Naim Audio DAC
The Naim DAC marks a technical milestone comparable to our first CD player, the CDS. The CDS demonstrated that CD replay and lifelike music reproduction were not mutually exclusive. Now, the Naim DAC demonstrates that the jitter and noise that bedevil traditional external digital to analogue converters can be overcome and a new route to the real enjoyment of music opened.
The Naim DAC provides eight S/PDIF inputs, two USB inputs, and is capable of handling audio data sampled at up to 768kHz and with up to 32bit resolution. It not only brings all the digital inputs together into the analogue domain, but does so with a level of performance that can compete with the finest from any Naim CD player to provide unrivalled musical fulfillment.
Listening to the Naim DAC is a revelation. Music, whether its source be an iPod, a CD or a high-resolution data file, is presented afresh, with more definition, more insight, more warmth, and simply more of those hard-to-define clues of rhythm, melody and emotion that distinguish the real thing from pale imitation. The Naim DAC is an advance that brings real music in the home closer to reality than ever before.
The Upgrade Path
Upgrades are a fundamental element of the Naim philosophy. As well as providing a significant performance upgrade for the CDX2 and CD5 XS CD players, and HDX Hard Disk player, the Naim DAC can itself be upgraded by the addition of an XPS or 555 PS external power supply.
Everything Comes Together
If exceptional music making is the first hallmark of the Naim DAC, the second is versatility. Versatility comes thanks to S/PDIF inputs that can accommodate either optical or coaxial formats and USB inputs that can accommodate memory sticks and Apple iPod and iPhone models. It arises also from the numerous Naim system upgrades that the DAC makes possible. Simultaneously with its introduction, the CDX2 and CD5 XS CD players have gained S/PDIF outputs and can now benefit significantly from use with the DAC. With the addition of a DAC, existing preamplifiers can be incorporated into digital audio systems.
The Naim DAC can be controlled by a Naim preamplifier remote control, seamlessly integrating analogue and digital inputs across the two units. The DAC becomes an extension of the preamplifier. And when a USB stick, iPod or iPhone is docked, the DAC front panel input buttons transform to operate as playback controls.
Cables play a part in the Naim DAC experience. The DC1 digital coaxial cable, available in all BNC and RCA Phono options, is the perfect conduit for connection to the DAC from any digital source.
The Essential Ingredients
Each element of the Naim DAC has a vital role to play in its musical virtuosity, but it is not just the specifics of each that is important, it is their organization also. The influence of signal path, the microphony of circuit boards, the impact of track layout, the noise contribution of components, the noise sensitivity of others - each one is vital, and each one influences every other.
The DAC signal path is fundamentally simple. The SHARC DSP, operating as a filter, receives the data, then over-samples and low-pass filters the data and feeds it to the SHARC’s peripheral memory. Also operating as a buffer; the memory outputs data clocked by the oscillator. The DAC chips turn digital into an analogue current, and the I to V converters turn current into voltage. The analogue low-pass filter removes high frequency artifacts, and buffers the signal for a preamplifier.
- Chassis: The 3mm aluminium chassis and die cast fascia provide the fundamental structural rigidity necessary for low microphony.
- Printed Circuit Boards: Six layer glass fiber PCBs optimised for low microphony and high speed data transfer.
- Analogue Filters: Two Cascaded third order Sallen-Key active filters giving 36dB/Octave roll-off. Each stage incorporates Naim zero-feedback complimentary buffers.
- I to V Converters: Convert the current output of the digital to analogue converters to a voltage waveform ready for analogue filtering.
- DAC Chips: Burr Brown PCM1704K. A true multi-bit digital to analogue converter chip as used in the CD555.
- Re-clocking Gate: Re-clocks the data immediately before it enters the DAC chips to remove any influence from the isolation circuits.
- Crystal Sine-wave Oscillators: Crystal oscillators have lower signal correlated noise and phase noise than voltage controlled clocks. The DAC employs ten separately tuned oscillators.
- DSP to Analogue Electrical Isolation: Ensures that the high frequency noise of digital electronics cannot leak into the analogue output stages.
- SHARC DSP: Operates on the digital data to filter the out-of-band artifacts. 40bit, 16 times over-sampling topology.
- Blackfin DSP: Handles USB, controls the DAC and conditions the incoming USB data.
- Data RAM: Buffers the incoming S/PDIF data stream ready for re-clocking by the appropriate crystal oscillator.
- Low Noise Power Supply: Multi-regulated and smoothed power supply with separate outputs for each element.
- Transformer: Low stray-field, multiple secondary windings.
- Apple Authentication Chip: Enables the DAC to access digital data from iPod and iPhone models. The Naim DAC is the World’s first Apple-Authenticated high-end digital to analogue converter.
Technology Under The Hood
Designing an external digital to analogue converter capable of offering the exceptional musical performance obligatory for a Naim product brings numerous technical challenges. In particular, the S/PDIF interface protocol for digital interconnection has significant jitter and noise problems. Original solutions to these problems had to be conceived and developed.
The Naim DAC has more in common with Naim CD players than with conventional external digital to analogue converters. It overcomes the jitter issues of S/PDIF by reading the data into a “rotating” data RAM buffer independently of its timing signal and reading it out again clocked by one of ten extremely low noise, fixed frequency crystal sine-wave oscillators. In terms of system topology, the DAC’s rotating memory is analogous to a rotating CD feeding raw data to be re-clocked. The rate at which the memory fills and empties is controlled by the DAC automatically selecting the oscillator that matches the average incoming clock frequency. The data entering the downstream digital filtering and DAC chips is then completely isolated from the incoming S/PDIF jitter.
Along with being a source of jitter, S/PDIF is a potential source of RF noise. The Naim DAC suppresses S/PDIF noise through electrical isolation of its DSP front end from the digital to analogue converter and analogue circuits. Each element is also run from separate power supplies.
The Naim DAC’s digital filtering is handled by a powerful SHARC DSP chip running unique Naim authored code to create an ultra high precision 40bit floating point filter. The filter over-samples by 16 times on 44.1kHz data and provides stop-band attenuation of 180dB on all data. Following the digital filter are the two mono Burr-Brown digital to analogue converter chips, as used in the CD555 CD player. Finally the Naim DAC features a very high performance, low noise, and low distortion fully discrete analogue output stage.
Ground breaking technology and digital audio engineering however are purely academic. Listening to the Naim DAC is something else entirely. Startling in its clarity, arresting in its detail, beguiling in its warmth and inspiring in its rhythm, the Naim DAC seduces from the first note.
See the Naim DAC White Paper [PDF 2.57MB] in the 'Related Files' tab above.