Accuphase DP 70 V Brochure

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DP-70V

COMPACT DISC PLAYER
0 20-bit Discrete D/A Converter. B-Time Oversampllng Digital Filter
0 3-Pole GIC Butterwonh Lowpass Filter 0 Digital Control Center
Functions 0 Digital and Analog Circuits Periectly Separated by Ultra-
high-speed Opto-couplers

COM PACY

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DIGIYAL AUDID

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The DP-70V is an integrated type CD player created to
meet the highest standards of sound reproduction by
employing the technology developed for the separate
type CD player model DPrSOUDC-BIL. This Model
oiiers a digital control center lunction to meet the
requirements ol the next generation of audio technolo-
gy This function allows DPV70V's the high-quality. pre-
cision D/A converter to demodulate and record digital
signal inputs irom multiple digital audio tape (DAT)
recorders or BS (Satellite Broadcast) tuners.

The DP-7OV was developed to meet the iollowing
basic objectives:

t Application of discrete components tor the genuine

20bit converter at the heart oi the unit to achieve the

performance oi the most precision and highest
quality D/A conversion available.

Digital control center function to allow the high»

periormance converter to process signals irom DAT

recorders and BS tuners.

. Comprehensive Vibration countermeasures to any
sure laithtul signal reproduction.

, Perfection oi construction design. circuit topology
and electrical as well as constructional isolation to
cut oil highvlrequency noise.

5 Emphasis on ensuring good sound quality. while
avoiding conscious eiiorts to artillcially tailor
sounds, in every part of the audio frequency specr
trunr irom low level to high level Signals as well as on
iaithiul reproduction of airy atmosphere oi concert
halls,

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We believe that the DP-70V meets these stringent
objectives. The lolloWing is a briel description oi the
DF-7OV

The D/A converters employed are Accuphases ex-
cluswe 20-bit discrete converterconstructed with care-
fully selected superb discrete components. Each con
verter ls carelutly adjusted at the manulacturing stage
to achieve exactly 16 times the conversion accuracy ol
a te-bit D/A converter

The noise shaper technique employed successlulty
reduces undesirable reouantized noise to extremely so
low levels that the feeling of silence in the sound
reproduction is sensational.

The digital filters employed are ol the 8-times over»
sampling type With A ttodB attenuation capability,
thus succussiully eliminating unwanted noise components over 328kHz.

The 3-pole GIC audio litters have been employed to
ensure optimum sound reproduction quality.

Digital input terminals and a sWItching lunction are
specially prowded to allow the processor section.

Equipped with the World-Proud,
High-Precision 20-bit Discrete D/A Converter,
8-Time Oversampling Digital Filter,

and Digital Control Center Functions
Corresponding to Three Sampling Frequencies.

which includes the D/A converter. to be operated as an
independent digital control center Two pairs each oi
optical and coaxial inputs are proVided. so that a total oi
4 dilterent DAT recorders or BS tuners can be con
nected. The sampling lreouencies oi ABkHz. 44 1kHz
and 32kHz are automatically selected.

One pair each ol optical and coaXial digital output
terminals is provrded. to enable digital recording to a
DAT recorder

The digital circuit section, which includes the CD
transport. is constructually separated lrom the analog
litter circuitry by means oi a metal shield in order to
eliminate intersection interlerences. In addition. these
two sections are electrically isolated by extremely last
AOMDiI/sec, optorcouplers to provrde perlect isolation.
Furthermore, a separate independent power transr
lormer is provided lor each 0! the digital and analog
circuit sections in order to eliminate all types oi noise
interierence,

The exquisitelysmoolhlinearrnotordnvenlaserpick-
up. that Accuphase has been employing since the lust
CD player. is also used ior the DP~70V. An HFAmp/itier
is newly built into the pickup unit. thus perlectly
eliminating noise interlerence to the minute Signal path.

The transpon unit section is sopported by a thick
aluminum diecast trame. and lurther mounted lirmly to
the main chassis to eliminate resonance and vibration.
This gives the DP-70V a total weight exceeding 24kg. a
weight unheard ol tor a CD player. All these additional
constructual countermeasures make an enormous
contribution to the excellent sound quality at the
DP-70V.

