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Dedicated CD Player with high-precision drive - High-quality disc tray
made from extruded aluminum, combined with ultra quiet and smooth
loading mechanism. Processor section features further re ned MDS++ type
D/A converters. Fully separate transport and processor section, with coaxial
and optical transport outputs and digital inputs, allowing easy insertion
of DG-48 into signal path for sound eld correction in the digital domain.
The Compact Disc format with its 20-year history offers an unsurpassed wealth of
musical treasures. It still is the most important source medium for many music lovers.
Many audiophiles have extensive CD collections and they want to get the best and most
up-to-date reproduction quality possible. In response to such demands, Accuphase
developed a CD drive in-house and fi rst incorporated it in the high-end dedicated CD
player DP-500, which has won enthusiastic praise the world over. The DP-400 inherits
the technical know-how of the DP-500 while employing the latest digital technology.
It offers CD reproduction bound to satisfy even the most discerning audiophile for
whom sound quality is paramount. By bringing out the full potential of the format
down to the fi nest nuances, it lets the listener rediscover the sheer exhilaration of
the music experience.
The high-precision drive mechanism in the transport section of the DP-400 uses
a chassis construction that not only keeps internal vibrations of rotating parts to a
minimum, it also is highly impervious to external vibrations. This is the secret behind
extracting the information on the CD one-hundred percent. The sophisticated know-
how gained while developing the DP-500 is fully in evidence here.
The processor section incorporates digital technology of the highest
order, with a further refi ned MDS++ type D/A converter, another
proprietary Accuphase development. In the DP-400, two strictly selected
high-performance delta-sigma devices are operating in parallel. This
signifi cantly improves performance parameters including conversion
accuracy, THD, S/N ratio, and linearity at low signal levels. The analog
fi lter is a Direct Balanced Filter with totally separate analog low-
pass fi ltering (3-pole Butterworth) for the balanced and unbalanced
signal paths. The transport and processor sections are confi gured
independently of each other, allowing separate use in conjunction with
other components. MDS++ D/A converter
Block diagram of DP-400 n Block diagram of MDS++ converter in DP-400
THD (
+ noise) vs. frequency response Linearity (digital input vs. analog output)
Optical input
indication Coaxial input
indication
n MDS type D/A converter principle
Note the ratio between signal
and conversion error. In the MDS
output, the error is very small in
relation to the signal.
Digital
Input
Signal
Conversion Error
(Normal Phase
Output)
(Normal Phase
Output) (Reverse Phase
Output)
(Reverse Phase
Output)
I (Current)/V (Voltage)
ConverterVoltage Summing
DAC Output
Subtraction
MDS Output
(Signal)
(Conversion
Error)
MDS (Multiple Delta Sigma) is a revolutionary design which employs several
delta sigma type converters in a parallel confi guration. In the combined output,
conversion errors cancel each other out, resulting in a drastic improvement in
all relevant aspects of converter performance such as conversion accuracy,
S/N ratio, dynamic range,
linearity, and THD.
In the DP-400, two delta-
sigma type PCM1796
converters (made by Texas
Instruments) are driven in
parallel. Compared to a
single converter, this results
in an overall performance
improvement by a factor of
1.41 (= ).
As shown in the diagram,
the MDS++ features an
enhanced current-to-voltage
(I/V) converter for processing
the D/A converter output
current.
A combination of current
summing and voltage
summing is used, providing
even better stability and
top-notch performance.
The music emerges from
a totally silent background,
with breathtaking detail
resolution and accurate
spatial information.
DIGITAL SECTION
ANALOG SECTION
CD
Focus Coil
&
Tracking Coil
Optical
Head
Spindle Motor
Sled Motor
Disc Clamp
& Tray Motor
RF
Signal
Processor
Spindle
Servo
Controller
Focus &
Tracking Servo
Controller
Master
Control
Computer
Key
Matrix
EFM Decoder
& Error
Corrector
From Remote CommanderDisplay
Driver
Infrared
Receiver
Clock
Generator
Display
Digital Audio
Interface
Encoder
Digital Audio
Interface
Decoder
Coaxial
Transmitter
Optical
Transmitter
Pulse Amp
Optical
ReceiverCoaxial
Optical
Coaxial
Optical Transport
Outputs
Digital
Inputs
MDS++
D/A Conversion
System
MDS++
D/A Conversion
System 3-Pole
Low-Pass Filter
3-Pole
Low-Pass Filter
3-Pole
Low-Pass Filter
3-Pole
Low-Pass Filter
3-Pole
Low-Pass Filter
3-Pole
Low-Pass FilterUnbalanced
Balanced
Unbalanced
Balanced
Left
Analog
Outputs
Right
Analog
Outputs
Analog output [dB]
Digital input [dB]
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n PCB assembly with transport outputs, digital inputs,
MDS++ D/A converter circuitry, Direct Balanced Filter
circuitry, balanced and unbalanced analog
output, power supply circuitry, etc.
Transport section features high-rigidity, high-precision CD drive
Mechanism
base
Viscous dampers
High-rigidity, high-precision
dedicated CD Drive
m Fully digital control of CD mechanism
m Laser pickup with integrated RF amplifi er for drastically reduced noise
interference
m Power-on play feature allows automatic playback
m Balanced drive circuitry for actuator control eliminates interaction with other
circuits n Sturdy chassis absorbs external vibrations
n Highly rigid and precise construction
n Traverse mechanism with fl oating design and viscous damping
n Integrated design with large bridge joined to mechanism base
n Low center of gravity and effi cient vibration control
n High-quality disc tray made from extruded aluminum, plus ultra
quiet and smooth loading mechanism
CD transport section features and functions
n Supplied remote
commander RC-100
provides access to direct play,
input source selection, level con-
trol, repeat play, program play
and other functions.
Bridge
Traverse
mechanism
Disc tray
