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By Gunter Fellbaum, September 15, 2011 12:51 pm

In this article, I will explain the term “total harmonic distortion”, often also called “THD” which is frequently used to describe the performance of wireless outdoor speakers.

Looking for the perfect model from the huge amount of products, you may have a hard time understanding some of the technical language and terms that you will find in the specifications of today’s wireless speakers. THD is usually not as easily understood as some other commonly used terms such as “signal-to-noise ratio” or “frequency response”.

In short, “harmonic distortion” describes how much the audio signal is being degraded as a result of the speaker or in other words how much the signal differs from the original signal. There are two common ways to express harmonic distortion, either in percent (%) or in decibel (dB). If a speaker specifies a distortion of 10% for example then one tenth of the energy radiated by the speaker is distortion. A distortion of 10% can also be expressed as -20 dB. 1% distortion equals -40dB.

A wireless speaker actually has several components which contribute to harmonic distortion. One of these is the built-in power amplifier. This amplifier is driving the speaker element. Usually the higher the amplifier is driven the higher the amount of amplifier distortion. For this reason, some manufacturers will list amplifier distortion depending on amplifier power.

Distortion specs for different power levels are usually given for several power levels or as a diagram showing distortion versus output power. Both of these methods allow to better evaluate the quality of the amp.Normally distortion is measured with a 1 kHz test tone. However, amplifier distortion will usually increase with increasing frequency, especially in digital class-D models.

The second contributing factor is the loudspeaker element itself. Most speakers use a diaphragm type driver which is driven by a coil that is suspended in a magnetic field. The coil will follow the magnetic field which is controlled by the audio signal to move the diaphragm. However, this movement is not perfectly linear. This results in the signal being distorted by the speaker element itself. Also, the larger to power level with which the speaker is driven, the larger the distortion. Often speaker manufacturers will show distortion for small to moderate power levels only.

As such both the amplifier as well as the speaker element itself contribute to distortion. In addition, there are other factors which also contribute to distortion. The total amount of distortion is the sum of all of these factors. Depending on the material used to build the speaker enclosure, there will be vibrations or box resonances. These usually depend on the sound pressure level, the box shape, the enclosure material and audio frequency. Therefore additional sound distortion will be caused by the box itself.

Total distortion is best determined by measurement. A signal generator is used which provides a highly linear sine tone to the speaker. The sound is picked up by a measurement microphone. The microphone signal is then analyzed by an audio analyzer. The audio analyzer will compute the amount of higher harmonics or distortion. Intermodulation distortion analysis is another method which gives better picture of the speaker distortion performance with real-world signals by using a test signal with two harmonics and measuring how many harmonics at different frequencies are produced by the speaker.

Another factor contributing to distortion is the signal transmission of wireless speakers, especially with models that transmit an analog signal at 900 MHz. More advanced models use digital audio transmission. Typically these transmitters work at 2.4 GHz or 5.8 GHz.

You can get further details about wireless speakers as well as wireless surround sound speakers from Amphony’s website.

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By Gunter Fellbaum, September 10, 2011 12:47 pm

Demands regarding audio power and audio fidelity of today’s speakers and home theater systems are constantly growing. At the heart of these systems is the audio amplifier. Today’s audio amps have perform well enough to meet these ever growing demands. With the ever increasing amount of models and design topologies, such as “tube amps”, “class-A”, “class-D” and “t-amp” designs, it is becoming more and more difficult to pick the amp which is ideal for a particular application. This article will explain some of the most common terms and clarify some of the technical jargon which amplifier manufacturers often use.

An audio amp will convert a low-level audio signal which often comes from a high-impedance source into a high-level signal which can drive a loudspeaker with a low impedance. Depending on the type of amp, one of several types of elements are used to amplify the signal such as tubes and transistors.

Tube amps were commonly used a few decades ago and utilize a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. Tubes, however, are nonlinear in their behavior and will introduce a fairly large amount of higher harmonics or distortion. A lot of people prefer tube amps because these higher harmonics are often perceived as the tube amp sounding “warm” or “pleasant”.

One drawback of tube amps is their low power efficiency. In other words, most of the energy consumed by the amp is wasted as heat rather than being converted into audio. Therefore tube amps will run hot and need sufficient cooling. Tube amps, however, a fairly expensive to make and therefore tube amps have mostly been replaced with amps using transistor elements which are less expensive to manufacture.

Solid-state amps use a semiconductor elements, such as a bipolar transistor or FET in place of the tube and the earliest type is known as “class-A” amps. The working principle of class-A amps is very similar to that of tube amps. The main difference is that a transistor is being used in place of the tube for amplifying the audio signal. The amplified high-level signal is sometimes fed back in order to minimize harmonic distortion. If you require an ultra-low distortion amplifier then you might want to investigate class-A amps since they offer amongst the lowest distortion of any audio amps. However, similar to tube amps, class-A amps have very low power efficiency and most of the energy is wasted.

