Accuphase DP 75 Brochure

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COMPACT DISC PLAYER

[DP-75

. MMB lype D/A converter achieves 20-bit linearity and
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The DP-75 incorporates a wealth of technology
originally developed for top-of-the-Iine separate-
type CD reproduction systems. Rather than
calling it a CD player, it therefore can be justly
called a CD Transport/Processor System. It
offers all the advantages of separate
components, conveniently housed in a single
enclosure,

The D/A converter in the processor section uses
the amazingly precise MMB principle which
delivers performance pushing physical limits.
This converter system stands at the pinnacle of
the multi-bit universe. It is complemented by the
Ultra Jitter-Free PLL Circuit developed by
Accuphase and a high-precision Sampling
Frequency Converter (SFC), Pulse distortion
and jitter are virtually absent, assuring absolutely
faithful conversion of the input signal. To allow
use of this ultimate D/A conversion system also
with external components, the DP-75 provides
versatile digital input and output facilities The
unit therefore can
function as a digital
control center which
enhances the sound
quality of the entire
system.

The CD transport side of the DP-75 is impressive
as well. For example, it uses fully digital circuits
for mechanism control. This allows optimizing
servo performance for each individual disc,
assuring improved operation stability and a
drastic reduction in error rate. The laser pickup
is an ultra-compact type with integrated RF
amplifier, and all actuators are driven by
balanced circuits which do not conduct any
current to the ground line. The tray lock feature
firmly secures the tray during playback, to
maintain the high purity of the digital signal.

External stenet display

[Digital Processor Section]

MMB Type DIA Convener Takes 20-Bit Lin-
earlty and Low Noise Performance to New
Limits

The D/A converter uses the amazing MMB

(Multiple Multi-Bit) principle which delivers
performance and sound quality previously
unattainable. It consists of eight strictly selected

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MMB DIA Convener Principle

20-bit D/A converters connected in parallel. This
revolutionary approach yields a dramatic
improvement in every important performance
aspect.

As can be seen from the illustration, the high-
speed output of an 8~times oversampling digital
filter is connected in parallel to the individual
converters. Immediately after D/A conversion,

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the output of the converters is combined while
still in high-speed form. But rather than simply
linking the converter elements in parallel, the

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The ultimate CD transport/processor system in a single bodszMB
type DIA converter, ultra jitter-free PLL circuit, high-precision
sampling frequency converter. Fully digital CD mechanism control
allows optimization of servo performance .

MMB circuit drives each converter separately,
so that it can develop its full potential. Special
attention was devoted to phase response at high
frequencies. Parts selection, layout and wiring
patterns were optimized to achieve perfect
phase matching. The end result is performance
which sets new standards regarding linearity and
absence of distortion and noise,

Ultra Jitter-Free PLL Circuit

The operation of the D/A converter must be
synchronized with the digital audio interface
(DAI) signal. For this purpose, a phase-locked
loop (PLL) circuit generates a master clock
which is used as system reference. it jitter or
pulse distortion are present, the master clock
precision will suffer, which has a detrimental
effect on the entire system.

The Ultra Jitter-Free PLL circuit in the DP-75
consists of a preamble detector and a voltage-
controlled oscillator (VCO) using a quartz crystal

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element. Pulse distortion occurs when the signal
fluctuates randomly in the intervals between "0"
and "1". But the so-called preamble signal
(which indicates the start of the L and R signals)
occurs in regular intervals at a constant level, it
is not subject to the effects of pulse distortion.
Therefore the DP-75 uses a detector which
extracts the preamble component from the DAl
signal and supplies it to the PLL circuit, for
elimination of pulse distortion. The VCO uses a
quartz crystal oscillator element with a very
narrow locking range and optimized loop filter
constant, to remove any jitter components from
the preamble signal,

High-Precision Sampling Frequency Con-
verter

A sampling frequency converter (SFC) serves
to transform the sam-
pling frequency of a digi-
tal input signal to a
different value. In the
DP-75, the sampling fre-
quency is converted to
48 kHz, resulting in a 48-
kHz, 20-bit, level i signal
for decoding. The highly

Highprecislon sampling
treqtteney converter