The DEQX PDC - 2.6P -- A Revolution?
my years as a reviewer, I've spent thousands of hours listening to and
evaluating a substantial number of products. In all that time, from speakers
to amplifiers to preamplifiers to cables to a variety of source components,
there has always been one dictum that seemed to make sense: one should
start a system with the best speakers one could find or afford and then
add the components to fill in the remainder of the system. It's always
been about the speaker. Why, you ask? Well, primarily it is a mechanical
device that produces sound waves as a result of converting electrical
energy into mechanical energy and it's what we finally listen to. This
production of sound waves is performed by cones or ribbons or panels or
some combination thereof that usually include some form of electronic
crossover network, differing materials of construction, mountings, enclosure
types, etc. In any transfer of energy, from one form to another, in this
case electrical to mechanical, there is usually a substantial loss of
energy and the actual conversion to the new form produces many unwanted
by-products. In the case of speakers, heat and various forms of distortion,
both time, phase, frequency and Intermodulation Distortion (IM), among
others, resulting in a degradation of the electronic signal and the sound
we finally hear.
electronics today, and for quite sometime, have had diminishing levels
of distortion. So much so, that often times, the measuring equipment themselves,
can skew the final result.
After discussions and e-mails with Kim Ryrie of DEQX (Ryrie has been mainly designing and building products for the pro audio field for over 30 years and his equipment is used industry wide, including the widely acclaimed Abbey Road Studios, in London) , he was kind enough to provide the following clarifications for this reviewer:
introduced by loudspeakers and other electronics include distortion that
tends to either be noticeable and disturbing, or at best, lacking resolution
as distortion approaches and exceeds “1%”. Unlike the audio
signal that drives them, where distortion is usually well under 0.1%,
even high-end speakers typically measure over 1% distortion, and more
at high volume and over crossover regions, much of it resulting in lost
resolution. The PDC-2.6 can provide ‘active crossovers’ that
minimize driver and crossover distortion by better quarantining frequencies
to each drivers ‘linear-operating region’ (reduced Intermodulation
distortion), that allows higher volume before distortion sets in, more
natural dispersion of highs by reducing driver ‘beaming’,
and reduced crossover distortion by introducing true linear-phase and
We also take for granted the fact that just about any piece of audio electronics has a flat (accurate) frequency response, so a CD player displaying the typical 'plus/minus 3dB' frequency response of a loudspeaker would be returned as ‘faulty’. DEQX corrects frequency response of the loudspeaker/amplifier combo to typically plus/minus 0.5dB (near-field on-axis). Even more important when trying to achieve ‘realism’ is time-domain accuracy, or phase and ‘Group–Delay’ accuracy. Group-Delay accuracy is rare in affordable loudspeakers, and among the most important factors that determine our perception of a real performance. This is where some ‘frequency groups’ actually lag in time behind others. In amplifiers, these timing or phase errors are minimal, being measured as phase shift, or at worst, a slight delay measured in microseconds. In loudspeakers however, these errors are measured in milliseconds! We believe that DEQX’s patent pending group-delay analysis and correction process is the first affordable and low-latency solution for loudspeakers. The bottom line is that however ‘good’ a speaker might sound, these tiny timing errors give the ‘is it real’ game away to our ever vigilant hearing mechanism'.
you, Kim, for that extended treatise. I do believe that adds some clarity
to the situation for those of you with a technical bent. For the rest
of you, keep reading. The PDC-2.6P is his solution, along with his design
team, currently headed by Sasha Case, to the problems of speaker induced
distortions all in one tidy compact package. This endeavor represents
twenty-one man-years of software development.
is the 2.6P? This one box contains a DAC/preamplifier, a digital speaker
corrector/equalizer, a room correction device, as well as an active, steep
slope, crossover network. There's a lot to explain here so stay with me.
unit is barely 1 3/4 inches high and 17 inches wide and 11 1/2 inches
deep. It comes with a detachable power cord, USB cable as well as a microphone
and its accompanying cable and most importantly, the software CD, the
key to the system. The included remote control unit offers input selection,
volume control and a 3-band (Lo Med. and Hi) parametric equalizer that
offers control of the full frequency spectrum. The 2.6P looks very unassuming
but looks can be deceiving. It typically comes in black with the option
of a clear metallic faceplate finish achieved with a polyurethane paint
that has the slightest of violet tints. For those who require more info
check out the website. Using the basic equalization via the remote does
not require a computer or microphone, but only your ears. You can save
up to a hundred settings with the remote. It only begins to scratch the
surface of what the unit can do. The PDC-2.6P processor can be connected
between an existing stereo or home theatre pre-amp and power amp for equalization,
speaker correction, and room correction, and act as the sole pre-amp.