To improve on the low efficiency of class-A amps, class-AB amps employ a series of transistors which each amplify a separate area, each of which being more efficient than class-A amps. Due to the higher efficiency, class-AB amps do not require the same amount 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, some amount of distortion is being generated, thus class-AB amps will not achieve the same audio fidelity as class-A amps.

Class-D amps improve on the efficiency of class-AB amps even further by using a switching transistor which is constantly being switched on or off. Thereby this switching stage hardly dissipates any power and thus the power efficiency of class-D amps usually exceeds 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal has to be lowpass filtered in order to remove the switching signal and recover the audio signal. Due to non-linearities of the pulse-width modulator and the switching transistor itself, class-D amps by nature have amongst the highest audio distortion of any audio amplifier.

More recent audio amps incorporate some sort of mechanism to minimize distortion. One approach is to feed back the amplified audio signal to the input of the amp to compare with the amplified signal. The difference signal is then used to correct the switching stage and compensate for the nonlinearity. “Class-T” amps (also called “t-amp”) use this type of feedback mechanism and therefore can be made extremely small while achieving low audio distortion.

You can find further information regarding t amps as well as stereo amplifiers from Amphony’s website.

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By Owen Jones, September 10, 2011 9:37 am

What is a clear computer casing and what might it do for you? Well, before we commence talking about the translucent computer case, permit me to inquire you something: what does your computer?s housing mean to you? I can even inquire: what does your computer signify to you? I ask this as your reply will establish what you want for your computer and its housing or case.

Most individuals have always been happy enough with the plain, average light-grey casing that comes as bog-standard with the preponderance of computers. A few have never even thought about it. But then there are others who have thought about their computer?s casing a lot and who yearn for something extraordinary for their computer.

A number of of these people were good at metalwork, others at woodwork and a few at glassware and there are some truly fantastic, innovative, home-produced housings out there. Especially among the gaming community. However, we are not all so talented with our hands, but that does not signify that we have to be stuck with the grey computer housing.

The easiest choice, if you want a custom computer casing is to construct one out of acrylic – the sort of substance used to construct the majority of fish tanks. You can buy and easily cut sheets of acrylic for the sides and bond them all together with acrylic resin. That may appear tricky, but it truly is not. In the beginning you would have to research the architecture of a normal computer case and then just copy it in acrylic. You can construct a clear computer casing in a weekend.

Or you could buy a transparent computer housing kit. These kits arrive in flat-packs just like most kitchen furniture and can be effortlessly assembled according to the instructions with a screwdriver. No cutting, no measuring, just a little gentle screwing.

And I mean gentle, because the screws that come with the clear computer case packs are generally made of acrylic too and will snap easily. It is the only element of the assembly procedure that calls for a warning note, for the reason that you don?t want to have to drill out a busted screw, do you? That would only put a downer on your fun.

So why would anyone want a translucent computer case? I think that there are loads of explanations. Some individuals may just want to be different and others may want to show that they can assemble or even create such a housing. However, the clear computer casing also has aesthetic and practical advantages. At least the good ones do.

On the Aesthetic Front: enthusiasts add neon lights and small LEDs that twinkle on and off or just glow eerily, possibly activated by some incident, like a hard drive coming to life. These displays are called ?themes? and are normally red or blue, but can be almost any conceivable colour. Then you can include coloured fans (or paint your existing ones). You already have at least one fan in your casing and probably two or three.

On the Practical Front: lots of individuals like to see what is happening inside their computer casing and it is neither practical nor safe to remove the cover all together. Additionally, assembling your own clear computer case allows you to insert more fans as over-heating is the foremost cause of hardware malfunction. The more fans the better.

A see-through computer casing would also allow you to see whether a fan has malfunctioned, which would result in over-heating in a normal casing and guaranteed hardware malfunction, whereas you would notice it going on through your transparent computer case and replace the fan before crucial damage and loss of data can take place.

If you are looking for one of those fantastic looking clear computer cases, just go over to our web site right away at http://clearcomputercase.biz for more information.

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By Alfred Tanya, September 7, 2011 9:15 am

When you have a USB wireless modem and wanted to share connection with other people, it can be greater which you get a USB wireless router. This can permit you to appreciate connection without having the need to have of cables and wiring which limits the distance of your World-wide-web connection.

The wireless method will permit you to completely take pleasure in the convenience of the web and giving you ease in relation to sharing of info and files amongst networks users utilizing a USB port.

When in search of wireless routers, you’ll surely be presented by a lot of alternatives but this ought to not confuse you or trigger you to have difficulty deciding on. The primary feature which you must appear into is whether or not it really is fully automated having a broad range of coverage and much better transfer speed.

