasma 2003 music editing master
9, Cakewalk Pyro mp3 MP3 edit master
10, Cakewalk SONAR1.3 sound localization editor
11, CakeWalk sonar2 Super sound localization editor
12, CAKEWALK.MUSIC.CREATOR.2003 Super music production masters
13, Cakewalk_Sonar_XL_v2.0 linear sound localization editor
14, CakewalkSONAR virtual piano piano edit master
15, Crakewalk Pro 9.03 Advanced MIDI Editor
16, FruityLoops loopback music editing master
Oh, this can be very expensive, not just the beginning. 　　Moreover, the BBE Sonic Maximizer will also enable and MOTU and Logic Audio compatible so that mainstream music production software is basically covers. MP3 and BBE hardware at present, the United States, Japan has a number of companies has launched the second generation of BBE chip. In our common chip with EXAR Corporation of United States and Japan XR1071 XR1075, Roma (ROHM) company BA3884S, Japan JRC company M2178, etc. At present, China's market to see AV amplifier and color TV, many products for cost reasons, the first generation of chips, such as M2150D BBE. Second-generation BBE chips than the first generation to superior, sound better. The first generation of products is to use a switch to force control is parsed, although you can obviously increase the music signal analysis and definition, but because the compensation is too rough and the music signal is easy to produce balance disorders, and less than ideal. 　　Second generation products in technical performance indicators has been greatly improved and increased resolution force control and low-profile regulates potentiometer, according to the specific use to adjust the appropriate compensation increases, therefore, the second generation chips than the first generation in audio signal processing, can make the sound more true to nature, a better balance. 　　Some people might think I'm here is to get a bunch of useless things, because it seems this and far away from the more MP3 because MP3 so far are resolved using the software, hardware, what's the use? but I'd like to list the hardware, because the development trend, which could be built into the MP3. 　　How to develop BBE? or mystery. One possible, update technology and algorithms, so, BBE, completed its historical mission, but in the history of digital music, we cannot forget that once existed a historical stage. To some extent, it can be said, and from apes to people that stood on the historic process can do. Because people are not simply consider the characteristics of the timbre and sound quality, but the pursuit of perfection purity, restore natural sound. At the same time, the pursuit and not depend on how many number of surround speakers to complete restore of the sound field, and is used to BBE as representative of advanced digital technology, will already be covered range features back to restore it. 　　To replace the BBE's new technology will inevitably be thinking along the continues to fundamentally change our present some of the flaws inherent BBE, to join the number sign, in a wider range of players to be more accurate to restore, and oh so brought more music. Another possibility, BBE technology as a standard for the introduction of a wide range of MP3. Methods are 2 types of manufacturers a lot into the BBE authorized, but in a short time, this seemed to still have some difficulties, because the BBE itself can also have so much energy to invest in a large number of manufacturers of so many design, European and American manufacturers have not had access to a list of BBE website. In fact this is easily one of the things that the front BBE hardware chip, we can see, the miniaturization has been making great strides in the development, in the foreseeable future, is likely to BBE authorized chip direct implantation of the circuit to MP3, MP3 software simulation is very good, but now there is no specialized BBEMP3 solutions, hardware BBE solution should be able to obtain better results. MethodBis, Philips chip still occupies a high-end, other chipset design is it possible to direct and BBE sound, directly in MP3 chip are placed in the BBE part of line, so that on the one hand, these manufacturers DPU will direct access to sound upgrade, on the other hand on BBE Sound can eliminate a large number of identification and design time, you can directly check the DPU. As a normal user, the above conjecture is a fanciful-imagine that these issues should belong to the DPU manufacturers, manufacturers of MP3 and BBE company. As an ordinary user, we are concerned with only one thing, it's more of the music, and oh so much more realistic sound effects. 　　I think this is BBE Sound development of the original purpose of this technical-technological progress is to give people a better life, not just to prove that technology. So let us put on headphones, to experience the BBE brings us the wonderful music.

【 Weak current College 】 video conference system consists of what constitutes---Power By 【 China power house network 】

Video conference system includes server-side software, client software, B/s components, Manager software. As the name implies, the video conference system including Terminal Server, the client terminal, network, video input and output devices. While users in the use of time according to demand, in the Terminal Server, the client terminal, network, video input and output devices provide further detailed requirements. Video conferencing Terminal what types

Major video conferencing Terminal: desktop and room type.

Desktop Terminal

Desktop Terminal is a powerful desktop or laptop computer and high-quality camera (built-in or external), Internet and video conferencing software's ingenious combination. It can effectively make the person at the desk or are travelling people to join your meeting, and you're face-to-face communication.
　　
Main application:
Desktop video conferencing Terminal usually assigned to the Office of special personal or business trip, the majority of people work for department heads and the leadership Conference on or between points in charge with the charge of meetings between headquarters or remote tutor, etc.

Room-type terminal almost any video meeting the required solution, integrated in a conference room in General. Room-type Terminal usually combine a large number of attachments, such as audio system, additional cameras to document the projector, and PC communication collaborative file. Dualview, rich communication interface, select the text flow allows terminal into upscale and integrated products.
Main application:
Conference-video conferencing for large group corporate or remote education. For example, an enterprise, factory production base, sales base, a business base, if you want to make the meeting, it is not possible to tens of thousands of employees are equipped with computers and network, this way is wasted costs, but also to good effect. To do this can be used to erect a large meeting room, Conference Hall, equipped with a microphone, audio, power amplifier, etc. will be able to meet this demand. This kind of plan for cost-effective video conferencing scenarios.

【 Weak current College 】 professional power amplifier and household power amplifier differences---Power By 【 China power house network 】

Professional amplifier and differences in household power amplifier
I believe a lot of sound fans have seen professional power amplifier and household power amplifier for electricity principle diagram. If only from the electrical schematics, it appears that the professional power amplifier and household power amplifier is no significant difference. Or from the use of perspective, both are used to drive speaker playback, it seems to be the same. From a performance perspective, the diligent and professional power amplifier of basic performance indicators are also similar. In fact, the amplifier and household power amplifier have many differences. Professional power amplifiers are long, continuous work in high power mode, so the professional power amplifier requires power margin, high reliability, output level temperature rise of smaller, better stability of the circuit. To meet such a request, the amplifier in the design, materials, wicked, etc. are different from home amplifier special consideration. For example, professional power amplifier power circuit capacity is often based on the actual consumption of the amplifier, plus enough rich content, and therefore better than the same nominal power of the capacity of the domestic power amplifier. Professional amplifier of high power devices are often choose maximum current and voltage is higher than the rated value of specifications, the output stage of the radiator also adopts large exposed radiator in order to facilitate heat dissipation and guarantee the inequality of temperature rise time at work is relatively low. If we look at rated output power is 2 100W× professional power amplifier and household power amplifier, you can find professional power amplifier of the radiator. This is because although household power amplifier with a nominal rated output power 100W, but actual use often only work in smaller output power of the State (General average power about 10W or so). Only some of the hottest music of sudden peak signal is possible in a short time to reach dozens watt output power. Thus household power amplifier output stage of the actual workload. The rated output power to the amplifier 100W, often in actual use often meet near the "full power" status, actual work load heavier, so the output level of a fever, need a larger radiator for good heat dissipation. From the amplifier design requirements, household amplifier often relatively quiet family environments, typically used for music and media playback. Home of HI-FI amplifier also to a truly provides the music of "original sound", the requirements to the hottest musical level and details. Thus household power amplifier on sound fidelity requirements are higher, and requires the sound softer, meticulous, pleasing to the ear. Professional power amplifiers are often used for big occasions of sound reinforcement, for driving professional speaker playback, and therefore require their driving ability, output power and sound bright and clear, and adequate. Therefore the sound characteristics of both a degree of difference. However, there is some very senior professional power amplifier is also a focus on broadcasting sound fidelity, to tie in more senior professional speaker, broadcasting out of sound is more clear, detailed, and also a better sense of depth. From the feature set, the professional power amplifier are often combined with a mixer, fore device, so much as plain after the class amplifier. Professional amplifier setting is very simple, often Panel only power switch and output level adjustment potentiometer (or step attenuator). But because the amplifier's real needs, often can work in two-channel status, or "bridge," a mono amplifier, so professional power zoom multiple settings "bridging" switch. Home power has many models are equipped with the front-stage amplifier "merge" amplifier, the merge type amplifiers feature more often with audio source selection, monotonous control, multiple audio input interface, etc. The status of work from the amplifier, professional power amplifier efficiency focused amplifier, so mostly AB class amplifier. Home power amplifier is the AB class amplifier, or "high" partial class AB amplifier, use A class amplifier, also with dynamic biasing A kind of "super" amplifier. From the output power, the amplifier output often larger, single output power greater than can be up to 1000W. Home power amplifier's rated output power is mostly 200W.