The remote control selects from four inputs, two digital (XLR balanced
and RCA unbalanced) and two analogue (XLR balanced and RCA unbalanced).
One PDC-2.6P unit processes two input channels in analogue or digital
(PCM) to 96KHz - compressed or surround digital formats are ignored. The
preamplifier section is not appropriate for use in a system that has more
than two analogue or two digital sources. For that, your system would
require the use of a separate preamplifier that is connected to the PDC-2.6P
or save money by using the 2.6 (the DEQX unit without the preamplifier
section) and use your own preamplifier to control volume and system functionality.
Levy, a friend and colleague, who piqued my interest in the DEQX, came
over and helped me install it. Let me preface this by saying I'm not a
strong technical or computer person and if one wants to maximize what
this unit can do to your current system, you will need the help of someone
with a facility for dealing with technical issues. An understanding of
speaker behavior wouldn't hurt. Ryrie assured me that long strides have
been made in making the PDC's software more user friendly. There is also
strong e-mail and phone support provided by DEQX. Onward.
I connected the unit after my Innersound i Control preamplifier using the balanced out to balanced in of the PDC-2.6P with Wasatch ULTAMA interconnects. Unfortunately the PDC I was using didn't have the balanced output option and I had to use single ended from the PDC-2.6P to my Innersound i 330 amplifier.
the fun begins.
connected the microphone and cable to the PDC as well as the USB cable
to Mike's laptop. All cables and microphone are included and you really
need a laptop computer unless your desktop computer is in your listening
space. The key to all this is the included programming CD that has to
be loaded on to the pc. It's the brains for the entire operation. Once
everything is connected and loaded the speaker calibration is next on
process of calibrating each speaker begins by getting the speaker as far
away from any surfaces in the room and placing the measuring microphone
1 meter from the speaker, on axis, pointed at the center of the midrange
driver. Then the actual measuring takes place when a test tone is generated
from the lowest frequencies through the entire audio range. This frequency
sweep repeats several times and the resultant measurement is plotted on
a graph on the computer screen showing the fluctuations, from neutral,
across the entire frequency range. This measuring is performed individually
for each speaker since differences can occur between supposedly 'identical'
units. Each of the speakers in the system can be individually corrected.
Then by setting up certain parameters on the computer, it applies the
correction to the frequency fluctuations and you are left with a new graph
that is for all practical purposes, ruler flat "to the extent that
power remains in the speakers design range".
simplified the actual procedure but outlined the essentials and after
Levy worked with the laptop computer and the new speaker correction responses
went into the PDC-2.6P and we were ready to listen. For a more technical
description read the following supplied by Ryrie.
to DEQX, is not only that it corrects frequency response at thousands
of frequencies simultaneously, but also that "Time Domain" errors
such as Phase and Group-Delay are corrected along with Frequency-Response
using DEQX’s “Proprietary very Low latency FIR (Finite Impulse
Response) and IIR (Infinite Impulse Response) filtering”. To be
“DEQX Calibrated”, a speaker’s "native" performance
(i.e. excluding the ‘power response’ caused by room interaction)
is "flat" and accurate in time in the near field (anechoically).
When doing room correction, the "flat" DEQX calibrated™
speaker is measured from the listening position to indicate its "power
response" (frequency response in room). From the sweet spot of the
listening room, DEQX recommends a flat frequency response (power response)
between 100Hz and 3kHz, above which highs should tend to roll off slowly
(about 2dB/octave) to be roughly 5dB down at 20kHz. Bass below 100Hz may
be a few dB "hot" at 50Hz. This is all subject to personal taste
however and you can use the parametric EQ to make any personal adjustments
to taste'. I did not use this recommendation but used my ears and preferred
the flat response. Now we can start listening.
I would like to refrain from being overly exuberant in my comments, but
I can't. What I heard was truly amazing, jaw dropping, illuminating, eye
opening, ear opening…well, you get the picture. Nothing I've ever
introduced into what I would call a pretty good system produced such an
enormous improvement to the quality of the sound. Not even close. I'm
not going to go through listing specific CDs or LPs but simply say that
whatever the source the improvements were consistent and wonderful.
soundstage is always is a good place to start. All the audiophile parameters
that usually apply were extended and broadened. Height, width and depth
were all bettered. Instrumental layering became clearer, as well as their
separation. Air around instruments took on a more vibrant quality and
at the same time the instruments themselves took on solidity and three
dimensionality that was beguiling.
