SACD-Player 746
User Manual
page 5
filter in its output in order to suppress high frequency noise and aliasing signals,
which adds phase shifts for higher frequencies. Despite its relatively high cut-off
frequency of 120kHz, the analog 3rd order Bessel-filter of the 746 shows a phase
shift of up to 15° in the audio band. A powerful DSP does pre-correct these poten-
tial phase errors in the digital signal. Once the signal passes the D/A converter stag-
es and its related low pass filter these errors get cancelled out. The phase error of
the resulting analog music signal remains below 1°, 20Hz - 100kHz! The Zero-
Phase-Technology brings you even closer to the beauty of the source material!
1.5 Digital/Analogue-Converter (DAC)
The SACD-Player 746 has one DAC board per audio channel (left/right). We use the
Burr-Brown 1792 DAC which guarantees excellent performance. Only the top quali-
ty converter section which runs up to 384 kHz of the chip is used. The internal up
sampling section is bypassed!
The DACs are operated in dual mono mode. At the output of the converter chip four
current signals (I1+, I1-, I2+, I2-) are available. The four current signals are not
combined directly after the DAC but are first converted in a voltage signal and fil-
tered. The I-V converter runs up to 100 MHz fast. The summig of the voltage sig-
nals is done on the output-stage board.
The digital section of DAC board is supplied by the digital power supply unit; the
analogue section is supplied by the analogue power supply unit. This allows with-
holding noise present in the digital ground from the analogue section of the player.
1.6 Clock and PLL (Phase Lock Loop)
Utmost precision of the clock signal is a must have for a top class D/A-Conversion.
The clock unit of the SACD-Player 746 runs at a precision of < 0.01ppm.
For the synchronisation to external digital data the clock/PLL must adapt itself very
fast to eventual changes of the external data. This is done by a special digital clock
circuit that allows synchronising its clock signal very fast and at the same time ex-
tremely precise to the incoming signal.
