A Glance At Some Of The Coolest Wireless Audio Devices
Recent wireless audio devices such as iPods, wireless headphones and cell phones support newest wireless protocols. These protocols are supposed to cut the cord and deliver perfect high-fidelity audio. I will look at several of the newest gadgets and technologies to discover how well they work and in which situations they work best.
These products fall into 2 categories. The first type of products already has wireless built in. Second-category products, including some streaming audio devices, have optional wireless capability. Generally they have a slot to add a wireless LAN card. Newest touch-screen iPods and iPhones already have WiFi and Bluetooth built in.
Bluetooth is relatively widespread as a low-cost wireless solution. Nonetheless, Bluetooth does have some limitations. These weaknesses are often overlooked but will have an impact on high-quality audio applications.
1) Limited operating range
Bluetooth usually only provides a 30 foot range. This is adequate for single-room applications. However, this limitation does not permit multi-room streaming utilizing Bluetooth.
2) Limited data transmission capacity
Bluetooth reliably supports data transmission rates of about 1 Mbps only which is not adequate for uncompressed CD-quality audio. As a result Bluetooth uses audio compression. The audio will be degraded to some extent because of the audio compression. For this reason higher-end audio equipment generally does not use Bluetooth wireless audio.
3) Audio delay
The signal transmitted via Bluetooth will undergo a small delay of a minimum of 10 ms. This is for the most part as a result of the audio compression. While being uncritical for MP3 players, this delay may be a dilemma for video and other real-time applications.
4) Lacking multi-headphone support
Bluetooth can’t stream to numerous headphones at the same time. This may be a problem in cases where several people want to listen to the same Bluetooth transmitter.
WiFi is another widely used wireless protocol that is also suitable for audio streaming. WiFi does support uncompressed audio but will have problems broadcasting to a large number of wireless receivers at the same time. It is suitable for streaming music from a PC due to the high availability but is generally not used in wireless headphone devices due to the fairly high power consumption of WiFi.
While newest-generation wireless speakers and wireless amplifier products utilize proprietary digital technologies, low-cost products frequently still rely on FM transmission which is noisy and has high audio degradation and high susceptibility to radio interference.
More recent wireless audio protocols are based on digital transmission. This eliminates audio degradation. Several protocols also incorporate error correction to deal with interference from other wireless devices.
Advanced wireless amplifier products support uncompressed digital audio streaming to preserve the original audio quality. A few of these protocols allow streaming to an infinite number of wireless amplifiers which is convenient for whole-house audio distribution.
Some of these protocols support low-latency audio transmission which ensures that the audio of all speakers will be in sync in a multi-channel application. These wireless audio transmitters normally work at 2.4 GHz. There are also some products such as Amphony’s line of wireless audio products that operate at 5.8 GHz. Products that work at 5.8 GHz have less competition from other wireless products than those utilizing the crowded 2.4 GHz frequency band.
These wireless amplifiers also differ in terms of amplifier output power, standby power consumption and audio quality. A high-quality audio amplifier is crucial for optimum sound quality. Digital Class-D amplifiers offer high power efficiency of a minimum of 80%. They also have low standby power, generally less than 5 Watts. This reduces heat and keeps them cool during operation. Some digital amplifiers, though, have fairly high harmonic distortion. Selecting a low-distortion amplifier is essential. Good-quality wireless amplifiers have audio distortion of lower than 0.05%.
Recent Technologies Make Setting Up Surround Sound Systems A Snap
The procedure of setting up multi-channel audio speakers in home theater systems is quite tedious and suppliers have invented new products and technologies such as wireless surround sound speakers or surround sound wireless”>http://www.amphony.com”>wireless headphones recently to help simplify the setup. I will take a look at several of the most recent technologies which were designed to make setting up home theater systems a snap. I will illustrate what to look out for when making your buying decision.
Historically, installing a TV would be swift since they would already come with built-in stereo speakers. This, on the other hand, has all changed with multi-channel sound. These days external speakers are used to create a surround sound effect. In case of 5.1 surround, 6 speakers are utilized: center, left and right front, left and right rear and a subwoofer. More recent 7.1 systems need a total quantity of 8 speakers by adding 2 extra side speakers.
Thus the installation of home theater products has turn out to be a fairly complex procedure. A lot of houses are not pre-wired for surround sound. In addition, long speaker cables are often unattractive. Part suppliers have designed a number of technologies to simplify the installation.
