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Re: SACD vs DVD-A article

68.111.86.48

Posted by Alex Striganov on August 19, 2004 at 08:53:07

In Reply to: SACD vs DVD-A article posted by Rod Paine on August 17, 2004 at 14:02:03:

Hi everyone!
I would like to thank Eric for invitation to this thread, It is always good to discuss anything with knowledgeable people. I would like to explain some parts of the article and logical approach to use different modes. Now after discussions around the world in different forums, I got even more information, confirming the results. Let's try to do it step-by-step. I have no problem to admit if I was wrong somewhere.
Dan Banquer: you are absolutely right, FIR Brickwall filters don't shift phase, I even made such experiment by myself before publishing of the article, using marqueee tool in Adobe Audition 1.5 - just to compare the the FFT graphs for the same signal with HF and without, cutted by marquee tool. Where in the article is the problem concerning your statement?
Dave Kingsland:
[i]they talk about Griesinger's observation that many SACDs and DVD-As don't contain the "advertised" ultrasonic frequency content.[/i]
Not many, all of them, used in experiment.
[i]Two of the examples they pick are the James Taylor Hourglass SACD and Steely Dan Two Against Nature DVD-A. Perhaps they didn't notice, but these are 24/44.1 and 24/48 PCM recordings, respectively.[/i]
24/44.1 and 24/48 PCM recordings - do you mean the original studio recordings? It was a reason to pick up those two recordings. Steely Dan was used in the previous experiment, is was a good point to compare it, and Taylor demonstrated some interesting difference in measurements - a bit later about them.
[i]Given that Two Against Nature is a 48k PCM recording and the DVD-A tracks are 24/48 MLP ... That extra frequency content could only be produced by some sort of non-linear processing in their playback chain because it isn't on the disc. But they fail to recognize this.[/i]
I have this disk (actually I buy only DVD-A Advanced resolution after some mistakes) Steely Dan Two against Nature and it is "Advanced resolution" DVD-A with "This disk playes 4 ways: Advanced resolution Stereo - Advanced resolution 6 channel surround sound ...", it means Giant Records give us an idea that it has 24/96 recordings. I REALLY doubt that Giant Records provides intentionally falsified statement on the disk, if the record is in 24/48 regular resolution.
Concerning Taylor, a bit later, I have some very interesting information.
[i]Unfortunately, their conclusion is exactly backwards because the disc's content is only 24/48 MLP.[/i]
If you have any information concerning additional ultrasonic imagas, created in the process of THX Music post processing, I would love to have it and immidiately admit that the assumption was wrong. Or I would like to have the confirmation that on this Advanced resolution DVD-A content is in 24/48 MLP.
Everywhere (AFAIK) "Advanced Resolution" meant 24/96, if it is 24/48 MPL, someone would sue Giant Records for the fraud ...
Here is the link how Advanced resolution recordings created http://www.soundonsound.com/sos/aug03/articles/steelydan.htm
http://www.audaud.com/audaud/MAR02/HIRES/hires1MAR02.html#steel
[i]If they had any question at this point about where that ultrasonic content was coming from, it should have been cleared up after they plotted the data from the Hourglass SACD. If you look at the last plot of the Hourglass multichannel data taken directly from the DV-47Ai player, you'll see exactly what you should expect from PCM data converted to DSD: signal content out to a brick wall cutoff at fs/2 followed by DSD's rising noise floor.[/i]
What is interesting, there is NO PCM to DSD conversion in 47Ai ... no such device exists. I will explain what happens with the Taylor a bit later again :) Did you mean DSD->PCM conversion? In 47Ai DSD stream processed through the analog filters in PCM1738 DACs, used for such purpose, for front channels, and through DSD1702 DACs for surround channels.
[i]The most likely cause is some sort of multichannel processing mode (e.g. THX, dynamic range compression) engaged in the receiver that they forgot to turn off. They even allude to the fact that THX processing is enabled.[/i] Do doubts dynamic compression was off, it is off all the time in my receiver. I used THX Music mode intentionally, this is the best mode for me to listen to the multi-channel music, and I was wondering why it is that good. In this mode I had been able to check front channels and compare the results with Direct mode in the receiver. People, who read the article, will also listen to the multi-channel sources in the best mode, in this case in THX mode. The reason to use receiver was that the path for SACD signals and PCM signals, except of DSD->PCM conversion in SM5816A, is the same - this allows to make the comparison better. The goal was to compare DVD-A and SACD in the best possible listening modes.
[i] But one thing you can be absolutely sure of is that frequency content is not on the disc, and unfortunately this exactly the conclusion they reached.[/i] Prove it. We will sue Giant Records for million of $ together with you in this case, and share the profit :) Why don't you talk here about another SACD, Diane Krall "When I look in your eyes", which gave almost the same results as Steely Dan DVD-A?
Sir, I admit the possibility of my mistake, why are you so sure that you can't make any?
[i]Incidentally, you can also see the same signature in the multichannel data from the DSTOM and Krall discs - what looks like extraneous content in the 22-32 KHz range. The only difference is that these examples have wider bandwidth to begin with because they're not sourced from lower-res PCM, and thus there isn't a clear notch in the data from the brick wall cutoff.[/i]
Take a look here, I had made the spectral comparison, all samples are from 47Ai, no THX processing in this case:
http://members.cox.net/alex_lat/Tests/Taylor-2.PNG
It means your theory concerning non-linearity in the DSP processing of receiver is not correct.
[i]As if the cutoff at 22 KHz is due to some sort of filtering during playback.[/i] You hit the nail on the head! It looks as I'd found the reason of such sharp cut-off in the process of playback comparing the different modes of DSD decoder CXD2753 ... http://members.cox.net/alex_lat/Tests/RFSACD.PNG http://www.avsforum.com/avs-vb/showthread.php?postid=4216351#post4216351
Below you will find the information, explaining the difference on Taylor SACD.
[i]Funny that playback on the 47Ai standalone and playback on the 49TXi via iLink were so different that even after matching levels, capturing them with a sound card, and playing them back on the computer they could still identify the difference 19 out of 19 times in an ABX test. Shouldn't that raise a few eyebrows, maybe hint that there may be some extra processing going on in the 49TXi?[/i]
Don't hurry to raise eyesbrow :) Lynx L22 is a good device to do such things, here are the results of it's measurements:
http://www.photosyndikat.de/RMAAtests/Lynx L22_24-96.htm
The difference IMO is in the ultrasonic images, but not separated from the audible contest, here is the scientific research, confirming it (the full article in in pdf file in the right upper corner of link)
http://jn.physiology.org/cgi/content/abstract/83/6/3548
[i]Naturally, because of their apparent failure to understand their own source material and playback setup, the conclusions they reach range from suspect to outright wrong.[/i]
Dave, you are a knowledgeable person, but I respectfully disagree :)

P.S. I would like to thank Cristine Tham, presented here, for the perfect article!

This post is made possible by the generous support of people like you and our sponsors:

Atma-Sphere Music Systems, Inc.

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