TAS 194: Weiss Engineering Jason CD Transport and Medea D/A Converter

Equipment report
Digital-to-analog converters
Weiss Engineering Jason
TAS 194: Weiss Engineering Jason CD Transport and Medea D/A Converter

Take a cleaver and hack a CD player into two functional halves. What you end up with is a transport and a digital-to-analog converter (DAC). Is that really necessary? Is there a good reason to break an integrated CD player, which is bound to be a more cost-effective design, into two pieces? The most compelling reason is flexibility—the ability to experiment with new DAC designs as digital technology continues to evolve. Having lived with the Jason for some time now, I am convinced that a good transport is essential to laying the foundation for a sonically superior digital front end. The notion, popular in some circles, that a good DAC can overcome the limitations of a mediocre transport gets crushed by the Jason. But then this is no ordinary transport.

The Weiss Engineering Jason was built without compromise in either electronics or software to partner with not only Weiss’ own Medea DAC but any DAC or digital amplifier out there. At the Jason’s core is the impressive Philips CDPRO2M top-loader mechanism. Push the “Eject” button and a motor drive lifts a heavy-duty lid. Push it again and the lid closes while securely capturing the CD. As with the Medea, the chassis consists of a twin frame. The inner steel chassis provides an effective shield against electrostatic and electromagnetic fields, while the outer anodized aluminum frame is responsible mainly for heat convection and the unit’s elegant cosmetics.

Attention to detail is abundant. All sensitive voltages have dedicated regulators. The power switch activates a solid-state-based relay which only switches on or off at zero crossings of the mains voltage, ensuring glitch-free power switching. An internal low-jitter clock generates all clocking signals, including those required for the CDPRO2M transport.

In order to ensure maximum compatibility with 196kHz/24-bit or 88.2kHz/16-bit DACs, the 44.1kHz/16-bit signal from the CDPRO2M may be optionally upsampled to 88.2kHz or 176.4kHz. When upsampling is engaged, the output word-length can be set to 16, 20, or 24 bits to accommodate the word-length requirement of the partnering DAC. Word-length reduction to 16, 20, or 24 bits is performed via proprietary on-board digital signal processing using the POW-R dithering algorithm, which is the de facto standard in professional audio for this operation.

In the case of the Medea DAC or any other DAC which can accept any of the Jason’s outputs, it is possible to experiment with the various upsampling options to determine which sounds best in the context of a particular system. The Medea’s onboard DSP upsamples 44.1 to 88.2kHz, while its DAC chip upsamples 88.2 and 176.4kHz input to 352.8kHz. Thus, for Jason and Medea users, the critical step of upsampling from 44.1 to 88.2kHz may be performed either by the Jason or the Medea. According to designer Daniel Weiss, some users prefer the 44.1kHz/16-bit output from the Jason. And I can understand why. For a single cable connection (e.g., Jason AES/EBU output #4 into Medea input #3), I absolutely, positively, preferred 44.1kHz/16-bit settings. However, for a dual AES/EBU cable connection (Jason output #1 feeding inputs 1 and 2 on the Medea), 176.4kHz/24-bit was definitely king. Image outlines became more robust. Soundstage depth perspective was enhanced. In a nutshell, the music flowed with greater microdynamic conviction and analog-like spatiality; timbre accuracy, the cornerstone of musical realism, was exceptional.

The Jason also incorporates an optional DAC+ circuit whose goal it is to mask discrete jitter frequencies with wideband noise. This spread-spectrum technology is based on the premise that raising a DAC’s noise floor is sonically benign while discrete jitter frequencies are not. With the Medea as the partnering DAC, activating the DAC+ circuit made no audible difference during my listening tests. Weiss does believe, however, that it would help inferior DACs perform better.

The remote control deserves special mention. It’s solidly built and provides complete control over all of the Jason’s functions, including selection of sampling rate and word-length. The Jason’s 0/180-degree phase inversion function is worth writing home about. The ability to invert signal polarity on the fly is essential to maximizing sound quality during CD playback. The ubiquitous multitrack recording process whereby 24 or more tracks are being mixed down to as few as two stereo tracks almost guarantees that one or more tracks in the mix are reversed in polarity. And the situation may differ from track to track. Quickly checking the 0 and 180-degree settings on the fly makes it extremely convenient to select the best sounding setting for a particular track. Generally speaking, one setting gives the most focused image outlines and is the criterion I use for setting polarity.

The main focus of this review is the Jason since the Medea already earned a TAS Golden Ear Award (from JV) in 2003. However, I felt it important to reunite these protagonists in order to experience Weiss Engineering’s best digital front end. The Medea uses the Analog Devices AD1853 chipset in mono mode. The AD1853 is a 24-bit/192kHz multi-bit sigma-delta DAC introduced around 1999. It continues a minor design trend I have noted over the past several years of giving preference to older DAC chipsets. To be perfectly honest, even vintage 1980s DAC chips were already sporting incredible dynamic range. The relevant technical stories in recent years have been jitter reduction, more benign digital and analog filters, and the significant reduction of digital artifacts and brightness.

In the past it has been easy for me to divide digital front ends into two distinct camps. On the one hand, there were the single-bit sigma-delta DACs that at their worst were harsh and grainy sounding, and at their best only mildly bright and grainy. On the other end of the spectrum were the multi-bit DACs that sounded pretty much de-fanged but also as if they had undergone a frontal lobotomy, being boring dynamically. This was not the sort of polite sound I could fall in love with, and at the end of the day, I would be willing to accept a bit of textural grit for the sake of convincing microdynamics.

