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New Technologies Make Building Multi-Channel Audio Products A Snap
Multi-channel audio has become mainstream and vendors have developed many types of basic and more sophisticated technologies including wireless surround sound speakers, virtual surround sound to simplify the installation of home theater kits. I will look at the most recent trends to determine which devices in fact work. I will also give some guidance for picking the ideal components.
Whilst in the past installing a TV has been fairly straightforward, the emergence of multi-channel audio has made installing home theater systems much more complex by requiring a number of external speakers to create surround sound. In case of 5.1 surround, 6 speakers are used: center, left and right front, left and right rear and a subwoofer. Newer 7.1 systems need a total amount of 8 loudspeakers by adding 2 extra side speakers.
Consequently installing a home theater has become pretty difficult and long speaker cable runs are normally undesirable for aesthetic reasons. A number of technologies have emerged to simplify this procedure.
The first option is known as virtual surround sound. This solution will take the audio components which would ordinarily be sent by the remote speakers. It then uses signal processing to those components and inserts special cues and phase delays. Next these components are mixed with the front speaker sound. As the signal processing is based on how the human hearing detects the origin of sound, the audio components which underwent signal processing can be mixed with the front speaker components and sent by the front loudspeakers. The viewer is in effect deceived into believing the sound is originating from a location other than the front speakers.
Virtual surround avoids the remote speakers and simplifies the setup and also avoids long speaker wire runs. Then again, it also has a disadvantage. The form of each human's ear is slightly dissimilar. Thus everybody processes sound in a different way. The signal processing is based on measurements which are done using a standard human ear model. If the form of the ear changes, sound will travel in a different way. As a result virtual surround will not function equally well for everybody.
One more approach for eliminating long speaker cable runs is to make use of wireless surround sound products or wireless loudspeakers. A wireless product consists of a transmitter and one or a number of wireless amplifiers. The transmitter connects to the source. The wireless amplifiers connect to the remote loudspeakers. Usually the transmitter part will come with amplified loudspeaker inputs and line-level inputs. This provides flexibility to connect to any kind of source. A transmitter volume control helps take full advantage of the dynamic range and eliminates clipping of the audio within the transmitter.
As some wireless speaker kits come with a wireless amplifier that connects to two speakers, other products offer individual wireless amplifiers for every loudspeaker. The most basic wireless kits use FM transmission. FM transmission is prone to noise and audio distortion. More advanced products employ digital audio transmission to perfectly preserve the original audio. To make sure that all speakers are in sync in a multi-channel application, ensure that you pick a wireless system that has an audio latency of a few milliseconds at most. Otherwise there will be a noticeable echo kind result. Wireless kits often utilize the 900 MHz or 2.4 GHz frequency band. Some products also utilize the 5.8 GHz band. These devices have less competition from other wireless products than products using the crowded 900 MHz or 2.4 GHz bands.
Another option are side-reflecting loudspeakers. These kits are also called sound bars. In this case the audio for the remote speakers will be broadcast by separate loudspeakers positioned at the front at an angle and reflected by walls as to appear to be originating from besides or behind the viewer. The effect largely is dependent upon the shape of the room and interior design and not function well in a lot of real-world scenarios because of different room shapes and obstacles in the room.
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