m High-precision CD drive, high-quality CD tray, and ultra quiet
and smooth loading mechanism m MDS++ D/A converters andlow-pass “Direct Balanced Filter” with totally separate balanced
and unbalanced signal paths m Two sets of transport outputs anddigital inputs allow insertion of DG-48 into signal path for soundfield correction m Balanced and unbalanced analog outputs

Dedicated CD Player with high-precision drive — High-quality disc tray
made from extruded aluminum, combined with ultra quiet and smoothloading mechanism. Processor section features further refined MDS++ type
D/A converters. Fully separate transport and processor section, with coaxial
and optical transport outputs and digital inputs, allowing easy insertionof DG-48 into signal path for sound field correction in the digital domain.
The Compact Disc format with its 20-year history offers an unsurpassed wealth ofmusical 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 mostup-to-date reproduction quality possible. In response to such demands, Accuphasedeveloped a CD drive in-house and first 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 forwhom sound quality is paramount. By bringing out the full potential of the format
down to the finest nuances, it lets the listener rediscover the sheer exhilaration ofthe 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 aminimum, it also is highly impervious to external vibrations. This is the secret behind
extracting the information on the CD one-hundred percent. The sophisticated knowhow gained while developing the DP-500 is fully in evidence here.
The processor section incorporates digital technology of the highest
order, with a further refined MDS++ type D/A converter, anotherproprietary Accuphase development. In the DP-400, two strictly selected
high-performance delta-sigma devices are operating in parallel. Thissignificantly improves performance parameters including conversion Coaxial input
indication
accuracy, THD, S/N ratio, and linearity at low signal levels. The analog
filter is a “Direct Balanced Filter” with totally separate analog lowpass filtering (3-pole Butterworth) for the balanced and unbalanced
signal paths. The transport and processor sections are configured
independently of each other, allowing separate use in conjunction with
Optical input
other components.
indication
DIGITAL SECTION

Focus Coil&Tracking Coil
OpticalHeadRFSignal
Processor

Spindle MotorSpindle
ServoController

Sled Motor

Focus &Tracking ServoController

EFM Decoder& Error
Corrector

MDS++ D/A converter
MDS (Multiple Delta Sigma) is a revolutionary design which employs severaldelta sigma type converters in a parallel configuration. 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 deltasigma type PCM1796
converters (made by Texas
Instruments) are driven inparallel. Compared to asingle converter, this results
in an overall performance
improvement by a factor of
1.41 (=).

Analog output [dB]

As shown in the diagram,
the MDS++ features anenhanced current-to-voltage(I/V) converter for processing
the D/A converter output
current.

Digital input [dB]Linearity (digital input vs. analog output)

A combination of current
summing and voltage
summing is used, providing
even better stability andtop-notch performance.
The music emerges froma totally silent background,with breathtaking detailresolution and accuratespatial information.

ClockGenerator

THD (+ noise) vs. frequency response

SignalConversion Error

CDDisc Clamp& Tray MotorMasterControlComputer

Display
Driver

KeyMatrix

InfraredReceiver

DigitalInput

Note the ratio between signal
and conversion error. In the MDS
output, the error is very small inrelation to the signal.

(Signal)
Display

From Remote Commander

Digital Audio
Interface
Encoder

Digital Audio
Interface
Decoder

CoaxialTransmitter

Coaxial

OpticalTransmitter

OpticalPulse Amp

Coaxial

OpticalReceiverMDS Output
DigitalInputs

Opticaln MDS type D/A converter principle

ANALOG SECTIONMDS++
D/A Conversion
System

3-PoleLow-Pass Filter

Unbalanced(Reverse PhaseOutput)

Balanced
3-PoleLow-Pass Filter

3-PoleLow-Pass Filter(Normal PhaseOutput)

Left
AnalogOutputs

3-PoleLow-Pass Filter

MDS++
D/A Conversion
System(ConversionError)

Transport
Outputs

DAC Output(Normal PhaseOutput)
Subtraction

Unbalanced
Right
AnalogOutputs

3-PoleLow-Pass Filter(Reverse Phase
Output)Balanced
3-PoleLow-Pass Filter

Block diagram of DP-400

I (Current)/V (Voltage)
Converter

Voltage Summingn Block diagram of MDS++ converter in DP-400

Transport section features high-rigidity, high-precision CD drive
High-rigidity, high-precision
dedicated CD Driven Sturdy chassis absorbs external vibrationsn Highly rigid and precise construction

Bridgen Traverse mechanism with floating design and viscous dampingn Integrated design with large bridge joined to mechanism basen Low center of gravity and efficient vibration control
n High-quality disc tray made from extruded aluminum, plus ultra
quiet and smooth loading mechanism

Traversemechanism

CD transport section features and functions
Mechanismbasem Fully digital control of CD mechanismm Laser pickup with integrated RF amplifier for drastically reduced noiseinterferencem Power-on play feature allows automatic playbackm Balanced drive circuitry for actuator control eliminates interaction with othercircuits

Disc trayn Supplied remotecommander RC-100

Viscous dampers

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.

provides access to direct play,
input source selection, level control, repeat play, program playand other functions.

