● High-grade SA-CD/CD drive ● MDS+ type D/A converter with fourparallel devices ● Support for playback of DSD discs in DSF file format● Direct Balanced Filter with separate line and balanced signal paths● HS-LINK and USB digital interface ● Transport outputs and digital inputs
allow insertion of DG-48 into signal path for sound field correction ● Phase
selector for balanced outputs ● Numeric indication of sampling frequency

High-performance integrated SA-CD/CD player — Newly developed high-grade
SA-CD/CD drive combined with exquisite disc tray and ultra-quiet disc loadingmechanism ensures smooth operation. Innovative MDS+ type D/A converter
using four parallel DAC circuits achieves straight D/A conversion of DSD signal.
Separate configuration of transport and processor sections, each equipped witha set of HS-LINK, coaxial, optical, and USB (input only) connectors.
On the occasion of the 40th anniversary of its founding,Accuphase released the separate type SA-CD/CD
player combo DP-900/DC-901, incorporating all of its
superb technology and heralding the beginning of a newage. The products were enthusiastically received inJapan as well as overseas and have found their rightfulplace as the ultimate reference for SA-CD soundquality. The DP-550 features an exclusive mechanism
developed in-house by Accuphase and benefits in many
ways from the advanced technology of the flagshipmodels. It is a high-performance integrated SA-CD/CD
player that represents the fruits of intensive research
and many extended listening sessions. Like otherAccuphase players before it, the DP-550 is dedicatedpurely to the optimal reproduction of two-channel musicsources. The player lets the listener experience thesonic splendor of SA-CDs and CDs without any
restraints or limitations.
The newly designed high-grade SA-CD drive
mechanism in the DP-550 is the ultimate tool for
extracting the information on SA-CD discs one
hundred percent. It not only keeps internal
vibrations of rotating parts to a minimum, but is also
highly impervious to external vibrations. This
ensures that the digital signal remains in a highly
pure and accurate state. A dedicated DSP chip
controls the digital servo, allowing the digital signal
encoded on the SA-CD in DSD (Direct StreamDigital) format to be processed with utmost
accuracy. The all-important laser pickup is a new
single lens/twin laser diode type with high-speed
access mechanism, achieving extremely precise
signal readout. The digital processor section of theDP-550 features an innovative method called
MDS+ (Multiple Delta Sigma+) developed byAccuphase. With MDS+, the DSD signal is supplied
directly to multiple D/A converters arranged in aparallel configuration. After conversion, the signals
from the converters are summed which has theeffect of minimizing conversion errors. The D/Aconverters in the DP-550 are the latest Hyperstream™ types (ES9008 from ESS TechnologyInc.). Using four of these superb devices in parallel
results in amazing conversion accuracy withdrastically improved parameters: minimal THD,
high S/N ratio, and excellent low-level linearity. The
full wealth of the musical information on the SA-CD
can finally emerge before the listener.

SA-CD/CD

SA-CD
OpticalHead

DigitalSignal
Processor

CD
OpticalHead

RF
Signal
Processor

Motor&Driver

DigitalServo
Processor

Infrared
ReceiverFrom
Remote Commander

MDS＋
D/A Conversion
System⊿Σ DAC×4HS-LINK

CoaxialDigital
Inputs
OpticalOpticalReceiverq Highly rigid and precise construction with sturdy, heavyweightchassis to absorb external vibrations.
w Traverse mechanism achieves floating design with newly developed
viscous dampers.
e Massive bridge cover.
r Non-resonant design and low center of gravity further reduce vibrations.
t High-quality disc tray extruded from an aluminum block, plus superquiet and smooth disc loadingmechanism.

■ SA-CD/CD transport outputs
ultra pure digital signal.
■ Single lens/twin pickup highspeed access mechanism.
■ Accuphase’s proprietaryhigh-quality digital audio
interface HS-LINK (carries both
SA-CD and CD signal).
■ New chucking magnet designusing neodymium with highflux density, together with 8pole magMechanism
netizingbase
yoke firmly
and evenly
grasps theturntable
Disc tray
and preChucking magnet
vents discwobble.
High-grade SA-CD/CD drive■ Support for DSD discs
recorded using DSF file format on a computer or similar.