Detail levels increased across the entire musical spectrum without adding
any clinical edge to the sound. Quite the contrary, an analogue-like smoothness
and liquidity pervaded what I heard. Scary.
Instrumental timbres took a further step towards reality with greater body and inner detail where subtle textures were further revealed. Voices were given a lifelike reality that hitherto didn't realize recorded music was capable. Orchestral dynamics, both macro and micro, were more dramatic in intensity, with greater orchestral weight bringing me closer to the live experience.
my past experience, there have been many touted 'Black Boxes' that have
been tried out in my system that purported to improve sound staging, dynamics,
palpability of instruments and voices, harmonic accuracy, etc. Some worked
to one degree or another but they all seemed to suffer from one major
problem, a loss of clarity and transparency. Put more electronics in the
chain and the sound always lost more than it gained…until now. The
level of transparency, with the 2.6P in the system, was affected-by being
further enhanced. Truly remarkable. The DEQX shows us that by removing
speaker inaccuracies and distortions our listening window becomes clearer
and more transparent then ever. Wait, we still haven't done the room correction
correction is a much easier task then speaker correction for the end user.
Plug in the mic and place it in your listening position and the computer
reads the response and makes adjustments as needed. DEQX recommends that
you might like to take several readings around the listening area. These
can be averaged, or just used to see what’s happening near by for
informational use. Being the rule breaker that I am, I only took one reading,
holding the mic dead center on my forehead at my listening position. And
away we went.
guess my room didn't have too many problems because the changes I heard
were more subtle than the speaker correction. A further improvement in
clarity in general and more specifically, of the bass performance and
an incrementally broadened sweet spot, (which had considerably grown with
the speaker correction). I also noticed another increase in overall system
smoothness and airiness that further increased my appreciation of the
capabilities of the DEQX. Even after all these processes were completed
and one still wanted to further tinker with the sound one could use the
three-band parametric equalizer on the remote control, make adjustments
in real time and save any changes. I didn't. I was too happy. I leave
further experimentation for future times.
final chapter in this story took place in Las Vegas at the Consumer Electronics
Show where I heard the full embodiment of the use of DEQX technology.
Remember that part in the introduction of this review where I touched
on crossovers and their contribution to the distortion picture. What if
you eliminated the internal speaker crossovers and designed speakers using
DEQX’s ‘linear-phase’ 100dB per octave slope crossovers
in the PDC 2.6P. Now, you have practically zero driver overlap negating
driver interference allowing each driver to perform optimally. Another
source of distortion is now eliminated and further gains in clarity can
ACOUSTICS, an offshoot of WASATCH CABLE WORKS, the makers of some truly
fine audio cables, showed their “DEQX-HD Calibrated™ Musina
Music System at The CES in Las Vegas. The WASATCH system incorporates
the full DEQX technology, (ala 2.6P) including preamplifier section, using
the steep slope crossovers and six individual amplifiers (each driver
gets it own amplifier) contained in a one-box unit called the UINTAH 2.2
AMPX. Connecting the MUSINA 2.0 full range monitor speakers and MUSINA
.2 subwoofers with the included ULTAMA speaker cables completed the package.
The high gloss black finish was simply gorgeous and only foreshadowed
what I was about to hear. Total system cost was roughly $40,000 US. You
supply your own source components.
to 2.6P. I couldn't finish this review without a few nits to pick. Like
the Innersound i control preamplifier, the very narrow casework of the
2.6P makes connecting today's cables difficult due to the cramped quarters
and the casework itself was at best utilitarian. And as stated earlier
this is not a plug n' play product, but requires some diligence and work.
The PD2.6 takes some working at it to properly obtain the maximal results
that the unit is capable of. But once it's in your system and properly
set up be prepared for some serious audio delights. The future has just
I had to return the unit to the manufacturer I went through 'withdrawal'
and 'grief counseling' from my audiophile buddies. If ever there was a
product that deserved an Audiophilia 'star' rating for sonics and its
impact on your system, this is it. This reviewer has placed his order
with DEQX and impatiently awaits its arrival. Viva
[It is with great pleasure that we award The Audiophilia Star Component Award to the DEQX PDC-2.6. Congratulations! - Ed]
Price: US$3,500, balanced outputs, calibrating microphone and other options are available. PDC-2.6 without preamplifier option is US$3,000
Source of review sample: Manufacturer loan
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