Latest wireless audio gizmos such as iPods, wireless headphones and cell phones support new wireless protocols. These protocols are supposed to eliminate the cord and provide perfect high-fidelity audio. We will examine some of the most recent devices to figure out which applications they work for.
Several products come with wireless already built in while others, particularly streaming audio products, frequently have optional wireless functionality. Modern cell phones and MP3 players already come with support for wireless. iPhones and touch-screen iPods, for instance, have Bluetooth and WiFi.
The Bluetooth protocol is a fairly low-cost solution. Still, its limitations have an effect on high-quality audio applications and are often overlooked.
1) Short range
Bluetooth usually just provides a 30 foot range. This is sufficient for single-room applications. On the other hand, this limitation does not permit multi-room streaming utilizing Bluetooth.
2) Audio compression resulting from limited data rate
Bluetooth will use audio compression because it does not reliably offer a high-enough data rate for uncompressed audio. The audio will be degraded to some degree as a result of the audio compression. For this reason higher-end audio equipment generally does not use Bluetooth wireless audio.
3) Signal latency
The signal broadcast via Bluetooth will undergo a slight delay of no less than 10 ms. This is mostly 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 is relatively limited in regard to supporting streaming to multiple headphones. Streaming to multiple headphones is useful for numerous people wanting to listen to the same transmitter. This is less of a problem for MP3 player applications.
Uncompressed audio streaming is supported by WiFi. WiFi is a very widespread protocol. Yet, WiFi also has limitations regarding simultaneous transmission to several receivers. Due to the high availability, WiFi is suitable for streaming audio from a PC. However, WiFi products have relatively high power consumption. Because of this wireless headphones usually do not utilize this technology.
Wireless speakers and wireless amplifier products for home theater speakers typically utilize their own proprietary protocol. Entry-level wireless headphones and speakers usually still utilize 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 distortion and incorporate sophisticated features including error correction to cope with interference from competing wireless devices.
Latest-generation wireless amplifiers employ uncompressed audio transmission. Recent protocols also allow streaming to an infinite number of receivers. This allows whole-house audio distribution.
Some of these protocols support low-latency audio transmission which ensures that the audio of all speakers will be in sync in a multi-channel application. Wireless audio transmitter products typically operate at 2.4 GHz or sometimes in the less crowded 5.8 GHz frequency band including Amphony’s wireless audio devices.
Wireless amplifiers are available with different levels of audio quality, power consumption and standby power. Getting a high-quality low-distortion amplifier is fundamental for good sound quality. Digital Class-D amplifiers offer high power efficiency of a minimum of 80%. They also have low standby power, typically less than 5 Watts. This reduces heat and keeps them cool during operation. Some digital amplifiers, however, have fairly high harmonic distortion. It is vital to select a wireless amplifier with low audio distortion. This will ensure good sound quality. High-quality amplifiers have audio distortion of 0.05% or less.