【 Weak current College 】 what is power amplifier line amplifier for main performance indicators---Power By 【 China power house network 】

Amplifier commonly known as "amplifiers" his role was to come from the sources or the front-stage amplifier of weak signal amplification, the promotion of sound-sound. A good sound system power amplifier's role. Power amplifier is the sound system in the most basic of equipment, its task is to come from the signal source (professional audio systems from mixer) to zoom in for weak signal to drive the speakers sound. In accordance with the use of different components, power amplifier and "danji" [tube amplifier], "Stoner" [transistor amplifier], the "IC amplifier" [IC amplifier]. In recent years because of new technologies, new concepts in danji, makes this old vacuum tube devices also in Germany, it's beautiful voice, many shaoyou admirers. Experienced enthusiasts almost all have a terrace. "IC amplifier" because his tone is not comparable with the two amplifier so HI-FI amplifier rarely saw his shadow. Amplifier generally can be divided into three main categories of "amplifier" and "civil power amplifier," "special amplifier". "Amplifier" is typically used for conferences, concerts, theatre, Church, farm, Museum of the loudspeaker. Designed to output power, protection circuit, good heat dissipation. Most "amplifier" sound replay for HI-FI, sound, dry and hard not resistant to listen. "Civil power amplifier breakdown" and "HI-FI amplifier" "AV amplifier," "KALAOK amplifier" and the various common feature set in one of the so-called "integrated amplifier". "HI-FI amplifier" is our enthusiasts amplifier, its output power General most 2X150 Watts the following. Designed to "tone is exquisite, high-fidelity". Various high-tech embodied in this amplifier. The price is $ from thousands to tens, etc. "HI-FI amplifier" and "split" [the former level amplifier independent], and "merge" [to the fore and back machine into one]. Generally speaking, in the same grade of models "split" in signal to noise ratio, reliability indicators such as channel segmentation than "merge machines" [absolute]. And easy-to-signal wire code. Merge-machine is easy to use, the advantages of a relative low cost, cheap combined machine output power most of the design in General and 2X100W following, many manufacturers to produce more than high-end merge 2X100W. "AV" amplifier is running out of a horse, with large screen TV, and a variety of image carriers universal, "sitting at home watching the film" demand growing, so set a variety of audio and video features in one multifunction amplifier came into being. "AV" is English, audio, video AODIOVIDIO's begin with a letter abbreviation. "AV amplifier," from birth until now, has undergone a Dolby Surround, Dolby, directional logic, DTS AC-3, AV amplifier and the difference between ordinary power amplifier is AV amplifier with AV select Dolby directional logic decoder, DTS decoder, AC-3, and five-channel power amplifier. And the finishing touch of digital sound field [DSP] circuit, for a variety of programs play a different sound field effect. However, due to AV amplifier in the circuit of signal circulation, after a long and complex processing circuit, the purity of the sound was "excessive" dyeing ", so use AV amplifier compatible with HI-FI replay is not ideal. This is a lot of HI-FI enthusiasts on AV amplifier unlikely a Gu. "KALAOK amplifier" is also grown in recent years, a power amplifier. Its general power amplifier differ "KALAOK amplifier" reverberator BBD simulation from the past to the present reverb DIGETAL digital reverb], diminutive device, microphone amplifier. In recent years a number of manufacturers to market demand, including AV amplifier, KALAOK amplifier, various functions into one that is, the so-called "integrated amplifier", this is a hybrid amplifier, nothing, nothing to do, is a rural resist power amplifier. "Special amplifier" as the name implies, is used in the special occasion of power amplifiers, e.g. alarm, auto-voltage power amplifier, and so on, are no longer in this introduction. Power amplifier for main performance indicators: power amplifier main performance indicators have output power, frequency response, distortion, Snr, output impedance, damping coefficients, etc. Output power: units of 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 of music. Music power: mean output distortion does not exceed the specified value, the power amplifier on the music signal instant maximum output power. Peak power: refers to the condition without distortion, amplifier's volume to the maximum, the amplifier's output for maximum music power. Rated output power: when harmonic distortion for 10% of the average output power. Also called maximum useful power. Generally, peak power is greater than the power of music, the music more than rated power, generally speaking peak power is the rated power of 58 times. Frequency response: indicates that the power amplifier frequency range, and frequency range not uniformity. Frequency response curve of flat or not usually expressed in decibels [db]. Home HI-FI amplifier frequency response usually 20HZ20KHZ and negative 1db. this range is wide, the better. Some of the best amplifier frequency response already done 0100KHZ. Distortion: the ideal amplifier should be put after the input signal amplification, no change of faithfully restored. However, for various reasons the power amplifier is enlarged by signal is compared with the input signal, often have a different degree of distortion, this distortion is distorted. Use a percentage, its value as small as possible. HI-FI amplifier distortion at 0 of the total. 03% 0. 05%. Amplifier distortion with harmonic distortion, intermodulation distortion, crossover distortion, clipping distortion, transient distortion, transient intermodulation distortion, etc. SNR: refers to the power amplifier output of various noise level and the ratio of the signal level, db, the higher the value, the better. General Home HI-FI amplifier of signal to noise ratio in more than 60db. Output impedance: pair of speakers the equivalent resistance, called output impedance.

【School】 teach you how weak current procurement KTV rooms of sound? .--- Power By China's weak home 【Network】..

<br> is to sing karaoke OK place, if the sound quality is not good, then how to sing it? .Do a guest not interested. .So, some places to spend big money to buy a professional sound to sing, but, Mike often whistle, spend money to buy cheap audio, effects and get out. .Therefore, the VOD system and sound system to the user adds a lot of trouble. .<BR> So, you want to buy a good sound KTV rooms must know the following points: <BR> 1, KTV factory system sources for what format? .The effect it will have an impact music. .If the source is the left and right channels VCD films, and original music in one channel, vocals in one channel. .OK karaoke accompaniment only, then the music will be worse, if you put original music, all the two-channel sound, the music will be better. .DVD film source is the left and right channels in the original singers, backing vocals sound all the time, only hours left and right channels in different layers, also known as audio tracks, so the music quality like some. .MPEG-4 is not readily available source of the film, it is coming from the DVD and VCD transit, so what new sources turn, will produce any different results. .Some manufacturers of the conversion process can not solve the problem of double track, you can only use the weld board, changing the way the circuit to resolve conflicts. .I am in the MPEG-4, the total is higher, better way to solve this problem, DVD, VCD of the film source, when generating MPEG-4, have all become a dual-track processing, and .So, whether or original music accompaniment is all double track. .<BR> 2, amplifier quality of the equipment itself is also a key, and some good amplifier, sound quality is good, and some are not, we should pay attention. .KTV use features with the size of your room, decoration materials combine to expert analysis of the sound field. .<BR> 3, combination of equipment problems: a good amp, good speakers, good Mike, good sources for good voice to come out good results, if a poor, how can the good results. .<BR> Again, they said, "till" sound good, you try, well, can you open the compartment in the equipment cabinet to see, people there are good things. .Therefore, audio devices, actuators on the whole with the market. .<BR> In the choice of audio equipment must be tailored, within our capabilities. .<BR>.

Weak current College】 【aided design and sound field design --- Power By】 【China power house network.

