Concert Fidelity DAC-040 Digital to Analog Converter
An irresistible treat!
Review By Dick Olsher
here to e-mail reviewer.
Schoolhouse Rock Revisited: Zero Is My
Why a zero oversampling DAC? In May of 2006 I
reviewed a quartet of DACs that challenged the assumption that an
anti-imaging filter is necessary to remove ultrasonics generated during
the digital to analog conversion process (click
here for that review). Recall that the earliest players
used 16-bit multi-bit DAC chips followed by analog "brick wall"
filters designed to steeply attenuate image spectra above 22 kHz. While
the specs looked good on paper, the emperor was soon discovered to have no
clothes. A chorus of complains emerged echoing a common theme: bright,
fatiguing sound that ultimately resulted in digititis — an allergic
reaction to digital sound.
Oversampling, also known as upsampling, and
digital filters were invented as a means of easing the analog filter
requirements. Instead of a 9th order or higher low-pass filter,
a third-order was now possible. In the years that followed, the old
Philips 16-bit DAC IC was replaced by cheaper, easier to calibrate,
single-bit sigma-delta DACs which featured fancy noise shaping techniques
to make them sonically palatable. Such noise shaping makes anti-imaging
filtration mandatory. However, it does not appear to be a necessity in the
case of a multi-bit DAC. It was Audio Note UK's Peter Qvortrup who first
opened Pandora's Box. These Philips chips were not considered anything
special in engineering terms either then or now. However, listening minus
analog filters and what he refers to as “digital trickery,” Peter
discovered a sound quality much more closely aligned to the vinyl
experience. And that my friends is the zero oversampling advantage: smooth
textures, solid image outlines, and the impression of a more believable 3D
soundstage in terms of depth and width perspectives.
Today it is hard to find anything but 24-bit DAC
chipsets in production. For example, my current reference, the Weiss
Engineering Medea, sports the Analog Devices AD1853 chipset. This is a
24-bit/192kHz multi-bit sigma-delta DAC introduced already 10 years ago
around 1999. My favorite low-cost DAC, the Altmann Micro Machines
Attraction uses the Philips TDA1543 dual 16-bit DAC IC introduced in 1991.
And a favorite for DIY projects, the Philips TDA1541, was introduced in
1985. These examples highlight a minor design trend I have observed over
the past several years of giving preference to older DAC chipsets. These
Philips 16-bit DAC chipsets are still available as New Old Stock (NOS) and
actually cost quite a bit more than current production 24-bit chipsets.
Some of these DAC ICs have become collectible: select versions of TDA1541A
(e.g., double crown markings) may fetch over $100!
Inside The DAC-040
Concert Fidelity's designer, Masa Tsuda, asks a
good question: Why is there a need for 18-bit or 20-bit DAC conversion in
CD playback system, when there is only 16-bit worth of data on a CD to
begin with? He says that in DAC-040 he undertook a radical approach given
that the goal was to find out what 16-bit sound is really like and exploit
its possibilities. Substantial listening tests and measurements were
conducted during the development process to determine the audibility of
filter circuits and DAC performance parameters. Masa was willing to trade
measured specifications for audible results. That's certainly a tradeoff
music lovers should embrace as it meets the time-honored criterion of
letting the human ear be the final arbiter in matters of sound quality. In
the end, both the digital filter and analog low-pass filter circuits bit
the dust. Towards that end, a NOS Philips multi-bit chip DAC was chosen not
because its performance was judged to be superior to that of other NOS
DACs but because it was felt that the best approach was to simply
eliminate problems inherent in the architecture of today's FIR type
digital filters. The DAC IC chosen allows for compact mounting and short
signal path – important priorities at Concert Fidelity. Masa believes
that these considerations are even more important in digital than in
analog circuits. By the way, in case you're curious, it is not the
TDA1541 because it apparently did not meet Concert Fidelity's criteria
for mounting due to its physical configuration. In fact, the specific
identity of the DAC is kept confidential and is hidden from prying eyes in
a black box. You should know, however, that each chipset undergoes a
critical selection process; only about 10% of the entire population makes
it into production.
