John Atkinson: Yes, MQA IS Elegant...

[mansr]

3 minutes ago, John_Atkinson said:

people who have not read what I have written or, if they have done so, have not understood it

It is difficult to understand a text when its author, apparently, doesn't understand the subject matter.

[John_Atkinson]

3 minutes ago, mansr said:

It is difficult to understand a text when its author, apparently, doesn't understand the subject matter.

 

So there we have it. No discussion of the points I raised, just another personal attack.

 

So be it.

 

John Atkinson

Editor, Stereophile

[mansr]

4 minutes ago, John_Atkinson said:

So there we have it. No discussion of the points I raised

Why do you refuse to address any of the objections people have raised? All you do is whine about being attacked while accusing everybody of not understanding.

[FredericV]

17 minutes ago, John_Atkinson said:

Does the MQA analog-analog chain behave in the same manner as the Charley Hansen's "Listen" anti-aliasing filter in the Ayre QA-9 and his experimental reconstruction filter for the Ayre QX-5 Twenty? You will note that I used the word "if" in my article. Without access to an MQA-equipped A/D converter, that must be speculation on my part. (I have asked to try Mytek's MQA ADC, but I would have to sign a non-disclosure agreement that makes my using it moot.

Why is there still no MQA enabled ADC? One vendor told me they have a great ADC and their CEO is talking to MQA to add some extra code to the firmware to make it MQA enabled. But it did not happen yet. It's a very big MQA partner.

So adding MQA to an ADC can be done by means of some software /firmware update.

But why are we not seeing a lot of MQA enabled ADC's if MQA wants to be the new world order of PCM? If MQA was a real breakthrough, ADC vendors would beg to adopt MQA. But obviously that did not happen.

[adamdea]

14 minutes ago, John_Atkinson said:

 

 

The experimental evidence I presented is incontrovertible. That unless the user of an A/D converter is prepared to accept the possibility of some aliased image energy in order to use an antialiasing filter that preserves the time-domain behavior of the original analog signal, the resultant digital data will have sinc-function content at the Nyquist frequency accompanying every musical transient.

 

I can’t see how this could be described as  incontrovertible- it seems to me doesn’t even get off the ground because you did not start with a musical transient, let alone one captured with a real microphone.

 

Or does this only appear to me because of my (undoubted) lack of knowledge? 

[John_Atkinson]

4 minutes ago, FredericV said:

30 minutes ago, John_Atkinson said:

I have asked to try Mytek's MQA ADC, but I would have to sign a non-disclosure agreement that makes my using it moot.

Why is there still no MQA enabled ADC?

 

I thought it clear from my post that Mytek has such an ADC. Some recording and mastering engineers in the NY area have been beta-testing it.

 

John Atkinson

Editor, Stereophile

 

[FredericV]

5 minutes ago, John_Atkinson said:

 

I thought it clear from my post that Mytek has such an ADC. Some recording and mastering engineers in the NY area have been beta-testing it.

 

John Atkinson

Editor, Stereophile

 

It's still not an official product. So MQA is how long on the market? And only one ADC with a beta version of MQA? From one of the earliest adopters - who also had one of the first DSD dacs, the previous hype.

So I repeat my question, which you are avoiding: why is there only one ADC with MQA (in beta)?. You would expect if MQA was such a big breakthrough with end-to-end potential, more ADC vendors would beg for MQA.

[John_Atkinson]

Just now, FredericV said:

I repeat my question, which you are avoiding: why is there only one ADC with MQA (in beta)?.

 

Your original question was "Why is there still no MQA enabled ADC?" To be clear, this isn't the same question, so you are hardly repeating it. But to answer this second question, I have no idea. Nor do I have any idea why you think I should know.

 

John Atkinson

Editor, Stereophile

[Brinkman Ship]

13 minutes ago, John_Atkinson said:

 

I thought it clear from my post that Mytek has such an ADC. Some recording and mastering engineers in the NY area have been beta-testing it.

 

John Atkinson

Editor, Stereophile

 

Please ask your Jim Austin why when asked about MQA ADCs he replied that anybody who asked about such a device had no understanding of what MQA is. It turns he clearly has no understanding..I bet he is still doing his 'research"...

[mansr]

24 minutes ago, FredericV said:

Why is there still no MQA enabled ADC?

