Accuphase DP-750 User manual

The new DP-750 is succession model of DP-720 launched in
2013.
DP-750 is the superlative integrated SACD/CD player that
reflects great technologies of the DP-950/DC-950 combo,
aiming for the best performance and sound quality.
Newly developed SACD/CD drive is equipped, with effective
control of vibrations, they are completely shut off from the
power transformer to the optical pick-up, and the operating
motion noise is also dramatically decreased.
The superb low distortion and noise performance exceeding
the former model allows DP-750 to dynamically express
even the sonic purity and emotions of music.
The DP-750 is dripping with Accuphase cutting-edge digital
& analog technologies, and offers the full enjoyment of music.
1

DP-750 can show the sampling frequency and the
number of effective bits of all input signals on the front
display.
Quantization bits are counted directly from raw data by
using a high speed Field Programmable Gate Allay.
2

The dimension of DP-750 is as same as those of DP-720.
The weight becomes slightly heavier than DP-720. This
is due to the long and heavy bridge dedicated to the new
SA-CD drive mechanism.
3

The Bridge cover of SA-CD drive mechanism is bigger
and longer than the former model. Outer rotor brushless
DC motor is installed at the spindle to drive the discs.
This is very effective for reducing the motion noise from
motor drive and air flow by disc rotation. Furthermore,
laser pick-up module is mounted with vibration absorbers.
They are made of the special silicon which is carefully
selected for this mechanism. It prevents the vibration to
the outside 4dB lower at the resonance peak.
These materials are mounted directly on the aluminum
base plate, and it contributes to reduce the motion noise
by half of DP-720.
4

DP-750 applies the systematical layout. Each circuit block
is logically placed to make the signal path short as
possible.
The digital circuit with DAC chip is on the right side, and
analog circuit equipped with glass cloth fluorocarbon resin
PC board is on the left side at the back panel side.
Logic control board is on the right side of SA-CD drive
mechanism, and on the left side, reinforced power supply
is located.
5

Ultra Low Noise is one of the main technical features of
DP-750.
The former model, DP-720 has the excellent noise
performance, however, DP-750 achieves another 18%
lower output noise voltage.
6

DP-750 proudly shows the great THD+Noise
characteristics which are quite important for sound
quality.
DP-750 makes an almost flat response from the low
frequency through to the high frequency, and it obtains
less than 0.0002% THD+Noise in all frequency bands.
7

For D/A converter section, for DP-750, Accuphase
updates the DAC chip to ESS Technology’s 32bit
Hyperstream Ⅱ DAC ES9028PRO.
ES9028PRO has 8 DACs inside, and DP-750 uses the 8
DACs connected in parallel per channel with Accuphase
unique technology, MDS++ conversion system.
Fully balanced structure is employed after D/A converter
section in DP-750.
In addition, the independent low pass filter is installed for
each audio output.
This enables the sound signals from the all outputs to
keep its unsurpassed quality without mutual interference.
8

MDS++ is a technique to make DACs parallel.
The same digital signal is supplied to each converter, and
the output of each DAC is summed before being sent to
subsequent stages.
The audio signal values are added up, but the conversion
error and noise themselves are canceled.
The ratio between the signal and conversion errors
increases, So the converter performance is improved.
The improvement degree works by a square root of the
number of DACs.
In DP-750, all performances are improved by a factor of 2.8.
9

MDSD stands for Multiple Double Speed DSD.
The DSD signal has big noise in the high frequency
outside the range of human hearing.
It must be removed.
MDSD works as a low pass filter to cut the noise in the
high frequency and also works as the MDS++ principle to
improve the characteristics in the low frequency.
The point of MDSD is the delay elements.
DSD signal in DP-750 is D/A converted with half-delayed
clocks and is combined when it comes to the output.
As the analog output becomes half-clock time resolution,
it allows the signal to work as the double speed operation.
This configuration means a moving-average filter.
It works completely as a linear phase low pass filter and
removes high frequency noise of DSD signal.
10