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It's hard to jet a good perspective on an audio component with the technology and price of the Wadia 27 Decoding Computer. What do you get from a D/A converter costing $8,450  that you don't get from less expensive models?
For one thing, the Wadia 27 possesses outstanding technology and specifications, a wide range of useful features, construction quality and styling that belong in the Museum of Modern Art, and superb sound. Ex pensive as it may be, it meets every test relating to value for money I can think of. Furthermore, the Wadia 27 can be used as a digital preamp, enabling you to eliminate the coloration inevitable in the use of a separate preamp and extra interconnects. The features that make this possible begin with six digital inputs (one AES/EBU input with an XLR connector, two coaxial inputs with BNC connectors, two ST optical in puts, and one Toslink optical input) and versatile analog outputs (the balanced XLR and unbalanced RCA outputs can be used simultaneously, and internal switches can set the audio output voltage to suit your pre amp). Equally important are the Wadia's digital volume and balance controls, which are free of any apparent coloration. You can even use the Wadia 27 to control a system containing both digital and analog sources, by adding the Wadia 17 A/D converter.
The Wadia 27's front panel has no buttons or controls, just an alphanumeric display that indicates control settings. Operation is handled by the remote control, which you can use to vary volume in steps of 0.5 dB and channel balance in 0.1 -dB steps. It also has muting and absolute-polarity buttons and can be used with any Teac-based Wadia CD transport.
The Wadia delivers 24-bit digital processing by way of two Motorola 56000 DSP chips, and 22-bit digital resolution and throughput via eight Burr-Brown 1702 DACs in full-differential mode. These chips are all surface-mounted; Wadia feels this improves performance because of the shorter lead lengths and reduced number of internal connections. Like most Wadia products, the 27 is easily upgradable: The ROM con trolling its software-based digital filtering is socketed for easy replacement, each of its six circuit boards is devoted to one specific function and is removable, and the rear panel is modular. This upgrade capability, which includes the possibility of sampling rates up to 96 kHz, may be of great value if the industry ever moves to a CD technology more advanced than today's system.
The Wadia 27 has full 64-times oversampling, accomplished by performing 16-times spline resampling in the Motorola chips and four-times first-order LaGrangian resampling in dedicated chips. Because a single DAC chip can't handle 2,822,400 samples per second (64 times CD's 44,100), the resampling chips feed each channel's four DAC chips sequentially, 705,600 samples at a time. The Wadia 27 has a proprietary jitter-reduction circuit called RockLok. The output stage uses surface-mounted Burr-Brown OPA642 current-to-voltage converters and Burr-Brown BUF634P output buffers. The circuits are on four- and six-layer boards with integral ground planes. The power supply uses dual toroidal transformers, 36 individual stages of regulation (plus a four-stage, 60-watt preregulator), and more than 30,000 microfarads of filtering and energy storage.
The cabinet is fairly compact (4½ inches high, 17 inches wide, and 16 inches deep). However, it weighs 32 pounds because of its thick chassis panels, which double as heat sinks, and because the transformers are on a subchassis that isolates them electrically, mechanically, and acoustically.
Even though I've heard more D/A converters than is good for my psyche, I can't say how the Wadia (or any other top D/A) sounds in comparison to all its competitors. I have not heard even a quarter of the con tenders in the $3,000+ range, but I did compare the Wadia 27 with the $15,950 Mark Levinson No. 30.5 and the $5,595 Theta Digital DS Pro Generation V-a Balanced, two of the finest-sounding converters I have heard.
Listening comparisons with even a few top-quality D/A converters are anything but easy to conduct. Even if you match the converters' output levels within a fraction of a dB, the sound characteristics of the reference system and room inter actions introduce extraneous colorations. Further, some CDs sound better with some D/A converters than with others, in ways that are atypical of CDs in general.
I tried to get around these problems by using CDs from many labels, using several different transports (principally the Mark Levinson No. 31.5), and using three different audio systems in different listening rooms. Such listening showed me that many of the sonic nuances that distinguish one D/A converter from another in one system and room are not repeatable in other systems and rooms. There are audible inter actions between the converter, the rest of the system, and the room. The most important differences were audible in all three rooms.
