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MQA part the 3rd - t't't'timing...

Jim Audiomisc said:
Looking with a fuller browser I'm not clear on some points. Most obvious one is that the signal plots give the times in a format I'm not sure I recognise. Give values like "00:00:04:05 and says "75 fps". How does that translate into second or millseconds, etc? Not knowing, it just looks like the timescale is too compressed to show the details of edges or impulses.
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Maybe it's SMPTE time codes. Whatever it is, it's clearly unsuitable for the data displayed. Unless you're trying to mislead, of course. Then it's perfect.
 
The square wave in bobsplots cannot be more than 1kHz. That gives you an idea of the timescale: milliseconds.

The plots seem to be made in what appears to be a descendant of Adobe Audition. But AFAIK (older versions of) Adobe's display routine automatically apply sinc-like reconstruction filtering, so should be wiggly.


Did you notice that there is now MQA and MQL, MQA being baserate, rectangular, and without origami, with MQL taking the role of the original MQA process with triangles and origami? Masterly Qonfused?

Did you also notice how in bobstalk the newly-named MQA takes CD-rate material, mutilates it in encoding, and only after decoding produces again near-pristine CD-rate material? Really amazing what they are trying to sell here.
 
Werner said:
Did you notice that there is now MQA and MQL, MQA being baserate, rectangular, and without origami, with MQL taking the role of the original MQA process with triangles and origami? Masterly Qonfused?
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MQA is a collection of pieces. One of these has always been called MQL as evidenced by various strings present in early software implementations. The "rendering" step is called MQB. Another part goes by the name of NGale.
 
Looks like the page and graphics are for impressing customers, not conveying useful technical information.

I recall a technician I used to work with who had a slab of clear perspex encapsulating a lump of bovine excrement. He used to use it as a paperweight for some of the paperwork he got. Helped him seperate material into related piles...

How I wish science and engineering were more widely taught in UK schools!
 
Jim Audiomisc said:
Looks like the page and graphics are for impressing customers, not conveying useful technical information.

I recall a technician I used to work with who had a slab of clear perspex encapsulating a lump of bovine excrement. He used to use it as a paperweight for some of the paperwork he got. Helped him seperate material into related piles...

How I wish science and engineering were more widely taught in UK schools!
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Wouldn't the simplest way to recieve answers to your questions about Stuart's plots be to send him an email?

The same with now months long speculation about the provenance of 2L "workbench" files.

I so wish engineers and scientist were comfortable with and capable of straightforward communication.
:)
 
mansr said:
It would be easier to perform acupuncture on a rock.
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Jim is very well known and I do expect Bob to answer his questions. If he chose to ignore it, that would be good to know as well.

I am a nobody, but when I reach out to learned academics to make sure I have implemented their paper correctly in an engineering application, I almost always get an informative answer.
 
DimitryZ said:
Wouldn't the simplest way to recieve answers to your questions about Stuart's plots be to send him an email?

The same with now months long speculation about the provenance of 2L "workbench" files.

I so wish engineers and scientist were comfortable with and capable of straightforward communication.
:)
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Actually, the simplest way would be if the graphs were clearly understandable in the first place. i.e. had scales we could make sense of, and which showed the relevant details of the waveforms! Then we wouldn't *need* to ask.

Frankly, when it comes to "straightforward communication" I would not have given any undergrad project report that contained such graphs and write up a high mark given the lack of the explanation they require and the failure to show the key details.

And *they* are the ones wanting to promote what they have to offer.

Do *you* think that webpage+images is an exemplar of what you "wish" above?

FWIW I only looked at it because you referenced it, presumably because you assumed it said something useful. If so, what did you think it told us? If I missed that, what was it?
 
Jim Audiomisc said:
Actually, the simplest way would be if the graphs were clearly understandable in the first place. i.e. had scales we could make sense of, and which showed the relevant details of the waveforms! Then we wouldn't *need* to ask.

Frankly, when it comes to "straightforward communication" I would not have given any undergrad project report that contained such graphs and write up a high mark given the lack of the explanation they require and the failure to show the key details.