Enter the Jason and Medea. Now there’s no longer the need for any such concession. Harmonic textures were remarkably pure, totally non-digital sounding. It’s ironic that 26 years after the introduction of the CD and digital recording, one of the highest compliments I could pay a digital component is to label it analog-like. But my musical values are closely aligned with analog sound’s forte of smooth textures, microdynamic passion, and stable image outlines. In the case of the Jason and Medea, my listening notes added up mostly to a litany of “No’s”: No harmonic grain, no hyped-up upper octaves, no digital artifacts, no monotonous microdynamics. In fact, the music’s kinetic energy was propelled forward with a veritable “soul train” of emotions. Timbre accuracy was exceptional, each instrument being portrayed with believable tone and harmonic bloom. Performance at the frequency extremes is critically dependent on the associated speaker. But when the rest of the system was finely tuned, I can safely state that bass lines were full, tight, and in time with the upper octaves.

Transients unfolded with startling clarity and precision. On the flip side, the decay of musical lines was resolvable in breathtaking fashion down to a velvety black background. There was simply no veiling of the music’s tapestry. As a consequence, a wealth of low-level detail was revealed, as if observing the soundstage though a microscope. Yet, the overall presentation remained quite natural. My favorite analogy to explain precisely what I mean is that it was like observing a school of fish in an aquarium. Most of the time it was the ensemble that captured my attention, but it was always possible to focus in on a specific instrument.

The Medea uses a solid-state Class A output stage that features exceptionally low output impedance and allows it to drive long interconnect runs without a problem. The output stage’s distortion figures are very low. How low, you might ask? Well, apparently the Medea’s distortion figures are predominantly driven by the D/A converter and not by the output stage. Yet, the output stage did imprint its solid-state character upon the soundstage. That much was immediately obvious in a direct confrontation with the PrimaLuna Eight CD player. Make no mistake about it, the Weiss Engineering front end was much purer-sounding than the PrimaLuna, but it lacked the latter’s palpable imagery and soundstage depth. To be fair, it’s obviously a case of transistors versus tubes. Most listeners will agree that tubes portray a soundstage with greater spatiality. I’ve been asked why that is, and I can’t say that I have a definitive answer. It may well be a consequence of a tube’s inherent distortion spectrum, and I’m willing to accept that as a means to an end since in the final analysis I’m after the illusion of “live.” And the gestalt of listening to a musical ensemble is typically much stronger with tubes.

There were still two more configurations to audition. First, having the Jason feeding my favorite under-$3k DAC, the Altmann Micro Machines’ Attraction DAC, and second, using the PrimaLuna Eight CD player as a transport with its digital output connected to the Medea. The Attraction DAC is the only zero-upsampling DAC to my knowledge that can accept a 16-bit/88.2kHz datastream in addition to 16-bit/44.1kHz. With the Jason it was obviously possible to try both sampling rates. To my surprise, I discovered that I actually preferred to upsample out of the Jason at 88.2kHz. In this context, the Attraction’s mids were slightly sweeter than the Medea’s, but clearly lacked the latter’s resolving power. And finally, the Medea was rather unhappy being coupled to the PrimaLuna Eight. Certainly, a good DAC can to some extent handle a lower-pedigree datastream, but the resultant sound quality was well below the standard set by the Jason. Hence, the notion that a DAC can fully overcome the limitations of an indifferent (i.e., inexpensive) transport bit the dust in these listening tests.

I was a bit skeptical initially about the importance of a good transport, but no more! The Jason made a believer out of me. I can now safely state that the even the best of DACs can benefit from a world-class transport. The Jason’s blend of design excellence, useful features, purity of tone, and intrinsic boogie factor catapults it to the head of the class. Coupled with the Medea DAC, this is a digital front end that will recalibrate your expectations of CD sound quality. Bottom line: I can’t think of a more enjoyable way to rediscover one’s CD collection.


Weiss Engineering Jason CD Transport

Outputs: Two XLR (dual-wire), one XLR, one BNC, two RCA, one ST-Type optical, one TosLink
Dimensions: 17.7" x 3" x 12.2"
Weight: 26.4 lbs.
Price: $19,600

Weiss Engineering Medea D/A Converter

Input sampling frequencies: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz
Input word length: 16, 20, 24 bits
Digital inputs: Four RCA, three XLR, one TosLink

Outputs: XLR and RCA
Dimensions: 17.7" x 3" x 12.2"
Weight: 22.2 lbs.
Price: $16,900

Weiss Engineering Ltd.
Florastrasse 42
8610 Uster
+41 44 940 20 06

Precision Audio & Video (U.S. distributor)
12277 Arbor Hill St.
Moorpark, CA 93021
(805) 523-3005

Associated Equipment

Final Sound 1000i electrostatic speakers, Esoteric MG-20 and Venture Audio Excellence III Signature speakers; Kuzma Reference turntable outfitted with Graham Engineering model 2.5 tonearm and Grado Reference cartridge; Air Tight ATE-2 phono preamplifier; PrimaLuna Eight CD player, Altmann Micro Machines Attraction DAC; Concert Fidelity CF-080 line preamplifier, Spread Spectrum Technologies Ambrosia preamplifier, First Watt B1 buffer preamplifier; Esoteric A-100 and Audio Space Ref. 3.1 (300B) amplifiers; Bybee Speaker Bullets; FMS Nexus-3, Acrotec 6N and 8N copper, Kimber Select KS-1030, Kimber KCAG interconnects; FMS Nexus-3 speaker cable .