Digital Processor Reviews

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Robert Harley  |  Apr 12, 2018  |  First Published: Jun 01, 1993  |  2 comments
Whoever invented the adage "Good things come in small packages" wasn't into high-end audio. Most high-end products are huge and heavy, with massive power supplies, thick front panels, and battleship build quality. This dreadnought approach is justified if it directly affects the unit's sonic performance (as in the Mark Levinson No.31 transport, for example). In some products, however, the massive build can reflect a shotgun, overkill approach by the designer, or a mere fashion statement.
Robert Harley  |  Apr 27, 2012  |  First Published: Mar 01, 1993  |  5 comments
There are as many ways of designing a digital-to-analog converter as there are engineers. One approach is to select parts from manufacturers' data books and build the product according to the "application notes" provided by the parts manufacturers. This is the electronic equivalent of a paint-by-numbers kit.

A more creative engineer may add a few tricks of his own to the standard brew. Bigger and better regulated power supplies, careful circuit-board layout, tweaky passive components, and attention to detail will likely make this designer's product sound better than the same basic building blocks implemented without this care. Indeed, the vast range of sonic flavors from digital processors containing very nearly the same parts attests to the designer's influence over a digital processor's sound.

Robert Harley, Lewis Lipnick, Thomas J. Norton  |  Jun 06, 2019  |  First Published: Oct 01, 1992  |  1 comments
A visiting manufacturer recently expressed the idea that digital processors and transports are the worst value in high-end audio. He contended that, because they all sound bad, their differences and degrees of imperfection are meaningless. In his view, the very best digital differed very little from the worst. His advice? Buy a moderately priced CD player and enjoy your LPs.
Robert Harley  |  Sep 12, 2019  |  First Published: Oct 01, 1992  |  1 comments
The $799 Theorem was originally shown at the 1992 WCES in a very small chassis that prohibited adding features or upgrades. Sumo has since become more ambitious, putting the Theorem in a full-sized chassis and offering several upgrade options that would have been impossible in the truncated version.
Robert Harley  |  Apr 05, 2016  |  First Published: Jun 01, 1992  |  2 comments
The night before I started to write this review, PBS began a five-part series on computers called "The Machine that Changed the World." The first episode described the development of the ENIAC (Electronic Numerical Integrator and Accumulator), the first electronic computer. The ENIAC used 18,000 vacuum tubes, had over 500,000 solder joints, required a room 30' by 50', had to be physically reprogrammed with patch cords to perform different tasks, and packed less computing power than today's $4.99 pocket calculator.
Robert Harley  |  Feb 13, 2014  |  First Published: Mar 01, 1992  |  1 comments
Since the first digital processor on the market using UltraAnalog DACs appeared (the $12,000 Stax DAC-X1t, reviewed in August 1990, Vol.13 No.8), there has been a proliferation of good-sounding processors using this extraordinary—and expensive—part. Among these are the Audio Research DAC1, Audio Research DAC1-20, VTL Reference D/A, and the groundbreaking Mark Levinson No.30 reviewed last month.
Robert Harley, Various  |  Jun 07, 2010  |  First Published: Feb 07, 1992  |  0 comments
Over the past two and a half years, I've auditioned and reviewed a number of digital audio products. It has been a fascinating experience both to watch digital playback technology evolve and to listen to the results of various design philosophies. The road to more musical digital audio has been a slow and steady climb, with occasional jumps forward made possible by new techniques and technologies. Making this odyssey even more interesting (and confounding), digital processors seem to offer varying interpretations of the music rather than striving toward a common ideal of presenting what's on the disc without editorial interjection.
Robert Harley  |  May 06, 2015  |  First Published: Nov 01, 1991  |  0 comments
In hindsight, it was inevitable that two sophisticated digital audio technologies—software-based digital filters and Bitstream D/A converters—were destined to be married in one product. The software-based D/A converters offered by Krell, Wadia, and Theta all used multi-bit ladder DACs, and Bitstream-based units have previously relied on off-the-shelf digital filters.
Robert Harley, Sam Tellig  |  Jun 18, 2014  |  First Published: Aug 01, 1991  |  0 comments
No, the $399 price listed in the specification block isn't a misprint. And yes, the Audio Alchemy Digital Decoding Engine v1.0 is indeed a full-function outboard digital processor. And since this is the August issue, not April, you can stop worrying that this review is some kind of joke.

