Nagra DAC D/A processor

Without having intended to, I seem to have collected several "statement" products. I've already reported on the Weiss Medea and Theta Digital Generation VIII digital-to-analog converters. I saw and expressed interest in the Nagra DAC at the 2002 Consumer Electronics Show, when prototypes of it were shown along with a forthcoming multichannel version, the Nagra Digital Audio Processor (DAP). The two units are based on the same chassis and interface, the DAP including additional modules and processing.

Why would anyone think about spending $10,000 or more for a DAC to play standard "Red Book" 16-bit/44.1kHz CDs? Assuming that you (or I) even have the bucks to consider such a move, the high-end parade has now moved on to the high-resolution SACD and DVD-Audio formats. Beyond that, PCs and the Internet will soon be offering such formats as Intel's High Definition Audio, which can handle 32-bit/192kHz multichannel sound. "Red Book" CDs were never "perfect sound forever"!

But that's not the issue. The reason I still update my phono system is that I want to hear the great music I've amassed on LPs that I could not bear to replace, especially at the considerable expense, with CDs. I've also got thousands of CDs—even if all those master tapes from which they were made were to be remastered and/or remixed and reissued on a hi-rez multichannel format, I ain't throwing 'em away. That library is part of my life's work; I just want to continue to hear it as well as I can.

Fortunately, all the cutting-edge, new-format players, including my new PC, have digital outputs, and there's a slew of high-quality DACs to take that signal and run with it. So there will always be a need for a really good DAC, even if, in the future, it has more than two channels or, dare I say it, lives in the loudspeaker!

Nagra's DAC
Like all Nagra products, the DAC has at least one foot in the world of professional audio, as reflected in its user interface and displays. The DAC has a module on the left of the front panel and another, smaller one to its right. The entire right half of the front is a blank panel covering real estate set aside for the additional components used in the DAP. The leftmost module is the main control section, which includes the power switch, input selector (left and right arrowhead buttons), master volume control (in 0.5dB steps via up and down arrowheads), switches for Mute and Escape, a multiline LCD display, and function keys.

The other module, called the "front panel" in the handbook, bears left- and right-channel modulometers that are similar in action to Nagra's traditional analog modulometers, though here they're in the form of two stacks of LEDs. These indicate analog output or digital input. The cross of LEDs on the right side of that panel reflects the trim of level and L/R balance, which are set with the array of arrowhead buttons below the cross.

The DAC's manual contains many pages of instructions for renaming the inputs, adjusting display brightness, contrast, backlighting, and response to ambient light, storing trim and modulometer settings, and setting channel polarity. In addition, three sets of instructions can be stored to use under different conditions. The average home user will need little of this, but a professional schlepping a DAC from studio to concert hall to club might find its programming and memory functions quite convenient.

The business end of the DAC is its rear panel. There are three coaxial S/PDIF data inputs, one AES/EBU, one TosLink, and one labeled only "Nagra digital in." The first five accept signals sampled up to 96kHz. In addition, there are pairs of XLR (selectable as balanced or unbalanced) and RCA analog inputs, but only one pair can be used at a time; apparently, they share input circuitry. The analog input signal is not routed directly to the outputs as analog bypasses or operated on by an analog volume control, but are digitized by an onboard ADC running at 24/48. While I understand that this might permit the DAC's stablemate, the multichannel DAP, to apply DSP to these signals, it seems hard to justify for the two-channel DAC. What can possibly be gained from digitizing and reconverting analog signals?

Finally, there are XLR and RCA jacks for each of the DAP's 7.1 channels, although, as with the analog input, you can't use XLR and RCA simultaneously, and in the two-channel DAC, only the front-channel jacks are hooked up. In addition, you can select output level and the "0dB" setting on the modulometer with a pair of jumpers on the DAC pcb. A power connector, fuse, ground post, and RS-232 connector complete the rear-panel array.

While all that may seem complex, installation and use of the Nagra DAC was a piece of cake. The remote control is the same model as comes with Nagra's MPA integrated amplifier and PL-L preamplifier; one remote can control up to six Nagra components, as each device can be set to a unique ID number corresponding to one of six numbered buttons on the remote. In fact, the DAC is really two units: the main panel has an ID of 1, the front panel an ID of 2. Thus, with appropriate selection of ID, the remote can emulate the arrowhead buttons of both modules, which can then be operated from the remote in the same manner as if from the front panel.

For those curious about the technology involved in the DAC, Nagra says it uses an Analog Devices Sharc ADSP 21065L, although an illustration in the manual indicates that the Sharc is part of an Anagram Technologies 24/192 Adaptive Time Filter. There is one of these devices on each D/A board (the two-channel DAC has one board); it upsamples and minimizes jitter by separating the input and output clocks. (Anagram's own Orpheus DAC is based on this same moduel.) The D/A devices are AD1853, from AD, and the analog/digital chips are Burr-Brown PCM1804s. All incoming signals, including the 24/48 digitized analog input, are upsampled to 24 bits/192kHz.

Listening
The display of the DAC's dancing modulometer LEDs was fascinating, but its sound was better. Connected to any of the transports I had on hand and feeding the Classé CAM-350 monoblock power amps and the Revel Ultima Studio loudspeakers, the Nagra conveyed a powerful, detailed sound, and distinguished itself by rendering a clearer, more solid representation of every program than did the inbuilt DACs of the players feeding it. In comparison with, say, the Sony SCD-XA777ES's analog output, the palpability of voices and instruments was enhanced and backgrounds seemed quieter and blacker. The Nagra was simply a quieter device that filtered nothing meaningful from the music.

The Nagra's frequency balance, whether running direct to the power amps or through a preamp, seemed ideal, conveying the same kind of "rightness" as did its compatriot, the Weiss Medea. Human voices were not only harmonically correct, but often had a presence in the room that verged on the scary—from David Johansen and the Harry Smiths (SACD, Chesky SACD225) to Será una Noche (CD, M•A Recordings M052A) to Alison Krauss's Forget About It (SACD, Rounder 11661-0465-6). Fuhgedabboudit, indeed! The Nagra took them all in stride, keeping each voice and instrument distinct in character and position as I graduated to more and more complex material, especially 24/96 signals from DADs and DVD-As.

COMPANY INFO
Nagra
US distributor: Audiophile Systems & ASL
8709 Castle Park Drive
Indianapolis, IN 46256
(317) 849-5880
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