Reference

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Keith Howard  |  Nov 26, 2006  |  0 comments
As Hans Christian Oersted, the Danish physicist and founder of electrodynamics, discovered in 1819, an electric current passed through a wire generates a magnetic field. Place that wire close to a permanent magnet and the interaction of the two fields will generate a force. That, in two sentences, summarizes the operating principle of the motor that energizes every moving-coil drive-unit in millions of loudspeakers worldwide. It sounds simple, but—like everything in audio—it isn't.
J. Gordon Holt  |  Apr 29, 1990  |  0 comments
When sociologists tell us America is a highly mobile society, they don't just mean we do lot of driving. What they mean is, we do a lot of moving. The good old three-generation family homestead, immortalized in nostalgia TV and literature, is a thing of the past. According to census information, almost 20% of America's population changes its address every year. Of course, it's usually a different 20% every year, but pulling up roots and moving---to a bigger house, a better neighborhood or a nicer city, not to mention a place where your employer decides to transfer you---is almost as commonplace across the US of A as marriage, divorce, and unbridled greed.
John Atkinson  |  May 19, 2016  |  41 comments
Jim Austin briefly discusses MQA in his review of the Explorer2 in this issue, but a more complete description of MQA can be found in an article posted on Stereophile's website at the end of 2014.

MQA involves two fundamental concepts, discussed in a paper presented to the Audio Engineering Society in October 2014, the first responsible for a potential improvement in sound quality, the second responsible for a large reduction in the bandwidth required for storage and streaming of high-resolution files...

Rémy Fourré  |  Aug 08, 2004  |  First Published: Oct 01, 1993  |  0 comments
Until recently, all problems in digital audio systems were blamed on either the analog/digital converters (ADCs) used in mastering or the digital/analog converters (DACs) needed for playback (footnote 1). As the performance of both ADCs and DACs improved, however, a previously unrecognized mechanism for distortion was unmasked: jitter. As we shall see, jitter—or, more correctly, word-clock jitter—can be a significant limitation in the technical and sonic performance of digital audio systems (footnote 2).
John Atkinson  |  Mar 07, 2004  |  First Published: Dec 01, 1990  |  0 comments
Jitter is not what digital sound quality induces in the listener; rather it is the instability in the clock signal that controls exactly when the analog waveform is sampled in the original A/D conversion, or when the digital word input into a DAC results in an analog voltage being produced at the chip's output. "So what?" is the response of digital advocates, "As long as a digital one is recognized as a one and a digital zero as a zero, then how can there be any difference in sound?" goes their argument, normally culminating in a fervently expressed "Bits is bits!"
Robert Harley  |  May 28, 2019  |  First Published: Nov 01, 1994  |  0 comments
If there's one buzzword in high-end audio for the 1990s, it's undoubtedly jitter. "Jitter" describes timing variations in the clock controlling the ones and zeros that represent the analog audio signal. If that clock isn't stable to an extraordinarily precise degree, the sound quality of the digital processor will be degraded.

A CD transport/digital processor combination introduces jitter in three ways: 1) the transport puts out a jittered signal; 2) the S/PDIF or AES/EBU interface between the transport and processor creates jitter; and 3) the digital processor adds its own jitter to the clock. These additive factors are largely responsible for the great range in sound quality we hear from different transports and interfaces.

Dick Olsher  |  Mar 08, 2018  |  First Published: Feb 01, 1991  |  27 comments
Why cable again?

Well, the obvious reason is that it has been a while since my last foray into Cableland (July 1988). Many new products have been introduced in the interim, so it appeared appropriate to once again open Pandora's Box. Those of you who still remember my speaker cable article of 2½ years ago will recollect the considerable controversy that evolved from that project.

Some of the response was quite predictable, though the venom with which it was laced was not. The manufacturers of those outrageously priced "garden-hose"–type cables that I failed to rave about were more than just perturbed.