Direct Balanced Filter withseparate balanced/unbalanced circuitry

Connection example for DG-48
The transport output of the DP-400 can be connected to the digital
input of the DG-48 (by coaxial or optical fiber cable) for soundfield processing of the CD transport signal in the digital domain.

The output of any D/A converter contains so-called aliasing noise in the very high frequency
range. In the DP-400, the analog filter designed to remove that noise is a 3-pole Butterworth
type with extremely flat frequency response in the passband. In order to prevent unwanted
interaction, completely separate filters are provided for the balanced and unbalanced signalpaths. A direct connection
from the balancing circuit
3-PoleButterworth
at the output of the D/AMDS++
LPF
D/A
Conversion
Unbalanced
converter to the filter
Systemcircuitry and symmetrical Digital
Analog
Input
Outputs
3-Pole+/– configuration ensures
Butterworththat the +/– output
LPF
impedance is also
identical. This provides
3-PoleBalanced
Butterworth
ideal transmission
LPF
conditions for the highquality MDS++ output.

Coaxial digital cable

Other featuresn Completely separate transport and processor sectionsn Two sets (coaxial and optical) of transport outputs and processor
inputs allow connection of DG-48 for sound field correctionn Balanced and unbalanced analog outputs
n “High Carbon” cast iron insulator feet with superior damping
characteristics further enhance sound quality

Delta-sigma D/A converter

High-quality, high-reliability parts

Digital signal processing assembly

DP-400 Guaranteed Specifications

n Front panel* Guaranteed specifications are measured according to the JEITA standard CP-2402A.
* Measurement disc: JEITA CP-2403A compliant

CD Transportm Standard CD format
Quantization:
16 bits
Sampling frequency:
44.1 kHz
Error correction principle: CIRC
Number of channels:
2Revolution speed:
500–200 rpm (CLV)
Scan velocity:
1.2–1.4 m/s, constantm Data read principle
Non-contact optical pickup
m Laser
GaAlAs (double hetero-junction visible-spectrum semiconductor laser diode)m Transport output level
COAXIAL (IEC 60958):
0.5 Vp-p, 75 ohms
OPTICAL (JEITA CP-1212): Light output –21 to –15 dBm
Wavelength 660 nm

Digital Processor

n Rear panel

m Input format (IEC 60958/AES-3 compliant)
Quantization:
16–24 bits, linear
Sampling frequency:
32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz,96 kHz
m Digital input level
COAXIAL (IEC 60958):
0.5 Vp-p, 75 ohms
OPTICAL (JEITA CP-1212): Light output –27 to –15 dBm
m Frequency response
4 to 20,000 Hz ±0.3 dB
m D/A converter
24 bits, MDS++ typem Total harmonic distortionMax. 0.001% (20–20,000 Hz, 24-bit input)m Signal-to-noise ratio
114 dB or betterm Dynamic range
110 dB or betterm Channel separation
110 dB or betterm Output voltage and impedanceBALANCED:
2.5 V into 50 ohms, balanced XLR type
UNBALANCED:
2.5 V into 50 ohms, RCA-type phono jacks
m Output level control
0 to –60 dB in 1-dB steps (digital type)

Play track indicator
Total track/index indicatorTime indicator
Output level indicator
Power switch
CD transport/processor selector button
Disc tray
Disc tray open/close button
Play/pause button
Track search buttons
Stop button

Digital input connectors (coaxial, optical)
Transport output connectors (coaxial,optical)
Balanced output connectors (analog)
Ground Inverted (–) Non-inverted (+)
Unbalanced output connectors (analog)
AC power connectorn Supplied accessories:m AC power cordm Audio cable with plugs (1 meter)m Remote Commander RC-100

Generalm Power requirements

AC120 V/230 V, 50/60 Hz (Voltage as indicated onrear panel)
13 W
Width 465 mm (18-5/16”)
Height 150 mm (5-7/8”)
Depth 393 mm (15-1/2”)
m Mass13.6 kg (30.0 lbs) net
20.0 kg (44.1 lbs) in shipping cartionm Supplied Remote Commander RC-100
Remote control principle: Infrared pulse
Power supply:
Two IEC R03 (size AAA) batteries
Max. dimensions:
56 mm × 175 mm × 26 mm
Weight:155 g (including batteries)m Power consumption
m Max. dimensions

Remarks
This product is available in versions for 120/230 V AC. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.

mSpecifications and design subject to change without notice for improvements.

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