вторник, 17 сентября 2013 г.

Virtual Surround Sound Systems - Big Sound Without Big Speakers

The newest must-have for anyone with a TV and stereo these days is a home theater setup. As usual for our got-to-have-the-best society, most people think big when they dream of their ideal home theater. How big? You know, big screen television, big sound from a powerful receiver and amplifier, and really big sound from the speakers spread all over the room.
But, once the dream dissolves into reality, many of us realize that this big setup just will not work in our homes. We might not have the room for all those speakers. After all, 5 speakers and a sub-woofer do take up a considerable amount of space. Or maybe, we just do not want all those cables running around the base boards. Or, we do not want the technical hassles of setting up and balancing such a large system.
Fortunately, those with limited space or minimalist design ideas still have options. The appeal of surround sound can be addressed in a different way. Technology has stepped in and developed what is being called virtual surround sound. Virtual surround sound has been developed to mimic the sound characteristics of a multi-speaker system. Even though it uses fewer speakers and cables, a virtual system approaches the overall sound of a 5.1 or 7.1 amplifier and speaker system. There are two primary varieties of virtual systems, the 2.1 surround system and the digital sound projection system.
The standard placement for the 2.1 speaker system is to place two speakers in front of the listener, along with a sub-woofer placed somewhere inconspicuously in the room. The system will recreate the effect of a larger 5.1 setup that has 5 speakers and the sub. On the other hand, digital sound projectors will use a single strip of relatively small speakers to produce the sound. Most often, the digital sound system will not have a sub-woofer.
In either case, even though the setup is different, the same basic principle exists. The technology behind the system is based on a knowledge of how humans process sound internally. There are certain techniques used to modify the sound waves to fool the human ear into thinking that there are more speakers than what really are present. These techniques come from studies of psycho-acoustics, or the study of the way that people perceive sound. To fully appreciate what technology has done, you need to understand a least a little about psycho-acoustics, as well as physical acoustics (the science of sound).
Charles Moore is a technical adviser for Audio Equipment Speakers questions and specializes in addressing unique sound reproduction problems. He has an extensive background in live sound applications for various size venues, as well as the recording studio. He believes that the best performance in the world can be ruined with just a second or two of bad sound reinforcement. The proof of a well-designed sound equipment speaker application is that it is not even noticed by the audience. Invisibility is the ultimate goal.

Some Insights Into Wireless Speakers


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 will give a short overview of the output power spec in order to help you better understand the meaning of this term and how they relate to the performance of an speaker.
Some of the terms which speaker manufacturers publish often are misleading and do not necessarily give a good indication of the actual performance of the speaker. Now I will give some details about "speaker wattage". This spec is often misunderstood. It is important to look fairly closely at how the manufacturer shows this parameter.
"Wattage" shows how loud your loudspeaker can sound. You want to pick the speaker wattage based on how large your listening environment is. For best audio quality, you may want to go with a speaker that has higher power than you need since many speakers will show increasing distortion as the audio power goes up.
There are two common ways to display loudspeaker 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. The peak power rating in the past often led to manufacturers showing large wattage ratings for small speakers. However, in reality those speakers would not be able to endure larger amounts of output power for larger amounts of time.
Today most speakers will specify rms power which gives a better indication of the speakers' true performance. However, please ensure that your speaker has enough headroom to avoid clipping of the audio. This is because at certain points in time the signal will have bursts of power which by far exceed the average power of the signal.
Usually the impedance of the speakers which you connect to your amp will determine how much power your amp can deliver. Speaker impedance is measured in Ohms. Typically speakers have an impedance 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.