And *they* are the ones wanting to promote what they have to offer.

Do *you* think that webpage+images is an exemplar of what you "wish" above?

FWIW I only looked at it because you referenced it, presumably because you assumed it said something useful. If so, what did you think it told us? If I missed that, what was it?
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I didn't understand the relationship between spectral content and the decoded impulse and square wave responses.

However, I am predisposed to giving people in my field a benefit of the doubt and allowing them an opportunity to explain, before declaring their work fraudulent. Professional courtesy, if you will.

Hence I was hoping that yourself, being well learned in the subject, can reach out to the author (ostensibly inhabiting the same small island?) and come back with an understandable explanation. This would have allowed for a better interpretation or for a convincing understanding of irrelevance.
 
DimitryZ said:
I didn't understand the relationship between spectral content and the decoded impulse and square wave responses.

However, I am predisposed to giving people in my field a benefit of the doubt and allowing them an opportunity to explain, before declaring their work fraudulent. Professional courtesy, if you will.

Hence I was hoping that yourself, being well learned in the subject, can reach out to the author (ostensibly inhabiting the same small island?) and come back with an understandable explanation. This would have allowed for a better interpretation or for a convincing understanding of irrelevance.
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Where did you get the "fradulent" idea from? I can't recall making such an accusation. Seems a particularly odd term for you to use just before the rest of your para.

The "interpretation" of the page I made was that:

1) The time axis scale wasn't of a form that I could make sense of. So I asked here to see what others made of it. No-one else seems certain, either.

2) lacking a clearly determined timescale the *plots* showed a lack of time resolution because they simply look to 'perfect'.

3) So my conclusion is that as they stand the plots tell us nothing useful.

Since they contribute nothing there seems little point in wondering further about them when my interest is in assessing/explaining MQA, not that set of graphics.

I've not seen any reason to doubt Bob Stuart's honesty or that he believes what he says. But my interest is in assessing MQA not Bob Stuart.

FWIW The good news from my POV is that - in terms of sound quality - I'd now say it was essentially 'mostly harmless', although I do wonder about how some companies will use it on some CD recordings that have a *lot* of HF and thus run into NOT being neatly "1/f spectrum". History is littered with music companies misusing the pretty tools they get due to delusions like LOUDNESS SELLS, etc. But for that, we need to blame the idiots in the music biz, not Bob Stuart.

But beyond that, my main wish would be not to have to pay for it because the only version available of something I want is MQA encoded. If others like it, that's fine with me. YMMV
 
Couple of points.

1. I experimented with filters and I concluded there is no need for an anti-imaging filter to undercut the anti-aliasing filter in order to work substantially. Put another way, the phase distortion of a minimum phase or intermediate phase anti-imaging filter is the very thing that shifts pre-ringing to post-ringing (rather than being a mere side effect). It's true different filters do this to different degrees, which becomes obvious with some intermediate phase filters. @Werner

2. The argument that it doesn't matter what happens at 20kHz or above because it's not audible, the ringing is too short etc. would imply anti-imaging filters, even conventional ones, are unimportant in general. Yet I don't see people arguing such. If amps and tweeters had zero distortion perhaps this would be true, but I don't think it is.

PS: for clarity, I dislike MQA for several reasons. I like intermediate phase filters though.
 
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Jim Audiomisc said:
Where did you get the "fradulent" idea from? I can't recall making such an accusation. Seems a particularly odd term for you to use just before the rest of your para.

The "interpretation" of the page I made was that:

1) The time axis scale wasn't of a form that I could make sense of. So I asked here to see what others made of it. No-one else seems certain, either.

2) lacking a clearly determined timescale the *plots* showed a lack of time resolution because they simply look to 'perfect'.

3) So my conclusion is that as they stand the plots tell us nothing useful.

Since they contribute nothing there seems little point in wondering further about them when my interest is in assessing/explaining MQA, not that set of graphics.

I've not seen any reason to doubt Bob Stuart's honesty or that he believes what he says. But my interest is in assessing MQA not Bob Stuart.

