Schiit Audio Yggdrasil DAC

By Any Other Name

Equipment report
Categories:
Digital-to-analog converters
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Products:
Schiit Audio Yggdrasil
Schiit Audio Yggdrasil DAC

The company unfortunately named Schiit Audio has developed quite a reputation for creating great-sounding products at bargain-basement prices. Founded in 2010, Schiit now offers 18 models of headphone amplifiers, preamps, amps, and DACs, with all but two of its products selling for less than a thousand dollars. Indeed, most are priced below $500. Schiit even offers a $99 DAC.

The company has been enormously successful in more ways than one. In addition to creating a thriving business for itself, Schiit has brought good-sounding products to an entirely new audience who may not otherwise have pursued quality-oriented audio. In fact, Schiit builds and ships more than 65,000 units per year—and the average customer age is under 30. That’s a huge boon for high-end audio in general—Schiit’s products are the “gateway drug,” if you will. Schiit has courted the hip young audience with its irreverent name, bizarre product monikers (Mjolnir and Gungnir, for examples), and conversational promotional copy (the company slogan? “Everything Else Ain’t”). The U.S.-built products are sold factory direct with a 15-day return privilege and a two-year warranty.

Behind the whimsy, however, lurks one of high-end audio’s pioneering digital engineers: Mike Moffat. Beginning in the Pleistocene Age of digital audio (the early 1980s), Moffat was at the forefront of making digital sound good. Does anyone remember California Audio Labs and its highly modified CD players? That was Moffat’s work. He went on to co-found, with Neil Sinclair, Theta Digital, one of the most iconic digital companies of the era. A Theta hallmark was its custom digital filter that ran on general-purpose DSP chips. At that time, virtually all other DAC manufacturers simply bought off-the-shelf filter chips. Even Theta’s first DAC, launched in 1984, was built around a custom-software-based digital filter. Theta’s DACs were universally praised (I reviewed many models beginning in the early 1990s). Moffat has now combined his expertise with that of Schiit partner Jason Stoddard, a long-time industry veteran responsible for designing many of Sumo’s acclaimed products in the 1990s.

The Yggdrasil DAC reviewed here is an outlier in the Schiit line; its $2300 price tag positions it far above the company’s other offerings. (By contrast, Schiit’s Delta-Sigma DACs sell for $99, $149, $399, and $849—the company also offers three multi-bit DACs priced from $249 to $1250.) But the Yggrasil is significantly different in design from those DACs, as well as from virtually all other DACs on the market. We’ll get to those technical details in a minute, but let’s first look at the Yggy’s features and operation.

Its rounded aluminum case is slightly reminiscent of an Airstream trailer from the 1950s. A cutout in the front panel is dominated by a round pushbutton that selects between the Yggy’s five inputs (AES/EBU, BNC, RCA, TosLink, USB). Small LEDs indicate the selected input, the incoming sample rate, whether phase inversion is selected (via a smaller round front-panel pushbutton), and when the Yggy is locked to the incoming source. The Yggy proudly eschews DSD support and MQA decoding; its singular mission is to decode PCM (up to 384kHz) with the highest fidelity.

Moffat says that the Yggy is a “modern descendent of the first Theta DAC.” Like the Theta DACs, the Yggy is built around a custom digital filter. But this time Moffat employs the Analog Devices SHARC DSP. These DSP chips are vastly more powerful than the Motorola DSP56000 devices of the 1980s. The additional DSP horsepower allows a much “longer” filter for better performance. The Yggy’s 8x oversampling filter is designed to retain all the original audio samples without alteration. Many oversampling filters, as well as delta-sigma DACs or those with integral asynchronous sample-rate converters, change the sample values from those created by the analog-to-digital converter when the music was originally digitized.

To preserve this “bit-perfect” datastream, Moffatt selected an unusual DAC—a 20-bit R/2R ladder device from Analog Devices (the AD5791) that is used in applications where bit-perfect conversion is essential, such as in instrumentation, weapons systems, and magnetic-resonance imaging (MRI) machines. No one else uses these DACs for audio. You’ll notice that the Yggy’s DACs have 20 bits of resolution, not the “24 bits” that are typically found in today’s digital-to-analog converters. That’s not a shortcoming; there’s no real information below the 20-bit level, and the state of the art in conversion is limited to 20 bits per balanced phase. The AD5791 is a dual-channel DAC, with two AD5791s employed in the Yggy for truly balanced operation (+L, –L, +R, –R). Shockingly in a $2300 product, the DAC chips cost a whopping $80 each (even purchased in quantity). Given the DAC architecture, it’s no surprise that the Yggy doesn’t support DSD. The design is optimized for CD-quality sources, which comprise the majority of most listeners’ libraries.

The analog output stage is fully balanced and built from JFETs rather than op-amps. It is simply a unity-gain buffer. No gain is required in the output stage because the Analog Devices DAC has a built-in current-to-voltage converter, and outputs a voltage at the appropriate level.

The power supply is over-the-top for any product, never mind one at this price. It starts with a choke input, and regulation is realized with current-source shunt regulation followed by cascaded regulation stages. Shunt regulation is rarely used because it’s so inefficient, but it delivers clean and stable DC to the circuits. Overall, the Yggy is an unusual and tweaky design from a mind that has been working on digital-to-analog conversion circuits for nearly 35 years.

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