Up ‘N’ Oversampled
DA-217 MK2-D Digital Processor
is a lot of talk about improving the recording and reproduction
of digital recordings nowadays. If it’s not the exuberance
over the discovery of what the DSD/SACD system might be able
to accomplish for us audiophiles, it is surely the wistful
yearning for a competing DVD-A system to take us from here
to “there!’ The DSD/SACD proposition seems painfully slow
and phlegmatic in its advancement (if you can even call it
that) towards fulfilling its initial promise. When are we
going to see some software that takes advantage of DSD recording
techniques? Apart from a few small, daring labels, we have
so far only seen old Sony (Columbia) staples regurgitated.
And, they still carry the drawbacks of ancient (well, in
a stereo sense!) recording techniques. Give us some new stuff
now! While you’re at it, give us some cheaper and better
DVD-A phalanx doesn’t seem to be able to get to first base.
They’re so skittish about security of their copyrights
that they cannot see the bits for the digits. Why wreck
a high-resolution recording system with a security watermark
that is bound to damage the musical content? Especially
since some snot nosed 14-year-old hacker, who ought to
busy himself with homework instead, will soon crack any
security code and hang it out for general consumption anyway.
Why don’t they just throw the axe in the lake and get on
with the music? Phew!
Am I dissatisfied with digital’s current state of affairs? You
have been developed for real high-resolution audio, but
I’m prevented from enjoying it because a bunch of suits
think that they can have their cake and eat it, too. I’m
fearful that the whole promise of high-resolution audio
will fall by the wayside in favor of some half-baked DVD
derivative that might make the masses happy but not many
audiophiles. What a waste of a great opportunity! That
ends my rant. You might wonder what prompted this outburst?
Impatience. We have these potentially great new recording
systems but precious few recordings that have taken advantage
In the meantime,
however, a lot is going on with our standard PCM 16/44.1 CDs. Recordings
are getting better and better (witness the new batch of outstanding
Chesky CDs), as is the playback equipment. Lately, a lot of attention
in digital replay is being paid to upsampling. Upsampling is simply
a means to add (arithmetically) more interpolation points between
those that are recorded through the 44.1 KHz sampling rate. It is
important to make a clear distinction between sampling, upsampling
and oversampling. Our current CDs (excepting the few available SACDs
and 24/96 DVD-As) are sampled at 44.1 KHz. That means that a musical
signal, when recorded, is sampled 44,100 times per second and each
of these samples (bits) becomes a point of interpolation. The bits
come batched together in 16 bit words by the A/D for decoding in
a DAC. Thus the 16/44.1 denomination. The 24/96 recording process
increases the sampling rate to 96,000 times batching in bigger 24-
bit words, thereby significantly improving the resolution of harmonic
detail, etc, as well as increasing the frequency bandwidth (see the
Nyquist theorem). On the other hand, DSD/SACD samples the signal
over 2.8 million times; the DAC then decodes the samples one bit
at a time. This is called direct bitstream and when properly implemented
can provide a very high level of resolution. Upsampling takes place
when a 16/44.1 (or other sample rate) is converted into a higher
level such as 24/96 or 24/192, or higher.
Upsampling, although a purely binary extrapolation process (ie, a mathematical
reconstruction), can have a beneficial effect on the sound of a standard
54 • ULTIMATEAUDIO,
I dissatisfied with
digital's current state
of affairs? You betcha!
the concept of oversampling relates to a method of pushing
the digital noise (a result of the conversion process)
up to a higher frequency area, well beyond human hearing.
Most DACs are oversampling at least twice, but some do
it four, eight or more times.
I’m going into this detail on sampling because
the new Dodson DA-217 MK2-D is blowing me away! I’ve lived
with a Dodson DAC as part of my reference system for several
years, going from the original DA-217 to the upgraded Mark
2 and now this amazing latest version, the Mark 2-D. They’ve
all been great, but this new one is really special!
Ralph Dodson is a retired scientist from the “secret” black box
division of General Dynamics. He has, as he says, spent at least
half of a lifetime designing digital circuits for warplanes and
missiles as well as space rockets. Rather than sitting on a San
Diego beach among other retirees, he’s putting this tremendous
experience to use in designing one of the finest digital products
I’ve seen. He knows that to get it right, every little detail must
be optimized in the digital-to-analog conversion process. “I can’t
do much about the recording/encoding process,” he says, ‘but I
can try to optimize the decoding process by designing crucial elements
with great care. There is a lot more to get out of a regular 16/44.1
CD than we’ve been able to do so far.” Damn right!
new version of the Dodson is the result of painstaking evolution
of a design that goes back 15 years. Part after part, element
by element, the design has been optimized utilizing the best
components available. Think about it. Here’s a guy with 30
years of high-quality, often critical, digital design experience
persistently refining his audio design over 15 years. Fanatic?