Aided design: halls of Architectural Acoustics requirements for the vast majority of professional audio works are carried out in the room, room of the senses, in addition to some important specifically designed for sound design of the building, most of the buildings in the layout and structure are not considered to acoustic requirements. However, audio works of architectural acoustics and very important, we can go to a rigorous scientific design of building experience again, its reasonable acoustic structure and good sound diffusion and dissemination of results, you get the beauty, the same sound amplifying devices run here, of course, will give full play to its exquisite sound quality; and an absence of acoustical design of sound engineering, regardless of whether it owns what luxury equipment, its acoustic effect is not very good. Visible, the Auditorium of the architectural acoustic design is a very important, but also very meaningful work, its role would be more effective. Although the general norms of audio engineering to make the necessary sound field design, but due to the constraints, relatively its effectiveness is not with the construction decoration of acoustic design compared with the earlier stage. Particularly in the implementation of the acoustic effects and processing, the architectural decoration engineering than sound engineering easier. Therefore, we emphasize here that the purpose of the acoustic requirements, is the hope in the overall design is timely, as soon as possible to and building design and construction units, they engage in acoustic effect design assistance, feasibility, generally includes both structural and decorative. First, the structure of the Auditorium of the overall structure of the first to avoid standing wave generation, this requires that the ratio of science halls. Among them in order to better achieve sound diffusion and light cast, halls and containers should be sufficient guarantee that the General requirements 4 meters; Secondly, the need to avoid the narrow curved walls, parallel effect of smooth structure of sound diffusion; Furthermore it is necessary to pay attention to the location of the control room, to facilitate site operation and observation, the attention of considering construction lay line, strictly avoid a very small space and field quarantined or control room. Second, the decorative aspects of architectural decoration,: consider artistic problems. but in the overall design of sound engineering, requires certain effects lighting effects of decorative scheme of the necessary limit. First requires the selection of decorative materials in strict accordance with the results of the acoustic calculations, at the same time to avoid using hollow or support unstable materials and structures; Secondly, to take into account the overall tone of the decoration to and the use of sound engineering, visually to bring the light of the shapes, patterns and colors. Sound design: a professional audio works of important work is the design of the sound field. For works of ultimate quality, sound field design is also a key point. The purpose of sound field design is that the calculation of the use of science, as do guidance sound equipment construction of an ideal sound reinforcement space, the device performance full of play. In a small number of strict construction decoration design generally to make the necessary sound field design, but for the specification in accordance with the procedure for professional audio engineering work, eliminate any irrational factors, or the need for comprehensive sound field design. 1. acoustic treatment: this is the sound field design is also the first step in many technology companies easily ignore steps. The purpose of sound insulation is in a specific area within the creation of a project are not subject to external influence or impact on the outside of the quiet sound field. It includes and the outside noise, sound amplification of noise between rooms, soundproof walls, are part of the Windows and doors and ceiling. External noise is not let outside noise incoming indoor or indoor voice to the outside. External noise through incoming indoor indoors total noise control, usually higher practical sound engineering requirements in the following 35-40dB; indoor voice to the outside world can look on the outside of the environmental impact, in accordance with the provisions of the environmental sector, generally not higher than the environment mean plus 10-15dB for good. 2. echoes and feedback: the echo generation because the reverberation time is too long to produce a noticeable lag in tone, ECHO can only improve by acoustic design; feedback is too strong for certain frequencies, microphone pickup after system to enlarge, and then pick and then zoom in this cycle, feedback through the feedback suppressor or frequency divider. Feedback suppressor upscale: SHUE DFR11EQ SONY SRP-FR300 SABINE FBX2220; low of BEHRINGER DSP1124P SPIRIT DSP8000, etc. Move the prescaler: domestic: l sound, Lake Hill, sky; imports: POLYFUSION (Pro).

【 Weak current College 】 how to create a good listening environments---Power By 【 China power house network 】

Apart from the moment of humanity is inseparable from the air, another time without (and want to leave it without) thing is probably the sound. ? We can close your eyes and see, but cannot close your ears and hearing. We live in this world, nor absolute silence, this illustrates the importance of the human voice. Because of this, the pursuit of a beautiful voice, the Elimination of harmful sound, people are always trying to achieve. Indoor acoustics phenomenon in everyone's life is at least 1/3 to 1/2 time is spent in the room, listening to music. Therefore an inevitable phenomenon of indoor acoustics of concern. As the mirror will reflect light, house walls, floor, ceiling will produce reflection about the sound, unfortunately Sonic and cannot be seen, this phenomenon is often neglected. In fact, the sound reflection phenomenon is very common and interesting (if Beijing tiantan echo wall). From housing in a sound that is transmitted in the form of waves, and from the numerous approaches to reach the listening position. The actual reflection phenomenon is very complex, and as housing shape and Interior objects of the senses, I believe that this is not difficult to imagine and understand. Due to the reflection of the existence of the phenomenon, in the listening position, we actually hear and not purely by the speaker sound is sound and sound directly to the various reflections superimposed. So, this kind of overlay effect after what? " Reverberation time "this concept is more popular and important, it refers to the sound, the sound continues gradual decrease in energy reflection time. Here the "mix" of the image because the application is in the Interior of a sound master is not a single, but from all directions to, chaos. Usually the reflections are collectively referred to as mixed noise (or subdivided into early reflections and the mixed sound). On the concept of the reverberation time, acoustics has its precise definition refers to sound sources stopsounding acoustic energy density after residual drops original values one millionth time elapsed time. It is worth pointing out that it can describe the audio clarity, chubbiness, generally speaking, the reverberation time is short the articulation, the reverberation time is the sound richness good long. The following then introduce another reflection on the phenomenon, which are called "normal room fire," "resonance," resonance "acoustic phenomenon. This refers to the room because of its geometric scale and for certain frequencies of sound waves to special offers, be strengthened (formation of standing waves), it is also a widespread phenomenon. For a typical family houses, this kind of resonance frequency of the pitch is about bass area in 100Hz. If the room can not be sound absorption we can start from the acoustic phenomenon to imagine, if there is no sound in the room, the room itself was not absorb sound, will be how a scene. Then the sound once issued is endlessly reflection on, and the sound will be mixed together. For example, in the room playing language broadcasting, the second pronunciation appeared the first pronunciation still ringing third pronunciation appeared for the first two simultaneous ringing sound is still ... Plus will inspire different frequency resonant sound, regardless of language or music we are completely unable to tell (apart from the first tone), let alone to enjoy it, you can only hear a noise! readers if you are interested, you can simulate this: find a complex organ (tremolo few better), in turn, screw-down its key don't let go and listen to listen music to noise. Of course these are just in an extreme case of imagination. In fact as the walls, the air, the human body can absorb sound energy, reflections always disappearing. However by imagining that allows us to further understand the importance of sound absorption in a room. Luckily we did not live in completely acoustic environment, otherwise it is unimaginable! Although thereal room can absorb some of the sound energy, but often very unsatisfactory. If we purchase a very good sound equipment, they issued a high-fidelity sound, because listening room acoustic characteristics, not the reverb and echo the voice of the original is severely distorted, that's what a pity!, therefore, a true high-fidelity playback of admirers, should also be room for reasonable sound absorption of admirers.
Sound-absorbing atmosphere method if there is a chance, it's best to visit anechoic rooms, recording studios and other professional acoustic environment, so you can explore our horizons. At least, it should be noted at the cinema or other acoustic design, draw point useful experiences. From the principle, if you want to replay the pursuit of a truly authentic, you should not affected by the interference of reflections, only listen to the sound. This requires a full acoustic environments, which are often difficult (anechoic room cost, use also inconvenience), it is usually a part of the room acoustic, retain some reflections and use. According to the author for some family listening environments, and most are not using the sound-absorbing design, although some families have used the expensive equipment and fever wire. Therefore, these family pursuit of small parts of the sound absorption is a fundamental choice, because it is from scratch, you can receive the stanchion see shadow effect that obviously low frequency ROAR, and make the sound becomes more clear and pleasing to the ear. Sound absorption for a small number have been adopted, the family may wish to recommend to the most balanced sound absorption and sound absorbing efforts, so that devices can be closer to the scene to produce high-fidelity sound. You can refer to books, the use of engineering calculation methods for sound design. General family room area is not large, the design of the times the reverberation time control in 0 6 seconds, the smaller the better, according to this calculationand select the appropriate sound-absorbing materials. As does not require very accurate, can be roughly estimated. The drawings are the author according to the formula, follow around small 15m2 listening room area calculated the reverberation time-average sound absorption system curve, is available for reference use. According to the author's experiences and feelings, that usually room sound-absorbing material always worry about it much, just worry its small, so in general you can also do not have to be calculated, below on this quantitative absorption treatment method. First look bad on the ground floor, makes strong reflections in low frequency, if you listen toSound room has a wooden floor coverings, it is desirable, it's a uniform sound absorption characteristics. If you are a hard surface, it should be covered with thick carpets. For the convenience of walking, carpet area can also be limited to the speaker and the listening position, the key is to have a thickness, you can use in their underlying cardboard, wood, fibreboard, etc. Ceiling and wall with different specifications of microperforated material to decorate. With a small amount of soft sound-absorbing material, or you can enable frequency characteristics even, but the need for housing decoration. It is not convenient to do so, may wish to use the room of the simpler approach: no ceiling, only four wall hanging sound absorbing materials, all kinds of soft materials such as cotton, linen, silk, wool or other fibres textiles are available, all kinds of foam on the surface it with attractive cloth decoration is also a good choice. For example, if the wall hanging 1mm thick wool quality (or other similar texture) curtain fabric, it can only absorb approximately 1/5 of the sound energy (in the medium and high frequency, low frequency worse), the rest of the reflex to go out, it will not be able to eliminate low-frequency vibrations. Solution: curtain fabric not matter against the wall, leaving around 10cmdistance (gap should be linked to other sound absorption in); curtain fabric at a discount or more layers of suspension; then with the use of low frequency sound absorption characteristics of a good large soft sofas, etc, you can achieve a certain effect. Here in passing that, in the sound absorption characteristics of listening room, is not that kind of hardwood sofa. Due to the absorption characteristics of various materials have different, so it is best able to selectively use, the goal is to high, medium and low frequency be symmetrical and balanced absorption. Schedule 1 lists several commonly used materials for sound absorption characteristics, for reference. Sometimes, it can also be combined with own equipment's characteristics and hobbies for the absorption of non-equilibrium, for example, some people prefer the bass, and the hard place of output power and is not large enough, or poor low frequency response of the sound, it may be appropriate to reduce the frequency of absorption. Although this is not a common sense of the Hi-Fi choice, but some of the equipment itself or you can use when defects. In addition, because of the nature of the high-frequency sound, listen and people behind the wall and the side wall rear on reflects high frequency in recent times reduced sound effects to larger, and for the Elimination of low frequency resonance, front and rear wall of the basic effect is the same, be dispensed with. Indoor sound absorption and reduce ambient noise-absorbing fabrics for interior layout of a fringe benefit is that the sound insulation of atrioventricular node gets some improvements, so that we can in a more favorable environment to enjoy the music. In the modern city, environmental noise has become a major nuisance, this has been known by most people. Please take a look at the Schedule 2, this is a request for environmental noise. As can be seen, in addition to recording rooms, listening to music room also requires very low noise level – this isa 30dB! what concept? you know, people normal conversation sound level at approximately 60dB. So the noise level, 30dB given is a very quiet environment, for example: in such an environment, you will be able to clearly hear the wall a quartz clock ticking sound of weak, even a spin down to the ground. Only in this quiet environment, will it be possible to drill down into the details of the music, can we truly listen to good music, especially those dynamic range very large symphonic music. Unfortunately, today the city inhabitants, most of all, there is no such place. Indoor noise level is usually more than 40dB, road residents more often affected by sound level noise in more than 60dB. Therefore, in order to listen to good music and to physical and mental health, care must be taken to reduce noise. As room with room to choose correctly, should not be selected on the side of the road in the Pro.
When we hear the sound of the sound-absorbing interior layout, it began to occur in a double function: not only can absorb Interior voice, also can absorb outdoor incoming voice and sound to the outdoor diffusion (although these effects on the poor). Since noise is from the Windows of the incoming, so there will be special attention, in addition to the use of heavy curtains to absorb noise, use a double window is a better way, glass thickness, distance between two layers of bigger, reduces noise up to 10 ~ 20dB. Building a sound absorption, sound is good, the room should be every family goal. Not only does it give ourselves to create a good environment, but also reduces disturbing adjacent, because even the best music that does not require it, are all noise!