Ultra-high precision resistors are used in the
current-voltage (IV) converter circuit. The output stage is a vacuum tube
gain stage (+6dB) featuring the same circuit originally developed for the
world-class CF-080 line preamplifier. As was the case with the CF-080, I
substituted Mullard box anode 12AU7 twin triodes for the stock tube
complement. The output stage provides response linearity within the audio
bandwidth. However, its main task is to prevent generation of
inter-modulation distortion caused by high-order harmonics, ultrasonics
normally attenuated by analog low-pass filter, from impacting the next
component in the system. Sound quality through simplification, I'm sure
it pleases Mr. Tsuda to note that in the final analysis, sound quality of
a DAC or CD player is largely determined by the analog section. Note that
only a single S/PDIF input is provided and a BNC connector at that. A BNC
to RCA adapter is included. That's appreciated, but it would be best to
replace the BNC with an RCA, something I'm told will happen in future
In recent years jitter reduction has been front and
center as a critical aspect of digital component performance. It should
therefore not surprise you to find out that my opinion of the DAC-040 varied dramatically based on the associated transport. Since the Weiss
Engineering Jason was on hand, the DAC-040 benefited from this coupling and
what you're about to read should be interpreted in this context. The
Jason, Swiss-engineered and admittedly very expensive, is simply the best
sounding transport I've ever auditioned. If you're skeptical about the
importance of a good transport, just give the Jason a listen.
Unfortunately, the DAC-040 wasn't tolerant of lower pedigree (i.e.,
higher jitter) digital input. When using the PrimaLuna Model Eight's
digital output, the DAC-040's performance was just a shadow of its former
self. By contrast, the Medea DAC (the Jason's partner) proved more
tolerant of the PrimaLuna Eight's digital output. Don't expect to make
this puppy sing unless you're willing and able to match it with a
What grabbed my attention pretty damn quickly was its
sweet midrange, vibrant harmonic colors, and remarkable timbre accuracy.
Female vocals were right on — as good as I've ever experienced on CD.
Now, this is no mean feat, as I'm quite fussy when it comes to the vocal
range, spanning a bandwidth of about 200 to 4000 Hz. My annoyance factor
for residual grain, grit, and gratuitous brightness is extreme. In fact,
the DAC-040 sounded quite the opposite, being smooth and refined. What a
find! I've struggled for over twenty five years to find a DAC that
captures the music's heart and soul. I've had to put up with either
bland, sterile sound that neither offends nor excites, or at the opposite
end of the spectrum, with dynamically nuanced reproduction that failed to
do justice to harmonic colors. The DAC-040 seemed to combine microdynamic
intensity with a textural palette that more closely approached my
impression of the real thing.
The tube nature of its output stage was very much in
play. Textures were slightly softer relative to the much more expensive
Medea DAC, probably a consequence of a treble range that was a bit dark in
character. Though not that far behind, the Medea with its solid-state
output stage also trumped the DAC-040 in terms of transient speed and
low-level detail. On the other hand, the Concert Fidelity clearly asserted
itself in terms of midrange suaveness, harmonic color saturation, and
imaging. It became clear that the root cause of some of these sonic
differences was nothing more that the age-old difference between tubes and
transistors. This is not the sort of DAC you would want to mate with an
overly romantic sounding line preamplifier lacking treble air and
extension. Not surprisingly, Concert Fidelity's own CF-080 line
preamplifier provided the most neutral tonal balance with excellent bass
control and definition. Other line preamplifiers were given room to impose
their own sonic character, which leads me to conclude that the DAC-040 is
inherently neutral and free of any significant euphonic colorations.
Image outlines were clearly delineated, superbly
focused, with plenty of palpability and analog-like stability. Soundstage
dimensions unfolded with the sort of depth and width perspectives I've
only heard once before from a DAC or CD player. I'm thinking here of the
PrimaLuna Eight, which however lacks the textural purity and integrity of
the Concert Fidelity DAC.
the end of the day I have to confess that I'm unable to resist the DAC-040's siren call. Vivid harmonic colors, superb rendition of
instrumental timbres, and an analog-like presentation that draws the
listener into a spacious and solid soundstage. Zero oversampling truly is
a gateway to a kinder, gentler, and ultimately more musical digital
experience. It's hard to believe that a NOS Philips multi-bit DAC
chipset can be engineered to put current 24-bit/196kHz Delta-Sigma DACs
to shame, at least in musical terms. But then, as I'm sure that Mr.
Tsuda would agree, it was never about the specifications.
Type: Digital to analog converter
Digital Inputs: One S/PDIF
Output: One pair single ended (RCA)
D/A Converter: Philips Multi-Bit 16-bit DAC
Sampling Frequency: 44.1kHz
Tube Complement: Two 12AU7 for gain and one 6CA4 for rectification
Dimensions: 100 x 450 x 310mm (HxWxD in mm)
Weight: 14 lbs.
United States Distributor:
Silicon Arts Design & Concert Fidelity U.S.
Ridgewood, New Jersey
Voice: (201) 444-3378