In Reply to: Interesting posted by Jim Austin on June 6, 2017 at 19:22:14:
>> exchanges like this help solidify my tenuous knowledge and provisional thinking <<
Same here. One would think that MQA would simply explain the technical details clearly for all to understand, but I am also trying to "solidify my tenuous knowledge and provisional thinking".
>> Curious, then, that the CD version and the MQA version should be nearly identical--what do you make of that? <<
Again I would like more data to avoid jumping to the incorrect conclusion (as I did previously). Is the "CD version" actually a physical disc? Whatever its source, it has clearly been run through an apodizing filter, directly in contradiction to Peter Craven's (originator of the apodizing filter) recommendations (see below).
It seems unlikely that there is some obscure "pro" manufacturer making a "state-of-the-art" A/D converter with an apodizing anti-aliasing filter mistakenly attempting to wring the very best sound out of 44.1kHz sample rates. To the best of my knowledge the first proposed use of an apodizing filter was in Peter Craven's AES paper of 2004. I believe the first commercial use was likely by Meridian a few years later and know that Ayre experimented with them during 2008 and released them as the new "Listen" filter in the MP upgrade of 2009 (and also the QB-9 and subsequent digital products). But all of these were reconstruction filters for use on the D/A side.
I would think the most likely possibility is that MQA had something to do with the application of the apodizing filter to this Beyonce release. Which raises at least three questions in my mind:
1) If MQA used an apodizing filter to remove any pre-ringing from the A/D converters used to create the Beyonce CD, why not simply sell, license, use, or give away that technology to improve the sound of all recordings? Or is there some other company or mastering engineer that is already doing the same thing but without using MQA's tools?
2) It would seem that the main change upon playback between the Beyonce CD and the MQA-encoded version of the same file is that upon playback, the "leaky" MQA filter is used. In your original trace of the CD version, I saw no evidence of aliasing - presumably because the reconstruction filter was not "leaky". In contrast the "leaky" MQA filter passed higher levels of aliasing artifacts than apparently even the "Slow" filter on the Mytek Brooklyn. (Again, I am unclear on all of the details of the test conditions.) But if that is the case and the Beyonce CD already has the "time blur" filtered out in the non-MQA version, all we have learned is that different digital reconstruction filters sound different - which wouldn't seem to be a revolutionary breakthrough.
3) If an apodizing filter has been applied to the Beyonce CD, this is in direct contradiction to Peter Craven's recommendation in his AES paper. Specifically, any filter sharp enough to filter out the "pre-ringing" introduced by the A/D converter will also introduce "ringing" of its own. The only advantage of the apodizing filter is that being minimum-phase, all of its "ringing" will be more natural sounding "post-ringing" rather than the nowhere-to-be-found-in-nature "pre-ringing" created by linear-phase filters.
Again, apparently More Questions than Answers...
As always, strictly my own opinions and not necessarily those of my employer or pet wombat.
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Topic - MQA Loses Part of Spectrum on Some Tracks? - Charles Hansen 23:23:05 05/29/17 (39)
- Charles, Please tell me if this makes sense. - Jim Austin 20:21:45 05/31/17 (25)
- To clarify ... - Jim Austin 13:06:30 06/05/17 (14)
- Something seems very wrong here - Charles Hansen 16:06:39 06/05/17 (13)
- RE: Something seems very wrong here - Jim Austin 18:08:50 06/05/17 (12)
- Hmmm... - Charles Hansen 19:31:32 06/05/17 (11)
- RE: Hmmm... - Jim Austin 19:37:30 06/05/17 (10)
- Something still seems wrong here - Charles Hansen 22:40:21 06/05/17 (9)
- Let's go back to Beyonce - Jim Austin 07:47:16 06/06/17 (8)
- OK, now we are on the same page - it is aliasing *and* it is a bug. - Charles Hansen 13:47:03 06/06/17 (7)
- On a different, yet related topic - Charles Hansen 14:54:02 06/06/17 (0)
- RE: OK, now we are on the same page - it is aliasing *and* it is a bug. - Jim Austin 14:34:09 06/06/17 (5)
- RE: Charles, Please tell me if this makes sense. - Charles Hansen 23:59:31 05/31/17 (9)
- P.S. - Jim Austin 05:03:44 06/01/17 (6)
- Now I think we are getting somewhere - Charles Hansen 15:17:11 06/01/17 (5)
- RE: Now I think we are getting somewhere - Jim Austin 15:35:36 06/01/17 (4)
- RE: Charles, Please tell me if this makes sense. - Jim Austin 04:53:40 06/01/17 (1)
- RE: Charles, Please tell me if this makes sense. - John Atkinson 20:07:59 06/02/17 (0)
- "More questions than answers" LOL! :) -nt - E-Stat 10:20:21 05/30/17 (0)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Isaak J. Garvey 07:33:57 05/30/17 (1)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Charles Hansen 08:24:35 05/30/17 (0)
- RE: MQA Loses Part of Spectrum on Some Tracks? - 13th Duke of Wymbourne 23:40:14 05/29/17 (9)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Charles Hansen 12:41:30 05/30/17 (8)
- RE: MQA Loses Part of Spectrum on Some Tracks? - 13th Duke of Wymbourne 14:37:38 05/31/17 (7)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Charles Hansen 18:50:48 05/31/17 (2)
- RE: MQA Loses Part of Spectrum on Some Tracks? - 13th Duke of Wymbourne 15:43:10 06/01/17 (1)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Charles Hansen 03:36:59 06/03/17 (0)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Isaak J. Garvey 15:44:50 05/31/17 (3)
- But, Issak, people take Charles seriously unlike your rants (nt) - 13th Duke of Wymbourne 12:21:14 06/01/17 (0)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Charles Hansen 19:07:06 05/31/17 (1)
- RE: MQA Loses Part of Spectrum on Some Tracks? - Isaak J. Garvey 19:15:37 05/31/17 (0)