College】 【weak to create "invisible" new wave audio and video player - into the wall Speaker Application Guide --- Power By China's weak home 【Network】.

<br> into the wall speakers, the name suggests is a can be installed inside the speaker in the wall. .The biggest feature is the speakers to save space, while well-concealed and does not affect the overall room design. .In the home theater systems, hidden speakers into the wall of the performance the audience's attention is more focused on the screen above, therefore, into the wall of speakers in Europe and America developed countries have been warmly welcomed. .Therefore, in this issue, we organized a special event planned speakers into the wall of the topic, and its characteristics, installation, and be aware of when buying a place were introduced one by one, to let potential readers of this audio-visual .New models have sufficient knowledge and understanding. .Describes the content of any deficiencies, but also hope forgive me and correct me. .Among the magazine in the future, we will introduce more into the wall of speakers on the practical application of case, hoping to play a guiding role of the consumer. .<BR> <BR> Status of the speaker into the wall <BR> <BR> In the past, most applications into the wall of speakers in the hotel, theater, public address system and other areas or situations, which are mainly used to play background music. .In general, these speakers into the wall in terms of the production process and performance indicators with the traditional home speakers there is a certain gap. .Therefore, the performance of the sound quality can not be compared with the traditional home to be the speaker. .However, most consumers years to continuously improve the quality of interior design and production of more and more professional loudspeaker manufacturers to use its own technology into the wall to join the ranks of the production of speakers, wall speaker is the sound quality of the production level and continue to .improved, so that they gradually become home market. .<BR> <BR> <BR> <BR> <BR> Sold into the market at present is generally divided into two kinds of wall mounted speakers. .The first is the in-wall speakers (In-WallSpeakef), this type of speaker can be installed in front, rear, left and right walls, and in the number of speaker units are also used more generally in the 2 .above, and thus volume also increases, the price is relatively expensive, is also present in the highest rates of home theater system, one of the products. .Like M & K, B & W, KEF, AtlanticTechnolony (Atlanta), SnellAcOLISitcS (rhyme), JMlabFocal (Jin Lang), Genelec (true power), Trlad other brands have similar products. .Another is the ceiling speakers (In-CeilingSpeaker), also known as the ceiling speaker. .The speaker and the former difference is that it is mainly installed in the ceiling, is very suitable for study, bedroom and other small area of space used as the background music playing. .In the speaker's appearance, we have a common ceiling baffle speakers are generally the first round, because of its relative use of the former speaker volume is less, in general, in two units or less, so much smaller, .prices are also cheaper than the former. .Speaker into the wall above the market price is usually calculated alone, consumers according to their actual need to purchase the number of speakers. .<BR> <BR> Advantage of the speaker into the wall where the <BR> <BR> Why are so many speaker manufacturers to launch their own horn it into the wall? The same time into the wall of speakers, compared with the traditional home-style speakers, built .Speaker of the advantages in the wrong? on this issue, and if so from the perspective of interior design, there will be the speaker into the wall cleverly installed in the wall speaker, the speaker not only to reduce the traditional use of the area occupied too much room, and .home audio and interior design can integrate with each other, so that the layout of the room is much more clean and comfortable and beautiful, this is one of its greatest strengths. .But if we have the technical analysis of the speaker into the wall, then we will find the speaker into the wall with solid walls can be easily solved by traditional home speakers need to address the noise problem. .<BR> <BR> Sound diffraction to solve: What is the sound diffraction culprit? Is the speaker cabinet itself. .The unit is not the only sound way to the front of the energy, as well as open to the expansion of the energy in all directions, so the edges and corners on the box next to the alt likely to cause diffraction. .Diffraction severe, it may cause interference, which affected the sense of high frequency energy, reducing the sound imaging and force. .As for how to reduce sound diffraction, which is one of many speaker manufacturers one of the most headaches, they exhausted all means. .The easiest way is to buy a piece of thin foam or cloth, cut into small pieces, then stick around in the tweeter (for example, commented ELACBS244 Issue the means used by speakers) can be improved. .More exaggerated way, is like WesflakeAudio (West Lake) will be the speaker company that chunks of foam embedded in the center. .While this is definitely on the immediate improvement of the sound, but its visual effect is extremely poor. .The best way is to try to expand the baffle to reduce sound diffraction, and the wall is the use of large wall speakers as a sound baffle diffraction to solve the problem. .<BR> <BR> Address box shock: shock box but the biggest enemy of speakers, this is because the shock will bring the speaker cabinet coloration produced, affecting the sound faithfully restored. .How to make a more robust and free box to shock effects? The traditional practice of home speakers in the cabinets using a variety of reinforcement measures. .Support such as wood frame, with internal partitions, etc., are more rigid box to enhance a good way. .The speaker will use some of the top metal as a box, hoping to use the weight of the metal box to suppress the vibration. .For example YGAcoustics, WilsonAudio other brand is representative of the metal box. .For the speaker into the wall, the wall is not only outside its front baffle of the box but also the equivalent of it. .Therefore, if your house wall has sufficient strength and thickness, in theory, this can easily solve the "box" of the vibration problem, send speakers into the wall so that more realistic and more accurate sound. .<BR> <BR> Buy into the wall of the speaker should pay attention to what <BR> <BR> <BR> <BR> speaker into the wall in the market as more types of consumers in general may be some .question. .How exactly should I choose? And in the choice of when to pay attention to what? In this, we would like to purchase for this part of the speaker into the wall, the following summarizes some of the points of consumers for your reference. .<BR> <BR> 1. .Frequency Response (Hz): I believe the majority of readers for this indicator is not strange. .Because it is an important indicator to measure the merits of one speaker. .In theory, the wider the frequency response of speakers meant to re-emit more sound signals. .The human ear can hear sounds between 20Hz-20kHz range. .But in fact, the existing products are basically very few can achieve this target, especially in the low frequency limit, we should reproduce the 20Hz frequency is very difficult. .As for the general speaker into the wall, its low frequency limit of 50Hz has been pretty good reach, while the frequency of 50Hz to reproduce the following is basically an external subwoofer to complete. .<BR> <BR> 2. .Sensitivity (dB): Speaker sensitivity is at a specific frequency to the speaker input 1W (2.83V or 1V) of power, then the speaker is the location of the measured axis sound pressure. .This value is equivalent to speaker efficiency. .In the case of the same input power, the higher the sensitivity of the Speaker of the output sound pressure will be high. .In other words, the higher the sensitivity of the speakers at the same sound pressure, the less power required. .In fact, today in the pursuit of efficiency, most manufacturers produced by the speaker of the sensitivity remained at a high value. .Therefore, consumers who do not have to worry about the choice of amplifier. .<BR> <BR> 3. .Power carrying capacity (W): Now almost every manufacturer will be given the power of this product is the recommended carrying capacity or if the reference amplifier power, and similar indicators. .Therefore, consumers can use their own amplifier and the combination of the reference value to select products that match. .For example: given speaker manufacturers recommended amplifier power is 30W ~ 150W, then you can use a 150W amplifier output power to match. .In fact, the speaker of the actual carrying capacity of the power is higher than the reference value. .Even with a higher nominal power amplifier speaker would not pose a great impact. .<BR> <BR> 4. .Movable type Tweeter Design: There are parts of the tweeter speaker into the wall to be movable design, which according to the actual needs of the consumer's point to point on the tweeter to fine-tune the sound to get better .. .<BR> <BR> 5. .High, the bass Function: This feature can be based on different consumer listening preferences and listening to the acoustic properties of space to make appropriate fine-tuning. .For example, a strong sense of rhythm are you listening to pop music when the bass can be enhanced for certain low-frequency to be more abundant; when listening to music Shiyou lively sense of rhythm can be some increase in frequency. .However, not all of the products currently on the market all have this feature. .Therefore, you can choose one with a high, the bass amplifier to adjust the regulatory function, can also achieve the same effect. .<BR>.

