Original: THG
Over time, the sound begins to play an increasingly important role in the PC world. Avid players, fans listen to MP3 or watch a DVD – they all need a good sound card and the appropriate sound system. The yield on the Klipsch and Videologic scene good audio quality and power has created a significant precedent, resulting in other, more well-known manufacturers have rushed to the market of computer speakers. Do not forget the contribution of Creative Labs and Altec Lansing, who made 4.1 and 5.1 audio standard for PC games. Without a doubt, sound systems for PCs have undergone significant changes over recent years. Once you try multi-channel sound, you are no longer able to'll do without it.
Criteria for testing
While there is no single test that would give clear criteria for evaluation of surround sound (surround sound). So ultimately it will solve your ears. The problem here is that the perception of sound and its quality is too subjective for an independent evaluation. But we still try to provide some simple criteria to help assess the quality of sound.
The sound quality is high, medium and low frequencies. High frequencies have to be crystal clear, congestion should not occur even at maximum volume. The average rate shall be clearly distinguishable, not greased, and low – deep and drums. It should not be used, for example, a subwoofer to drown out all the details of his acoustic bumkanem. Must comply with a certain balance. High frequencies do not have to drive out low, and vice versa. So it's best to buy acoustic kit and use the default settings. Otherwise, you may have to choose the ratio of power subwoofer and satellites, it is recommended ratio of 2:1 to 4:1.
Separation. While listening to the tools should be clearly differentiated. You should not doubt what instrument now sounds, say, a violin or a bass. It is important the correct layout of the channels. If poorly cut low, they will go from the subwoofer, and from satellites. For better quality, of course, will not.
Power. Large values of power are not a necessity. So do not assume paramount power. Look only on the RMS power (rms), is also desirable to compare the number of W and the size of the aperture dynamics. In principle, the larger the speaker, the more power it consumes. In the hi-fi systems, which are often very large, complicated relationship. For example, a speaker can consume less than 10 watts.
Connectors. As in sound cards, the quality and format of the inputs are the decisive factor in the computer acoustics. Two-column or 2.1 system would be enough for stereo mini-jack, plus headphones, while the 4.1 and 5.1 the more the system must be equipped with multiple digital and analog connectors. For example, AC-3 decoder must have a S / PDIF input formats RCA or Toslink. In principle, do not interfere with the support of both formats. You should also pay attention to management, which should be plenty, and to be exact. Plus screening of the speakers, the overall dimensions, ergonomics and, of course, design.
Dolby Digital
In 1965 an American physicist and engineer Ray Dolby (Ray Dolby) organized a company Dolby Labs in London. He worked on the idea of creating a noise reduction system that would improve the sound quality. Technology was supposed to come on both professionals and ordinary public. Since then the name Dolby became known around the world, as created in the laboratory standards used as the surround sound in movie theaters, and in the homes of our citizens. Briefly recall the two predecessors of the standard Dolby Digital:
Dolby Surround – three channels, two for the audio front, one for the sound back. The range of transmission frequencies from 100 Hz to 7 kHz.
Dolby Pro Logic – improved Dolby Surround, by increasing the number of channels to four, including a center channel, and the use of special circuit layout, the sound from behind.
Dolby Digital 5.1 is also known as AC-3 (Audio Code-3). The standard provides for six channels – two front, two rear, one center and one subwoofer. Unlike Dolby Surround and Prologic, this frequency bandwidth has been expanded from 20 Hz to 20 kHz. 5.1 means five front and rear channels plus a subwoofer. Subwoofer channel is also called LFE (Low Frequency Effects – low frequency effects). The term means the AC-3 audio coding technology, in which is dropped inaudible sound, the rest is decomposed into six channels. Accordingly, for the reproduction of Dolby Digital sound requires an external decoder such as supplied in a set of Creative Labs Ispire 5700, or a sound card like Audigy or Acoustic Edge, decoded 5.1 sound and equipped with the corresponding outputs.
