NEW: Audio Note's Peter Qvortrup discusses the development of Audio Note's digital design philosophy and the new DAC5. To read the essay, click here.
Audio Note waited until 1993 to introduce their first DAC because we felt there were serious problems with the digital format. Only after years of research did we feel we had developed significant enough insight to create a converter that moved the design goalposts forward. We wanted a DAC that would remain state of the art and retain its value for many years. To this end, Audio Note digital products now represent the most original and effective solutions to the design of digital circuitry and to the digital to analogue interface. In digital our approach is the same as it is in analogue; keep it simple and gentle and employ the highest quality components. The digital signal should also be handled with great care. Less processing; treat the original bitstream as fundamental truth.
Our goal is to create a line of classic D/A converters. We started by reducing the digital circuitry to its absolute minimum level and selecting the highest quality (and highest cost) digital chips (i.e.. the Burr-Brown PCM-63, K-type). Then we developed a battery of tests that allow us to further select higher quality chipsets. We do five separate tests to grade our D/A chips and reserve the very finest chips for the DAC-4 Signature, DAC-4, DAC-3 Signature and DAC-3.
In front of the D/A chip most companies use a high-order, "brick-wall" filter to "erase" frequencies above 20KHz. These high-order filters create resonant back waves (ringing) that result in energy reflections that add mechanical artifacts and hardness to the musical signal. This filter is the most critical juncture in a digital based system and how the signal is handled, how the energy is transferred, at this point will make or break a high quality system. Multi-pole filters are subject to ripple in their passband and poor transient response. Additionally, the high-Q ringing causes irregular and uneven dynamic and transient behavior, resulting in hardness, opaqueness, diffusion, exaggerated high frequencies and a false sense of detail. Additionally, the brick-wall filter is one of the primary causes of listening fatigue. Brick wall filters make music sound canned and artificial. Audio Note's solution to this problem was to use the only filter that does not ring or suffer transient or phase problems; a first-order, single pole. This simple filter employs a very high quality 1:1 interstage transformer. This original (patented) strategy gives our digital to analogue converters a very real musical advantage. This unique interface strategy allows the best type of energy transfer. Again, Audio Note has worked to preserve the original proportions and energy distribution of the music signal. Audio Note believes the signal must not be manhandled or subjected to unnecessary manipulations. The simple 'transient-perfect' single-pole filter/interstage transformer combination is the gentlest way to bandpass limit the output of a digital/analogue chipset.
The sonic benefits? Audio Note DACs have an uncanny sense of musical continuity; the listener's awareness of tempo and musical flow are distinctly enhanced. Their retrieval of small scale detail and timing information is second to none. These DACs can only be compared to the best analogue not other DACs.
All Audio Note DACs use the 6DJ8/6922 dual triode, except the DAC-4 Signature which uses the 7119/7044/E182CC. As you move up from the lowest priced DAC-1 to the higher priced DAC-4 Signature the parts quality improves with the DAC-3 and above using AN silver wire. The DAC-1 uses Audio Note Aluminum foil, paper in oil capacitors and copper wired interstage transformers. The DAC-2 is similar to the DAC-1 except that it uses either a 1:1 or a 1:2 interstage transformer for higher output and is designed to drive the Audio Note power amplifiers directly. Maximum output on the DAC-2 is 10VAC. The DAC-2 also has a higher quality component selection. The DAC-3 takes the parts quality to the next level with the introduction of a higher quality interface transformer, a higher grade of PCM63P chip and a more careful component selection. The DAC-3 uses AN-V Silver interconnect between the digital and analogue sections and between the analogue board and the output jacks. The DAC-3 Signature would be the best DAC in the world, were it not for the DAC-4 and DAC-4 Signature The DAC-3 Signature has even more and higher quality Black Gate caps, silver interface transformers, and a individually adjusted silver filter coil. The PCM-63s (K-type) are critically selected and auditioned especially for the DAC-3 Signature. The 4-Series DACs push that critical selection a step further with regard to the PCM-63s. In the DAC-4 Signature these chips are further selected by audition with musical program. The DAC-4 Signature uses the highest grade Black Gate caps, AN-Vx silver wire, and selected copper foil paper in oil coupling capacitors. The Production of the DAC-4 Sig. is generally VERY LIMITED due to lack of suitable chip sets, so delivery time can and should be expected.
The DAC-4 uses separate power supplies for the digital and analogue sections. The DAC-4 and DAC-4 Sigs. both are built on heavy, pure copper chassis. The DAC-4 employs still further power supply and parts upgrades over the DAC-3s. The DAC-4 Silver Signature is our current 'statement' DAC. It has a very improved, tube rectified, choke filtered power supply, the very best Black Gate Caps and Audio Note silver-foil, paper in oil, coupling capacitors. The exotic, E182CC/7044/7119 tube, used in the DAC-4 Signature, brings a greater sense of transparency and power to music reproduction. These DACs are designed to give at least a decade of analogue-like musical enjoyment. Jonathan Valin described the DAC-4 Signature in Fi magazine as "the best there is at any price".
Jonathan Kettle writes about the DAC-3 Signature D/A converter in Cyber-fi, Virtual Publishing, London, UK, 1995:
"The startling vibrant reproduction of the music was exemplary. By comparison other DACs sounded two-dimensional and lifeless...the drama and color to the sound of orchestral instrumentation seemed thoroughly lifelike and natural...The longer I listened (to his) solos the more I found the DAC-3 Sig. capable of pulling me into the performance...quite mind-blowing...and thoroughly uplifting."
NEW! For more information on Audio Note's CD2 integrated CD player, click here.
This page was updated on: 06 Aug 1998
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