The $399 Digital Decoding Engine is for real.

Robert Harley  |  Aug 08, 2011  |  First Published: Jun 01, 1991  |  2 comments
The past 12 months have seen some remarkable developments in digital playback. Standards of digital musicality are far higher than they were a year ago, both on an absolute performance basis and in terms of what you get at various price levels. No other component category has seen such tremendous gains in value for money or number of new products introduced. It seems hard to believe that since Vol.13 No.6 (12 issues ago), we've reviewed such noteworthy digital processors as the Meridian 203, Proceed PDP 2, Stax DAC-X1t, Theta DSPro Basic, Wadia X-32, Esoteric D-2, PS Audio SuperLink, and VTL D/A. Each of these converters brought a new level of performance to its price point—or, in the case of the Stax and VTL, established a new benchmark of ultimate digital performance.

Just as these units provided stiff competition for previous products, so too will they come under the assault of improving technology. The art of digital processor design is so young that we can continue to expect further improvements coupled with lower prices as designers move up the learning curve.

Robert Harley  |  May 07, 2015  |  First Published: Jun 01, 1991  |  0 comments
666wawaWadia2000.1250.jpgDuring my reviews of digital processors in the past year or so, I've made comparisons with the Wadia 2000 Digital Decoding Computer first reviewed by Arnis Balgalvis in Vol.13 No.1. I've felt that, as good as the 2000 is, other processors—many costing less than the 2000's $8500 price tag—are now superior.

However, a visiting Wadia representative looked inside our sample and used the word "ancient" to describe its circuitry in relation to current production. In addition, I was never able to audition the 2000 with a glass fiber-optical interface, standard equipment on Wadia's transports. Similarly, the $2000 Wadia X-32 had undergone a minor circuit revision, including the inclusion of the glass optical input. Consequently, a follow-up of these two excellent processors seemed in order.

Robert Harley  |  Aug 07, 2009  |  First Published: Dec 07, 1990  |  0 comments
I find it more than a little ironic that in 1990 the only two digital-to-analog converters to employ a new state-of-the-art DAC also use vacuum tubes. Many in the audio community consider tubes an anachronism, and find it surprising and humorous that they are still used in newly designed audio products. The fact remains, however, that these two tubed digital processors achieve the best digital playback currently available—and by a wide margin. Moreover, their respective designers' technical savvy and passion for building leading-edge products is reflected in their choice of these superlative and very expensive new DACs. Is it mere coincidence that both designers also chose vacuum tubes to realize their vision of no-compromise digital playback?
Sam Tellig, Robert Harley  |  Jul 09, 2006  |  First Published: Sep 09, 1990  |  0 comments
Gotta get this one written up right away—you never know with digital products. Always something new.
Robert Harley  |  Nov 05, 2009  |  First Published: Aug 05, 1990  |  0 comments
As an equipment reviewer, I find it helpful to talk to audiophiles and music lovers about their systems and upgrade plans. Fortunately, Stereophile's computer supplier and troubleshooter, Michael Mandel, also happens to be an avid audiophile. I say "fortunately" because I rarely get a chance to talk to people who put down their hard-earned money for hi-fi components. Instead, I usually converse with equipment designers, technicians, and marketing types, hardly people who reflect the buying public. It is thus a valuable education to get feedback from real-world consumers to find out what kind of products they want, their priorities, and how much they're willing to spend for certain levels of performance. They have a view distinctly different from that of the often jaded reviewer who is used to enjoying the best (albeit temporarily) without agonizing over its cost.
Robert Harley  |  Nov 02, 2009  |  First Published: Aug 02, 1990  |  0 comments
During an Audio Engineering Society meeting where a former colleague of mine was giving an arcane technical discussion of the optical considerations of data retrieval from a Compact Disc, a longtime AES member whispered to me: "What happened to the good old days of AES meetings when we talked about things like tape bias and saturation?"

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