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01-03-2009, 01:55 PM
Class D amplifiers present us with a revolutionary solution, which would help us eliminate loss and distortions caused due to conversion of digital signals to analog while amplifying signals before transmitting it to speakers. This inchoate piece of knowledge could prove to detrimental in improving and redefining essence of sound and take it to a different realm.
This type of amplifiers do not require the use of D-A conversion and hence reduce the costs incurred for developing state of art output technology. The digital output from sources such as CD's, DVD's and computers now can directly be sent for amplification without the need for any conversion.
Another important feature of these unique and novel kind of amplifiers are that they give us a typical efficiency of 90% compared to that of the normal ones which give us a efficiency of 65-70%. This obviously means less amount of dissipation that indirectly means lower rated heat sinks and low waste of energy. This makes the use of D type amplifiers in miniature and portable devices all the more apt.
All these years D type amplifiers have been used for purposes where efficiency was the key whereas now developments in this technology have made its entry possible into other domain that are less hi-fi. Thus showing up in MP3 players, portable CD players, laptop computers, cell phones, even personal digital assistants.
Digital Audio's Final Frontier-Class D Amplifier
Digital technology continues its march from media like CDs and DVDs toward your audio speakers. Today, amplifiers based on digital principles are already having a profound effect on equipment efficiency and size. They are also beginning to set the standard for sound quality.
An old idea, the Class D amplifier has taken on new life as equipment manufacturers and consumers redefine the musical experience to be as likely to occur in a car, on a personal stereo, or on an airplane as in a living room. For most consumers today, portability and style outweigh other factors in the choice of new audio gear. Class D amplifiers are ideally suited to capitalize on the trend. They are already starting to displace conventional high-fidelity amplifiers, particularly in mobile and portable applications, where their high efficiency and small size put them in a class by themselves. For example, they are fast becoming the dominant technology for entertainment systems in cars, where passengers are now apt to watch a DVD-and expect from the vehicle's compact, ill-ventilated electronics the same rousing surround-sound experience they get at home.
The new amplifiers can provide it. They are typically around 90 percent efficient at rated power, versus 65-70 percent for conventional audio amps. Such high efficiency means, for one thing, that the amplifiers can get by with much smaller heat sinks to carry away the energy they waste. Also, portable devices like MP3 players can go much longer on a battery charge or can be powered by tinier, lighter batteries.
Class D amplifiers have been used for decades in industrial and medical applications when high efficiency is key. They have been applied with great success in devices as small as hearing aids and as large as controllers for hefty motors and electromagnets. They blossomed as a significant force in high-fidelity audio a few years ago, when Class D power amplifier chips were released by companies like Tripath Technology, Texas Instruments, and Cirrus Logic in the United States; Philips and STMicroelectronics(partnering with ApogeeDDX) in Europe; and Sanyo (partnering with Bang & Olufsen) in Japan.
More recently, Class D amps have expanded beyond the hi-fi niche, showing up in MP3 players, portable CD players, laptop computers, cellphones, even personal digital assistants (PDAs). At the same time, they have been making forays into the world of home audio in the form of products based on those new chips. Notable entries include amplifiers from Bel Canto Design Ltd. (Minneapolis, Minn.) and PS Audio (Boulder, Colo.).
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