Phase Technology DFS-525-C, DFS-525-LR, DCB-112-SUB, DARTS 525 Reference Manual
A
bout a year and a half ago, I got my first taste of Phase
Technology’s remarkably advanced and utterly unforgettable
DARTS speaker system, whose name is an acronym that
stands for Digital Audio Reference Theater System. The self-powered,
DSP-controlled system was something of a technical marvel, and it
even offered a fuzzy logic-driven room EQ system designed to optimize
response across multiple listening locations at once. Since I come from
the “simpler is better” school of thought, I am sometimes skeptical of
technically complicated solutions, but I had to admit that the DARTS
system sounded extremely transparent and that its high-tech EQ system really worked. “A future TPV review subject,” I thought to myself.
Phase Technology DARTS 525:
Better Music Through Science
by Chris Martens
In a very real sense the DARTS 525 system is
the brainchild of three companies: Phase Technology, which contributed speaker/drive unit
design know-how, D2Audio, which contributed
Class D switching amplifier technology, and
Audyssey Laboratories, which provided a customized version of its sophisticated MultEQ XT
automated speaker setup/room EQ system.
From the start DARTS 525 was conceived as a
self-powered or “active” speaker system where individual drive units would be powered by dedicated
Class D amplifiers, with all traditional crossover
functions handled by digital signal processing
(DSP) engines built into the amplifier module. One
reason the speaker system performs so well is that
its drive units and amplifiers were literally designed
for each other. D2Audio’s Class D amplifiers are
capable of very wide bandwidth, nearly grain-free
resolution of textural details, lightning-fast transient
response, and high damping factors (which describe the amplifier’s ability to control driver motion
without overshoot). Phase Technology designed
the DARTS 525 drive units to take advantage of
these characteristics to the fullest extent possible.
Another advantage is that DARTS 525 is a
DSP-controlled speaker system where output
level matching and crossover frequencies and
slopes are controlled in the digital domain.
But the DARTS 525 system takes DSP further
still, applying DSP-driven frequency and time
response EQ curves at the driver level to yield
ruler-flat frequency response, ideal phase response, and perfect time alignment between
drivers. In short, DARTS 525 would be a tremendously accurate speaker system even if it did not
provide automated setup/room EQ features.
But DARTS 525
does
provide those features,
and they add an extra dimension to the system’s
performance. Unlike other EQ technologies,
Audyssey Laboratories’ DSP-powered MultEQ
system optimizes the speaker system’s in-room
frequency and time response characteristics for
multiple listener locations—not just for one central
“sweet spot.” Through a comprehensive set-up
and calibration process, it gathers room/speaker
response data from multiple seating locations,
collecting as many as 32 complete sets of measurements. Then, the MultEQ system applies
fuzzy logic techniques to analyze the data and
calculate optimal frequency and time response
correction filters for each speaker in the system.
The term “fuzzy logic” means that the Audyssey
system does not simply average response data
as some competing systems do but rather takes
the more sophisticated approach of analyzing
data to identify specific “clusters” or patterns of
response problems within the room. Then, taking
a “whole system” approach, the system plots
channel-specific correction filters that together
work to compensate for room/speaker problems
across multiple listening locations at once. The
DARTS 525 system correction filters are extremely
precise, providing an astounding 512 individual
correction points per speaker, which result in
remarkably smooth in-room response curves.
The real genius of the system is that it
is an exceptionally accurate speaker that
does not try to achieve “perfect” response in
any one room location. Instead, it aims to
achieve very good response at multiple locations within real-world listening rooms—a
job at which it succeeds brilliantly.
The Technologies Behind the DARTS 525
Self-Powered, DSP-Controlled,
5.1-Channel Speaker System
ECHNOLOGY FOCUS
DFS-525C center channel
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Now let’s fast-forward to the 2006
CEDIA show, where
Phase Technology
announced the new
DARTS 525 system,
which in 5.1-channel
configuration sells for
between $11,000 and
$12,800 (depending
upon whether you want
one sub or two). The
system price buys you
5.1-channel’s worth of
speakers plus a powerful DSP-controlled, 16channel Class D amplifier. Sixteen channels
are needed because
the DARTS 525 system
powers each individual
speaker drive unit
(or set of drive units)
with its own amplifier channel. Don’t
be fooled by the tiny
525 main speakers,
though, because
there is nothing
miniature about this
system’s sound.
