Selecting A Pair Of Efficient Wireless Speakers

I am going to take a look at the phrase “power efficiency” which lets you know how much wireless loudspeakers waste to help you select a set of wireless loudspeakers.

Various problems are the result of cordless loudspeakers which have low power efficiency: A lot of squandered energy naturally will mean larger operating cost which means that a more expensive pair of wireless speakers can actually in the long term possibly be less costly when compared to a cheaper type with lower efficiency. Lower efficiency wireless loudspeakers will dissipate a whole lot of energy as heat. Cordless loudspeakers that have lower power efficiency typically have several heat sinks to help dissipate the wasted energy. Heat sinks and fans demand room and are costly. The cordless loudspeakers thus is going to turn out to be rather large and expensive. Furthermore heat fans are going to produce operating noise. Low-efficiency wireless speakers further require a great deal of circulation around the wireless speakers. Consequently they cannot be placed in close spaces or inside air-tight enclosures.

Low-efficiency versions need more overall power to output the identical level of audio power as high-efficiency types. As a result they need a bigger power supply which makes the wireless loudspeakers more costly to produce. An elevated level of heat brings about extra stress on components. The lifespan of the wireless loudspeakers could be reduced and reliability might be jeopardized. High-efficiency cordless loudspeakers however tend not to endure these problems and may be designed small.

You should look for the efficiency value whilst on the lookout for a set of cordless speakers. The best spot to look is the bluetooth outdoor loudspeakers data sheet. Efficiency is generally displayed in percent. Different amplifier architectures deliver different power efficiencies. Class-A amps are amongst the least efficient and Class-D the most efficient. Typical power efficiencies range between 25% to 98%. From the efficiency percentage it is possible to work out just how much power the amplifier is going to waste. An amplifier with a 50% efficiency will squander half of the used power. An amplifier with 90% efficiency is going to waste 10%. Take note, however, that efficiency depends on how much energy the amp provides at a given moment. Every music amplifier will consume a certain amount of power regardless of whether or not it supplies any power to the speaker. For that reason the smaller the power the amplifier delivers, the lower the efficiency. For that reason audio makers generally specify the efficiency for the greatest audio power that the amplifier can provide.

In order to measure the power efficiency, typically a test signal of 1 kHz is fed into the amp and a power resistor connected to the amp output to imitate the speaker load. Then the amplifier output signal is tested and the wattage calculated which the amplifier delivers to the load which is then divided by the total energy the amplifier utilizes. Ordinarily a full power profile is plotted in order to display the dependency of the efficiency on the output power. This is why the output power is swept through several values. The power efficiency at every value is tested and a power efficiency graph generated. While switching (Class-D) amplifiers have among the largest power efficiency, they have a tendency to have larger music distortion than analog audio amplifiers and smaller signal-to-noise ratio. As a result you are going to need to weigh the size of the cordless loudspeakers against the music fidelity. However, digital amplifiers have come a long way and are providing improved audio fidelity than ever before. Cordless loudspeakers which employ Class-T amplifiers come close to the audio fidelity of products that contain analog amplifiers. Therefore choosing a couple of wireless speakers which utilize switching amp with great audio fidelity is now feasible.

A Short Overview Of Music Amps

Stereo amplifiers are at the very heart of each home theater product. As the quality and output power demands of today’s loudspeakers increase, so do the requirements of mini stereo amps. There is a big amount of amplifier designs and types. All of these vary regarding performance. I will explain some of the most popular amp terms such as “class-A”, “class-D” and “t amps” to help you figure out which of these amps is best for your application. Furthermore, after understanding this guide you should be able to comprehend the amp specs which producers show.

Simply put, the purpose of an audio amplifier is to translate a low-power music signal into a high-power audio signal. The high-power signal is big enough to drive a loudspeaker sufficiently loud. To do that, an amplifier uses one or more elements that are controlled by the low-power signal to create a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.

Tube amplifiers were frequently used a couple of decades ago and utilize a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. Sadly, tube amplifiers have a reasonably high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. Though, this characteristic of tube amps still makes these popular. A lot of people describe tube amps as having a warm sound versus the cold sound of solid state amps. A different drawback of tube amplifiers, however, is the low power efficiency. The bulk of power that tube amplifiers consume is being dissipated as heat and only a fraction is being converted into audio power. Yet another drawback is the big price tag of tubes. This has put tube amps out of the ballpark for the majority of consumer devices. As a result, the majority of audio products these days utilizes solid state amps. I am going to describe solid state amplifiers in the subsequent sections.