■ MDS+ type D/A converter with four DACs driven in parallel.
■ Digital level control allows adjustment down to -80 dB.
■ Separate transport and processor sections, with inputs andoutputs for HS-LINK, coaxial, optical, and USB (input only).
■ Sampling frequency indication(kHz) during transport operation
and when using external input.
Sampling frequency
display example■ Triple layer bottom plate and carbon
cast iron insulator feet with superior damping characteristics absorb vibrations for optimum sound quality.
■ Phase selector for balanced outputs.
■ Balanced and line analog outputs (1 set each).
Clock
Generator

LVDS
Driver/Receiver

HS-LINK

Digital Audio
Interface
Encoder

CoaxialTransmitter

Coaxial

OpticalTransmitter

OpticalMaster
ControlComputerKey
MatrixTraversemechanism

Transport
Outputs

Interface
Decoder

MDS＋
D/A Conversion
SystemNewly developed viscous dampers

Digital control PCB

Digital signal processing and DAC PCB

Display

5-PoleButterworth
Low-Pass Filter

LineLeftAnalog
Outputs

5-PoleButterworth
Low-Pass Filter

5-PoleButterworth
Low-Pass Filter

High-reliability parts selected for sound quality■ Assembly with 5-pole analog
filter, line/balanced analog
output circuitry, power
supply circuitry etc.

Line

RightAnalog
Outputs

5-PoleButterworth
Low-Pass Filter

USB
ReceiverDP-550 Block Diagram

BridgeFeatures and Functions of Digital Processor Section

5-PoleButterworth
Low-Pass Filter⊿Σ DAC×4USB■ High-grade SA-CD/CD drive.

Balanced

HS-LINK
Decoder

CoaxialReceiverFeatures and Functions of Transport Section

Balanced

5-PoleButterworth
Low-Pass Filter

■ Supplied remotecommander RC-110

Give access to various functions
including direct play, repeat,
input switching, and level control.

Further Refined MDS+ Type D/A Converter
MDS+ is a revolutionary approach that employs multiple delta-sigma type
D/A converters connected in parallel, for drastically improved performance.
The same digital signal is supplied to each converter, and the output of theconverters is summed before being sent to subsequent stages. The signal
components in the combined output are simply added up, thereby increasing their level, but components that are due to conversion errors may cancel each other out, causing
a reduction in level compared to simple summing.
This is turn increases the ratio of the target signal
to error components, resulting in a drastic improvement in all relevant aspects of converter performance, such as accuracy, S/N ratio, dynamic
range, linearity, and THD. (When the number ofconverters is taken as "n", the improvement is √n.)In the DP-550, four Hyperstream™ DACs (ES9008 from ESS TechnologyInc.) are used in parallel. Compared to a single converter, this results in anoverall performance improvement by a factor of 2 (= √4).
Because the performance improvement afforded by the MDS principle is
not dependent on signal frequency or signal level, noise at very low levels
that has plagued the output of conventional delta-sigma converters can also
be reliably reduced.

I (current) / V (voltage) converter(Normal phaseoutput)

I -VDAC 1(Reverse phaseoutput)

DAC 2

Digital input

DAC 4

Current summing

4 circuits driven in parallel

Block diagram of MDS+ converter in DP-550
THD+NOISE vs FREQUENCY

〔%〕

0＋×4
MDS＋
D/A Conversion
System−＋ 5-Pole

Butterworth
− LPF

−40

0.0100Line＋

0.0050

AnalogOutputs−60

0.00300.0020−80

0.0010−1000.0005
0.00030.00020.0001＋ 5-Pole
Butterworth− LPF−200.0300
0.0200⊿Σ DAC

Balanced−

LINEARITY

Analog output〔dB〕

0.0500＋ 5-Pole

DigitalInput

DAC output

I -V

0.1000Butterworth− LPF＋DAC 3

Subtraction

Direct Balanced Filter With Separate Line/Balanced Circuitry
The analog filter designed toremove so-called aliasing
noise in the very high frequency range employs 5-pole
Butterworth analog filterswith extremely flat frequency
response in the passband. Inorder to prevent unwanted interaction, completely separate low-pass filters are provided for the line and balanced signal paths.

−Current
Source−120203050100

2005001k2k 3k

THD + noise vs. frequency

5k

10k

20k
〔Hz〕

−140−140−120−100−80−60−40−200Digital input〔dB〕Linearity (Digital input vs. analog output)

— Accuphase Exclusive Digital Interface — HS-LINK: High Speed LINKUtilizing the USB port

HS-LINK is an ultra high-quality digital audio interface developed by Accuphase using latest digital signal transmission technology. It supports
send/receive verification for copyright protection. The LVDS (Low Voltage Differential Signaling) principle allows a single dedicated HS-LINK
cable to transmit all audio data with utmost fidelity, including conventional digital signals as well as 2.8224 MHz/1-bit and 192 kHz/24-bit signals.

The USB port (Type B) on the DP-550 can beconnected to a computer using a USB cable (USBType B connector).

