HDTV TELEVISIONS

The newest range of wireless audio transmitter devices claims streaming of music throughout the house without limits. We will take a look at numerous products and technologies to find out in how far these products are practical for whole-house audio uses and what to look out for when buying a wireless system.

Getting audio from your living room to your bedroom can be quite a challenge in particular in houses which are not wired for audio. The following technologies are used by products solving this problem: infrared, RF, wireless LAN and powerline.

Infrared wireless audio products are restricted to line-of-sight applications, i.e. only operate within a single room because the signal is sent as infrared light which can’t penetrate walls. This technology is often found in wireless speaker kit products.

RF wireless products will send the signal as RF waves. These waves can without difficulty go through walls. RF wireless audio devices either utilize FM transmission or digital audio transmission. FM transmitters are the least expensive alternative. They offer good range but the music signal is prone to audio distortion and static and is extremely susceptible to interference from other wireless transmitters.

Products which employ digital wireless audio transmission use a digital protocol. Such products include transmitters from Amphony. In this protocol, before transmission the audio signal is converted to digital data. This method ensures that the audio quality is completely maintained. Some transmitters use some sort 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 maximum fidelity.

WLAN products are useful for broadcasting audio from a PC. However, wireless LAN was never designed for real-time audio streaming. As a consequence, products using WLAN will introduce some amount of delay to the signal. Also, a number of products require to buy separate wireless LAN modules that are plugged into every audio receiver.

Powerline products broadcast the audio by means of the power mains and provide great range. They run into problems in homes where there are separate mains circuits in terms of being able to cross over into another circuit. Powerline products have another challenge in the form of power surges and spikes which can cause transmission errors. To prevent audio dropouts, these products will commonly have an audio latency of several seconds as a safeguard.

Now we’ll give you some guidelines for shopping for a wireless system: Pick a system that supports multiple wireless receivers if you plan to stream audio to a number of rooms so that you don’t have to purchase a separate transmitter for each receiver. Some products have some sort of error correction built in which will help guard against dropouts in case of strong wireless interference. Select 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.

Select a transmitter that has all the audio inputs you need, such as speaker inputs, line-level RCA inputs etc. Pick a system where you can add receivers later on which provide all of the necessary outputs, e.g. amplified speaker outputs, RCA outputs etc. Because you may want to connect the transmitter to several sources, you should select a transmitter that can be adjusted to different signal volume levels to prevent clipping of the audio signal inside the transmitter converter stage.

Check that the system offers amplified receivers with a digital amplifier to ensure high power efficiency. This will help keep the receiver cool during operation. In addition, make sure the amplifier offers low audio distortion. This is important for good sound quality. Verify that the amplified receiver can drive speakers with the preferred Ohm rating and that it is small and easily mountable for simple installation. Devices which work in the 5.8 GHz frequency band will have less problems with wireless interference than products using the crowded 900 MHz or 2.4 GHz frequency band.

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