【 Weak current College 】 audio standard (THX Surround EX) resolution---Power By 【 China power house network 】

THX is a United States Lucasfilm company cinema with audio system known as the professional standard, THX is not a stand-alone playback system for Dolby Surround directional logic systems improvement, make the surround sound effect can be further enhanced.
THXSurroundEX in September 1999, the first for the movie star wars episode, is Dolby and have THX for Lucasfilm Ltd. (LucasFilm) cooperation in the field of the result, agreed by the professional, as authorized by Dolby and civil DolbyDigitalSurroundEX machine certification is to LucasFilm, called THXSURROUNDEX. Therefore, early market support DolbyDigitalSurroundEX decoding machine, Panel beating logo actually THXSURROUNDEX flag. THXSurroundEX and DolbyDigitalSurroundEX completely is built on the same technology.

Specifically, THXSurroundEX is a set of established on the basis of the 5.1 channel 6.1 or 7.1 channel system. Early THX is 5.1 channel system, it is very close and DolbyDigital5.1 channel (in fact they were built in Dolby Surround directional logic systems technology). This 5.1 system contains left, Center, right, left surround and right surround, and isolated from the lower-frequency signals 200Hz following the merger of the subwoofer channel, the total is 5.1 channel. THXSurroundEX this 5.1 channel system by adding one or two surround, it is placed in the middle of the original left and right surround, known as the rear surround, you can see, and in fact the same DolbyDigitalSurroundEX. THXSurroundEX will 5.1 channel becomes 6.1, 7.1 channel methods and the same are DolbyDigitalSurroundEX matrix encoding technology, the rear surround is the use of matrix encoding technology from left and right surround in separating out the rear surround channel. In other words, when you record audio, you put the rear surround channel to matrix encoding mixed with left and right surround, wait until the replay again to matrix decoding manner after the surround left and right surround channels. The advantage of this is that it contains more realistic from the top or side effects, flying with more stable sound like background music and film, so that the atmosphere in both the cinema or home appreciation has more harmonious surround effect.

You cannot fail to mention mentioned THX THX certification. THX certification on replay equipment, such as audio source, amplifier, speakers and even connect wire has a set of strict and specific requirements, meet this standard and the Lucas certification through the product, before granting THX logo. For home theater, the THX logo refers to the system's components, such as sound processor and speaker system that meets the Lucas companies (LucasFilm) THX and their unique treatment of parameters required for playback. So in short, "THX" is a kind of like ISO9001 certification specifications, it is a quality certification standards, with the identification of the home entertainment system hardware and software quality. Those with "THX" tag home entertainment system products have been a series of strict laboratory testing and listening test, these tests by Lucasfilm's experts.

At present there are THX certified THXSelect, THXUltra and THXUltra2 three. THXSelect designed for more than 2000 cubic feet of space (about 5.5 ping) service, THXUltra designed for more than 3000 cubic feet of space (about 8.3 ping). Simply put THXSelect provides budget limited consumer choice to provide a reference, THXUltra professional consumers. At present the latest certification is THXUltra2, this new specification is to full output 7.1 channel sound design, offers a very wide scale of sound field to cover a wider range of listening to the space and the tone balance between the channels of control for more delicate. In addition, performance is also required to promote low-impedance speaker capability and high noise ratio characteristics to correspond with the latest high-quality digital audio sources, this rigorous testing through to get THXULTRA2 certification. The following is every home THX audio systems are equipped with:

1. wait in line, the line main Re-equalization of feature films produced in the deliberately la high-frequency, again in back home theater play too sharp in sound, a complex phenomenon eliminates it on sound mixing procedure appears sound too sharp phenomenon was amended.

2. sound match the line of TimbreMatching function mainly in the provisioning of surround sound audio quality, and the former main channel sound interface more compliant, surround sound and is fully integrated into the surrounding the arena. Sound match is designed to bring your front speakers and listen to the environment of a technology, this is because in a typical home theater, only two surround speakers, instead of cinema in the full specification of the configuration.

3. solution of dependency line, this line main Decorrlation functionality is implemented in two side-channel two-way sound design of loudspeaker, regeneration and cinema more surround sound speakers the same effect. Solutions for dependency lines let you enjoy music with "stereoscopic" sound, even if the sound is played as a calendar, simplified and automated press disconnect will not affect the sound.

It is important to note that the product is obtained the THX certification does not represent the goods quality, THX certification achieved can only be said to represent their products under specific norms, can easily result in home theatre balance. After all, THX recognitionPermits are not compulsory, in fact it is a business tool — that is, developed by a specification, the collective marketing, monopoly of truth. Non-THX certification has many excellent products, your ability to know the hero.

【 Weak current College 】 from sensitivity and frequency response to infer the microphone of the quality and performance

We can phone structure (dynamic or capacitor) and point to properties (cardioid, Omni-etc), to determine if a microphone is suitable for our requirements. However, we infer that a microphone quality and performance will not be so simple.
Recording quality and ultimately by the device in the lowest quality, a component of the decision that the recording quality is good, does not exceed the worst component of the quality. If you do not have pickup accurate high-quality microphone, you will not be able to make high-quality vocal or instrumental recorded. High quality microphone can help you get from the scene show the best results.
Evaluation of a microphone performance, sensitivity and frequency response are two very important aspects. Microphone sensitivity depends on — for sound pressure signal generation of signal level. — Like cases, the larger the better the signal. The larger the resulting signal signal level higher, microphone, the higher the SNR. In any of the energy conversion, there are some invalid energy transformed into noise. For the same sound signal, the receiver output signal level of effective, means that the smaller the relative noise.
On the microphone sensitivity, we often encounter — some people confused. If you want to only consider one of these, then, from the sound pressure level (SPL). Low impedance microphone's output signal level — like below input sound level, but are you really SPL tell how much lower. SPL is a negative number, such as DB-50dB (at the indicators-50dB ratio-60dB large).
We need to draw your attention to: point: not every manufacturer gives the SPL is relative to the same — input signal. Comparison of different manufacturers of receiver, you must ensure that they all use the same reference signals, you must pass the cumbersome for mathematical calculation to be under the same conditions as a result of the comparison. Reference signal is usually listed in the SPL, as-74dB (OdB = 1V/mb, 1kHz).
Frequencyresponse is the microphone from low to high frequency sound of the different "hearing" a sense of competence. Visitors can feel the sound frequency of maximum range is 20Hz-20kHz. Therefore, the ideal microphone should also be able to voice within 20Hz-20kHz response. On the actual handset frequency response of a reasonable expectation is 50Hz-15kHz. In a musical instrument pickup, you'd better be able to use a frequency range and is on these frequencies have a very good response of the receiver. For example, the most general piano bass about 27Hz, brilliance about 4.2kHz, people singing voice frequency range of about 100Hz-1.2kHz. You can see, the pickup for piano and singing pickup microphone, frequency response is not required — sort of: singing pickup microphone does not require a response below 100Hz voice, for piano pickup microphone you must have a wide range of responses. Cymbals (cymbals) pitch range 7.5kHz-10kHz, cymbals of pickup the handset needs to have good high-frequency response characteristics.
For a microphone, the sound can cover useful throughout the frequency range is important: it is equally important, it must also be able to on the wide range of frequency response of the sound evenly. Subject to limitations of the physical structure, microphone to respond to various frequencies within the range of sounds for uniform response is very difficult, therefore, in the frequency response curve on the high response of the Peak District and the Valley area, lower xiangyin, ideal frequency response curve should be like the desktop —-like flat, it curves on both ends of the limit response point suddenly straight down.
But why many vocalists and recording are fond of using the range in response to the peak of microphone 1kHz-5kHz? this is because the frequency response curve in the range of the microphone to increase clarity of song and luminance. Therefore, not all of the frequency response curve is more even better. As for the painter, and there is no absolute ideal of a red. Similarly, there is no ideal microphone, its frequency response is applicable for any occasion. Sometimes, flat response curve is definitely what you need, but in other cases, the response curve has a projection but is better. Of course, these should not be the factory manufacturing defects caused by when the microphone.

