A Few Recommendations For Choosing Wireless Loudspeakers

Let me have a look at the word “power efficiency” that lets you know how much wireless loudspeakers squander to aid you to select a pair of cordless loudspeakers.

Several issues are the result of cordless speakers that have low power efficiency: Low-efficiency wireless loudspeakers will squander a certain amount of energy as heat and so are more expensive to operate when compared with high-efficiency models due to their greater energy consumption. Heat will not dissipate well through tiny surfaces. Consequently low-efficiency wireless speakers must use heat sinks. Heat sinks as well as fans are heavy, consume room and also produce noise. Cordless loudspeakers with low efficiency can not be put into tight spaces or inside sealed enclosures as they need a good amount of circulation. Wireless speakers with small efficiency need a bigger power supply to output the identical amount of music power as high-efficiency types. An increased level of heat causes further stress on elements. The life expectancy of the cordless loudspeakers could be lowered and reliability could be compromised. High-efficiency cordless loudspeakers in contrast don’t suffer from these issues and can be built very small.

The power efficiency is displayed as a percentage in the wireless speakers data sheet. Various amp topologies deliver different power efficiencies. Class-A amplifiers are usually the least efficient and Class-D the most efficient. Normal power efficiencies range between 25% to 98%. The higher the efficiency figure, the less the amount of power squandered as heat. A 100-Watt amp which has a 50% efficiency would have a power consumption of 200 W. What is less known about efficiency is the fact that this figure isn’t fixed. Actually it differs depending on how much energy the amp offers. For that reason in some cases you will discover efficiency figures for several energy levels in the data sheet. Every music amp will consume a specific amount of energy regardless of whether or not it supplies any kind of power to the loudspeaker. Because of this the smaller the power the amplifier delivers, the lower the power efficiency. For this reason audio producers normally specify the efficiency for the highest audio power that the amplifier can deliver. In order to figure out the efficiency, the audio energy that is consumed by a power resistor which is attached to the amplifier is divided by the total energy the amplifier utilizes whilst being fed a constant sine wave tone. Ordinarily a full power report is plotted to display the dependency of the efficiency on the output power. For this reason the output power is swept through several values. The efficiency at each value is tested plus a power efficiency graph generated.

Wireless speakers that employ switching-mode amplifiers have a switching stage that causes some amount of non-linear behavior. Therefore bluetooth outdoor loudspeakers that use Class-D amps usually offer smaller audio fidelity than types utilizing analog Class-A amplifiers. Subsequently you will need to base your decision on whether you need small dimensions and low energy consumption or maximum music fidelity. Then again, digital amps have come a long way and are providing improved audio fidelity than in the past. Wireless speakers that use Class-T amps come close to the audio fidelity of products that contain analog amplifiers. Therefore selecting a set of cordless speakers which utilize switching amp with good music fidelity is now feasible.


Just How Do Advanced Wireless Speakers Overcome Interference?

I’ll take a look at just how modern sound transmission systems which are employed in nowaday’s wireless speakers operate in real-world environments with a large amount of interference from other wireless devices. The most popular frequency bands which are used by wireless devices include the 900 MHz, 2.4 Gigahertz and 5.8 GHz frequency band. Primarily the 900 MHz and also 2.4 Gigahertz frequency bands have started to become crowded by the increasing amount of products such as wireless speakers, cordless phones and so forth. Customary FM transmitters generally operate at 900 MHz and don’t have any specific means of coping with interference yet changing the transmit channel is a strategy to cope with interfering transmitters. Digital audio transmission is generally used by modern-day sound products. Digital transmitters normally work at 2.4 Gigahertz or 5.8 Gigahertz. The signal bandwidth is higher than 900 MHz transmitters and thus competition in these frequency bands is high. Quite a few cordless systems for example Bluetooth products along with wireless telephones use frequency hopping. Hence just changing the channel won’t steer clear of these types of frequency hoppers. Real-time audio has quite rigid requirements with regards to dependability and low latency. In order to offer those, other means are required. One technique is known as FEC or forward error correction. This approach enables the receiver to repair a damaged signal. For this purpose, supplemental data is transmitted from the transmitter. From this additional data, the receiver can restore the original information whether or not the signal was corrupted to some degree. FEC is unidirectional. The receiver does not send back any kind of data to the transmitter. As a result it is often used by products just like radio receivers in which the number of receivers is large.

A different technique employs bidirectional transmission, i.e. every receiver sends data to the transmitter. This strategy is only helpful if the number of receivers is small. Additionally, it requires a back channel to the transmitter. The information which is transmit has a checksum. From this checksum the receiver may detect whether any particular packet was received correctly and acknowledge. As lost packets will have to be resent, the transmitter and receivers have to store information packets in a buffer. This will create an audio latency, often called delay, to the transmission which is often a dilemma for real-time protocols including audio. Normally, the greater the buffer is, the greater the robustness of the transmission. Video applications, however, need the audio to be in sync with the video. In such cases a large latency is a problem. Devices that incorporate this particular procedure, nevertheless, are restricted to transmitting to a small number of receivers and the receivers consume more energy.

Often a frequency channel may become occupied by another transmitter. Ideally the transmitter can realize this fact and change to a different channel. To achieve this, a few wireless speakers continuously check which channels are available so that they can instantly switch to a clean channel. Considering that the transmitter has a list of clear channels, there is no delay in trying to find a clear channel. It is simply picked from the list. This approach is frequently termed adaptive frequency hopping spread spectrum.