A Peek At A Few Of The Latest Wireless Audio Gizmos

Lately a great number of wireless audio products have appeared such as latest-generation wireless headphones, iPods, cell phones and wireless amplifier products that promise to cut the cord. I will examine if these products keep their claim to deliver perfect-quality audio. Moreover, I will take a look at the underlying technologies.

These products fall into 2 categories. The first sort of devices already has wireless built in. Second-category products, such as some streaming audio devices, have optional wireless ability. Generally they have a slot to insert a wireless LAN card. Newest generation iPods and cell phones already come with built-in WiFi and Bluetooth support.

Bluetooth is relatively common as a low-cost wireless solution. However, Bluetooth does have some limitations. These weaknesses are often overlooked but will have an influence on high-quality audio applications.

1) Short range

The range of Bluetooth devices is normally merely 30 ft. This excludes Bluetooth from multi-room applications.

2) Limited data transmission capacity

Bluetooth provides a maximum reliable data rate of around 1 Mbps only. This rate is not large enough to send 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) Signal latency

The signal transmitted via Bluetooth will undergo a slight delay of a minimum of 10 ms. This is for the most part due to the audio compression. While being uncritical for MP3 players, this delay may be a dilemma for video and other real-time applications.

4) No support of multiple headphones

Bluetooth does not support any number of headphones which might be a dilemma if you have a larger number of people who want to listen to headphones from a single transmitter device.

WiFi is another widely used wireless protocol that is also suitable for audio streaming. WiFi does support uncompressed audio but will have problems transmitting to a large number of wireless receivers simultaneously. It is practical for streaming music from a PC as a result of the high availability but is usually not utilized in wireless headphone devices due to the fairly high power consumption of WiFi.

While newest-generation wireless speakers and wireless amplifier products employ proprietary digital technologies, low-cost devices often still depend on FM transmission which is noisy and has high audio distortion and high susceptibility to radio interference.

Newer wireless audio protocols eliminate audio degradation by employing digital transmission. These often also have mechanisms such as forward error correction to deal with interference from other wireless devices.

Latest-generation wireless amplifiers employ uncompressed audio transmission. New protocols also allow streaming to an infinite number of receivers. This allows whole-house audio distribution.

The audio latency of these wireless amplifiers is normally between 1 ms and 20 ms. A small-latency amplifier is important for home theater audio. This ensures that all speakers will be in sync. Wireless audio transmitter products generally operate at 2.4 GHz or sometimes in the less crowded 5.8 GHz frequency band including Amphony’s wireless audio products.

These wireless amplifiers also differ regarding amplifier output power, standby power consumption and audio quality. A high-quality audio amplifier is vital for optimum sound quality. Digital Class-D amplifiers offer high power efficiency of not less than 80%. They also have low standby power, generally less than 5 Watts. This minimizes heat and keeps them cool during operation. Some digital amplifiers, however, have fairly high harmonic distortion. It is vital to choose a wireless amplifier with low audio distortion. This will guarantee good sound quality. High-quality amplifiers have audio distortion of 0.05% or less.