【 Weak current College 】 EIA-426-B standards introduction

Part I introduction to CD drive power test
ANSI/EIA-426-B-1998 (Loudspeakers, OptimumAmplifierPower) is about power amplifier fed to speakers of standard best power from the United States national standardization organizations, ANSI (AmericanNationalStandardsInstitute) and EIA electronics industry association (ElectronicIndustriesAssociation) joint publications. The standard audio system by EIAR-3 Committee working group, as the amendments to the standard EIA-426-A. EIA-426-A mainly provides for wide-band systems accelerated life test method. In revision before the speaker manufacturer survey respondents broadly considered necessary for the test signal in EIA-426-A standard spectrum, test duration and power calculation methods and other issues. Revised criteria for extended 426-A 426-B, recommended and speakers connected an audio amplifier of maximum rated output power, contains the best amplifier output power of power compression, distortion, and other performance assessment method, described in power compression, distortion and accelerated life test areas of acceptable performance limit.
Speakers can bear the ultimate power is actually a very complex issue. It depends on the speakers in the relevant parts of the heat damage and mechanical damage limits, both with the input signal power, and with the input signal such as peak factor, rise time, spectrum distribution and other factors. Also, do not consider the quality of the ultimate power and not much practical significance. In fact, it should be concerned not exceeding the number of Watts of amplifier power output, for most programs, you can get from the speaker's sound quality is acceptable. I think that this should also be the reason why EIA-426-B standards named best of the speakers, amplifier power (Loudspeakers, OptimumAmplifierPower).
United States speaker Manufacturers Association ALMA (AmericanLoudspeakerManufacturersAssociation) in 2001, launched and coordinated EIA-426-B standard test signal discs. Used as a substitute for expensive signal generation equipment, improving the reliability test, with a view to promoting the broader EIA-426-B standards. This disc also contains a number of criteria other than the signal EIA-426-B, such as the higher frequencies of pure tone, and explosive sounds, and so on. All signals in the dish by signal processing and data analysis program synthesis by mathematical methods and on PC using IgorPro4.0 program generate wav file. At present this dish in the United States market retail price of 100 USD. In many of the audio-related Association, to the Member's price is usually US $ 50.
This section simply describe the dish containing the test signal, not the application relates to its depth. On the test signal of the specific application, in this article described in part II.
A detailed description of the test signal
Track 1: level set the reference tone
Track 1 is 1000 Hz reference signal that is used to calibrate other tracks on this CD test signals in the signal level. Recording time of peak is negative 6 DB, duration is 60 seconds. In addition to the explosive sounds, this CD discs on all test signals are used and reference tracks the same peak recording. At the start and end time, each with a width of four cycles of the slopes of signal for improved transient response. Track 35 to 68 in the explosion sounds is just the peak recording 6dB.
Track 2: for life test of random noise
Track 2 is an in-band 40Hz to 10kHz between Gaussian random noise, suitable for a pair of speakers to do accelerated life test. In equal percentage bandwidth Spectrum Analyzer on the test, the signal spectrum in the following order with 6 40Hz Butterworth high pass filter (Butterworth) filter from 40Hz to 1kHz is flat, in between the 10kHz 1kHz per octaves negative rate of 3 DB down in the above 10kHz 4-order Butterworth (Butterworth) low-pass filter filter. Its peak factor for 6dB by software simulation of symmetric clipping diode, the result is the amplitude of clipping of Gaussian random noise. This signal duration is 30 minutes.
Track 3: for power compression test of variable sweep frequency sine wave signal
Track 3 is a variable sweep frequency sine wave test signals for power compression test signal, its spectrum is basically the track 2 is the same as noise. The composition is a signal from 40 Hz to 10k Hertz uplink frequency scanning, duration 0.25 seconds, and then by 10k Hz to 40 MHz for the downlink frequency scanning, duration is 0.25 seconds. This length 0.5 seconds synthesized signal continuously repeated, a total of 10 minutes. Because the Head-Office of frequency are equal, so the transition is seamless and smooth.
Track 4-34: for distortion test-tone signal
Track 35 to 68: for peak power and dynamic margin assessment of explosive sound signal
The second part of the test method
First, test the required facilities
With a sound track repeat playback of CD Player; output power greater than the required test power audio amplifier; and EIA-426-B standard matching test signal discs, you can also use comply with the criteria in Appendix A EIA-426-B other test signal generator; RMS voltmeter, input impedance at least speakers rated impedance of ten times more bandwidth to at least communicate to 10kHz 40Hz; bandwidth covering 40Hz to 10kHz sine wave signal generator; a third octaves real-time audio Analyzer, use 2 or 3 types of filters, to display the overall sound pressure level; Test the microphone, the whole direction in 40Hz to 10kHz frequency response between the non-uniform degree is smaller than 0.5 DB sound pressure level dynamic range upper limit to the minimum standard consistent with EIA-426-B 140dB; specified in Appendix b in switched 20 DB attenuator.
2. test conditions and considerations
Each test should be done with a no other test of a new speaker to do. Speakers should be provided by manufacturers for testing, in the absence of provisions should be in the area of the appropriate barrier Board tests. Continuous power under accelerated life test can be done in the free space. Tests should be maintained in the ambient temperature is below 20-30 ° c, relative humidity up to 30-80% of the room or Cabinet, speaker resonance frequency changes shall not exceed 5 per cent.
If the manufacturer provides a divider or crossover network, you should follow the manufacturer instructions for installation; if no such provision, the amplifier and the voltmeter should be connected directly to the speakers terminals. First confirmed the speakers with a rated impedance of, and then use EIA-299-A this rated impedance calculation should be imposed, to test voltage on the speakers, the test voltage must be equal to the power amplifier and speakers the best rated impedance of the square root of the product.
To test the speaker in a long time in one equivalent to half the best amplifier power of test signals and its performance parameters or product integrity will not be unrecoverable or unacceptable variations in capacity, thereby simulating the speaker working life. In this test, the speakers should be can't quickly fail because its the same product in the previous test has experienced the entire frequency range in power test. This test is that speakers such as free air resonance frequency and other parameters will not create permanent change. So, the speaker had a permanent damage, we found that it did not pass this test. If you need to reduce this damage to the measured product risk, you can experiment with a Spectrum Analyzer or ear the speakers have been closely monitored, in the event of unusual, immediately disconnect the test signal. At this point, the speaker may have had a permanent damage, and no permanent damage. If you do not have permanent damage, cannot think it passed the test, nor can it fail test. But if the speakers are adopted this test, you think its rated power has been verified.
Before burning machine, select the test signal of the disc with a sine wave signal correction, adjustment of the power amplifier output level, so that the ratio of the second section is the test voltage (power amplifier rated the best power and speaker impedance of the square root of the product)-3 DB, which is the test voltage multiplied by 0.707. In the CD player set the repeat playback, so that it repeats the test signal discs in weighted random noise test signals (track 2), the signal applied to the speakers, continuously repeat one hour, in the end make magnetic circuit cooled to below 35 degrees Celsius, test and document the speaker resonance frequency.
Then an official test, in test signals disc select calibration sine wave signal, adjust the power amplifier output level to make it equal to the second section of the work of the test voltage (power amplifier rated the best power and speaker impedance of the square root of the product). In the CD player set the repeat playback, so that it repeats Gaussian random noise signal, the signal applied to the speakers, continuously repeat eight hours.
After the end of the test, at least one hour of recovery and confirm the magnetic structure of surface temperature has cooled to below 35 degrees Celsius, then feed the speakers a equivalent to half of the test voltage of sine wave signal in the factory to the rated bandwidth, no scanning frequency rated bandwidth, 40Hz to 10kHz. If no tests caused by noise or structural damage will result in the speaker is not suitable for booking application, and the resonant frequency of decline than pot is the records refer to the resonant frequency of 10 per cent, the speaker has adopted accelerated life test.
Test sequence: first do power compression tests, and then do the distortion test, final do accelerated life test.
III. power compression test
Used to test the power of the power amplifier, speaker, the best acoustic output is compressed.
IV. harmonic distortion
5. continuous power under accelerated life test
Closing remarks
And speaker that matches the power amplifier is one of the best output power, using a power too great a power amplifier increases the chance of damage to the speakers. EIA-426-B standards is trying to find the best power.
However, even if the user is completely in accordance with the standards selected EIA-426-B power amplifiers, or there is no way to fully guarantee the security of the speakers. Because even if amplifier output power is not high, if the gain control, bass boost, Equalizer control, volume control, etc., causes the output of the amplifier is a flat clipping signal, so the speakers still exists the risk of burn-out. Clipping is the enemy of the speakers, because clipping, the topping-out phase to signal that the fed to speakers of DC, speaker vibration parts no movement, input power 100 percent are converted into thermal energy, and no back-EMF, therefore particularly vulnerable to damage.
In addition, it should be pointed out that, under this standard, also referred in particular to the protection of the operator listening and related protective measures.

