The arrival of the Mark Levinson No.30 digital processor more than 2½ years ago marked a turning point in digital-audio reproduction. Although the No.30's $13,950 price tag put it out of reach of all but a few audiophiles, its stunning performance suggested that much more musical information was encoded on our CDs, waiting to be recovered by better digital processors. Further, it was inevitable that this level of performance would become less expensive over time. I was more excited by the No.30 than I've been over any other audio product. In fact, its musical performance was so spectacular that it alone occupied the Class A category in Stereophile's "Recommended Components."
While headphone listening remains secondary to that of loudspeakers for most serious listeners, it's still an important alternative for many. And while good conventional headphones exist, electrostatics are usually considered first when the highest playback quality is required. As always, there are exceptions (Grado's headphones come immediately to mind), but most high-end headphones are electrostaticsuch designs offer the benefits of electrostatic loudspeakers without their dynamic limitations. Last year I reviewed the Koss ESP/950 electrostatics (Vol.15 No.12), a remarkable set of headphones from the company that practically invented headphones for serious home listening. Here I listen to examples from two other companies, each known for its headphones since Pluto was a pup.
Compared to the Krell KSA-300S power amplifier that I also review this month, the KRC preamp's design is, at first glance, almost conventional. But its thoroughly high-end internal design has been equally well thought-out and executed. Its main, four-layer, glass-epoxy circuit board is for the audio signal, DC power, and groundtwo layers for the latter are said to minimize noise. The gain stages are pure class-A and complementary. As in the amplifier, the circuit is direct-coupled, with servo circuits controlling the DC offset. The fully regulated power supply is housed in an external chassis. Seven inputs are provided: four single-ended, two balanced, and one single-ended tape. All inputs are line-level except for the optional, single-ended phono stage. (This review will address the line stages; a Follow-Up will discuss the phono stage's operation.) There are three outputs: balanced and single-ended main outputs, and a single-ended tape output.
It was a dark and stormy night. A biting, cold wind cut through Sam's skimpy jacket; ice crystals clung tenaciously to his bushy moustache. As he approached his front door, visions of a toasty-warm, Krell-heated listening room softened the chill. He could feel the glow already; his Krell amp had been on all day, awaiting his return.
While Clearfield Audio may be a new name to many of you, it represents the marriage of two well-established members of the high-end community: Counterpoint and designer Albert Von Schweikert. Counterpoint had been working to add speakers to its product lineup for some time. The partnership with Von Schweikert, whom Stereophile readers will remember as the designer of the Vortex Screen favorably reviewed by Robert Harley in July 1989, fills out Counterpoint's high-end product line from sourcethe company showed a CD transport at the June 1993 CESto speaker.
The Metropolitan
The developmental history of Vortex speakers provides a meaningful framework for the design of the Clearfield offerings, especially the Metropolitans, or Mets. Like the Vortex designs, the Mets are three-ways with transmission-loaded bass. Like the Kevlar Reference Screen (reviewed by Robert Greene in The Abso!ute Sound's "double-issue" 83/84, December '92), the Mets use Kevlar-coned midrange units from Focal that cover a broad range from 125Hz to 2kHz. What's dramatically different is the overall driver layout.
Owning a powerful tube amplifier is like owning a classic automobile. Great pleasure may be had, but ownership involves a little more care and maintenance than usual.
Jadis, an audiophile company specializing in all-tube amplifiers and operating out of a small French town, has enjoyed a good reputation for some years, even if some of its models have suffered from the reliability problems that occasionally afflict the largest tube amps. Another problem area is that of power consumption and heat output. In common with class-A amplifiers and high-bias A/B types, including solid-state models, larger tube amps give off substantial heat. The Defy-7's 240W idling consumption may or may not be welcome, according to your location and the season.
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.
In its comparatively few years in the marketplace, the line-level preamplifier appears to have established commercial parity with its full-function big brother. That this was inevitable was clear as far back as the mid-'80s. The advent of the CD and the proliferation of digital sources argued for a modular approach to preamp design. In such an environment, line-level sources (eg, DAT, CD, even analog tape) deserve special attention.
Designer Dr. Roger West got his first taste of electrostatic transducers many years ago during a stint with Janszen (remember the Janszen tweeter?). To realize the potential of the full-range electrostatic loudspeaker (ESL), he and Dr. Dale Ream formed a new company dedicated to ESL research and development. West describes this company, Sound-Lab Corp., as "the electrostatic speaker specialists."
I think I've finally figured out the secret of Stereophile's success. You, cherished reader, don't read this mag because it's chock full o' reviews of tantalizing audio gear (even though it is). And you don't read this mag because JA and RL strive so hard to keep the literary quotient as hi as the fi (even though they do). And I know you don't read this mag cuz trusting yer own sensory input is a mighty scary proposition indeed so you look to Stereophile as to a Holy Bible that eases your Earthly burden by telling you, Ah say Ah say TAILING YEW what to buy (do you?).
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.
"In the fields of observation, chance favors only the mind that is prepared."
When Louis Pasteur uttered these words more than a hundred years ago, he must have speculated that they would apply equally well to future circumstances as to the events of his day. What he couldn't anticipate, however, was the technology to which his insight now seems so appropriate.
To judge from the $6400 Mimesis 8, Goldmund walks its own way when it comes to power amplifier design. High-end solid-state amplifiers from US companies like Krell, Mark Levinson, Threshold, and the Jeff Rowland Design Group marry massive power supplies to large numbers of output devices (these often heavily biased to run in class-A), built on chassis of such nonmagnetic materials as aluminum. By contrast, the Mimesis 8 has a magnetic (steel) chassis, and uses a relatively modest power supply, that for each channel based on two main 4700µF reservoir capacitors. The 8 offers just two pairs per channel of complementary output MOSFETs (Hitachi K134/J49). These carry a modest bias current of around 80mA total.
During 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 processorsmany costing less than the 2000's $8500 price tagare 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.