Yes, I guess you could call him that, but Ralph Dodson might
prefer descriptors like meticulous or fastidious. Whatever;
it’s amazing either way you put it!
The MK 2-D is a complete 24/96 KHz design. This means that any given
input signal (16/32 KHz, 16/44.1 KHz, 16/48 KHz or 24/96 KHz) will
be treated as a 24/96 KHz signal. Thus, anything that isn’t a 24/96
KHz signal is converted into one by the process of upsampling. Once
upsampled, the now 24/96 signal is then oversampled eight times to
an astounding 768 KHz before being decoded (at the absolutely blinding
speed of 25 MHz!). Thus, for all practical purposes, the Dodson DA-217
MK 2-D is a 24/768 DAC!
The phenomenal computing power of the DA-217 MK 2-D allows for an
analog filter with an effective bandwidth of 100 KHz (see Technical
Highlights). “What good is that,” you ask, “since humans can’t hear
much above 15 to 16 KHz?” This is a much-debated issue, and I don’t
want to stoke the various fires by showing my
ignorance. However, based on my personal observations it would
appear that, for instance, a wider bandwidth certainly can be very
beneficial to the harmonic content of the music. A case can probably
also be made for better dynamic contrast and perhaps for other
parameters as well. After all, who in their right mind would buy
a preamplifier or amplifier with a bandwidth limitation at 22 KHz
as the current CD redbook standard prescribes?
Playing some new DVD-A 24/96 CDs from Chesky it was pretty obvious that
the Dodson offered a level of resolution well beyond that of the normal
16/44.1 CDs. The bass was significantly better with more realistic transient
attack and more extended and truthful decay. The mids were better developed
with better resolution and transparency that made it easier to identify
instruments’ location, size and timbral characteristics. Likewise, the
top end was unfatiguing and smooth, extending way out. My favorite peeves—unnatural
sibilance and cymbals as well as strident massed first violins—came across
just right. Indeed, it was quite an experience.
How does it compare to my reference high-resolution digital
player, the Sony SCD-1 playing SACDs? It’s impossible to say in the
absence of comparable DVD-A and SACD recordings of the same event,
but both systems sure offer a worthwhile improvement over current
standard. It may well be a while before we can determine which one
is better. Subjectively, I still feel that SACD produced a better-
delineated and more dimensional soundspace. On the other hand, the
DVD-A might have the slightest advantage in dynamics. As I said,
it is very difficult to determine with available software, so I may
well be wrong.
Truth be told, while I appreciate the Dodson’s ability as a high-resolution
DVD-A decoder, this is not why I’ve been so
55 • ULTIMATEAUDIO,
away by it. Excellent as the new 24/96 Cheskys are (and they’re
really something special’), I still don’t have enough music that
I love on DVD-A, or on SACD for that matter. Nothing I played
could engage me like some of my older CDs can, in spite of the
additional insights into the musical event offered through the
What really excites me to no end about the DA-217 MK2-D is what it does
to my several thousand regular 16/44.1 CDs! It is quite clear to me now
that there is more to our standard CDs than what I have experienced with
the various DACs and CD players I’ve used in the past. I know that it
may not be real in an authentic sense. But whatever interpolation Dodson’s
algorithms perform on the basic samples sure as hell sounds realistic
to these ears. To coin a famous phrase from my buddy ST: There is definitely
more “there” there!
All (and I mean all) of my CDs passing through the Dodson displayed a
better “understanding” of what went on at their recording. There is more
harmonic richness, better dynamics, better-developed frequency extremes
and a much better sense of the recording venue than I’ve heard from the
same CDs during hundreds of previous listening sessions. What’s happened
to some of these CDs is almost miraculous. No, of course it is not the
same as an SACD or a DVD-A, but in some respects it comes surprisingly
close, it seems. Clearly, on some CDs there was a greater difference
between the original 16/44.1 replayed as such and the up ‘n’ oversampled
version than I could discern between the latter and a SACD version of
the same CD. In other words, the Dodson version at 24/768 was closer
to the SACD than it was to itself when played as a normally decoded 16/44.1.
