Espen Braathen
2004-09-02 17:41:58 UTC
http://www.digit-life.com/articles2/sacd-dvd-a/index.html
"
What is the Correct Way for SACD Playback?
How can we play back SACD correctly? We can agree to well-known Russian
engineer Dmitry Andronnikov, who expressed the idea to convert the
DSD-signal to PCM and then reproduce this signal via multibit DAC. This
approach is implemented in the AX10 (49TX) receiver and then used in all top
receivers from Pioneer. What's the reason, why do we get better quality with
seemingly extra "additional conversions"? The point is in reduced
distortions (it sounds as a non-sense, but please don't make fast
conclusions) due to these additional conversions. In fact the point is in
DSD->PCM converters (for this purpose they usually use SM5816 or in the new
devices - SM5819A), which in fact are high quality digital filters operating
at the frequencies 2Fs and 4Fs in the aforesaid devices, which filter all
high frequency noises in SACD at the level of -130dB not allowing these
noises to create intermodulation products in the audible region and to
"overload" the operational amplifier with HF components in I/V after DAC.
Using a digital filter before DAC, operating in the oversampling mode, we
cut-off the remains of HF interferences from the DSD steam achieving for the
SACD signals the same quality as for DVD-A of the high definition. Top
Pioneers use multibit (Sign-Magnitude) PCM1704 as DAC, the top receiver
Yamaha Z9 contains a new multibit delta-sigma DAC PCM1792, which allows to
compare playback modes via DSD->PCM conversion (the same SM5819A is used for
such purpose) or via analog filters (implemented in PCM1792) as it was done
for PCM1738. However, after all our measurements the result is predictable.
Dmitry's hypothesis is supported by the fact that in the new digital top
receiver Sony STR-DA9000ES the entire signal processing is done in the PCM
format, the DSD circuits after the DSD->PCM conversion are not used, and the
corresponding chip pins are grounded (DSD to PCM conversion is up to
SM5819A, which is re-bandged by Sony as CXD9742).
Pay attention to the difference in noise levels and spectra when playing
back multi-channel tracks and stereo tracks from the same discs . You can
see that the common stereo tracks are created from stereo sources, often
with a pass band limitation at 22 kHz or 24kHz and a considerably higher
noise level. Multi-channel tracks, which are usually completely remastered
or recorded anew from the 24bit 96 kHz original master sources, feature
quite a different signal quality. In one's time many people discovered an
essential difference in quality when playing back SACD multi-channel Dark
Side of The Moon using multi-channel and stereo tracks (SACD in both cases),
but after our measurements we already know the reason."
Esp1
"
What is the Correct Way for SACD Playback?
How can we play back SACD correctly? We can agree to well-known Russian
engineer Dmitry Andronnikov, who expressed the idea to convert the
DSD-signal to PCM and then reproduce this signal via multibit DAC. This
approach is implemented in the AX10 (49TX) receiver and then used in all top
receivers from Pioneer. What's the reason, why do we get better quality with
seemingly extra "additional conversions"? The point is in reduced
distortions (it sounds as a non-sense, but please don't make fast
conclusions) due to these additional conversions. In fact the point is in
DSD->PCM converters (for this purpose they usually use SM5816 or in the new
devices - SM5819A), which in fact are high quality digital filters operating
at the frequencies 2Fs and 4Fs in the aforesaid devices, which filter all
high frequency noises in SACD at the level of -130dB not allowing these
noises to create intermodulation products in the audible region and to
"overload" the operational amplifier with HF components in I/V after DAC.
Using a digital filter before DAC, operating in the oversampling mode, we
cut-off the remains of HF interferences from the DSD steam achieving for the
SACD signals the same quality as for DVD-A of the high definition. Top
Pioneers use multibit (Sign-Magnitude) PCM1704 as DAC, the top receiver
Yamaha Z9 contains a new multibit delta-sigma DAC PCM1792, which allows to
compare playback modes via DSD->PCM conversion (the same SM5819A is used for
such purpose) or via analog filters (implemented in PCM1792) as it was done
for PCM1738. However, after all our measurements the result is predictable.
Dmitry's hypothesis is supported by the fact that in the new digital top
receiver Sony STR-DA9000ES the entire signal processing is done in the PCM
format, the DSD circuits after the DSD->PCM conversion are not used, and the
corresponding chip pins are grounded (DSD to PCM conversion is up to
SM5819A, which is re-bandged by Sony as CXD9742).
Pay attention to the difference in noise levels and spectra when playing
back multi-channel tracks and stereo tracks from the same discs . You can
see that the common stereo tracks are created from stereo sources, often
with a pass band limitation at 22 kHz or 24kHz and a considerably higher
noise level. Multi-channel tracks, which are usually completely remastered
or recorded anew from the 24bit 96 kHz original master sources, feature
quite a different signal quality. In one's time many people discovered an
essential difference in quality when playing back SACD multi-channel Dark
Side of The Moon using multi-channel and stereo tracks (SACD in both cases),
but after our measurements we already know the reason."
Esp1