Digital
Audio
SignalHS-LINK
Encoder

HS-LINKcable

RJ-45
Connector

HS-LINK
Decoder

Digital
Audio
SignalRJ-45
Connector

Security
Control

PC

Security
Control
TIA/EIA-644
LVDS
Driver/Receiver

TIA/EIA-644
LVDS
Driver/Receiver

USB port● Depending on the computer, it may
be necessary to first install the software on the "USB Utility" CD-ROM
supplied with the DP-550.
● The capability for playing back music data via USB depends on theoperating system and the music
playback software of the computer.
● For information on computer settingsand connection methods for USB, referto the documentation of the computer.

USB cable

High-resolution music data up
to 192 kHz/24-bit downloaded
to the computer can be playedback via the USB link.

HS-LINK Block Diagram
USB port

DG-48 connection example
The DG-48 can be connected between the transport outputs and digital inputs of the DP-550 (using HS-LINK, coaxial,
or optical connection). This allows sound field compensation of the signal from the CD transport in the digital domain.
HS-LINK cable supportstransmission of both
SA-CD and CD signals.

Analog output

DIGITAL OUT
DIGITAL INPUTS

Audiocable

DIGITAL IN

DG-48

DP-550HS-LINK cable
TRANSPORT OUTPUTS

DP-550Preamplifier■ Front Panelqw

DP-550 Guaranteed Specifications
specifications are measured according to the JEITA standard CP-2402A.
* Guaranteed* Measurement disc: PHILIPS 3122-783-00632

Transport section● Compatible disc formats

2-channel Super Audio CD
CD
DSD disc (DSF file format)● Data read principle

Non-contact optical pickup● Laser diode wavelength

SA-CD:CD:650 nm
780 nm● Transport section outputs

HS-LINK

Connector type: RJ-45
Suitable cable: Dedicated HS-LINK cable
Format:IEC 60958 compliant
JEITA CP-1212 compliant
Format:COAXIALOPTICALert y uio !0 !1 !2 !3 !4 !5■ Rear Panel

Digital processor section● Digital inputs

HS-LINK
COAXIALOPTICAL
USB!6!7

q Input indicator:
HS-LINK / COAXIAL / OPTICAL /USBw Repeat indicatore Power switchr SA-CD/CD selector buttont Input selector buttony Current track indicatoru Total number of tracks indicatori Disc trayo Time indicator!0 Disc tray open/close button!1 Output level indicator!2Play button!3 Pause button!4BACK /NEXT track
search buttons!8!9@0 ★

!5 Stop button!6 Digital inputs (USB, OPTICAL, COAXIAL, HS-LINK)!7 Transport outputs (OPTICAL, COAXIAL, HS-LINK)!8 Balanced output phase selector!9 Analog outputs
Balanced output connectors
q Ground w Inverted (-) e Non-inverted (+)(Can be changed with phase selector !8)
Line output connectors@0 AC power connector ★

Supplied accessories● AC power cord
● Audio cable with plugs (1 meter)● Remote Commander RC-110

Connector type: RJ-45
Suitable cable: Dedicated HS-LINK cable
Format:IEC 60958 compliant
JEITA CP-1212 compliant
Format:Format:USB 2.0 Hi-Speed(480 Mbps compliant)● Sampling frequency

HS-LINK
32 kHz to 192 kHz/24-bit (2-channel PCM)
2.8224 MHz/1-bit (2-channel DSD)
USB, COAXIAL
32 kHz to 192 kHz/24-bit (2-channel PCM)
OPTICAL
32 kHz to 96 kHz/24-bit (2-channel PCM)

● D/A converter

4 MDS+ principle● Frequency response

0.7 - 50,000 Hz +0, -3.0 dB● Total harmonic distortion

0.0007% (20 to 20,000 Hz)● Signal-to-noise ratio

118 dB● Dynamic range

115 dB (24-bit input, low-pass filter off)

● Channel separation

108 dB (20 to 20,000 Hz)● Output voltage
and impedance

BALANCED:
LINE:● Output level control

0.0 dB to -80.0 dB, 1-dB steps (digital)

2.5 V 50 ohms, balanced XLR type
2.5 V 50 ohms, RCA phono jacks

General● Power requirements

AC120 V/220 V/230 V (Voltage as indicated on rear panel)
50/60 Hz● Power consumption

23 W, standby: 0.5 W● Max. dimensions

Width 465 mm (18-5/16")
Height 151 mm (5-15/16")
Depth 393 mm (15-1/2")● Mass18.5 kg (40.8 lbs) net
25.0 kg (55.1 lbs) in shipping carton

Remarks★ This product is available in versions for 120/220/230 V AC. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
★ 230 V version has an Eco Mode that switches power off after 120 minutes of inactivity.
★ The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.

●Specifications and design subject to change without notice for improvements.

http://www.accuphase.com

L1205Y PRINTED IN JAPAN

850-2178-00（B1）