Some Crucial Things You Should Know Regarding Wireless Loudspeakers

| Sunday, August 28, 2011
By Gunter Fellbaum


Looking at some of the technical specs of today's wireless speakers, one cannot help but be at a loss in trying to compare different models. I am going to explain the term "speaker wattage" a bit more in this article. "Wattage" is one of the most fundamental terms describing speaker performance. However, it is often misunderstood. Some manufacturers also in the past have used this term in a confusing manner to hide the real performance.

Speaker specifications are sometimes hard to interpret since they are not fully standardized. As such it may be difficult to figure out the true performance of the speaker simply by looking at the specs. One good method though is to do a listening test before purchasing your speaker. During this test you ideally want to set up the speakers in a similar environment as your application. Let me now go ahead and explain the wattage rating of loudspeakers.

"Wattage" shows how loud your speaker can sound. Depending on your application, you can go with a small speaker tolerating only a few watts or a larger one tolerating several hundred watts. Many smaller home speakers only can be driven with a few watts power which usually is enough for a small room. If you plan to shake your walls then you obviously want to opt for a speaker that has up to several hundred watts. Please note that many speakers will start distorting the audio once the audio reaches higher wattage. If you want to enjoy low-distortion audio then you may want to pick a speaker which will give you more wattage than you will actually need.

There are two common ways to display speaker wattage. These are "peak power" and "rms power". "Peak power" describes how much power the speaker can tolerate for a short burst. On the other hand, "rms power" describes how much power the speaker can tolerate for a prolonged amount of time without being damaged. In the past, vendors have usually preferred listing the "peak power". This number is higher than the average or "rms" power. However, "peak power" can often be misleading since there is no standard showing the amount of time that the speaker has to be able to tolerate this amount of power.

Nonetheless, while the rms rating will tell you more about the speaker's actual performance, be sure though that the speaker has a peak power rating which is substantially higher than the rms rating. This is because most likely you will be using the speaker to reproduce music or voice. Music and voice signals by nature always fluctuate in terms of their power, i.e. the power envelope of the signal will vary over time. The main reason is that music signals will have short bursts of high power which the speaker has to handle. Rms power is measured with a constant sine signal which hardly compares with a music signal in terms of the power envelope.

Please note that often the peak power that your amp can deliver to your speakers depends on the impedance of your speakers which is typically between 4 and 8 Ohms. An audio amplifier which has a fixed internal supply voltage will have a maximum output signal swing that is limited by that supply voltage. If you are driving an 8-Ohm speaker then your amplifier must deliver twice the output voltage than when driving a 4-Ohm speaker in order to deliver the same amount of power to your speaker. Usually maximum power is specified for a 4-Ohm speaker impedance. However, ideally the manufacturer of your amplifier will tell which speaker impedance the amplifier can drive. Please note that some amplifiers cannot drive speakers with very low speaker impedance.




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Buying Tips For Wireless Surround Sound Kits

| Thursday, August 18, 2011
By Gunter Fellbaum


A large number of wireless audio transmitter products have emerged over the years. They promise to cut the cord to your audio equipment. We will examine the impact of new technologies on the performance of these products. Also, we'll examine if they keep their promise of eliminating the cable clutter.

The first form of wireless audio transmission was in the form of AM and FM radio stations. FM radio is still popular today. However, newer technologies have started to replace it. These include DAB broadcasts, satellite and HD radio. Today's wireless consumer devices such as wireless surround sound kits, baby monitors, Bluetooth audio transmitters and wireless microphones eliminate the cord.

Setting up speakers in another room and distributing music throughout the house are some of the applications of wireless audio. Many homes are not wired for audio. The technologies used today all have pros and cons as we will examine.

FM transmitters are using the most traditional technology in which audio is sent by changing the frequency of a radio-frequency carrier. This technology is called frequency modulation or FM. It is fairly simple to implement. Thus FM transmitters are very cost-effective. Also, FM transmission offers high range. As a result, most of today's 900 MHz wireless headphones use FM transmission. However, FM has some major drawbacks.

The first is the fact that the transmission will pick up noise and thus there will be some hiss or static. The amount of noise will actually vary depending on the location of the radio or receiver. This is due to the fact that the radio signal is bouncing off walls and will cancel itself out at different locations. This phenomenon is called multi-path fading. Using two antennae is one method some devices cope with this problem (diversity receivers). Another problem is that FM radios easily pick up interference from competing wireless transmitters.

