Latest-generation wireless surround sound kits such as iPods, iPhones and wireless surround sound products claim to cut the cable while delivering crystal-clear audio. I will investigate whether these products keep their claim to provide perfect-quality audio. In addition, I will take a look at the underlying technologies.
A few products are available with wireless already built in while others, specifically streaming audio products, frequently have optional wireless functionality. Latest generation iPods and mobile phones already come with built-in WiFi and Bluetooth support.
Bluetooth is fairly common as a low-cost wireless option. Nonetheless, Bluetooth does have some limitations. These weaknesses are frequently ignored but will have an effect on high-quality audio applications.
1) Short range
Bluetooth devices typically only have a 30-foot range which limits Bluetooth to single-room applications.
2) Audio compression due to restricted data rate
Bluetooth offers a maximum reliable data rate of around 1 Mbps only. This rate is not high enough to transmit uncompressed CD-quality audio. Therefore Bluetooth wireless devices utilize audio compression. Audio compression will degrade the audio quality to some degree. High-quality audio transmission normally does not tolerate this kind of distortion. As a result Bluetooth is typically not used in high-end audio products.
3) Audio latency
The audio will experience a delay of a minimum of 10 ms mostly because of the audio compression which is a problem for real-time audio applications but less serious for MP3 players.
4) No support of multiple headphones
Bluetooth does not support any number of headphones which may be a problem if you have a larger number of people who want to listen to headphones from a single transmitter device.
Another common protocol is WiFi which supports uncompressed audio but also has limitations simultaneously streaming to multiple receivers. Due to the high availability, WiFi is suitable for streaming audio from a PC. Yet, WiFi products have relatively high power consumption. For this reason wireless headphones generally do not use this technology.
While newest-generation wireless speakers and wireless amplifiers employ proprietary digital technologies, low-cost products regularly still depend on FM transmission which is noisy and has high audio degradation and high susceptibility to radio interference.
Newer wireless audio protocols avoid audio degradation by employing digital transmission. These frequently also come with mechanisms such as forward error correction to cope with interference from other wireless devices.
Sophisticated wireless amplifier devices support uncompressed digital audio streaming to preserve the original audio quality. A number of of these protocols permit streaming to an unlimited number of wireless amplifiers which is practical 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. Wireless audio transmitters usually work at 2.4 GHz or sometimes in the less crowded 5.8 GHz frequency band such as Amphony’s wireless audio devices.
These wireless amplifiers also differ in regard to amplifier output power, standby power consumption and audio quality. A high-quality audio amplifier is crucial for optimum sound quality. Wireless Class-D amplifiers generally have standby power of 5 Watts or less and a power efficiency of greater than 80% but sometimes high audio distortion. Audiophile wireless amplifiers offer an audio distortion of 0.05% or less.
You can find additional details concerning wireless surround sound system models at Amphony’s web page.