The first option is generating so-called virtual speakers by applying signal-processing to the audio and introducing phase shifts and special cues to those audio parts that would ordinarily be broadcast by the remote speakers. The signal processing is engineered based on how the human hearing determines the location of a sound. The audio signal is then sent by the front speakers. Due to the signal processing, the viewer is tricked into assuming the audio is coming from virtual remote surround loudspeakers.
This technology reduces the number of required speakers and eliminates long speaker cords but each human will process sound somewhat differently because of the shape of the ear. The signal processing of these virtual surround systems is based on a standard model which was measured with a standard ear. However, virtual surround will not work equally well for every person.
Wireless surround sound products are one more option for simplifying home speaker setups and normally include a transmitter module which connects to the source as well as wireless amplifiers which will connect to the remote speakers. This transmitter will generally come with line-level and also amplified loudspeaker inputs. Ideally it should come with a volume control to adjust it to the audio source.
Some wireless speaker devices are designed to connect 2 speakers per wireless amplifier. A superior option would come with a wireless amplifier for each remote loudspeaker to avoid the cable runs between each of the 2 remote speakers. Entry-level wireless products utilize FM transmission or audio compression which will deteriorate the sound quality to some extent. More advanced wireless kits utilize uncompressed digital audio broadcast. To make certain that all speakers are in sync in a multi-channel application, ensure that you pick a wireless system that has an audio latency of just a few milliseconds at most. A large latency would lead to an echo effect. This effect would deteriorate the surround effect. Many wireless products operate in the 900 MHz and 2.4 GHz frequency bands. Some products utilize the less crowded 5.8 GHz frequency band and consequently have less competition from other wireless gadgets.
A third technology uses side-reflecting loudspeakers. This method is referred to as sound bars. In this case the sound for the remote speakers will be broadcast by separate loudspeakers located at the front at an angle and reflected by walls as to seem to be coming from besides or behind the viewer. This method works best in a square room with minimum interior design and obstacles. It will not work well in many real-world scenarios with diverse room shapes though.
Wireless Surround Sound – The End Of Cable Clutter?
Recently more and more manufacturers have started to offer home theater systems with wireless speakers or a wireless surround sound kit. From a homeowners standpoint, eliminating long speaker cable runs is certainly a big plus. Multi-channel surround sound is a fairly new phenomenon and as such many older houses are not wired for rear speakers, not to mention 7.1 systems. As such a wireless solution might be the logical conclusion. But how reliable are these wireless surround sound kits in a real-world scenario and do these options really eliminate the dreaded cable clutter?
Some wireless surround sound kits, such as the LG or Rocketfish allow to connect 2 speakers to a wireless receiver unit. This eliminates the cables from the front to the back. However, still cables need to be run from the receiver to each speaker and as such the amount of cables is just reduced but not eliminated. Another wireless surround sound product from Amphony comes with separate receivers for each speaker which in comparison to the other products does reduce the cable clutter, albeit not eliminate cables completely.
Will the wireless have any effect on performance? Audio quality is a main concern. In picking a wireless system, one should choose a system where (a) the transmission itself does not pick up any noise or degradation in order to maintain the audio quality and (b) the wireless amplifier itself should be a high-quality amplifier with minimal distortion. Also, the size of the wireless speaker amplifier is a consideration as the receiver should be invisible.
In a surround sound application, such as a home theater setting, the audio from each speaker naturally should be in sync with the video and also with the audio of the other speakers. Some wireless surround sound kits, such as the product from Rocketfish, will introduce a significant delay to the signal. Therefore when choosing a wireless surround sound kit, it is important to look closely at how much latency the wireless unit will introduce. The Amphony product adds a little less than 1 ms delay which should be sufficiently low for pretty much any application.
One of the main issues with wireless devices of any sort is interference from other devices. As more and more consumer devices go wireless, the available frequency space becomes more and more limited. Especially the 900 MHz and 2.4 GHz bands are exceptionally crowded, due to WiFi hot spots, cell phones with Bluetooth etc. Picking a system that avoids these frequency bands may be the logical choice, such as systems working at 5.8 GHz.
While wireless speakers and wireless surround sound kits are suited for use in a home theater setting, their use is not limited to that application. In particular setting up speakers in another room often poses a challenge in terms of running speaker wires or using speakers outdoors. Just imagine being able to set up a speaker in your backyard in minutes. The possibilities are endless.