That said, my listening experience convinced me that the Wadia 27 will likely be a top performer in any system. Its timbre was consistently accurate in reproducing my reference CDs and DATs that contain natural acoustic performances of classical music, jazz, solo voice, and solo instruments.
There are more euphonic D/A converters than the Wadia 27, and it may not have the warmth or slightly softened treble of some top-of-the line models that use vacuum tubes in their output stages. On the other hand, the Wadia 27's rendition of the over all timbre, of strings, woodwinds, brass, percussion, and voice was simply as "right" in reproducing what was on the original CD or DAT as that of any D/A converter I've en countered. Although you can fully appreciate the Wadia 27's timbral accuracy only by listening to a wide range of music, the instrumentals and vocals on Alan Parsons' and Stephen Court's Sound Check (Mobile Fidelity SPCD 015) provide a good starting point for understanding why I praise the Wadia's musical realism and accuracy.
The only D/A converter I have heard that produces a slightly more natural timbre on some CDs is the Levinson 30.5, which costs nearly twice as much as the Wadia 27. The Levinson's midrange sounded a bit more natural on strings and piano, although it may not have been quite as realistic as the Wadia in the bass. The Theta unit also had a musically natural timbre but slightly more upper-octave energy than I believe was actually in the recordings.
The Wadia's transients and dynamic response were excellent and musically natural. The Wadia resolved low-level detail, complex musical passages, and complex musical harmonics without any artificial hardness or spotlighting of detail. This high resolution also gave the Wadia an unusual ability to reveal sonic differences between CD transports and various types of CD mastering without adding significant colorations of its own.
I would rank the Levinson 30.5 as slightly superior in sheer resolving power, particularly with very low-level musical passages and old CDs. However, the Levinson's dynamic transients seemed a bit soft, and the match between dynamics and timbre was better with the Wadia. The Theta's dynamics and detail also matched its timbre, but a touch of synergistic coloration made its performance seem closer to the instruments than was entirely natural.
There were some interesting differences among the three D/A converters in specific areas of the frequency spectrum and in soundstage performance. The Theta had the most bass dynamics and energy, the Levinson had the most bass definition and tightness, and the Wadia struck a balance between them (although its sound was closer to that of the Levinson). These differences in the bass emerged clearly in Eiji Oue's recording of several Stravinsky pieces (Reference Recordings RR-70), in Jacques Loussier Plays Bach (Telarc CD-83411), and in the National Philharmonic Recording of The Mysterious Film World of Bernard Herrmann (Mobile Fidelity UDCD 692). I admit that these bass differences had limited over all musical significance, but they were more immediately apparent than other sonic differences between converters. (I suspect these differences in bass energy and definition may explain why some reviewers refer to one converter as doing more to preserve the beat or rhythm of the music than an other. A D/A converter cannot introduce meaningful timing errors in the bass beat, but the "beat" may seem stronger if the bass sounds louder or more dynamic.) The differences in the midrange and treble related more to the reproduction of dynamic contrasts than to differences in frequency response or timbre. The midrange timbres of the Wadia 27 and Levinson 30.5 were almost the same, but the dynamic contrasts in the Wadia were a little sharper. The apparent midrange response of the Theta Generation V tilted just slightly to ward the high end, and dynamic contrasts were sharper than in the other two units.
In the treble region, there were no striking differences among the converters in energy or extension. All three had excellent air and harmonic definition in the top octaves, although the Levinson seemed to have slightly cleaner harmonic detail and the Theta had a touch more apparent treble.
