Introducing the DAC-V1 and NAP 100

Uncategorised By Jan 08, 2013

Getting brilliant sound quality from a computer just got easier. Naim launches its first USB DAC together with a matching compact power amplifier

Naim today launched its first DAC (Digital to Analogue Converter) with an asynchronous USB input. The DAC-V1 is designed for the customer who uses a computer as their main source of music; they often choose to spurn physical media altogether in favour of downloads. The DAC-V1 will allow them to play back those audio files in stunning Naim sound quality. This is the second DAC in Naim’s range, sitting below the award-winning Naim DAC in the hierarchy.

The DAC-V1 is also a remote controlled digital preamplifier with five S/PDIF digital inputs, a volume control and a very high quality headphone facility; Naim’s research indicates an increasing number of computer audio listeners are spending a significant amount of time listening through headphones.

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The matching NAP 100 power amplifier delivers 50 watts per channel into 8 ohms – enough to fill all but the largest of rooms with sound – and together with the DAC-V1 makes a compact and stylish system. Naim’s UnitiServe hard disk player/server with CD ripping is also an ideal match, and can be introduced to make a truly versatile three-box system.

Both DAC-V1 and NAP 100 are due to enter production in February 2013.

The compact design of the DAC-V1 is suited to being positioned near a computer on a desk or work station as well as matching Naim’s existing products and working especially well on a Naim Fraim.

Key features DAC-V1

  • 1 x high-speed asynchronous USB input up to 24bit/384kHz
  • 5 x S/PDIF inputs up to 24bit/192kHz (1 x BNC, 2 X RCA, 2 x TOSLINK)
  • Selectable fixed or variable analogue outputs (DIN or RCA)
  • Zero S/PDIF Jitter design in common with the original Naim DAC
  • Naim custom designed Digital Filtering with 16 times oversampling
  • SHARC ADSP21489 DSP for Digital Filtering and zero S/PDIF jitter
  • Classic discrete Naim preamplifier gain stage topology with selected components
  • High-quality Burr Brown PCM1791A DAC, in common with NDX and SuperUniti
  • Single ended Class-A headphone amplifier. Front panel ¼ inch headphone output
  • Galvanically isolated – optical isolation between digital and analogue sections
  • Naim digitally controlled analogue volume control for performance and precision
  • Linear power supply with 210VA transformer, windings for Digital, DAC and analogue stages
  • Operates with computers running OSX, 10.7 and above, Windows 7, 8 and XP
  • Bit perfect testing
  • Floating or Chassis ground switch for optimum performance with any system
  • Field upgradeable firmware
  • OLED display for adjusting settings and checking incoming bit-rates
  • Control via IR remote control or front panel controls
  • DAC-V1 can control computer playback and volume
  • Compact non-magnetic low-resonance chassis and sleeve
  • British design and build

NAP 100 key features

  • Compact Design
  • Classic Naim discrete transistor power amplifier
  • 50 Watts per channel into 8 Ohms (100 W into 4 Ohms)
  • Dual Mono Design
  • Audiophile grade selected components
  • Linear power supply with a large toroidal transformer
  • Compact non-magnetic low-resonance chassis and sleeve
  • British design and build

More about Asynchronous USB

Digital audio isn’t just about the data – 0s and 1s – and ensuring that each sample value is accurately converted into a corresponding output voltage. Also vital to achieving the highest fidelity is ensuring that each successive sample is reproduced at a precise time interval from those around it. If that time interval varies – an effect known as jitter – then the output waveform will be distorted. To prevent this, the master clock that controls the process should, ideally, be placed right next to the digital-to-analogue converter circuitry, not remote from it. Asynchronous mode USB provides for this because it allows data to be ‘pulled’ from the source as required, whereas in other modes the data is ‘pushed’ down the interface under control of the inferior and distant clock in the computer.

Naim partnered with Audiophilleo the specialist in asynchronous USB during the development of the DAC-V1.  Audiophilleo’s expertise short cut the product’s development time and ensured 100% solid computer compatibility.

More about Isolation

Electrically, computers are noisy objects.  They include high-speed processors and switch mode power supplies that generate RF noise that can contaminate the connected audio equipment. The DAC-V1 is isolated from these deleterious problems in many ways.  The 5V power supply from the USB cable is not used by the DAC-V1. The USB ground is filtered. The digital and analogue sections of the DAC-V1 are isolated using optical isolators (Galvanically Isolated i.e. no current flows) so that unwanted noise does not pass. In addition the S/PDIF inputs are transformer coupled to isolate noise and prevent current loops from S/PDIF sources.

More about zero S/PDIF jitter design

The DAC-V1 overcomes the jitter issues of S/PDIF and further reduces the jitter from the asynchronous USB engine by reading the data into a “rotating” data RAM buffer independently of its timing signal and reading it out again clocked by one of 1024 extremely low noise oscillators.

In terms of system topology, the DAC’s rotating memory is analogous to a rotating CD feeding raw data to be reclocked. The rate at which the memory fills and empties is controlled by the DSP 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 or USB jitter.

The DAC-V1’s buffering and digital filtering is handled by a powerful SHARC DSP chip running unique Naim authored code to create an ultra high precision 40-bit floating-point digital filter. The filter oversamples (integer upsampling) by 16 times on 44.1kHz and 48kHz data and provides stop-band attenuation of 156dB.

More about the single ended Class-A amplifier headphone output

Naim has a long tradition of using discrete transistor, single ended class-A amplifiers for all its pre-amplifier stages. This has now been extended to the headphone amplifier of the DAC-V1.

The headphone amplifier cleverly uses the pre-amp output amplifier for headphone drive. The moment headphones are plugged in, the output current drive is automatically turned up five times to give dynamic drive for all headphone impedances. The amplifier runs from a high voltage power supply so has the ability to drive high impedance headphones with the voltage swing they require for open and dynamic sound. The result is the audio stages are kept as simple and pure as possible for both normal and headphone modes.

Single ended Class-A is long known for its natural sound quality and exhibits zero crossover distortion. Its Achilles’ heel is that it is inefficient, for headphone drive however this is not important, so all the benefits can be exploited. Most headphone amplifiers are Class-AB, where the amplifiers output stage is in two halves; one pushing and one pulling. Here the two halves meet in the middle and can produce non-consonant distortion or distortions that do not occur naturally in music.