How Does Cordless Loudspeaker Energy Efficiency Influence Sound Quality?

If you are about to acquire brand new cordless loudspeakers, you most likely are concerned about how efficiently your wireless speakers function. Let me explain exactly what the term “power efficiency” means and also why you should take a closer look at this number throughout your selection of new cordless loudspeakers.

Numerous challenges are a result of cordless speakers which have low power efficiency: A lot of wasted power naturally means larger running expenditure which means that a more expensive set of cordless loudspeakers can in fact in the long term possibly be more affordable when compared to a cheaper type which has lower efficiency. Lower efficiency wireless speaker systems will radiate a great deal of energy as heat. Wireless loudspeakers that have low efficiency routinely have various heat sinks in order to help dissipate the wasted power. These heat sinks consume a fair amount of space and make the wireless speakers bulky and heavy. Further, they increase the price of the cordless loudspeakers. To help dissipate heat, low-power-efficiency amplifiers will need adequate air movement. So they cannot be placed in areas without circulation. Also, they can’t be fitted in water-proof enclosures.

Low-efficiency models need more total power in order to create the same level of audio power as high-efficiency models. Thus they require a bigger power supply which makes the cordless speakers more expensive to make. In addition, due to the large amount of heat, there will be significantly greater thermal stress on the electric elements as well as interior materials that might result in reliability problems. In comparison, high-efficiency cordless speakers can be produced small and light. When looking for a couple of wireless speakers, you will find the efficiency in the data sheet. This value is usually listed as a percentage. Different amp architectures offer different power efficiencies. Class-A amplifiers are amongst the least efficient and Class-D the most efficient. Typical power efficiencies range from 25% to 98%. From the efficiency percentage you’ll be able to figure out how much power the amp will squander. An amp with a 50% power efficiency will waste 50 % of the consumed energy. An amp that has 90% efficiency is going to squander 10%. What’s less well-known about efficiency is the fact that this figure isn’t fixed. The truth is it fluctuates depending on how much energy the amp provides. As a result in some cases you will find efficiency values for different energy levels within the data sheet. Each audio amplifier is going to use up a certain level of energy regardless of whether or not it supplies any kind of power to the speaker. For this reason the smaller the power the amp delivers, the smaller the power efficiency. For that reason audio makers usually specify the efficiency for the highest audio power that the amp can supply. To determine the efficiency, the audio energy that is used by a power resistor which is connected to the amplifier is divided by the total power the amp consumes whilst being fed a constant sine wave signal. Ordinarily a complete power report is plotted in order 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 every value is measured and a power efficiency graph generated.

When selecting a couple of cordless loudspeakers you will need to weigh efficiency versus fidelity because cordless speakers which use low-efficiency analog amps often provide the maximum audio fidelity while digital types will have larger distortion. Nevertheless, the most up-to-date cordless speakers that use switching-mode music amplifiers, such as Class-T amplifiers, offer audio fidelity that comes close to that of low-efficiency analog amplifiers and can be made extra small and light.

A Short Primer For Music Amps

Stereo amps are at the very core of every home theater product. As the quality and output power requirements of today’s loudspeakers increase, so do the requirements of music amps. There is a large amount of amplifier concepts and models. All of these vary in terms of performance. I am going to describe a few of the most common amp terms such as “class-A”, “class-D” and “t amps” to help you figure out which of these amps is ideal for your application. In addition, after reading this article you should be able to understand the amp specifications that producers issue. The basic operating principle of an audio amp is fairly clear-cut. An audio amp is going to take a low-level music signal. This signal usually originates from a source with a comparatively large impedance. It subsequently converts this signal into a large-level signal. This large-level signal may also drive loudspeakers with small impedance. Determined by the type of amp, one of several kinds of elements are used in order to amplify the signal such as tubes as well as transistors.

Tube amps used to be popular some decades ago. A tube is able to control the current flow in accordance to a control voltage which is attached to the tube. Sadly, tube amplifiers have a reasonably high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. On the other hand, this characteristic of tube amps still makes these popular. Many people describe tube amplifiers as having a warm sound versus the cold sound of solid state amplifiers.

Besides, tube amps have quite low power efficiency and therefore dissipate a lot of power as heat. Also, tubes are rather expensive to manufacture. Thus tube amplifiers have by and large been replaced by solid-state amps which I will glance at next. The first generation types of solid state amplifiers are referred to as “Class-A” amps. Solid-state amplifiers utilize a semiconductor instead of a tube to amplify the signal. Typically bipolar transistors or FETs are being used. In a class-A amp, the signal is being amplified by a transistor which is controlled by the low-level audio signal. Class-A amps have the lowest distortion and usually also the smallest amount of noise of any amplifier architecture. If you require ultra-low distortion then you should take a closer look at class-A models. The major downside is that just like tube amplifiers class A amplifiers have quite low efficiency. Because of this these amplifiers need large heat sinks in order to radiate the wasted energy and are typically quite heavy. Class-AB amps improve on the efficiency of class-A amplifiers. They use a number of transistors in order to split up the large-level signals into two separate regions, each of which can be amplified more efficiently. As such, class-AB amplifiers are typically smaller than class-A amps. When the signal transitions between the 2 separate areas, however, a certain level of distortion is being generated, thus class-AB amplifiers will not achieve the same audio fidelity as class-A amplifiers. In order to further improve the audio efficiency, “class-D” amplifiers use a switching stage which is constantly switched between 2 states: on or off. None of these 2 states dissipates power inside the transistor. Therefore, class-D amplifiers frequently are able to attain power efficiencies beyond 90%. The switching transistor, which is being controlled by a pulse-width modulator generates a high-frequency switching component that needs to be removed from the amplified signal by using a lowpass filter. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amplifiers exhibiting bigger audio distortion than other types of amps.

To solve the dilemma of large audio distortion, modern switching amp designs incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. One kind of mini audio amplifiers that employs this type of feedback is called “class-T” or “t amp”. Class-T amplifiers feed back the high-level switching signal to the audio signal processor for comparison. These amplifiers have small music distortion and can be made very small.