| Lately a large number of wireless audio products | | | | wireless receivers simultaneously. Due to the fairly |
| have emerged such as latest-generation wireless | | | | high power consumption it is rarely used in |
| headphones, iPods, cell phones and wireless | | | | wireless headphones though. WiFi is convenient for |
| amplifier products which promise to cut the cord. I | | | | streaming audio from a PC however since almost |
| will take a look at some of the newest gadgets | | | | all PCs have WiFi access. |
| and technologies to find out how well they work | | | | Wireless speakers and wireless amplifier products |
| and in which situations they work best. | | | | for home theater speakers typically use their own |
| Products can be categorized into products with | | | | proprietary protocol. Entry-level wireless |
| built-in and those with optional wireless capability. | | | | headphones and speakers typically still use FM |
| Streaming audio products will often have a plug-in | | | | transmission which offers low cost but is prone to |
| slot for adding a wireless LAN card. Latest | | | | noise and audio distortion. |
| generation iPods and cell phones already come | | | | More advanced wireless protocols are based on |
| with built-in WiFi and Bluetooth support. | | | | digital formats which eliminate audio degradation |
| Bluetooth is a fairly low-cost solution but has | | | | and incorporate advanced features such as error |
| some drawbacks which are often overlooked. | | | | correction to cope with interference from |
| 1) Limited range | | | | competing wireless devices. |
| Bluetooth devices typically only have a 30-foot | | | | Advanced wireless amplifier devices support |
| range which limits Bluetooth to single-room | | | | uncompressed digital audio streaming to preserve |
| applications. | | | | the original audio quality. Some of these protocols |
| 2) Low data rate - audio compression | | | | allow streaming to an unlimited number of wireless |
| Bluetooth reliably supports data transmission rates | | | | amplifiers which is convenient for whole-house |
| of around 1 Mbps only which is not enough for | | | | audio distribution. |
| uncompressed CD-quality audio. Therefore | | | | The audio latency ranges from below 1 ms to up |
| Bluetooth applies audio compression. This is less | | | | to 20 ms. A small latency is important for wireless |
| critical though for compressed audio such as MP3 | | | | surround sound applications. These wireless audio |
| audio but excludes Bluetooth from use in | | | | transmitters typically work at 2.4 GHz. There are |
| high-quality audio applications. | | | | also some products which work at 5.8 GHz. |
| 3) Audio latency | | | | Products that operate at 5.8 GHz have less |
| Due to audio compression, Bluetooth will introduce | | | | competition from other wireless devices than |
| a signal delay of at least 10 ms which will cause | | | | those using the crowded 2.4 GHz frequency band. |
| the audio to be slightly out of sync in case of | | | | These wireless amplifiers also differ in terms of |
| video and real-time applications. This is again less | | | | amplifier output power, standby power |
| of a problem for MP3 players. | | | | consumption and audio quality. A high-quality audio |
| 4) No multiple headphone support | | | | amplifier is vital for optimum sound quality. Digital |
| Bluetooth does not support any number of | | | | amplifiers typically offer a power efficiency of at |
| headphones which may be a problem if you have | | | | least 80% and standby power consumption of |
| a larger number of people who want to listen to | | | | less than 5 Watts which keeps them cool during |
| headphones from a single transmitter device. | | | | operation and helps save energy. However, some |
| WiFi is another widely used wireless protocol that | | | | Class-D amps have fairly high audio distortion. |
| is also suitable for audio streaming. WiFi does | | | | Audiophile wireless amplifiers offer an audio |
| support uncompressed audio but will have | | | | distortion of 0.05% or less. |
| problems transmitting to a large number of | | | | |