It ought to also be firewall-enabled, uncomplicated to setup or install and user-friendly. Keep in mind that not all wireless routers are exactly the same. Ensure which you acquire the 1 that gives connectivity to your USB-enable personal computer.

Deciding upon the wireless Web service will entail setting up the connection getting choices for your wireless mode to be utilised for your bandwidth like 802.11b, g or n, you may also set up your security alternatives, firewall settings.

You’ll be able to also restrict the number of persons allowed to utilize the wireless connection. You’ll find various kinds of wireless routers that you simply can decide on from. Have the ability to know all about your alternatives so as to maximize the functionality of your wireless connection.

Pick a USB wireless router that has high speed to ensure that in return you get to transfer information rapidly and load pages quicker so as to get rid of lag along the way. The speed of connection is incredibly critical specially once you are running an on the net web site for your company as each second counts as you may either acquire or shed feasible earnings.

Constantly appear into the attributes of the wireless router closely. If it provides you what you specifically require then go for it, if not greater get going and discover for your other choices.

When buying wireless routers, some offers could come in packaged bundle. This may possibly incorporate a wireless routed and also a USB wireless adapter. This package will function much better should you do not own an adapter or present 1 is incompatible using the new router.

USB wireless router will permit you to share connections with other people hence performing away with additional expense and also the inconvenience of some complicated cables and wires. You will find numerous sorts of wireless routers and some are even portable and convenient to make use of.

So far better be cautious if you shop about and usually appear for much more alternatives to ensure that you may wind up using the correct deal, both giving you much better speed and reasonably priced cost.

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By Alfred Tanya, September 5, 2011 9:06 am

iPad vs Laptops- this is 1 problem users have been grappling with ever due to the fact the very first iPad had been released in 2010. Probably the most considerable questions performing the rounds is no matter whether an iPad can replace the laptop. You can find a number of tech blogs discussing iPad vs laptop pros and cons to be able to offer users having a clear view of what every single 1 does nicely. It has been additional than a year right after the launch of the iPad as well as the dilemma surrounding iPad vs laptop has nonetheless not been solved. But has there been any alter? Nicely, as reported by a lot of tech blogs users have adapted to the tablets fairly simply. Apple had sold additional than 14 million iPad units in 2010 itself and aims to 40 million units in 2011. This clearly indicates the massive recognition of the iPad tablets amongst users.

Most tech blogs approach the topic of iPad vs laptop by discussing the pros and cons of every. Here, we will see how the suitability of every of the devices modifications using the type of function you use it for or the kind of user you might be.

iPads are fantastic at accomplishing uncomplicated computing tasks. These straightforward tasks which you can perform with ease on a laptop or desktop, becomes much more individual when performed on a tablet. For anyone who is a casual user who intends to scan news websites, check emails, read eBooks, do some social networking or just browse the net lying down on your couch absolutely nothing could get superior than the iPad.

Not just that, the iPad is also becoming common as a gaming console. Despite the fact that, individuals had been a bit jittery about making use of touch screen controls to play games, they’ve now got employed to it.

So, you see that you simply don’t actually want a laptop if these are all which you wish to do.

When the iPad was launched, the thought performing the rounds in numerous tech blogs was that the iPad was meant for content consumption instead of content creation. This, much more or much less sums up the functionality of the devices in question.

Producing uncomplicated content is becoming doable on the iPad but for developing advanced content, you nonetheless need to depend on the laptop.

In case you are a writer you definitely cannot function on the iPad. Needless to say numerous will argue that writers can use the Bluetooth keyboard. But the question is when you have to add a keyword, you may too use a laptop. Besides, internet sites for instance WordPress aren’t optimized for tablets.

For anyone who is thinking of photo editing at a skilled level, the iPad is surely not going to be of any aid, at the least, not in its present form. Getting a touch screen interface, the iPad does have the possible to give advanced photo editing alternatives but which will take some time to take place.

Photoforge 2, which claims to be the counterpart of Photoshop for the iOS can be a far cry from what Photoshop enables its users to accomplish.

iPad vs laptop – who wins the tug of war?

The growing reputation of the iPad is testimony to the reality that iPads undoubtedly have the capability to capture the imagination of the users. Despite the fact that the iPad proves to be advantageous owing to its portability and enhanced computing capability, it nonetheless has some limitations which stop it from entirely more than powering the laptop. Storage space is really a key limitation of iPads. Besides, the lack of a physical keyboard makes particular activities difficult as per some tech weblog which makes clear and deciding comparisons.

The question of no matter whether an iPad can replace a laptop depends upon what you need to utilize it for. It is completely a no-brainer that casual personal computer users can use the iPad as an alternative to the laptop given that it delivers a a lot more individual expertise and is also additional comfy and portable. But unless it truly is able to overcome its limitations it can’t replace the laptop totally.

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