John Atkinson  |  Dec 05, 2017  |  First Published: Nov 01, 1980  |  22 comments
The problem confronting the magazine reviewer when organising the necessary listening tests to accompany/reinforce the measured behavior of a device under test is complex. There has never been a problem with the measurement aspect; as long as someone has access to the same test gear—and full knowledge of the test conditions—then he should be able to replicate the critic's findings exactly (assuming an infinitely narrow spread of behaviour from sample to sample—a rasher assumption with some manufacturers' equipment than of others). However, when it comes to determining reliably the audible (or inaudible?) effects on music program by an amplifier/cartridge/loudspeaker etc. then the going gets tough.
John Atkinson  |  Aug 18, 2016  |  67 comments
Last June, Jim Austin briefly discussed the operation of MQA in his review of the Meridian Explorer2 USB DAC, but you can find a more detailed explanation on Stereophile's website here and here. MQA involves two fundamental concepts, discussed in a paper presented to the Audio Engineering Society in October 2014. The first is responsible for a large reduction in the bandwidth required to store and stream high-resolution files, the second for a potential improvement in sound quality. . .
Peter W. Mitchell, Robert Harley  |  Dec 10, 2013  |  First Published: Dec 01, 1991  |  13 comments
Editor's Introduction: In 2013, lossy compression is everywhere—without lossy codecs like MP3, Dolby Digital, DTS, A2DP, AAC, apt-X, and Ogg Vorbis, there would be no Web audio services like Spotify or Pandora, no multichannel soundtracks on DVD, no Bluetooth audio, no DAB and HDradio, no Sirius/XM, and no iTunes, to quote the commercial successes and no Napster, MiniDisc, or DCC, to quote the failures. Despite their potential for damage to the music, the convenience and sometimes drastic reduction in audio file size have made lossy codecs ubiquitous in the 21st century. Stereophile covered the development of lossy compression; following is an article from more than two decades ago warning of the sonic dangers.—Editor
John Atkinson  |  Nov 07, 1998  |  2 comments
This series of articles was initially written (in slightly different form), as a paper presented at the 103rd Audio Engineering Society Convention, New York, September 1997. The preprint, "Loudspeakers: What Measurements Can Tell Us—And What They Can't Tell Us!," AES Preprint 4608, is available from the AES, 60 East 42nd Street, Room 2520, New York, NY 10165-0075. The AES internet site, offers a secure transaction page for credit-card orders.
John Atkinson  |  Jan 28, 1999  |  0 comments
This series of articles is based on a paper presented at the 103rd Audio Engineering Society Convention, New York, September 1997. The preprint, "Loudspeakers: What Measurements Can Tell Us—And What They Can't Tell Us!," AES Preprint 4608, is available from the AES, 60 East 42nd Street, Room 2520, New York, NY 10165-0075. The AES internet site, www.aes.org, offers a secure transaction page for credit-card orders.
John Atkinson  |  Dec 14, 1998  |  0 comments
This series of articles was initially written (in slightly different form), as a paper presented at the 103rd Audio Engineering Society Convention, New York, September 1997. The preprint, "Loudspeakers: What Measurements Can Tell Us—And What They Can't Tell Us!," AES Preprint 4608, is available from the AES, 60 East 42nd Street, Room 2520, New York, NY 10165-0075. The AES internet site, www.aes.org , offers a secure transaction page for credit-card orders.
John Atkinson  |  Apr 06, 2006  |  First Published: Feb 06, 1990  |  0 comments
Wouldn't you just know it. As soon as I decide on a formal regime of measurements to accompany Stereophile's loudspeaker reviews—see Vol.12 No.10, October 1989, p.166—along comes some hot new technology that changes everything. Robert Harley reported in last month's "Industry Update" column how impressed he and I were with the new MLSSA measurement system from DRA Laboratories.
Jim Austin  |  Feb 13, 2018  |  173 comments
When you come to a fork in the road, take it.—Yogi Berra

Over one busy week in 1986, Karlheinz Brandenburg laid the foundation of a technology that a few years later would upend the record business. Brandenburg, a PhD student in electrical engineering at the Friedrich-Alexander University Erlangen-Nuremberg, was figuring out how to code digital music efficiently enough that it could be delivered over digital telephone lines. A patent examiner had concluded that what the application proposed was impossible, so over a week of late nights, Brandenburg produced the proof of concept and more. It was another decade before the technology—MPEG-2 level III, more commonly known as MP3—would find its true home, the Internet.

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