I know that some of you might get a slight headache from reading what
might seem like such a preposterous statement. However, that’s what I
I’ve had other 24/96 DACs in my system, with and without upsamplers/oversamplers
of a similar type (maybe not as advanced as 24/768, but certainly 24/192)
and they never produced anything like the results I’ve heard with the
Dodson DA-217 MK2-D. The Dodson is by far the best CD playback device
I’ve ever heard, rivaled only by the Sony SCD-1 when playing SACDs (Ralph
is working on a DSD chip for future upgrading capability to SACD). The
smoothness and liquidity is awesome, the
much has changed on the outside of the Dodson DA-217 MK2-D
compared with its predecessor—save for the name, and the
fact that the HDCD indicator has been changed to a DVD
light. All the other functions, including the polarity
reversal, are still there.
Changes, both several and significant, are found in the innards of
the DA-217 MK2-D. As the input signal (32, 44.1, 48 or 96 KHz sampled)
guided by its original clock enters the DAC, it is immediately changed
from single ended to fully balanced by means of a proprietary circuit
designed by Dodson. The signal then goes into a digital receiver
where the clock is recovered and separated from the signal. The clock
signal goes into a PLL (Phase Lock Loop) for “clean up” and removal
of any jitter and is then used to clock the data into a memory buffer.
A master system clock, with ± 2 Pico second phase jitter is used
to remove the stored data from the memory buffer. The now jitter
free data is passed on to the upsampler where it is upsampled to
96 KHz. This upsampler has a new, and very advanced, algorithm.
The signal coming out of the upsampler is always 96 KHz as it is
transferred to the digital filter, which oversamples it eight times
to 768 KHz. Then the 24/768 signal goes in to a second re-clocking
circuitry this one controlled by the master system clock and a reclocking
oscillator running at a phenomenal 25 MHz (virtually all other DACs
are running at a fraction of this, for instance the Sony SCD-1 is
running at 2.8 MHz), to prevent any reintroduction of jitter on the
up- and oversampled signal. The 25 MHz re-clocking is also, separately,
controlling the digital-to-analog converter where the signal is converted
to analog before passing on to the analog filter. The analog filter
has a 100 KHz bandwidth and is of an FDNR-type (Frequency Dependent
Negative Resistor) with less than ± 0.04 degrees of phase shift.
Finally, the signal passes through a buffer/driver stage for output.
The truly unique aspects of this design lie (among other things)
in the proprietary circuitry in the input receiver, which has been
tested and perfected over many years. In addition, a Faraday shield
protects the whole digital section and the circuit boards are 4-layered,
using fully differential paths inside the boards; these aspects protect
the signal from undue outside interferences. Dodson obviously carefully
picked the algorithm options to give the desired Dodson specifications.
To manage the enormous information flow of 24/768 conversion, Dodson
employs a 25 MHz re-clocking oscillator to control the re-clocking
circuitry. By current standards in digital audio this is, in all
probability unheard of.
At the final checkout stage in the manufacturing process there is
a very detailed control of left and right channel phase shifts. Both
channels are adjusted to the very fine tolerance of 0.04 degrees
of each other.
The Dodson DA-217 MK2-D is a technological masterpiece in all its
simplicity. It is a meticulous design by a master craftsman who sets
the music before everything else and who eschews any unnecessary
bells and whistles.
is much enhanced by the extra sense of “air” and dimensionality
and the soundspace just devours you. Unreal! (Exclaimed here
as a positive, not as a descriptor.) If the high-resolution
replay systems and recordings do not become a reality in
the near future, it would be a pity for sure. But the extraordinary
Dodson DA-217 MK 2-D has brought us a long way, and I can
live with that. Actually, now I can’t live without it.
DA-217 MK2-D Digital Processor, Dodson Audio, 14340 Marianopolis
Way, San Diego, CA 92129. Tel.: (858) 484-8199.
Web site: www.dodsonaudio.com.
response: 20 Hz-45 KHz; Channel separation: >110 dB @
1 KHz. Digital domain, sampling frequencies: 32 KHz; 44.1
KHz; 48 KHz and 96 KHz (automatically selected). Output voltage:
2.3 Volts RMS. Digital inputs: 2 Coax, 1 Toslink (AESIEBU
or AT&T ST optional). Analog outputs: single-ended (RCA)
and XLR outputs. Absolute polarity switch: Yes, Upgradability:
the Upsampler module, Microprocessor, Digital filter and
Analog IC’s socketed for future format upgrades. Detachable
power cord: Yes. Dimensions: 3 x 17 x 12 inches (h x w x
d); Weight 16 lbs. Price: $4,995 (Optional: AES/EBU: $250;
AT&T ST: $275).
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