Bluetooth has gained popularity recently for wireless audio transmission even though this protocol was primarily designed to connect computer peripherals. Bluetooth audio transmitters will convert the audio signal to digital information and then transmit via the Bluetooth protocol. Bluetooth is fairly robust in terms of interference in is well standardized. Bluetooth, however, has some problems in regard to wireless audio since it was not designed for wireless audio originally. The range of the transmission is only 30 ft or less. Also, Bluetooth does not have enough space to send an uncompressed CD-quality audio signal. Therefore the audio is compressed prior to the transmission. As a result of the audio compression, the audio quality will decrease. The final problem is the fact that Bluetooth will introduce a delay in the signal (also called latency) which is a problem when used together with video since the audio will be out of sync or if used in a surround sound setup where some of the speakers would be out of sync with the hard-wired speakers.

The technologies used for satellite radio and terrestrial digital radio offer high range. However, they also use extensive audio compression. Further, a delay of up to several seconds is introduced.

Another technology transmits the audio signal without compression digitally. This technology is used in wireless audio transmitters from Amphony. The audio signal will retain CD quality because no audio compression is used. The audio latency of this technology is less than 1 ms. Therefore it can be used for real-time applications such as wireless speaker kits in home theater setups.

By using error correction, this technology can cope with interference from competing wireless devices which is key in today's noisy environment. The Amphony transmitters operate at 5.8 GHz. This frequency space is less crowded than the 900 MHz or 2.4 GHz bands thus leading to a further improvement of reliability. In contrast to Bluetooth, any number of wireless receivers can operate from a single wireless audio transmitter which is a concern when distributing audio to several rooms within a home.




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Iridium Satellite Phones Offer You Worldwide Protection

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By Anton Schrud


"After I arrive in the South Pole, I am going to deliver you having a consult my Iridium Satellite phone." Appears like an argument that could be created with the hero in the sci-fi novel, right? Even though it may possibly sound peculiar, satellite phones are not as foreign as you might believe. Really, they are the simplest technique to communicate from places which have little if any phone service from a lot more advanced sources as an example land-line phones and cell phones. Because of the character from your phone, you are in a position to actually make use of it to simply call all more than the globe you would like.

Determined by details printed regarding the Iridium Satellite's web site, this phone service is alone that gives reliable service all through the entire globe. They credit score this achievement for his or her constellation of 66 low-earth orbit (LEO) satellites. The web site states the business's particular program allows each and every location about the globe, even including all of the oceans and polar regions furthermore to airspace, to turn out to be very easily utilized by phone. The web site also signifies the Iridium phone program surpasses other satellite phone techniques simply because you may find no significant delays in details transmissions. Other constructive alternatives that come with this phone program range from your realization they use less power, generating battery maintain going more time. Iridium's fingers held phones will also be a lot more compact than people supplied by another providers.

Together with voice solutions, the Iridium organization gives a number of other information transmission alternatives. These alternatives incorporate a chance to send faxes, pages and information messages. These alternatives allow you to stay in connection together with your organization or family members and trade details by any usually means you've got to. Although these phones are perfect for industries and providers, they're also ideal for people today. For example, these phones are utilized by people today through the U . s . States military when they're positioned in places not integrated in traditional phone services.

The phones will also be well suited for people within the building market who're employed in places exactly where you might find no phones in position yet. Satellite phones will also be well suited for use within emergency preserve or catastrophe places that land-line phones and cell phone towers are not functioning.

You will find also several other solutions to use these phones including journey reasons. Satellite phones are perfect for people in aviation or maritime positions simply because the phones function everywhere they could go. People on tv positions could also reap the benefits of satellite phones to make certain that journalists within the location to remain in touch making use of their home workplace. People within the mining, forestry furthermore to gas and oil fields could also delight in the toughness for any satellite phone. When you want to help keep in contact anywhere you may roam, or anywhere your function could just take you, you might be an awesome candidate to possess an Iridium Satellite phone. These phones can transmit messages actually throughout the world which means if you're regarding the North Pole, or up previously mentioned Australia, you will hold the capacity to interact with people whom you may have to speak.




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