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Irving M. Fried  |  Jun 06, 2019  |  First Published: Sep 01, 1962  |  15 comments
Ever since the first electrical loudspeaker—a glorified headphone with a horn on it—was outmoded by the balanced-armature cone speaker, paper has been the standard diaphragm material for speakers reproducing low frequencies. The Rice-Kellogg moving-coil transducer replaced the balanced-armature driving system in 1925, but the paper cone remained. And although many improvements have since been made, were no more major changes in loudspeaker design for over 30 years!
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.

John Atkinson  |  Mar 19, 2019  |  9 comments
High Performance Loudspeakers: Optimising High Fidelity Loudspeaker Systems, Seventh Edition, by Martin Colloms. John Wiley & Sons, Inc., 2018. Paperback, 696 pp., $95. Available as an eBook, $79.99.

"Listen to that—that's what I mean by 'cone cry!'"

It was 1979. I'd been taking part in a blind listening test of loudspeakers organized by Martin Colloms (footnote 1) for the British magazine Hi-Fi Choice and, after the formal sessions had ended, had asked Martin to explain something I'd heard. A drive-unit's diaphragm produces cone cry when it resonates at a frequency unconnected with the musical signal it is being asked to produce; we had been using an anechoic recording of a xylophone, and one of the loudspeakers we'd been listening to was blurring the pitches of some of the instrument's notes.

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.

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.
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.
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.
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.

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.

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.

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.
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.

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.

Jim Austin  |  Jan 06, 2018  |  27 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.

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.