Technology Information

Recently more and more wireless audio transmitter products have emerged which promise to bring the ultimate freedom of broadcasting music throughout the home. We will look at the most widespread technologies for wireless audio and give some advice for choosing the best wireless audio product.

If your home is not wired for audio then you face quite a problem when you want to get your music from your living room to your bedroom. Frequently the audio source cannot be moved. Running speaker wires between rooms will be expensive and for that reason a lot of people are looking for other options. There are a number of technologies solving this problem. These include infrared wireless, RF wireless, wireless LAN (WLAN) and powerline.

Infrared wireless audio products are limited to line-of-sight applications, i.e. only work within a single room since the signal is broadcast as infrared light which can’t go through walls. This technology is often found in wireless speaker kit products.

RF wireless products broadcast the music as RF waves - either by using FM transmission or digital transmission - and can for that reason easily transmit through walls. FM transmitters are the cheapest alternative. They provide good range but the audio signal is prone to audio distortion and noise and is extremely susceptible to interference from other wireless transmitters.

Products utilizing digital wireless audio transmission, such as Amphony audio transmitter products, employ a digital protocol in which the audio is converted to a digital signal prior to transmission. This method ensures that the audio quality is entirely maintained. Some transmitters utilize some type of audio compression, such as Bluetooth transmitters, which will degrade the audio to some degree. Transmitters which send the audio data uncompressed will achieve the highest fidelity.

Wireless LAN (WLAN) products are useful when streaming from a PC but will add some amount of latency or delay to the signal because wireless LAN was not originally designed for real-time audio streaming. WLAN receivers usually require buying a separate LAN card to be plugged into every receiver.

Powerline products employ the power mains to distribute audio and provide great range but run into problems if there are individual mains circuits in the house in terms of crossing between circuits. Another problem confronting powerline products are strong power surges and spikes. Such surges can cause drpouts in the audio due to errors in the transmission. To safeguard against these errors, powerline products normally build a delay of several seconds into the transmission.

Here are some recommendations for selecting the optimum wireless audio system: Try to find a system that can run several wireless receivers from a single transmitter. Ideally an unlimited number of receivers should be supported. That way you don’t need to purchase additional transmitters when you begin adding receivers in different rooms of your house. Some devices have some type of error correction built in which will help guard against dropouts in case of strong wireless interference. Pick a digital RF audio transmitter to guarantee that the audio quality is maintained. Make sure the audio delay is less than 10 ms if you have a real-time application such as video.

Pick a transmitter that has all of the audio inputs you need, e.g. speaker inputs, RCA inputs etc. Make sure that you can purchase additional receivers later on as you expand your system. Check that you can get receivers with speaker outputs for connecting regular loudspeakers as well as receivers with line-level RCA outputs. Choose a transmitter that can adjust the audio volume of the input stage. This will give you the flexibility to connect the transmitter to any kind of equipment with different signal levels. Otherwise the audio may get clipped inside the transmitter converter stage or the dynamic range is not fully utilized.

For high amplifier power efficiency and best sound quality, check that the amplified receiver has a built-in low-distortion digital amplifier. Verify that the amplified receiver can drive speakers with the preferred Ohm rating and that it is small and easily mountable for easy installation. 5.8 GHz wireless products normally have less problems with interference from other wireless transmitters than products operating at 900 MHz or 2.4 GHz.