Latest-generation wireless audio products such as iPods, iPhones
and wireless surround sound products promise to cut the cord while
delivering crystal-clear audio. We will look at some of the most recent
products to find out which applications they work for.
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 fairly common as a low-cost wireless solution. However, Bluetooth does have some drawbacks. These weaknesses are often overlooked but will have an impact on high-quality audio applications.
1) Short range
The range of Bluetooth devices is typically only 30 ft. This excludes Bluetooth from multi-room applications.
2) Limited data transmission capacity
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 delay
The audio will experience a delay of at least 10 ms mostly due to the audio compression which is a problem for real-time audio applications but less critical for MP3 players.
4) No support of multiple headphones
Bluetooth cannot stream to multiple headphones at the same time. This may be a problem in cases where several people want to listen to the same Bluetooth transmitter.
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.
Home wireless speaker products and wireless amplifiers normally use proprietary protocols. These protocols are specially designed for real-time audio applications. However, entry-level wireless speakers and headphones still use FM transmission. FM transmission suffers from fairly high audio distortion and hiss / static.
More recent wireless audio protocols are based on digital transmission. This avoids audio degradation. Some protocols also incorporate error correction to deal with interference from other wireless devices.
Newest-generation wireless amplifiers allow streaming to an unlimited number of receivers and support uncompressed audio transmission.
The audio latency of these wireless amplifiers is normally between 1 ms and 20 ms. A small-latency amplifier is critical for home theater audio. This ensures that all speakers will be in sync. Wireless audio transmitters typically work at 2.4 GHz or sometimes in the less crowded 5.8 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 fairly common as a low-cost wireless solution. However, Bluetooth does have some drawbacks. These weaknesses are often overlooked but will have an impact on high-quality audio applications.
1) Short range
The range of Bluetooth devices is typically only 30 ft. This excludes Bluetooth from multi-room applications.
2) Limited data transmission capacity
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 delay
The audio will experience a delay of at least 10 ms mostly due to the audio compression which is a problem for real-time audio applications but less critical for MP3 players.
4) No support of multiple headphones
Bluetooth cannot stream to multiple headphones at the same time. This may be a problem in cases where several people want to listen to the same Bluetooth transmitter.
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.
Home wireless speaker products and wireless amplifiers normally use proprietary protocols. These protocols are specially designed for real-time audio applications. However, entry-level wireless speakers and headphones still use FM transmission. FM transmission suffers from fairly high audio distortion and hiss / static.
More recent wireless audio protocols are based on digital transmission. This avoids audio degradation. Some protocols also incorporate error correction to deal with interference from other wireless devices.
Newest-generation wireless amplifiers allow streaming to an unlimited number of receivers and support uncompressed audio transmission.
The audio latency of these wireless amplifiers is normally between 1 ms and 20 ms. A small-latency amplifier is critical for home theater audio. This ensures that all speakers will be in sync. Wireless audio transmitters typically work at 2.4 GHz or sometimes in the less crowded 5.8 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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