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HistoricalReference
Analog vs Digital: Home-Brew Science at the Edge of the Art
Jay Clawson, Chuck Zeilig  |  Mar 07, 2019  |  First Published: Jun 01, 1986  |  39 comments
Publisher's note: The following article, from the early days of Compact Disc, is presented with no claim for absoluteness. (In fact, just as we go to press in the spring of 1986, we received a manuscript from Philip Greenspun, Product Review Editor of Computer Music Journal (Cambridge, MA), who had precisely the opposite result when comparing CD to analog versions of the same recording, though it was unclear that his test procedures were as thorough as in the tests by these authors.) The tests described are neither single- nor double-blind, and the author's decision to forego conversation while listening to the same products does not by any means guarantee lack of mutual influence—especially because their musical tastes are so well known to each other. Moreover, repeating the test with different phono equipment, a different CD player, and a different replica of the master tape would likely yield somewhat different results.

Nevertheless, I think the basic conclusion is sound: good CD reproduction is remarkably close to a fairly good version of master tape sound; there's a good chance that it's more accurate than what you'll get from the average cartridge, tonearm, and turntable.

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HistoricalJ. Gordon HoltReference
The Pros & Cons of Electrostatic Loudspeakers
J. Gordon Holt  |  Feb 07, 2019  |  First Published: Jul 01, 1985  |  8 comments
The main inherent advantage of the full-range electrostatic loud speaker system is that it allows a single diaphragm to embody the conflicting attributes needed for optimal performance at both extremes of the audio range. Its thin-membrane diaphragm can be made exceedingly light, for superb transient response and extended HF response, yet it can be about as large in area as desired, for extended LF response.
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Reference
Blind Listening at Harman International
Kalman Rubinson  |  Jan 22, 2019  |  64 comments
Revel began demonstrating prototypes of the Performa F228Be, reviewed elsewhere in this issue, at the Consumer Electronics Show and other audio events in 2015, though they had yet to settle on the model name. The most salient feature that distinguished the F228Be-to-be from the established Performa3 F208 was the new beryllium tweeter, and while it sounded more than okay under show conditions, I always heard a bit of brightness and harshness. I knew it was still a work in progress, but I wasn't very eager to want to take it home.
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InterviewsReference
Power According to Pass
Jim Austin  |  Nov 01, 2018  |  10 comments
Virtually all of the active components in your system—DACs, preamplifiers, power amplifiers—work by modulating the DC output of their power supplies with an AC music signal. Surely, then, the more perfect your household AC is, the more perfect your audio system's output will be. Analogies abound—to dirty water used in distilling good whiskey, to inferior thread used to weave fine fabrics—and all amount to the same thing: you can't make a silk purse out of a sow's ear.
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FeaturesMQAReference
Zen & the Art of A/D Conversion
John Atkinson  |  Aug 14, 2018  |  47 comments
In a series of recent feature articles for Stereophile, Jim Austin has examined how the controversial MQA codec works: "MQA Tested, Part 1," "MQA Tested Part 2: Into the Fold," "MQA Contextualized," "MQA, DRM, and Other Four-Letter Words," and, most recently, "MQA: Aliasing, B-Splines, Centers of Gravity." I doubt there is a Stereophile reader who is unaware of the fracas associated with MQA, and I have been repeatedly criticized on web forums for describing its underlying concept as "elegant."

But elegant it is, I feel.

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FeaturesInterviewsReference
HDCD: Keith Johnson, Pflash Pflaumer, Michael Ritter
Robert Harley  |  Jul 10, 2018  |  First Published: May 01, 1995  |  11 comments
The men behind HDCD (L–R: Pflash Pflaumer, Michael Ritter, Keith Johnson

High Definition Compatible Digital® (HDCD®), the proprietary process for improving the sound of 16-bit digital audio, has finally arrived. More than a dozen digital processors using the technology are on the market, and the professional encoder used to master HDCD discs is following closely behind.