Solid-state amps utilize a semiconductor element, like a bipolar transistor or FET rather than the tube and the earliest kind is generally known as “class-A” amps. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps employ a feedback mechanism in order to reduce the harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest amongst all types of music amplifiers. These amps also typically exhibit quite low noise. As such class-A amplifiers are ideal for very demanding applications in which low distortion and low noise are vital. However, similar to tube amplifiers, class-A amplifiers have quite low power efficiency and the majority of the power is wasted.

Class-AB amps improve on the efficiency of class-A amplifiers. They employ a number of transistors in order to split up the large-level signals into two separate areas, each of which can be amplified more efficiently. Because of the larger efficiency, class-AB amplifiers do not need the same number of heat sinks as class-A amps. Therefore they can be made lighter and cheaper. When the signal transitions between the two separate regions, however, a certain level of distortion is being produced, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amplifiers.

Class-D amplifiers are able to attain power efficiencies higher than 90% by making use of a switching transistor which is continuously being switched on and off and therefore the transistor itself does not dissipate any heat. The on-off switching times of the transistor are being controlled by a pulse-with modulator (PWM). Standard switching frequencies are between 300 kHz and 1 MHz. This high-frequency switching signal needs to be removed from the amplified signal by a lowpass filter. Normally a straightforward first-order lowpass is being utilized. Both the pulse-width modulator and the transistor have non-linearities that result in class-D amps having larger audio distortion than other types of amplifiers.

In order to resolve the problem of large audio distortion, new switching amplifier styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. A well-known architecture that uses this kind of feedback is generally known as “class-T”. Class-T amps or “t amps” achieve audio distortion which compares with the audio distortion of class-A amps while at the same time having the power efficiency of class-D amps. Thus t amps can be manufactured extremely small and still attain high audio fidelity.

How Have Contemporary Wireless Speakers Gotten Better Lately?

I am going to take a look at how modern-day sound transmission systems which are employed in current wireless outdoor loudspeakers work in real-world environments having a great deal of interference from other cordless devices.

The most common frequency bands which can be used by wireless gizmos are the 900 MHz, 2.4 Gigahertz and 5.8 GHz frequency band. Usually the 900 MHz and also 2.4 Gigahertz frequency bands have started to become crowded by the ever increasing number of devices such as wireless speakers, cordless phones and so on.

The most cost effective transmitters generally broadcast at 900 MHz. They operate similar to FM radios. Since the FM transmission uses a small bandwidth and therefore only consumes a tiny part of the free frequency space, interference can be avoided simply by changing to an alternative channel. Modern-day audio gadgets utilize digital sound transmission and in most cases operate at 2.4 Gigahertz. Those digital transmitters send out a signal which takes up much more frequency space than 900 MHz transmitters and so have a greater potential for colliding with other transmitters. Merely changing channels, on the other hand, is no reliable solution for avoiding specific transmitters which use frequency hopping. Frequency hoppers which include Bluetooth devices or a lot of wireless telephones are going to hop throughout the full frequency spectrum. As a consequence transmission over channels will be disrupted for brief bursts of time. Real-time audio has quite rigid demands regarding reliability and minimal latency. In order to provide those, other mechanisms are needed.

One approach is known as FEC or forward error correction. This technique allows the receiver to correct a corrupted signal. For this reason, extra data is sent by the transmitter. By using a number of sophisticated calculations, the receiver can then repair the information which may partially be corrupted by interfering transmitters. As a result, these products may transmit 100% error-free even if there is interference. Transmitters utilizing FEC can transmit to a large number of cordless devices and does not require any kind of feedback from the receiver. One more approach makes use of bidirectional transmission, i.e. every receiver transmits information back to the transmitter. This method is only useful if the number of receivers is small. Additionally, it requires a back channel to the transmitter. The transmitters includes a checksum with every data packet. Every receiver can easily detect whether a specific packet has been received properly or damaged because of interference. Subsequently, each cordless receiver will be sending an acknowledgement to the transmitter. If a packet was corrupted, the receiver will alert the transmitter and request retransmission of the packet. Therefore, the transmitter needs to store a great amount of packets in a buffer. Equally, the receiver will have to have a data buffer. This buffer will cause an audio delay which is dependent upon the buffer size with a larger buffer improving the robustness of the transmission. Video applications, however, need the sound to be in sync with the movie. In this instance a big latency is problematical. Systems which incorporate this mechanism, however, are limited to transmitting to a few receivers and the receivers consume more energy.

In an effort to better handle interference, some wireless speakers will monitor the accessible frequency band as a way to determine which channels are clear at any point in time. If any specific channel becomes crowded by a competing transmitter, these devices can switch transmission to a clean channel without interruption of the audio. The clear channel is chosen from a list of channels that has been identified to be clear. One modern technology that employs this particular transmission protocol is referred to as adaptive frequency hopping spread spectrum or AFHSS