The DARTS 525
system consists of
two 2-way biamplified DFS-525LR
main speakers, a
3-way triamplified
DFS-525C center channel, two
bipolar/dipolar
biamplified DCBSURR surround
speakers, a pair
of 500-watt DCB-112S
powered subwoofers, and
a DP-2000 DSP-controlled
16-channel Class D power
amplifier that cranks out
250Wpc. We describe
the distinctive technologies and set-up procedures used for the DARTS
system in two sidebars,
but for now let’s focus on
how the system performs.
Clar ity Comes Fir st
Right off the bat the
DARTS 525 system bowls
listeners over with its
stunning openness and
transparency. With many
AVRs and some A/V controllers, I’m used to hear-
ing a certain amount
of low-level hash with
DSP circuits, but in
the DSP-controlled
DARTS 525 system I
really couldn’t hear any
hash or graininess at all.
What I heard, instead,
was a veritable smorgasbord of sonic details
and textures spread out
as if on a banquet table.
With the DARTS 525 rig
you’ll want to put on favorite music recordings
and movies one after
another, just to see if
the system will reveal
any cool new pieces
of low-level information you might have
missed before. It’s an
addicting experience.
On movie soundtracks in particular,
I heard low-level details that often get
lost or buried in other systems. One
good example would be the shootout
scene from Open Range , which enthusiasts know for its violent action—and
many sonic subtleties. As Charlie and
Boss face down their opponents, for
example, you can hear insects chirping and the prairie wind whistling faintly
and mournfully in the background.
Through the DARTS 525 system these
subtle details become crystal clear
and serve—on an almost subliminal
level—to remind us how terribly alone
and exposed the cowboys are.
But beyond finesse, the system also
serves up explosive dynamics that
seem impossibly powerful given how
small the DARTS speaker modules are.
The “Omaha Beach” scene from Savin g
Priv ate Ryan convinced me the system
could at once play loudly and cleanly,
technology focus focus: Phase Technology
DFS-525LR main speaker
DCB-SURR
surround speaker
When DARTS 525 systems
are sold, the dealer sends
a DARTS-qualified installer
to the user’s home to
calibrate the system (the
dealer may or may not
charge for this service).
The installer brings a calibration system consisting
of a laptop equipped with
test/calibration software,
a calibrated microphone,
and a special “umbilical”
cord that connects the laptop to the DARTS 525 system amplifier. The installer
runs a series of laptopdriven tests (pulsed sweep
tones that are played
through each speaker
in succession), taking
multiple measurements
from locations in and near
every seat in the room.
Once data gathering
is complete, the installer
runs a computation-intensive, Audyssey Laboratories-developed computer
program that calculates
frequency and time response correction filters
for each speaker in the
system. Phase Technology
offers users four possible
EQ tuning curves to allow
for rooms that are large or
small and whose acoustics may be reverberant
or dead. For reverberant
spaces, the system rolls
off upper midrange and
treble response a bit to
compensate for the fact
that “live” rooms tend to
make speakers sound
overly bright. Once a
preferred EQ tuning curve
is selected, the installer
downloads filter settings
to the amplifier’s DSP
engines via a faceplate-
mounted USB port.
As the last step in the
set-up process, the installer disconnects the
calibration system and
configures the system’s
preamp/multichannel controller to drive the DARTS
525 amplifier. During the
data analysis process,
DARTS calibration software
calculates recommended
speaker distance settings
(accurate to with a tenth
of a foot) and channel
level settings (accurate to
with a tenth of a dB). The
installer then connects the
controller to the DARTS
amplifier and loads the
recommended settings,
at which point the system
is ready to play music or
movie soundtracks in a
way most people have
not experienced before.
DARTS 525 System Setup
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