Accuphase DP 80 L Brochure

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Accuphase DP 80 L Brochure

Extracted text from Accuphase DP 80 L Brochure (Ocr-read)

Page 3

DP780L, A professionaquuality line lilter is used
to block any interference through the AC power

1 1 Simple and beautiful Accuphase

The lronl panel presents an uncluttered appear-

ance, as the controls are located behind a hing-

ed sub panel door. The brushed gold aluminum

linish and the side panels made of exquisite
persimmons wood further enhance the visual
appeal of the unit The D081 L perfectly matchr
es other Accuphase components and blends
harmoniously with the listening room.

The digital processor DCVBIL employs a digital ltlter with B-times oversampling A digital ltller is
a circuit which carries out the liltering process while the signal is still in digital torm Unlike
analog tillers, the operation principles ol digital tillers are quite complex The lottowing is a duel

outline or the concept cl digital liltering
I The D/A converter output contains a large amount at high-trequency noise
components which must be removed by a low-pass irttor
Fig l shows the circuit ccntiguraiion or a conventional CD player lroni the D/A converter to the
output As the input signal to the converter is sampled at 44.1 kHz. the original wavetorm (3)
becomes superimposed with the 44 l kHz square wave signal resulting in the staircase
wavelorm lb) The output or the D/A converter contains the spectrum shown in Fig 2 (a) in
addition to the audio signal extending up to 20 kHz. there are highrlrequency noise components
at multiples oi the sampling lreouency (44 1120 kHz, as 2:20 kHz. l32 3:20 kHz, etc).
teaching into the range ol radios lrequency signals Although these signals are outside the
audible range, their removal is very important. as they can cause the lotloyving proolems

(l) lntermodutation distortion in the nonlinear. ultrahigh lrequency range or audio circuits in the
processor unit. preamplirier. or power ampliiier Such modulation generates distortion
products which spread into the audible range and can degrade sound quality

(2) intrusion or noise components into other equipment such as tuners or tape recorders.
causing the same problems

(3) Output stage overload in Wide-band amptiliers (such as all transrslor amplitiersl oue io
constant l’llghrlrequency current.

(4) Overheating and damage or loudspeaker voice coils (especially tweeters) due to excessive
high~lrequency energy

yr the above reasons. every CD player requires a llller to Cut all highrlrequency noise
components above 20 kHz and to correctly restore the original signal.

I Low-peas tillers with sharp cutorl tend to degrade irequency response and phase


A low-pass litter. as its name implies. is designed to let signals below a certain irequency pass

and cut oil higher irequencies A desirable characteristic lor CD players is ltat response (no

attenuation) up to 20 kHz. and sharp attenuation above that, reaching at least

(preleraoly —90 dB) at 24 kHz Low-pass tillers are also used in other audio components such

as preamplitiers, out the steepest slopes are usually — l8 dEl/ocl,

Fig 2 (b) shows the characteristics at a *18 dB/Oct tiller. At 46 kHz, attenuation IS *18 dB. at

50 kHz. il is *36 dB. and al 160 kHz, it reaches -54 dB. For a CD player. lhls cl course Will not

do. In Order lu achieve [he required characteristics shown In Fig. 2 (CL several litters can be

employed in tandem (multirpple tillers), out it is a very diilicult teat to ensure llat response to 20

kHz while introducing steep cutolt above this point.

in conventional CD players, lirotder litters were oiten employed, but such designs invariably

introduce phase distortion and cause undulations (ripple) in the lreouency response. Another

disadvantage or such analog lillers is the large number or circuit components required, which is
an additional cause tar nonlinear distortion.

ll it were possible to use ltlters Wilh a more gradual rollrolt these problems could be eliminated

The digital lilter approach provides the ideal solution which does exactly that.

I Digital litter increases sampling troguency to multiples or u i rim. permitting

gentle analog lllter characteristics

Fig 2 (d) shows the lrequency spectrum when the sampling lrequency is multiplied by 5 times.

lo 352.8 kHz As lhe components which have to be removed are now lat Outside the audlble

range. the low-pass lilter can have a gentle cutoli slope. which is highly desirable in view or
phase and ripple characteristics The purpose oi the digital litter is to periorm the arithmetic
rations required to multiply the sampling ireouency The coniiguration or a CD player with

lal llller is Shown In Hg. 3. The D/A converter is preceded by the dtgital lilter and lollowed by

the analog low~pass tiller.

igltal Filters
(c) Wavelorm after passing
(a) Original wavelemi (o) D/A oovener output low-pass tiller
portals-cw nevi o—. mm" mm :3 0mm
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(c) Mum-pole Analog llltor developed for CD players
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2m max Frequency
(d) Mlmu nvnumpllng Increases nmpllng lraquency to
352.3 kit: and porrriltc use or gentle rlltar stops as In (D)
Fig. 2 DIA Converter Output Spectrum, Low-pus Flltcr
Cmrmerlnlcs and oversampling
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Fly. 3 Operational Concept at Digital Ovemmpllng Fitter

Page 4

Peerless optical fiber transmiSSI n

Highly rigid massive construction Diecast mechanism frame


The DCrBlLotterstwoopticaloutputoonnectors
which correspond to the ElAJ standard that is
proposed by Accuphase and is known as the
Digital lntertace standard In addition. a cameo
tor for 7570hm coaxial cable Is also provided
The transmisSion rate of the wrderband optical
connection is a full 10 MBit/sec When the sup-
plied high quality optical liber cable is used,
this ensures transmission purity of the highest
order‘ without any degradation of signal quality
As the player and processor units are electrical
ly isolated lrom each other any nOise interfere
ence is eltectively prevented A professional
quality line lilter blocks possmle Interlerence
through the AC power line

The reference Signal tor varlous control lunc-
tions Within a CD player is created by a crystal
clock oscillator In conventional players‘ two
osCillators are used for the digital Signal proces-
sing circuttry and lor the microprocessor. This
approach has a distinct disadvantage, Even a
slight lreouency difference between the two
clock signals can lead to beatsi which in turn
impair sound quality As can be seen from Fig l,
the DP-80L uses a srngle master clock to control
the entire operation of the player. Thls leaves no
room tor sound quality degradation

A great advantage ol the CD tormat is easy track
selection at the Simple touch ot a button. The DP-
80L minimizes track access time with highly
sophisticated technology A linear motor mech»
anism moves the laser pickup under exclusive
control ol a specrally developed 8»bit micropror
cessor, Thanks to this approach locating any
track never takes longer than one second Disc
tray action also is exceptionally smooth and
switt‘ with excellent (eel


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