【 Weak current College 】 purchase experience video conference equipment

Difficulty analysis
And medium-sized enterprises as an important component of the national economy, economic development and social stability of the pivotal role. In competitive pressure, the SME has begun to realize that effective communication on the importance of improving operational efficiency. However, due to the large number of domestic SMEs, the varying degree of information, and their IT investment cost sensitive, its system selection is limited by many factors.
According to a survey of China IT lab, small and medium-sized enterprises use video conferencing system exists in several aspects.
1. the "racking our brains," the problem is serious
IT projects of small and medium-sized enterprises and large enterprises are very distinctive compared to features, they usually pay more attention to production and sales, underestimate internal management of IT investments will have different considerations.
In recent years, the SME market maturing, the rapid development of industry and enterprise information level is low, the management behind a striking contrast, this does not suit to compel SMEs increased information technology hardware and software investments. In the information construction boom, some SMEs due to their business needs and not enough precise positioning, video conferencing system is not enough to know that result in investment behavior irrational.
2. cost control difficulty
Video conference system as a long-term investment, the need for business-to-use cost for a good control. Compared with large enterprises, SMEs and limited scale, the structure of a single, large enterprises often do not have the internal resources such as scheduling capabilities, lack of funds use strict comparison, randomness.
On the other hand, compared to large enterprises, small and medium-sized enterprises use video conferencing system less frequently, often dealing with some unexpected events, therefore the video conferencing application cost control difficult.
3. the system difficult to effectively safeguard
Through our investigation, many SMEs are not satisfied with the video conference system provider of the service, especially after the system online. This behavior is by video conference system provider strong psychological "alone". Because when a user in promoting the project, some video conferencing vendors to get orders in project negotiations initially very positive. But once the system is on the line, the system provider on the user system follow-up support maintenance service consciousness is not enough.
With the advance of Informationization construction, SMEs are increasingly aware of the importance of the service, the service has gradually shifted from the hardware maintenance, system maintenance, IT consulting, etc. Importance of SMEs, through advisory services determine the enterprise's own management status, current problems and create suitable for enterprise information construction process itself.
Selection procedure
Understanding of technical standards
And medium-sized enterprises in the selection of video conferencing system, you must rely on video conference system technical standards.
Currently, video conferencing vendors generally take the International Telecommunication Union (ITU) video coding standards, which efficiently saving video conferencing application valuable bandwidth resources has great advantages.
Where the MPEG4 and H.264 can not only be applied in a narrow band (bandwidth is less than 64Kbps), you can flexibly extend to high-quality, high-definition of broadband, this ensures that you can meet different needs of the actual application.
With the continuous development of the network technology, based on the MPEG4 and H.264 compression standard application has become increasingly common, incontestable become video products.
Inspection system architecture
Enterprise video conferencing system schema determines the stability of the system and can easily support extended bulk users. In General, the video conferencing system is composed of multiple function modules, whether the user wants to inspect the system adopts the international advanced distributed, modular, the bulk of the schema.
This distributed, modular system architecture features for future application provides powerful scalability and high configuration flexibility. SMEs in project planning and implementation can according to their own network size and business function needs to make a video conference system configuration deployment.
Furthermore, SMEs characteristics determine their system scalability, higher demand exists.
Consider network adaptability
Based on the IP network and the network of video communication quality varies widely. In General, small and medium-sized business users running mainly based on the IP network, so there is a higher network packet loss rate and a larger network jitter. These are in the process of using the quality of video conferencing especially sound quality have a greater impact. [fenye]
Therefore, the basic network features of small and medium-sized enterprises requires manufacturers to provide a network environment is highly adaptable product, instead of always requires the user to expand the network bandwidth and improve the quality of the network.
Video Conferencing vendors provide products are suitable for up to 10% packet loss rate of the network environment; changes in network bandwidth, ensuring the continuity of the sound, and supports a variety of file transfer, making the entire Conference intact; can allow multiple bit rates co-exist in the Conference. These are medium-sized enterprises in the presence of the product performance of factors must be taken into account.
In addition to the above factors, enterprises also need to know the following situation.
Manufacturers of video conferencing products can be compatible with other brand products; video conferencing vendor can offer the level of service is to provide stable audio and video transmission, videoconferencing systems in IP standard series, such as H.323 standard; video conference system supports multipoint Conference video conferencing multipoint join, whether users need additional investment in hardware and software; video conference system on the market the length of time, and the future of systems and technology integration, system provider is doing a more strategic planning. These SMEs video conference system selection is also important.
Specialists: choose the video conferencing equipment experience at seven
According to the domestic video conference system of practical application, we summarized the following seven experience for video conferencing systems engineering enterprise reference selection.
1. the network bandwidth to achieve 1M above
SMEs useHouseholds in the selection of former must confirm their network bandwidth enough run video conference communication. In General, SMEs to video conference system must achieve exclusive bandwidth 1M above.
2. in a real experiment in a network environment
In General, the programme providers in a specific environment for enterprise users of technology demonstration, almost all companies have the ability in exceptional circumstances make your own video products behave is watertight. Therefore, the user must be in their network environment to verify product performance.
3. understand the scheme of technology maturity
At present, the comparison of the leading on the market is based on standard solutions and H.320 is based on the H.323 standard solution. From the time perspective, the programmes based on H.320 standard technology relatively mature, wider, more full conference features, but its a one-time investment. The H.323 and H.320 programme compared to the investment is small, and the ability to easily transition to broadband or other, more convenient and efficient communications network. So the cost is relatively sensitive to small and medium-sized enterprises in the selection of programmes should be select support H.320/H.323 duplex mode products, so that in the existing infrastructure and future development can be balanced, could be longer protection of the established investment.
4. whenever possible, choose the simple operation of equipment
Small and medium-sized network environments generally not too complex, so the choice is simple, user-friendly video conferencing will be able to meet user needs. But it also can minimize business-to-video conferencing equipment use training costs.
5. focus on the practical use of equipment
Most manufacturers claiming that their video conferencing terminal can synchronize open dozens or even hundreds of road road video image, but this feature is not practical. The user session is not possible to listen to a lot of people talking at the same time, it can use spokesman video switch manner and different people video interactive, open multiple video screen is really just a waste of bandwidth.
6. the pros and cons of scalability concerns programmes
For small and medium-sized enterprises, the video conferencing system is a long-term investment, so you have to consider options for its scalability. Manufacturer independent development of video conference system based entirely on the implementation of software in General, you can easily create components or middleware products for secondary development and transplantation, and hardware products upon inputs expandable range are much smaller. Determined according to the needs of enterprises.
7. seek third-party agencies help
For small and medium sized enterprises Informationization, the enterprise itself is difficult to ensure that policy makers to make the right decision. Therefore, seeking external brain is to solve the problem.
Enterprises are to targeted advance information application, may wish to contact some professional advice, or looking for a video conference system expert help, so you can process the entire selection to better understand the needs, clear objectives, make the right decisions.

Weak current College】 【public broadcasting system debugging and open testing.

