Lately a large number of wireless audio products have emerged such as latest-generation wireless headphones, iPods, cell phones and wireless amplifier products which promise to cut the cord. I will take a look at some of the newest gadgets and technologies to find out how well they work and in which situations they work best.
Some products come with wireless already built in while others, in particular streaming audio products, often have optional wireless capability. Newest touch-screen iPods and iPhones already have WiFi and Bluetooth built in.
Bluetooth is a fairly low-cost solution but has some drawbacks which are often overlooked.
1) Limited range
Bluetooth devices typically only have a 30-foot range which limits Bluetooth to single-room applications.
2) Audio compression due to limited data rate
Bluetooth will apply audio compression since it does not reliably offer a high-enough data rate for uncompressed audio. Audio compression will degrade the audio quality to some extent. High-quality audio transmission typically does not tolerate this type of degradation. Therefore Bluetooth is normally not used in high-end audio products.
3) Audio latency
Due to audio compression, Bluetooth will introduce a signal delay of at least 10 ms which will cause the audio to be slightly out of sync in case of video and real-time applications. This is again less of a problem for MP3 players.
4) No multiple headphone support
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 problems simultaneously streaming to multiple receivers. It is convenient for streaming music from a PC due to the high availability but is normally not used in wireless headphone products due to the relatively high power consumption of WiFi.
Wireless speakers and wireless amplifier products for home theater speakers typically use their own proprietary protocol. Entry-level wireless headphones and speakers typically still use FM transmission which offers low cost but is prone to noise and audio distortion.
More advanced wireless protocols are based on digital formats which eliminate audio degradation and incorporate advanced features such as error correction to cope with interference from competing wireless devices.
Advanced wireless amplifier devices support uncompressed digital audio streaming to preserve the original audio quality. Some of these protocols allow streaming to an unlimited number of wireless amplifiers which is convenient for whole-house audio distribution. The audio latency ranges from below 1 ms to up to 20 ms. A small latency is important for wireless surround sound applications. These wireless audio transmitters typically work at 2.4 GHz. There are also some products such as Amphony's line of wireless audio products which work at 5.8 GHz. Products that operate at 5.8 GHz have less competition from other wireless devices than those using the crowded 2.4 GHz frequency band.
Wireless amplifiers offer different levels of audio quality, output power and standby power. Wireless Class-D amplifiers normally have standby power of 5 Watts or less and a power efficiency of greater than 80% but sometimes high audio distortion. Picking a low-distortion amplifier is key. Good-quality wireless amplifiers have audio distortion of less than 0.05%.
Some products come with wireless already built in while others, in particular streaming audio products, often have optional wireless capability. Newest touch-screen iPods and iPhones already have WiFi and Bluetooth built in.
Bluetooth is a fairly low-cost solution but has some drawbacks which are often overlooked.
1) Limited range
Bluetooth devices typically only have a 30-foot range which limits Bluetooth to single-room applications.
2) Audio compression due to limited data rate
Bluetooth will apply audio compression since it does not reliably offer a high-enough data rate for uncompressed audio. Audio compression will degrade the audio quality to some extent. High-quality audio transmission typically does not tolerate this type of degradation. Therefore Bluetooth is normally not used in high-end audio products.
3) Audio latency
Due to audio compression, Bluetooth will introduce a signal delay of at least 10 ms which will cause the audio to be slightly out of sync in case of video and real-time applications. This is again less of a problem for MP3 players.
4) No multiple headphone support
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 problems simultaneously streaming to multiple receivers. It is convenient for streaming music from a PC due to the high availability but is normally not used in wireless headphone products due to the relatively high power consumption of WiFi.
Wireless speakers and wireless amplifier products for home theater speakers typically use their own proprietary protocol. Entry-level wireless headphones and speakers typically still use FM transmission which offers low cost but is prone to noise and audio distortion.
More advanced wireless protocols are based on digital formats which eliminate audio degradation and incorporate advanced features such as error correction to cope with interference from competing wireless devices.
Advanced wireless amplifier devices support uncompressed digital audio streaming to preserve the original audio quality. Some of these protocols allow streaming to an unlimited number of wireless amplifiers which is convenient for whole-house audio distribution. The audio latency ranges from below 1 ms to up to 20 ms. A small latency is important for wireless surround sound applications. These wireless audio transmitters typically work at 2.4 GHz. There are also some products such as Amphony's line of wireless audio products which work at 5.8 GHz. Products that operate at 5.8 GHz have less competition from other wireless devices than those using the crowded 2.4 GHz frequency band.
Wireless amplifiers offer different levels of audio quality, output power and standby power. Wireless Class-D amplifiers normally have standby power of 5 Watts or less and a power efficiency of greater than 80% but sometimes high audio distortion. Picking a low-distortion amplifier is key. Good-quality wireless amplifiers have audio distortion of less than 0.05%.
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You can get additional information regarding wireless audio products at Amphony's website.
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