Recently more and more wireless audio transmitter products have appeared which promise to deliver the ultimate freedom of sending music throughout the home. We will look at numerous products and technologies to find out in how far these devices are useful for whole-house audio uses and what to look out for when buying a wireless system.
If your residence is not wired for audio then you face quite a challenge when you want to get your music from your living room to your bed room. Often the audio source cannot be moved. Running speaker wires between rooms will be costly and therefore many people are searching for alternatives. Devices which resolve this problem are commonly based on the following technologies: infrared wireless, RF wireless, wireless LAN or powerline.
Infrared products send the audio as lightwaves. Light cannot penetrate walls. Consequently products using infrared, such as wireless surround sound kits, are restricted to a single room.
RF wireless products send the audio as RF waves - either by using FM transmission or digital transmission - and can therefore without problems transmit through walls. The least expensive option is FM transmission. Products utilizing FM transmission, however, have a number of drawbacks. These include degradation of the audio quality due to noise or hiss and audio distortion. In addition, FM transmitter products are also rather susceptible to interference from other wireless transmitters.
Products which employ digital wireless audio transmission utilize a digital protocol. Such products include transmitters from Amphony. In this protocol, prior to transmission the audio signal is converted to digital data. Some wireless audio transmitters will utilize audio compression, such as Bluetooth transmitters which will reduce the audio quality to some degree. Digital wireless audio transmitters which send the audio uncompressed provide the highest audio fidelity.
Products utilizing wireless LAN are useful when streaming audio from a PC. Their disadvantage is that they typically have some fairly high latency, i.e. the signal will be delayed by some amount since wireless LAN was not particularly designed for real-time audio streaming. WLAN receivers often do not have built-in network access. As a result, such products frequently require buying separate LAN cards. These cards are then plugged into every receiver.
Powerline products broadcast the audio by means of the power mains and provide large range. They run into trouble in houses where there are individual mains circuits in terms of being able to cross over into another circuit. Another problem facing powerline products are strong power surges and spikes. Such surges can bring about drpouts in the audio due to errors in the transmission. To safeguard against these errors, powerline products typically build a delay of several seconds into the transmission.
Here are some suggestions 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 extra transmitters when you begin adding receivers in different rooms of your house. Selecting a product with some sort of error correction will help mitigate against strong RF interference. Such interference can be brought on by other wireless transmitters. Pick a digital RF transmitter to preserve the original audio quality, ideally one with an audio latency of less than 10 ms in case of video or other time-sensitive applications.
Pick a transmitter that has all of the audio inputs you require, e.g. speaker inputs, RCA inputs etc. Pick a system where you can add receivers later on which offer all of the necessary outputs, e.g. amplified speaker outputs, RCA outputs etc. If you go with a digital audio transmitter, pick one with an input audio level control knob to prevent the music signal from clipping inside the transmitter audio converter. This will ensure optimum dynamic range regardless of the signal level of your equipment.
For high amplifier power efficiency and best sound quality, confirm that the amplified receiver has a built-in low-distortion digital amplifier. Select a system which offers receivers that can drive speakers with the desired Ohm rating. Make sure the receivers have a small form factor and are easily mountable. This will help during the installation. Products using the less crowded 5.8 GHz frequency band will normally have less problems with wireless interference than 900 MHz or 2.4 GHz devices.