All operational controls except a lew essential lunc-
tions are incorporated into Accuphase's tranditional
sub-panel to present an extremely simple and elegant
overall appearance

DIGITAL PROCESSOR UNIT
World's First 20-bil Discrete D/A Convener
Achieves Theoretical Limit Performance
The zo-bil D/A converter at the heart oi the digital
processor unit was developed to achieve a theoretical
limit at periormance. The bit precision ol 1/2m
t=9.54x107) is 16 times higher than the preciSion
ollered by a 16bit D/A converter. The resulting meas»
ured distortion (distortion component excluding ri0ise
at tkHzl oi only 0.0007% equals the theoretical limit at
CD player pertormance. Quantization noise. which is
detrimental to high quality audio reproduction. has

Digital circuit 3 liming circuit
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i

Ultra ltiu'n Speed
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rum. uiqirai Filter--

rransier

. Audio Ovlin

Fig.1 Principle of Multiplying .
D/A Convener $3?

been considerably reduced.

The D/A conversion method employed is a current
addition type, which leatures excellent linearity charac-
teristics. The digital processor unit is constructed oi
carefully selected discrete components to ensure the
maximum theoretical 20-bit performance. The cone
slruction is shown at the right oi Fig, 1 . The iigure shows
that the construction includes a current switch element
and an extra high precision resistor ior each bit oi
conversion. To ensure periect operation, each indi-
vidual unit of the converter is iinely adyusted to give the
ideal linearity throughout the entire output range from
minute tevels to high levels. to attain an ideal periormr
ance in elimination of zerorcross distortion and low-
output distortion.

Independent ZO-Bit B-Yime Oversarnpling Dlgltal Fil-
tars for Both Lelt and Right Channels
By increasing the sampling ireouency in integer multi-
ples oi the iundamental ireduency. it makes it possit
tor a digital litter to diminish the attenuation character
tics oi the audio iilters. which remove the undesirable
noise components. However. it is insullicient tor a
digital iilter to only olier a large number oi multiples. The
litter must also be able to suppress the unwanted
components between the audio band and sample tre-
ouency

The digital filters used lor the DF-7DV employ a
sophisticated digital algorithm to suppress unwanted
components in the range oi 2AM kHz to 328.7kHz to the
astonishing level oi -tt0dB. Bandpass ripple. which
can cause deterioration oi the sound quality. is kept
Within :ODDOOSdB. proving that these litters are of the
highest quality currently available

3-Pole Discrete GIC Butterworth Active Filter with
Strictly Selected Components

Because the sampling lrequency is increased eight
times to 352.8kl-tz. the signal output irom the D/A
converter contains high irequency components over
332.8kHz (352 8~20l Naturally. unwanted compo»
nents also exist, even it the sampling lrequency is
increased t6 times or 24 times for example. Thanks to
the high order oi the oversampling. audio Iowpass
tillers With moderate 3-pole (t BdE/oct.) characteristics
are sufliclent to eliminate these unwanted components
and to contribute to the sound quality. The discrete 3-
pote GIC Buttetworth type active tiller employed 5 \
constructed oi strictly selected components to eli
nate any possibility ol sound deterioration

Digital and Analog circuits are completely Isolated
to Prevent Deterioration of Sound Quality by High
Frequency Noise

Digital signals contain components oi extremely high
lrequency. which may reduce the sound quality by
interiering With the demodulated audio signals This
ellect can be eliminated by completely isolating the
digital circuits irom the analog circuits electrically, sta-
ticrelectricatly, and electrormagnetically.

In the DP77DV, all analog circuits iollowing the D/A
converter. including the CD transport section are elecr
trically isolated from the digital circuits by means ot
optorcouplers. The four ultra high speed, 40Mbitlsec
opto-couplers per channel provide excellent electrical
insulation, while laithiully transmitting signals in the
term ol light.

High trequency noise can also be transmitted
through the power supply circuitry, even if the digital
and analog circuits are isolated, To cut otithis noise. an
independent power transformer is provided for each ot
the digital and analog circuits.

To further improve the audio characteristics. the
power for the left and right channel is supplied irom
ditierent windings oi analog transformer.

High frequency noise can also be transmitted
through air as static-electric or electromagnetic interv
ierence. This interference is eliminated by shielding the
digital and analog circuits from each other by means of
a thick metal plate placed between the two circuit
sections