We are very excited to bring you the long awaited DAC kit 2.1 Level C. This represents the ultimate in DAC kits; building upon the highly regarded and popular DAC Kit 2.1 Level B, the Level C DAC comes with a new driver board (taken from the new L3 Line Mk2 Pre-amplifier) which then drives two 33:1 step-down output transformers.

Using such a transformer coupled output stage has many advantages both sonically and for matching purposes. It's low impedance output means that it will match with virtually any pre-amplifier or integrated amplifier - valve or transistor - making it highly versatile.

Audio Note Dac 2.1
Level C

Here are some of the things that make this DAC kit a clear cut above the rest:

The M2 power supply is taken from the Audio Note finished products line. This uses a Mains transformer/Choke combination with 6X5 for tube rectification and the ECL82 for regulation. This powers a high quality, 5687 analog driver section which drives two high quality 33:1 step-down output transformers.

As with all the very latest Audio Note DAC's, the DAC Kit 2.1 comes without an analog filter in all its available versions.



General Specification

The USB interface option allows you to use your computer as a transport system to supply the digital signal. The board is powered from the computer (via the USB lead) so installation is very simple. The USB interface take over from one of the standard input options so you can still have either S/PDIF (RCA) or AES/EBU (XLR) as your other input sources and switch between the two at will.



Signature Digital Board

The signature Digital Board includes an Audio Note Digital Interface Transformer
(with toroidal core made from very thin laminate spun 80% nickel strip).
Digital Interface Transformers are used in all Audio Note's finished product DAC's from their Level 1 range upward.








Anatomy of the DAC Kit 2.1 - Level C-version













Level B (and C) I/V Transformers





The I/V transformers were specially designed by AudioNote engineering to provide an affordable yet highly effective transformer for the DAC2.1 Kit. I/V Transformers are used to maximize the energy transfer during the Current-to-Voltage phase of the conversion; resulting in increased dynamics.

An extract from the article 'Why is Audio Note's 1x oversampling unique?'
Andy Grove describes the use and advantages of the I/V transformer:

The output of most resistor ladder DAC chips is in the form of a current rather than a voltage. There are many ways to convert the current into a voltage but the most commonly used system is that of an op-amp connected as an I to V converter. This system requires the use of a high degree of feedback, and as a result there are problems associated with it. One of those is internal slew rate limiting of the op-amp itself. The rate of change of current at the output of even an audio DAC is very fast indeed. Even modern fast op-amps will slew limit internally and that affects sound quality. Some engineers have found that using extremely fast op-amps improves the sound quality, but we have completely sidestepped the issue by using a transformer I/V system. The transformer not only provides an I to V function but the way it is used in our latest DACs transfers maximum energy from the DAC chip itself. This in itself reduces overshoot and ringing and because the system is slightly overdamped the rise time is reduced to an acceptable rate as well.

Signature Upgrade (RCA output)
I/E core output transformers for RCA (single-ended) output
5687 Line Board (Hard-wired or PCB) with Audio Note Tantalum resistors and
Audio Note Copper capacitors and Black Gates

Output Transformer Upgrades
The above Level B to C upgrades come with I/E core output transformers for RCA
(single-ended output).
The following alternative transaformers are also available:
• I/E core with balanced output
• C-core (HiB) output transformers with balanced output
(a transformer with balanced outputs can always be configured for single ended output)

The low frequency response has been expanded lower. This is very noticible on things like base drum sounds. The strike can almost be felt as much as heard, as in a live performance...


Paul Folbrecht (click here for the full review)
Well, I just finished my DAC 2.1C Sig and I have to say it's just fabulous. It pulls off the truly amazing trick of being ultra-highly-resolving, extended, and dynamic whilst still being about as subliming musical as possible - perhaps what Audio Note's all about? Anyway, it's far & away the best digital source I've had here and I've had many all the way up to $7500 cost-wise.

Some time later...
The DAC C is so damn good it has made vinyl less necessary.


Colin Smith - www.soundstage.com, (click here for the full review)
...The DAC Kit 2.1 Level C is smooth, natural and, generally speaking, neutral. The Level C has lots of drive and packs a terrific bass wallop without sounding tubby. I really enjoyed listening to acoustic bass through the Level C. Ray Brown’s "Bass Face," from Bassface: Live At Kuumbwa (Telarc CD-83340), was an especially enthralling listen, as the Level C captured the subtlety and power of the master’s playing in fine detail. Quieter details like offstage crowd noises were much more clear than through my old DAC Kit 2.1...
...In the middle range, the Level C is warm, as would be expected of a tube-based product, but it doesn’t push the midrange way out in front of the rest of the music. Instead, the Level C makes vocalists sound a little more human and acoustic instruments a little more natural, with neither being given any more prominence than the recording engineer intended. Jethro Tull’s Irish-folksy "The Whistler" from Songs from the Wood (Chrysalis 81570), for example, offers a well-recorded interplay between Ian Anderson on acoustic guitar and Ian Anderson on the flute. The Level C faithfully captured the essence of these instruments, those resonances and tones that tell your ears that you’re hearing natural materials in all their glory...

...In the end, is the DAC Kit 2.1 Level C worth the effort and expense? In a word, yes! For such a high-grade kit, the Level C is very easy to build and is well within the reach of the novice builder. I’m pretty confident in saying that you won’t find another DAC in the Level C’s price range that comes close to matching it in parts quality, or one that was engineered by someone who designs five and six-figure components in his day job. Twenty-five hundred dollars may seem a lot for a kit, but just imagine what the DAC Kit 2.1 Level C would cost as a finished product.


Sai Pong Siu
"Hi Brian,
My AN DAC is up and running now. It sounds a lot better than my Denon 2910 SACD player. AN Dac is very transparent and detailed. I love this DAC.

I can't wait to start working on my L2 pre amp."


Isaku
I have finally completed installing the Level C upgrade (with C-Core Hi-B transformer) to my DAC 2.1 Level B Signature and I am writing to share my initial impressions.
The upgrade not only met my expectations but exceeded it quite significantly. Granted I only have it running for few days and it is still breaking-in, almost every attributes of the sound seemed to have improved quite significantly. More detail (but not being a distractively hyper detailed) and sense of space/”air” (but not sounding harsh or bright), better sound stage and imaging, significantly improved musical coherence and sense of pace, perceptively flatter frequency response etc. etc. My writing skills are not good enough to articulate why or how but it seems to highlight the essence of the musical performance much more prominently than any digital front-end equipment that I have ever owned. The well recorded/mastered CD sounds significantly better but it now also highlights the imperfections of the poorly recorded/mastered CD bit more prominently than before but still in an understated way typical to AN products that I have heard in the past (i.e. never makes them un-listenable.)

I feel like wanting to listen to all of my favorite CD again and playing them louder than ever before. As you can tell, I am very happy that I installed this upgrade.