FWIW The good news from my POV is that - in terms of sound quality - I'd now say it was essentially 'mostly harmless', although I do wonder about how some companies will use it on some CD recordings that have a *lot* of HF and thus run into NOT being neatly "1/f spectrum". History is littered with music companies misusing the pretty tools they get due to delusions like LOUDNESS SELLS, etc. But for that, we need to blame the idiots in the music biz, not Bob Stuart.

But beyond that, my main wish would be not to have to pay for it because the only version available of something I want is MQA encoded. If others like it, that's fine with me. YMMV
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I beg your pardon, but:

1) and 2) were explained by @Werner today.

3) If the plots are fake - i.e. they don't represent actual MQA impulse and square wave response, yet are clearly presented as such - this would undoubtedly represent fraud (certainly in the technical, if not legal sense). That's clearly the inference in your words as well, when you say the plots are "too perfect," "impossibly perfect,' "are for impressing customers," and compare the effort to "plastic encased bovine excrement." Indeed, If they are, in fact, fake, they are fraudulently presented - and you are ostensibly telling us that they are. Are you 100% sure of this? Is it not worthwhile to check and verify such a serious accusation?

I have now observed a long pattern where private research is conducted and conclusions made (and popularly published) with no effort to check with the primary author(s) to verify one's assumptions and resulting conclusions. This is perhaps the cloistered nature of Internet publishing, but given your storied history, academic background, lively "journalistic" writing style and otherwise great attention to detail, I guess I expected that final gesture as well - it would make the work professionally sound and complete, in the view of this engineer (who is married to a technical writer). But, as always, you are the chief editor of Jim's Research and Publishing :).

Otherwise, I have certainly enjoyed reading your technical essays and look forward to many more.
 
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darrenyeats said:
2. The argument that it doesn't matter what happens at 20kHz or above because it's not audible, the ringing is too short etc. would imply anti-imaging filters, even conventional ones, are unimportant in general. Yet I don't see people arguing such. If amps and tweeters had zero distortion perhaps this would be true, but I don't think it is.
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Darren, as I’m sure you know if you don’t have an anti imaging filter you get spuriae at the same level as the audible signal (subject to the inherent sample and hold filtering) repeated ad infinitum with perhaps more total energy than the true signal. The problem is not that it’s directly audible although the consequences may well be. There is nothing even remotely inconsistent with saying that pre ringing can be dismissed as inaudible whilst saying that an unfiltered dac output is dangerous.
 
adamdea said:
Darren, as I’m sure you know if you don’t have an anti imaging filter you get spuriae at the same level as the audible signal (subject to the inherent sample and hold filtering) repeated ad infinitum with perhaps more total energy than the true signal. The problem is not that it’s directly audible although the consequences may well be. There is nothing even remotely inconsistent with saying that pre ringing can be dismissed as inaudible whilst saying that an unfiltered dac output is dangerous.
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I think you are generally correct.

However, I owned a filterless DAC in the 1990s (Audio Note), with seemingly no Ill effects. My system at that time really didn't have ultrasonic bandwidth, so that's probably why.

The current trend of bare DXD files (that some, frankly misguided, audiophiles buy) with tons of frequency shaped ultrasonic noise, seems equally, if not more worrisome. My system now is wide bandwidth, and I wouldn't play one of those through it.
 
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I admit I over-egged the pudding there Adam.

My intended point is smaller: i.e. frequencies not being audible etc. arguments are not sufficient. That's inconvenient because it opens up a new front of argument about what levels would be of interest (dependent on context, as Dimitry wrote about).

I get that phase distortion below 20kHz of M/I phase filters would be a respectable explanation for any audibility, and am still open-minded as to why I like them. I don't think that invalidates the aforementioned point.

This is getting geeky even by my standards!
 
DimitryZ said:
giving people in my field a benefit of the doubt and allowing them an opportunity to explain, before declaring their work fraudulent. Professional courtesy, if you will.
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Of course.

And we did. In 2014-2015.

But all that has emanated from MQA since then is more obfuscation. How long should one extend that courtesy? To 2050?

The (well ... some) amateurs chipping steadily at the codec are the source of valid information.
 
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