Tuesday

Home Theater Products Are Going Cordless

By Sherry Lambert


The procedure of setting up multi-channel audio speakers in home theater products is relatively tedious and vendors have invented new products and technologies like wireless surround sound system models recently to help simplify the setup. I will take a look at a number of of the newest technologies which were developed to make setting up home theater systems a snap. I will illustrate what to look out for when making your buying decision.

The majority of recent TVs will be set up as a multi-channel audio system. As historically TVs would contain built-in stereo speakers, nowadays a number of external loudspeakers are used to let the viewer experience 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 number of 8 loudspeakers by adding 2 additional side speakers.

As a result setting up a home theater has turn out to be pretty hard and long speaker cable runs are normally undesirable for aesthetic reasons. Vendors have lately released new products and technologies. These products were designed to help simplify the installation of home theater systems.

One solution is reducing the quantity of speakers by making virtual loudspeakers. This approach applies signal processing to the sound and adds phase shifts and cues to the sound that would normally be sent through the remote speaker. The audio is then sent by the front speakers along with the front speaker sound components. The signal processing is modeled after the human hearing. It utilizes the information about how the human ear can determine the source of sound. Due to the signal processing, the viewer is tricked into thinking the audio is coming from virtual remote surround loudspeakers.

This technology reduces the quantity of needed speakers and avoids long speaker cords but each human will process sound somewhat differently due to the shape of the ear. Because the signal processing is based on a standard human ear model, virtual surround will not function equally well for each person dependant upon how much the viewer differs from the standard model.

An alternative option for simplifying home theater setups and eliminating long speaker cord runs is to employ wireless surround sound devices or wireless loudspeakers. A wireless solution will usually incorporate a transmitter component that connects to the TV or source and in addition wireless amplifiers that will be connected to the remote loudspeakers. This transmitter will usually provide line-level in addition to amplified speaker inputs. Ideally it should have a volume control to adjust it to the audio source.

Some wireless speaker systems are designed to connect 2 speakers per wireless amplifier. A better solution would provide a wireless amplifier for every remote loudspeaker to get rid of the cable runs between each of the 2 remote loudspeakers. Entry-level wireless devices use FM broadcast or audio compression which will deteriorate the audio quality to some extent. More advanced wireless systems use uncompressed digital audio transmission. In multi-channel audio products, it is important to pick a wireless option with a latency of merely a few milliseconds. This will guarantee that the sound of all speakers is in perfect sync. If the latency is larger than 10 ms then there will be an echo effect which will deteriorate the surround sound. Wireless kits often use the 900 MHz or 2.4 GHz frequency band. Some products also use the 5.8 GHz band. These devices have less competition from other wireless products than devices utilizing the crowded 900 MHz or 2.4 GHz bands.

Other product models which are often referred to as sound bars uses side-reflecting loudspeakers. There are extra loudspeakers positioned at the front which broadcast the audio for the remote speakers from the front at an angle. The sound is then reflected by walls and seems to be coming from besides or behind the viewer. This approach works best in a square room with minimum interior design and obstacles. It will not work well in many real-world scenarios with different room shapes however.




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