AURALiC VEGA G2 streaming DAC/preamp

Digital-to-analog converters,
Music servers and computer audio

AURALiC describes Precise mode as a “traditional filter design using a single filter algorithm for all sampling rates,” which is said to provide the most exacting representation of the source material. Meanwhile, Dynamic mode offers “the same pass-band and stop-band performance as Precise mode,” with less group delay, with Dynamic mode offering an “ideal balance between measurable precision and subjective quality.” Balance mode is “designed to achieve minimum pre-echo and ringing effects,” while “slow roll-off filters show moderate pass-band and stop-band performance,” with minimal group delay. Finally, Smooth mode features filters that are all minimum phase types with “no pre-echo at all” and they are also designed with “very small group delay” to help eliminate ringing. Of the four, Smooth mode scored highest on AURALiC’s subjective tests during development.

The VEGA G2 promises jitter-free operation thanks to a scheme where, instead of trying to lock on the input signal’s frequency, the G2 instead buffers a large quantity of inbound digital audio data (the amount is configurable via a menu setting) and then re-clocks the data using one the G2’s two, hyper-accurate, low-noise 72 femtosecond Femto Master Clocks. One clock handles samples in multiples of 44.1kHz while the other handles samples in multiples of 48kHz. AURALiC claims this design makes the VEGA G2 “the industry’s first signal independent ‘Master DAC’.”

Noise minimisation (and isolation) is a consistent theme in the VEGA G2 design, which makes extensive use of digital audio galvanic isolation throughout. AURALiC designed a “high speed galvanic isolator that’s configured between primary circuits in the VEGA G2.” This means the D/A converter, Femto Clocks, and analogue audio circuits are all isolated from the central processing circuit in an effort to eliminate EMI noise. 

In a similarly vein the G2 benefits from a very low noise, high-performance, low power, fully passive volume control. The volume control uses an R-2R resistor ladder network driven by a set of “eight coil-latch relays” that, once set, draw no current and hence produce no EMI noise. AURALiC concedes that this volume control is “an expensive solution to construct,’ but argues that its sonic benefits more than justify the added costs.

Finally, the VEGA G2 features a pair of the firm’s signature Purer-Power linear power supplies. One supply feeds the G2’s processing circuit, network interface, and LCD front-panel display, while the other supply powers the G2’s D/A converter, Femto clocks, and analogue audio sections. The dual Purer-Power supplies help isolate noisier circuitry from noise-sensitive circuitry, in part because the two supplies are—you guessed it—galvanically isolated from one another.

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