Lately a large number of wireless audio devices have emerged such as latest-generation wireless headphones, iPods, cell phones and wireless amplifier products which claim to cut the cord. We will take a look at some of the latest products to learn which applications they work for.

A few products are available with wireless already built in while some others, specifically streaming audio products, frequently have optional wireless functionality. Latest generation iPods and cell phones already come with built-in WiFi and Bluetooth support.

Bluetooth is a fairly low-cost solution but has some pitfalls which are regularly ignored.

1) Short range

Bluetooth normally just offers a 30 foot range. This is adequate for single-room applications. Yet, this limiting factor does not allow multi-room streaming using Bluetooth.

2) Small data rate - audio compression

Bluetooth provides a maximum reliable data rate of roughly 1 Mbps only. This rate is not large enough to send uncompressed CD-quality audio. Consequently Bluetooth wireless devices apply audio compression. Audio compression will degrade the audio quality to some extent. High-quality audio transmission usually does not tolerate this sort of distortion. As a result Bluetooth is usually not used in high-end audio devices.

3) Signal latency

The audio will experience a delay of a minimum of 10 ms mostly due to the audio compression which is a dilemma for real-time audio applications but less serious for MP3 players.

4) No multiple headphone support

Bluetooth is fairly limited in regard to supporting streaming to numerous headphones. Streaming to multiple headphones is helpful for numerous people wanting to listen to the same transmitter. This is less of a dilemma for MP3 player applications.

Another common protocol is WiFi which supports uncompressed audio but also has drawbacks simultaneously streaming to multiple receivers. It is suitable for streaming music from a PC because of the high availability but is normally not utilized in wireless headphone products as a result of the fairly high power consumption of WiFi.

Home wireless speaker devices and wireless amplifiers generally employ proprietary protocols. These protocols are specifically designed for real-time audio applications. However, low-cost wireless speakers and headphones still use FM transmission. FM transmission suffers from relatively high audio deterioration and noise / static.

More advanced wireless protocols are based on digital formats which eliminate audio distortion and incorporate sophisticated features like error correction to cope with interference from competing wireless devices.

Newest-generation wireless amplifiers permit streaming to an infinite number of receivers and support uncompressed audio transmission.

The audio latency of these wireless amplifiers is usually between 1 ms and 20 ms. A small-latency amplifier is vital for home theater audio. This assures that all speakers will be in sync. These wireless audio transmitters normally work at 2.4 GHz. There are also some devices such as Amphony’s line of wireless audio devices which operate 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.

These wireless amplifiers also differ in regard to amplifier output power, standby power consumption and audio quality. A high-quality audio amplifier is vital for optimum sound quality. Wireless Class-D amplifiers usually have standby power of 5 Watts or less and a power efficiency of larger than 80% but sometimes high audio distortion. Selecting a low-distortion amplifier is crucial. Good-quality wireless amplifiers have audio distortion of less than 0.05%.

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