If your system consists of two satellites and a subwoofer, you can use the Virtual Dolby Digital, when the two front channels are used to create a virtual center channel. The two rear channels creates a sound processor with HRTF filters.
Dolby Digital audio compression uses a fixed ratio of 2:1. In other words, no matter what you do not have sound after compression you get a well-defined flow. It has its pluses (disk space) and the bad – because the sound quality is still deteriorating. However, due to the sound of the DVD is not so much space that allows you to add a translation into different languages and various bonuses. AC-3 uses 18-bit encryption, so that the output AC-3 stream is 384 kbit / s. To restore the sound picture in Dolby Digital decoder adds a delay of 1 ms to the front channels, as the listener is often closer to the rear speakers, not the front. The delay allows the balanced sound picture. Some decoders allow you to change the delay.
The main advantage of the standard is precisely what has become a standard Dolby Digital surround sound on DVD. In the description of the DVD standard says that the disk can not be used other audio technologies, if it does not have a separate track with Dolby Digital. So you will never find a disk with a DTS. Therefore, Dolby Digital versatile. The first film released with sound Dolby Digital, became "Batman Returns" in 1992. Since virtually all using the standard DVD.
DTS
The standard DTS (Digital Theater System) was developed by Steven Spielberg during the release of "Jurassic Park" in 1993. DTS itself is more suitable for a wide screen, not apartments. However, DTS is now gaining popularity, especially as it can be decoded and software. In DTS as well as in Dolby Digital, the sound is decomposed into six channels. But despite the excellent sound quality DTS, because it is even a little bit better than the Dolby, remember that movies are not produced only one DTS track. Dolby Digital is recognized as a standard, DTS – no.
The main advantage of DTS is a quality, since the coding priority is quality, not the occupied space. Therefore, DTS encoded audio at 24 bits instead of 18 as in Dolby. Dynamic compression, with a floating compression ratio from 1:1 to 1:40. As a result, we get the best sound compared to Dolby Digital, with an average flow of 1.5 Mbit / s. The main disadvantage of DTS is more occupied space (about three times more) than the Dolby. So DTS DVD are usually available in one language and with a limited number of bonuses. Now the market is not so much a DVD with DTS, even though there is a tendency to increase their numbers.
THX
THX – it does not sound like standard DTS or Dolby Digital. This is a certification mark of quality established by Lucasfilm. A sort criterion for collectors home video. The term is derived from the THX «THX 1138", the first science fiction film made by George Lucas, who quickly became a cult. Movies about Indiana Jones, "Star Wars" and other brand gradually developed THX, mainly on the big screen. Lucas found that the sound equipment in movie theaters is often too low quality. Like any filmmaker, Lucas wanted the movie played out with a good sound regardless of the theater. Thus was born, and certification of THX. Now you can find it in many movie theaters around the world.
Promedia from Klipsch, and then the Z-560 from Logitech THX certification opened the world of multimedia sound systems. While at THX little attention, but soon such certification may be significant criterion in the purchase. But as the THX certification is just a recognition of the quality of the sound system, it does not mean that one system is automatically better than another. Indeed, many excellent sound systems meet or even exceed the criteria of Lucasfilm. Just their manufacturers did not want to have to pay a fee for George Lucas trademark THX.
THX certification is based on three main criteria.
The quality of sound. Evaluated on the basis of the noise band of frequencies, frequency balance, integrity, sound front and rear speakers, the quality of positioning. Also verify the compliance of the sound system specified parameters of power.
Ergonomics of the interface. The sound system should be simple to install and use.
The quality of workmanship. On a system that is certified by THX, two front speakers and the average speaker is usually the same, and dipolar (two stops). Generated sound should be sent directly to the listener, it must not reflect off the walls or ceiling. They overlooked the frequency should not be below 80 Hz, so that all the THX system must be equipped with a subwoofer.
Test configuration and testing technique