 January 2010
Tools of the Computer Trade: Part One
In my review of
NAD’s C 565BEE CD player last month, I said that it may well be the last CD
player that I ever review, and that in 2010 I’d be concentrating on the future of
high-end sound: computer-based playback of digital audio files stored on a computer and
decoded by a high-quality digital-to-analog converter.
The audio world is going in this direction for some good
reasons. One is that a computer can be more convenient than discs and a disc player.
Today, with a decent high-speed Internet connection, a typical three-minute music track of
uncompressed CD quality (16-bit/44.1kHz) constitutes about 30 megabytes, which can be
downloaded in a few minutes. The contents of an entire CD (upward of 700MB) can be brought
down in under an hour -- or even less, with a blazing-fast connection. Such rates of data
transfer weren’t feasible a decade ago, and they weren’t even imaginable back in
1982, when the Compact Disc was introduced -- but they’re here today, and transfer
speeds are likely to continue to increase. No more going to the record store -- the
Internet is the perfect delivery vehicle for digitally encoded music, and your computer,
provided you have enough storage space, is a great place to keep it: once those files are
on your computer, songs and albums can be cataloged and indexed, making access to a
virtually unlimited number of songs and albums only a few mouse clicks away.
Another benefit of computer storage and playback is the
better sound quality of higher resolutions. The CD standard, set nearly 30 years ago, was
a two-channel format with a word length of 16 bits and a sampling frequency of 44.1kHz.
The CD’s 16-bit word length allows up to 96dB of dynamic range, and its sampling
frequency was chosen because of the Nyquist Limit, which dictates that you must sample at
twice the highest frequency that you wish to record; a sampling frequency of 44.1kHz
allows the recording of frequencies up to 22.05kHz, which, at the time, seemed
satisfactorily above what’s generally regarded as the upper limit of human hearing:
20kHz.
Not surprisingly, that decades-old standard has been
surpassed. It’s now normal to make digital recordings with a 24-bit word length and a
sampling frequency of 96 or 192kHz -- or 48, 88.2, or 176.4kHz. These longer word lengths
allow a theoretical limit of 144dB of dynamic range, and the higher sampling frequencies
of 96 and 192kHz permit the recording of sound frequencies up to 48 and 96kHz,
respectively. These are significant improvements -- why shouldn’t our stereo systems
at home support them? With a computer system, you can easily take advantage of these
improvements; with CD playback, you can’t at all.
Of course, computer-based playback isn’t the only way
to get this kind of resolution. DVD-Audio, SACD, and now Blu-ray Disc all offer hi-rez
playback, and are still attractive to those happy with buying discs, and who don’t
miss the convenience of downloading from the Internet. And all of these physical formats
offer multichannel playback -- such files can still be time-consuming to download at high
resolutions. But these disc-based formats have never generated much interest or
"buzz" among audiophiles, let alone the masses: the DVD-Audio disc has been a
complete failure in the marketplace, SACD has been relegated to the status of a niche
product for audiophiles, and the music-only Blu-ray Disc has yet to catch on. A physical
format might have been a necessary evil when the CD was born, but with the proliferation
of the Internet and the continuing increases in download speeds, there’s no longer
much need or desire for one. Show me one new music-only disc format that, since the advent
of the Compact Disc, has caught on with the masses.
The future of high-resolution digital-audio playback
involves, for audiophiles, the marriage of desktop and laptop computers to components made
by high-end-audio companies, such as high-quality D/A converters, and the loudspeakers,
cables, and other devices necessary to make it all work. It is these products, and how to
combine and use them, that will be the focus of much of what I write about in 2010 and
beyond. Next month, in "Tools of the Computer Trade: Part Two," I’ll tell
you about my own computer-based audio system, which is taking me further away from CD and
straight into the new, exciting world of high-resolution digital sound.
. . . Doug Schneider
das@soundstage.com
|