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FeaturesMQAReference
MQA: Aliasing, B-Splines, Centers of Gravity
Jim Austin  |  May 17, 2018  |  160 comments
The right thing at the wrong time is the wrong thing.—Joshua Harris

The sampling theory formulated by Claude Shannon in the late 1940s had a key requirement: The signal to be sampled must be band-limited—that is, it must have an absolute upper-frequency limit. With that single constraint, Shannon's work yields a remarkable result: If you sample at twice that rate—two samples per period for the highest frequency the signal contains—you can reproduce that signal perfectly. Perfectly. That result set the foundation for digital audio, right up to the present. Cue the music.

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FeaturesMQAReference
MQA, DRM, and Other Four-Letter Words
Jim Austin  |  Apr 19, 2018  |  47 comments
In an article published in the March 2018 Stereophile, I wrote that critics have been attacking MQA, the audio codec developed by J. Robert Stuart and Peter Craven, by accusing it of being lossy. The critics are right: MQA is, in fact, a lossy codec—that is, not all of the data in the original recording are recovered when played back via MQA—though in a clever and innocuous way. For MQA's critics, though, that's not the point: They use lossy mainly for its negative emotional associations: When audiophiles hear lossy, they think MP3.
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Cable ReviewsReference
Lindsay-Geyer Highly Magnetic Cables
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.

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FeaturesMQAReference
MQA Contextualized
Jim Austin  |  Feb 13, 2018  |  177 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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FeaturesMQAReference
MQA Tested Part 2: Into the Fold
Jim Austin  |  Jan 06, 2018  |  28 comments
Loss is nothing else but change, and change is Nature's delight.—Marcus Aurelius

Master Quality Authenticated (MQA), the audio codec from industry veterans Bob Stuart and Peter Craven, rests on two pillars: improved time-domain behavior, which is said to improve sound quality and what MQA Ltd. calls "audio origami," which yields reduced file size (for downloads) and data rate (for streaming). Last month I took a first peek at those time-domain issues, examining the impulse response of MQA's "upsampling renderer," the output side of this analog-to-analog system (footnote 1). This month I take a first look at the second pillar: MQA's approach to data-rate reduction. In particular, I'll consider critics' claims that MQA is a "lossy" codec.

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FeaturesMQAReference
MQA Tested, Part 1
Jim Austin  |  Dec 12, 2017  |  213 comments
I don't think I've ever seen an audio debate as nasty as the one over Master Quality Authenticated (MQA), the audio-encoding/decoding technology from industry veterans Bob Stuart, formerly of Meridian and now CEO of MQA Ltd., and Peter Craven. Stuart is the company's public face, and that face has been the target of many a mud pie thrown since the technology went public two years ago. Some of MQA's critics are courteous—a few are even well-informed—but the nastiness on-line is unprecedented, in my experience.
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Audiophile EssentialsFeaturesHistoricalReference
Listening Tests and Absolute Phase
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.
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InterviewsReference
Nelson Pass: Circuit Topology and the End of Science
Jim Austin  |  Aug 29, 2017  |  66 comments
Nelson Pass is a consummate engineer, but he got his start in physics, earning a bachelor's degree from UC Davis. As he worked on his degree, he was already an audio designer, focusing on loudspeakers—great training for a designer of audio amplifiers. Soon, in 1974, he cofounded Threshold Audio with René Besne, of audio and folk-dancing fame; their goal was to build electronics, partly because the field is less competitive—it's harder than building speakers.
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FeaturesReference
CD Tweaks & Listening Tests
John Atkinson, Will Hammond  |  Dec 08, 2016  |  First Published: Nov 01, 1990  |  9 comments
In "Music and Fractals" in the November 1990 issue, I discuss how digital audio's quantization of amplitude information in what was originally a continuous waveform represents a fundamental difference between analog and digital representations of music. In a letter published in the English magazine Hi-Fi Review in January 1990, John Lambshead conjectured that naturally originating sounds were pseudo-fractal in character; that is, their waveforms have a wealth of fine detail, and that detail itself has an even finer-structured wealth of fine detail, and so on, until the crinkliness of the waveform is finally enveloped in the analog noise that accompanies every sound we hear.
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