Latest-generation wireless surround sound transmitters such as iPods, iPhones and wireless surround sound products promise to cut the cord while delivering crystal-clear audio. I will take a look at several of the newest gadgets and technologies to see how well they operate and in which conditions they operate best.
A number of products are available with wireless already built in while some others, specifically streaming audio products, often have optional wireless capability. Recent touch-screen iPods and iPhones already have WiFi and Bluetooth built in.
The Bluetooth protocol is a relatively low-cost option. However, its limitations have an effect on high-quality audio applications and are often ignored.
1) Short range
Bluetooth generally merely offers a 30 foot range. This is satisfactory for single-room applications. On the other hand, this limiting factor does not permit multi-room streaming using Bluetooth.
2) Audio compression due to limited data rate
Bluetooth provides a maximum reliable data rate of approximately 1 Mbps only. This rate is not high enough to transmit uncompressed CD-quality audio. As a result Bluetooth wireless devices utilize audio compression. This is less critical however for compressed audio such as MP3 audio but excludes Bluetooth from use in high-quality audio applications.
3) Audio delay
The signal sent via Bluetooth will bear a small delay of at least 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 cannot stream to multiple headphones at the same time. This might be a dilemma in cases where several people like to listen to the same Bluetooth transmitter.
WiFi is an additional widely used wireless protocol that is also suitable for audio streaming. WiFi does support uncompressed audio but will have limitations transmitting to a large number of wireless receivers at the same time. It is practical for streaming music from a PC due to the high availability but is generally not utilized in wireless headphone products because of the relatively high power consumption of WiFi.
Home wireless speaker products and wireless amplifiers usually utilize proprietary protocols. These protocols are specifically engineered for real-time audio applications. On the other hand, low-cost wireless speakers and headphones still employ FM transmission. FM transmission suffers from relatively high audio degradation and noise / static.
More advanced wireless protocols are based on digital formats which get rid of audio distortion and incorporate advanced features including error correction to cope with interference from competing wireless devices.
Latest-generation wireless amplifiers utilize uncompressed audio transmission. New protocols also allow streaming to an unlimited number of receivers. This enables 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 regarding amplifier output power, standby power consumption and audio quality. A high-quality audio amplifier is critical for optimal sound quality. Digital amplifiers usually offer a power efficiency of a minimum of 80% and standby power consumption of less than 5 Watts which keeps them cool during operation and helps save energy. However, some Class-D amps have relatively high audio distortion. It is crucial to choose a wireless amplifier with low audio distortion. This will ensure good sound quality. High-quality amplifiers have audio distortion of 0.05% or less.