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In Reply to: RE: A test that I did. posted by jsm on September 11, 2007 at 12:00:10
"My conclusion: RBCD encoding is capable of doing very well with the information content in vinyl and CD playback, but it clearly falls short in handling a signal derived from a SACD source."
You may want to find out, in a future test, if such derivation fares any better via DSD..... Which on paper synchronizes conversion between CD, SACD, and DVD-A.
Follow Ups:
I was dealing with the analog signal put out by three different devices and asking how well I could encode that signal with RBCD. For two devices RBCD worked quite well, for one (SACD original source) it didn't. I have no doubt that if I used a better digital encoding method than RBCD I would have done better with SACD, which would further strengthen the point I am trying to make (probably not very well).
Joe
"I was dealing with the analog signal put out by three different devices and asking how well I could encode that signal with RBCD."
Oh I see..... So if it was originally digital, it was sent to the DAC and then converted to RBCD.....
"For two devices RBCD worked quite well, for one (SACD original source) it didn't."
Interesting..... You may have dug up some underlying flaw in the SACD format..... It would be interesting to see if it shows up in a scope trace......
Re-digitizing a signal after a D/A can have side effects. For example, if the jitter is encoded onto analog media, and then sampled again in A/D, the jitter will be seen as "amplitude errors" in the new data. Which is noise. (The new sampling doesn't see the jitter from the previous digitization, it only sees deviations in amplitude as a result of the jitter.)
"I have no doubt that if I used a better digital encoding method than RBCD I would have done better with SACD, which would further strengthen the point I am trying to make (probably not very well)."
It's hard to say. SACD is a totally different format/conversion, involving pulse density modulation instead of data numerically depicting amplitude (pulse code modulation).
I am not claiming that I have dug up a flaw in the SACD format. Just the opposite! I am simply saying that SACD is better than RBCD as revealed by the fact I can make a very good, compelling RBCD copy of the analog signal coming out of a RBCD player, but a RBCD copy of an analog signal derived from a SACD doesn't do it justice. SACDs are better. There is something advantagous to the higher sampling rate and/or more bits of SACD that comes through in the analog signal. This thread started by citing a study claiming the opposite.
Joe
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