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Hands-On Project: Low-Cost, High-End Class-D Amplifier

Build a sweet-sounding class-D amplifier for $500

6 min read

Several months ago, I gave in to my son’s fervent wish for a Sony PlayStation 3. I don’t have the space for multiple entertainment systems, so this acquisition forced me to abandon my lovingly chosen audio system, which included a Sony NS999ES disc player, a separate digital-to-analog converter based on the wonderful Analog Devices AD1853EB evaluation board, and a class-D integrated stereo amplifier built from a kit offered by Hawk Audio of Ledegem, Belgium.

I decided to assemble a new audio-video system based around the Sony PS3. Some aspects of this switch were obvious: The PS3 plays almost any kind of disc, so it simply replaced the NS999ES as my disc player (sadly, new versions of the PS3 cannot play superaudio CDs, as older versions could). A potential showstopper loomed when I discovered that the PS3 outputs high-quality audio only as an optical digital signal in the TOSLINK format. But then I realized that my AD1853EB converter board happens to have a TOSLINK input jack (thank you, Analog Devices).

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
Photo of Jacob Ziv
Photo: Rami Shlush

Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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