All three units reproduced an excellent soundstage, but the apparent soundstage of the Theta was a bit more forward than that of the other two units. The Levinson's soundstage was more mid-hall, and the Wadia's was just a bit forward of that. All of the D/A converters presented excellent width and depth, but the Levinson and Wadia portrayed a bit more depth than the Theta. Soundstage detail, ambient information, and imaging were very good with all three, but the Levinson had a trace more sound-stage detail than the other two. Interestingly, my son-who is no fan of either classical music or listening comparisons-picked this difference out consistently in blind comparisons using fairly ordinary recordings (such as the Haydn trumpet concerto on L'Oiseau-Lyre 417610).
Performance did vary according to the type of CD I played, but not always in the ways I would have predicted. Somewhat to my surprise, I did not notice any consistent change in the three converters' sonic characteristics when I played CDs labeled "20-bit" or discs made with advanced mastering technologies like Sony's SBM or JVC's XRCD. Although some CDs did sound cleaner than others, their recording and production values shaped sound quality far more than any specific recording process or D/A converter did. The "techno-hype" on the CD's cover rarely correlated with how good the recording really was.
The Wadia 27 does not have HDCD de coding. But prolonged listening to HDCD recordings through the Wadia and through the Levinson and the Theta in their HDCD modes convinced me that the Wadia's lack of this circuit was no drawback. It also convinced me that HDCD is largely a waste of time. I have been impressed by the overall quality of recent HDCD recordings and of the filter used in HDCD decoding, but playing HDCD discs through the Levinson and Theta did not reveal any musical information that I could not hear from the Wadia. I also detected no musical detail on HDCD recordings that was not available, and just as musically convincing, on many top CDs without HDCD encoding.
It was interesting to use the three D/A converters to listen to the same recordings with and without HDCD. These comparisons are available on HDCD Sampler 2 (Reference Recordings RR-905CD) and Doug MacLeod's You Can't Take My Blues (AudioQuest AQ 1041). Even though the Wadia 27 does not provide HDCD decoding, the HDCD-encoded tracks on the Reference Recordings disc still sounded better than the tracks mastered with Sony's 1630 and KOJ-701ES A/D converters-possibly reflecting the fact that neither the 1630 nor the KOJ-701ES is a state-of-the-art converter. In contrast, the non-HDCD passages on the Doug MacLeod album sounded better than the HDCD-encoded passages. This held true with the Wadia, the Levinson, and the Theta. Apparent dynamic range and soundstage detail were slightly better with out HDCD via all three converters, and the upper midrange seemed more harmonic and natural. In fact, the recordings made using the Apogee A/D 1000-20 Super En coding System sounded as superior to those made with the HDCD encoding system as the HDCD-encoded tracks seemed to those made with the Sony 1630 and KOJ-701ES. And none of these recordings, incidentally, approached the transparency and musical integrity of the best true 18- and 20-bit recordings I have heard.
I also compared the sound of the Wadia / to that of top mid-priced D/A converters from Adcom, Audio Alchemy, and PS Audio. On many types of music, the differences between it and the mid-priced units were scarcely to die for. Today's best mid- priced D/A converters are very good in deed. And the differences I did hear again depended on the recording and the associated components. However, there were some sonic differences that were musically significant when I played really good recordings on a really clean system.
Such differences in sound quality involve the same diminishing returns you expect when making an investment in any high- end electronics. You do not get the kind of sharp audible differences you do when you compare top speakers with similar price differences. What you do get is more harmonic detail and natural harmonic integrity-particularly with strings, piano, and woodwinds-and a sweeter, more detailed sound. Soundstage resolution is better, as is the overall quality of left-to-right and back- to-front imaging. Depth is as natural as the recording permits, without the slight fore shortening or slight sense of echo common to the less expensive units. Bass and dynamic contrasts are better defined.
Yes, there are diminishing returns in paying thousands of dollars for a D/A converter. However, the differences are important enough for me to find that a converter like the Wadia 27 is aesthetically competitive with the best in analog sound, while mid- priced converters are not. This is the name of the game in high-end audio, and it gives you the same justification for buying the Wadia 27 that a different set of passions does for buying a Rolex or a Mercedes.
[by ANTHONY H. CORDESMAN. Orig. publ. in Audio magazine/APRIL 1997 ]
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