Pioneer PD-R555RW Manuel d'entretien - Page 31
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7.6.3 Hi-bit IC (PDR-19RW Only)
The PDR-19RW has a Hi-bit IC. It transforms 16-bit audio data
from the encoder into 24-bit audio data.
7.6.4 D/A Converter
The PE8001A is used as the D/A converter (the PDR-509/KU/CA
uses the PCM1716).
The PE8001A can switch the characteristics of digital filters. The
switching is made in accordance with the serial data output from the
mode-control microcomputer. The digital filter settings are switched
depending on the product destination, as shown in the table below:
Types of the Digital Filter Models/Destinations
Normal digital filter
Legato link
(With the PCM1716, switched between normal digital filter and slow
roll off)
"Enhanced multilevel sigma-delta techniques" are employed for the
DAC block. They convert the output from the digital filter block
into an 8-level sigma-delta modulation signal. Their anti-jitter
efficiency of the operation clock is superior to that of the normal 1-
bit DAC.
7.6.5 Analog Audio Output Block
The output from the D/A converter is output via the buffer amplifier,
which has a gain of about 7 dB.
There are two audio-mute circuits. One is a mute circuit controlled
by a microcomputer, and the other is a zero-detection circuit
controlled by the ZERO terminal of the D/A converter.
This ZERO terminal outputs a signal when the audio input to the D/
A converter becomes Infinity or Zero for both channels.
PDR-555RW, PDR-V500, PDR-19RW, PDR-509
PDR-555RW/KU/CA
PDR-V500/KU/CA
PDR-509/KU/CA(using PCM1716)
PDR-555RW/MY
PDR-19RW/KU/CA
PDR-509/MY
7.7 DIGITAL CIRCUITS
7.7.1 Digital Audio Interface Input Block
There are two systems of digital interface input: coaxial and optical.
The coaxial input is sent to IC308 (LC89585, pin 4) via the duty-
ratio adjustment circuit composed of IC313 (TC74HC00AF) and
IC314 (NJM2940M), after its waveform being adjusted by IC305
(TC74HCU04AF).
The optical digital input ( JA301 (GP1F32R) output) is sent to IC308
(LC89585, pin 1) via the duty-ratio adjustment circuit, composed of
IC313 (TC74HC00AF) and IC314 (NJM2940M).
The PDR-509 has no waveform adjustment circuit in the digital input
block.
7.7.2 Sampling Rate Converter
The AD1893JST, the asynchronous type, is used as the sampling
rate converter.
The sampling rate converter is bypassed as for PDR-509 when the
sampling rate of the input is 44.1kHz.
7.7.3 Clock-jitter Suppressor Circuit
(PDR-509 only)
The clock-jitter suppresser circuit of the encoder IC is used to absorb
the jitter from the digital interface receiver when the sampling rate
converter is in through mode.
7.7.4 Data Selector
The DIR block output, the clock-jitter suppressor block output, or
the 384-fs clock input from the XTALIN terminal is output from
the DACCKOUT and ENCCKOUT terminals in accordance with a
signal from the microcomputer.
7.7.5 Digital Fader, Level Meter, Mute
Blocks
The output range of the digital fader block is +17.99 to -66.22 dB.
The level meter interface block provides the data select output and
the fader output. The selected input data are processed to provide
total 16-bit data for L channel and R channel. The level meter
interface block has a zero detection circuit, which outputs to
microcomputer interface block when detecting that the input data to
both channels are all zero.
Muting can be turned on/off for the output from the fader block.
The digital volumes of the PDR-509 also use this block. The variable
range is +12 dB to -48 dB.
7.7.6 Memory Control
The encoder IC can control an external D-RAM (1 or 4 Megabits).
It receives signals from the mute block, the clock-jitter suppressor
block and the encode block.
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