<br> Broadcasting system debugging mainly refers to the broadcasting system installation has been completed, the device installation process is complete, the routine check and made opening test and quality evaluation, its main work content: transmission line check, with checks, insulation resistance measurement ., grounding resistance measurement, test and debug, power supply, antenna, system test, the opening of the sound pressure measurement and quality evaluation: <br> 1. transmission line check <br> <br> Broadcasting transmission lines are divided into various indoor .and outdoor wiring, checks should be checked line terminals from the device disconnected, follow construction plans, broadcasting system map to check the transmission wiring is correct, the existence of a short circuit, circuit breaker, mixed line failure; Terminal numbers are complete, correct ., and whether there is a terminal block welding. Fault for being discovered each exclude tricks and Terminal retightened connection; various plugs, socket connection is used for welding, wiring is correct, reliable, complete shield connection is good, and meet the requirements. < .br> <br> Second, the matching check <br> <br> Follow the construction drawing examination each loop or how the device line transformer with correctly, especially the multi-tap transformer connectors are often easily mistake then, pay attention to check missed ., received, transformer primary secondary reversed; the figure check transformer, capacity and impedance matching, <br> <br> III. determination of insulation resistance <br> <br> Will be broadcast at the ends of the connector line, used to measure .its 500V megohmmeter, wire insulation resistance. Measuring project: wire and cable and wire and insulation resistance of the insulation resistance is generally not less than 0.5 M Ω, the for each loop resistance shall be carried out by numerical measurement, the measuring loop should complete .records, as the debug report to construction unit. <br> <br> Fourth, grounding resistance measurement <br> <br> Broadcasting system grounding resistance, mainly in the broadcast room on the ground; measuring with grounding resistance tester. <br> .<br> Broadcast room amplifiers, power surge arresters, grounding resistance is usually not greater than 10 Ω, when the broadcasting system's capacity is over, such as single 150W set of ground very difficult indeed mission, and electric equipment combined with a set of ground ., but the ground require grounding resistance should not be greater than 4 Ω, and should set up a dedicated grounding line. <br> <br> 5. power test <br> <br> On the measurement of AC power supply voltage, power .supply wiring should not appear short circuit, open circuit, in the power switch on / off operation test, check the power display signal; standby power supply interchangeable equipment check test, battery voltage measurement of output; on rectifying charging device check measurements; do simulation .power test, verify that the power supply does changeover devices work reliably. <br> <br> 6. system opened test <br> <br> In the above check problems discovered in all changes have been completed, the check test shall meet the .requirements, you can do a system test, systems opened opened test should separate equipment, individual service. <br> <br> 1. open the amplifier <br> <br> First disconnect all output lines, pull the plug on the whole of .the input signal, the amplifier's "volume" spin button to spin and power it on, open the amplifier switches, observation of the displayed signal is normal, no machine noise. <br> <br> 2. open the front-stage amplifier < .br> <br> When the amplifier opened everything works, you can open the front-stage amplifier. Connecting the front-stage amplifier power, the observation of various display and plug in the front-stage amplifier and power amplifier of the join line. .<br> <br> 3. microphone test <br> <br> When the amplifier and the front-stage amplifier works fine, the front-stage amplifier and amplifier "volume" knob to the minimum, insert the microphone plug to the microphone .with voice signal, adjust the volume knob "," listening on headphones to hear the sound output. At this point the amplifier or the front-stage amplifier "function" knob rotation to the microphone. When all the way to the microphone jack test finished ., in the same way on each microphone input channels to experiment. <br> <br> 4, the recorder input <br> <br> The front-stage amplifier or amplifier "function", rotary knob to enter the stall, and the .recorder is switched on the recorder input circuit to play the recording tape, adjust the volume size, the observation of the input signal, distortion and noise. <br> <br> 5, receiving tuner opening test <br> <br> Connecting the .tuner power, receiving broadcasts test receive, according to FM radio reception, repeatedly adjust the FM receiver antenna for optimal reception. And watch the interference and distortion. <br> <br> 6. output circuit test <br> <br> The front .-stage amplifier or amplifier input recording or record signals, the "volume" to a minimum, opened the way how the device, the "volume" to the middle position, the observation by the speaker volume, clarity and noise; and then the " .volume "rotary to most, there is no distortion observed; and adjust the speaker volume controller, listening to the sound distortion and volume changes. For serious distortion of the speakers should be line transformers, speakers, coil, identify problems and should be repaired or .replaced. <br> <br> Using the above methods on each loudspeaker equipment circuit to test, if each speaker on the circuit are pronounced correctly (ie, low noise, clear, low distortion), you can open all speakers, sound columns, .adjust the volume size, repeated tests multiple times, exclude a variety of installation problems. <br> <br> <br> <br> <br> <br>.

Weak current College】 【five points help you to purchase high-quality speaker.

The rapid development of multimedia technologies, from the previous PCSPEAKER to today's multi-channel digital sound, feel the sound changes when we should have an understanding of related technologies. This article has some technical speakers do a more detailed introduction, I hope everybody is using and purchasing process can be aware of in order to better enjoy the wonderful sound.

What is digital speaker

Sound card digital modeling transformations work is accomplished by CODEC chip, but since the computer chassis memory in electromagnetic waves, which will make digital/analog, analog/digital conversion are serious interference, so many professional audio recording card widely used methods of the CODEC external, digital/analog conversion parts and various external ports individually made an external box, used to improve the sound quality. But this kind of design will greatly improve the cost, so some speaker manufacturers to come up with the digital/analog conversion work on the transfer from the sound card to the speaker of the programme, i.e. digital multimedia speakers. Digital multimedia speaker's basic principle is that the sound signal does not pass through audio CODEC chip for conversion processing, direct to PCM format with a sound card on SPDIFOUT port to pure digital transfer to digital sound box, and then through the speaker built-in digital/analog converter for resolution, then amplified output, thus reducing disturbance, improved signal to noise ratio.

USB speakers and disadvantages

What are the advantages of USB speakers? first, because the USB speaker system is directly from the USB port of the digital signal to the speakers inside, so it can effectively improve the sound signal to noise ratio; and second, because the ordinary speakers the received signal is transmitted by the sound card to analog signal, therefore, vulnerable to interference, and the USB speakers can make the audio output of analog signals from from electromagnetic interference in the chassis, allowing sound more pure clear; third, the USB audio device can also be carried out by the CPU, thus the data processing using its bandwidth advantage of multiple-channel surround sound system for audio playback (but only with USB2.0 specification).

Then, that the shortcomings of USB speakers. First, because many older motherboard does not have a USB port, causing many users will not be able to use USB speakers; second, the USB speaker system cannot support DOS game, can only support DirectSound3D voice sound; third, EAX, A3D, that require hardware chip to handle voice sound synthesis, USB speakers can no longer support this for gaming fans undoubtedly great regret; fourth, the USB speakers cannot implement hardware wavetable, so users cannot use it to listen to the MIDI; fifth, when the system has more than one task and intensive data bus, USB speaker system is not functioning properly.

Woofer speaker identification

Woofer speaker direct determines the sound frequency response and bass. From the speaker's cone design point of view, the current market mainly "dialysis cone" and "packing tape pots," "bullet-proof material woven basin", "wool woven Bowl" and "CD film" and other materials. "Dialysis cone" advantage is low cost, the disadvantage is that power too large bass seemed dull and poor durability; "packing tape basin" also has the advantage of low price, durability, a little better, also not suitable for high power use; these two categories of product positioning in General enthusiasts can also, but definitely not very professional. "Bullet-proof fabric fiber woven Bowl" has the advantage that the bass is powerful, rock music, percussion performance quite prominent, suitable for high power amplifier using the main speakers, the disadvantage is that the complex manufacturing process, the price of natural not cheap; "wool woven Bowl" advantage on light music, soft music effect is ideal for positioning in the bass range, the disadvantage is the lack of strong bass performance, and are also less; "CD film" is the market for a new product, as compared to the excellent bass speaker materials, it is obvious to all aspects of performance, just as there has not been accepted by many manufacturers, so that the speaker and the speaker to do.

Case material and quality of the speakers

The current speaker of the materials used are plastic boxes and wooden box. Material thickness and quality of speaker costs have a direct relationship, also affect the performance of the sound. Speaker enclosure for material density, the larger the sounds box generated by the vibrations, especially with high-power amplifier powered speakers, and plate thickness to a certain extent, is the powerful Super bass, therefore, plastic speaker bass effect is not afraid to flattered. Clearly, the low end of the audio product must be molded case. But it sure is a mid-range speaker made of wood? answer is no. The grades of speaker both wooden and plastic imitation of wood, just some of the products fully meet the standards of the confused as real ones. Upscale products must be made of wood, but uses the medium density boards, or multilayer sheet that has a different impact on sound quality. Even if the selection board are the same, the same power output, different design structure, different box sizes, the sound quality may still be quite different. However, some speakers are using plastic box, Excel, such as the CREATIVE Soundworks speaker, not only the plastic casing, but the volume is not great, first impression there is nothing special, but after a trial comparison before feeling indeed through, whether it be voice or sound quality have been professional, bass also has a strong shock force, of course, price is not cheap.

Selection of speakers that what

First, pay attention to the speaker out of timbre is uniform, as multimedia music sound source mainly to games and General music-oriented, so one treble the proportion of larger proportion smaller bass. Second, it is necessary to pay attention to the orientation of the sound field. Speaker positioning capability of direct relationship to the users play games, watch DVD movies on-the-spot effect. Third, it should be noted speaker frequency movement-Zoom limit, that is, when the user moves the speaker's volume up and exceed a certain limit, the speaker is also longer remain throughout its range even clear sound source signal amplification. Fourth, we should pay special attention to the speaker box for resonance. General Cabinet thinner or plastic casing speaker in the low frequency band 200Hz following large volume output, resonance phenomena can occur. A Cabinet resonance will seriously affect the output of the sound, so users in selecting speakers should try to choose wooden shell's speakers. Fifth, it is necessary to pay attention to whether with Magnetics chassis. Because the monitor is sensitive to the magnetic field around, if the speaker is the Assembly of magnetic field so that the image on the screen, or even result in the life of the monitor, so the selection is to be noted. Sixth, it is necessary to pay attention to speaker box closed. As speaker of the airtight as possible, the better the output sound quality. Airtight check is very simple, you can put your hand on a speaker's inverted phase hole, if you feel there is an obvious air rushed out or inhaling phenomenon, speaker of the airtight performance is good.

Having said that, with regard to the speaker's topic is far from finished, limited to space, pick up important talk with you. For sound this thing has always been a matter of opinion, we just want to be able to convey a concept, that is, sound is an important part of the computer, be sure not to underestimate it.