There would be very little point in that. MQA encoding has to be the very last step after final mastering. You can't do any mixing or editing whatsoever of MQA-encoded content.

[Brinkman Ship]

3 minutes ago, mansr said:

There would be very little point in that. MQA encoding has to be the very last step after final mastering. You can't do any mixing or editing whatsoever of MQA-encoded content.

That is not what they are selling. They are selling and "end to end" solution..and you could theoretically do editing and mastering with the "MQA Mastering Tools" that Stuart promised over 3 years ago..in fact he paid several mastering engineers to discuss this scenario.

[John_Atkinson]

30 minutes ago, adamdea said:

I can’t see how this could be described as  incontrovertible- it seems to me doesn’t even get off the ground because you did not start with a musical transient, let alone one captured with a real microphone.

 

That is correct. I used an artificially generated, non-musical test signal with the necessary properties to investigate the subject in a repeatable and diagnostic manner. The use of such signals to investigate the behavior of audio components and infer the results of that behavior with music is routine. You can find myriad examples in the review archive at www.stereophile.com.

 

John Atkinson

Editor, Stereophile

 

[FredericV]

1 minute ago, mansr said:

There would be very little point in that. MQA encoding has to be the very last step after final mastering. You can't do any mixing or editing whatsoever of MQA-encoded content.

MQA claimed they had some DAW plugins to preview certain MQA encoder settings, but in the end, all content is still being sent to an MQA facility for them to encode. Even if some plugin could emulate the MQA process, it's still an emulation as the real encoding is not happening in the studio.

Mastering engineers do a lot of work on tight deadlines. Change a knob on a compressor/limiter/equi and instantly hear the difference. Changes in the style of a fraction of a dB (like Brian Lucy). With MQA such interactive process is not (yet) possible.

I don't remember mastering engineers having direct access to an encoder.

There is no finalized MQA enabled ADC product, because (pick your favorite)

- MQA is not a breakthrough
- MQA does not matter
- MQA's end-to-end was sold to audiophiles in order to accept lossy DRM pseudo hi-res, but in fact MQA exists for a whole different reason: to add DRM, to avoid giving access to the actual PCM data of the actual master - instead they give the right to listen to an approximation and to sell licenses and control the whole chain

The fact that no actual finished MQA ADC exists, proves MQA is not about end-to-end. If end-to-end was so important, we would already have seen an ADC. The ADC vendors would beg MQA to implement it's breakthrough. But that did not happen.

[mansr]

21 minutes ago, John_Atkinson said:

I thought it clear from my post that Mytek has such an ADC

The Mytek ADC is basically the inverse of an MQA "renderer." It records at some rather high rate (I have no way of knowing the exact number) and downsamples to the selected output rate using the super-leaky MQA filters. The output of this can be edited as usual and sent off for encoding when mastering is completed.

[mansr]

11 minutes ago, Brinkman Ship said:

That is not what they are selling. They are selling and "end to end" solution..and you could theoretically do editing and mastering with the "MQA Mastering Tools" that Stuart promised over 3 years ago..in fact he paid several mastering engineers to discuss this scenario.

You still wouldn't be working with MQA-encoded files. It's like mp3 in this sense. You don't encode until you're done editing.

[vl]

9 minutes ago, John_Atkinson said:

 

That is correct. I used an artificially generated, non-musical test signal with the necessary properties to investigate the subject in a repeatable and diagnostic manner. The use of such signals to investigate the behavior of audio components and infer the results of that behavior with music is routine. You can find myriad examples in the review archive at www.stereophile.com.

 

John Atkinson

Editor, Stereophile

 

 

Could you enlighten us how does your artificially generated test signal relate to a music signal or a musical listening experience?

[John_Atkinson]

2 minutes ago, vl said:

Could you enlighten us how does your artificially generated test signal relate to a music signal or a musical listening experience?

In the context of testing audio components, this is an enormous subject. All I can suggest is that you read the tutorial articles in the free on-line archives at the Stereophile website.

 

John Atkinson

Editor, Stereophile

 

[mansr]

Just now, John_Atkinson said:

In the context of testing audio components, this is an enormous subject.

So there we have it. No discussion, just another deflection.

[vl]

2 minutes ago, John_Atkinson said:

In the context of testing audio components, this is an enormous subject. All I can suggest is that you read the tutorial articles in the free on-line archives at the Stereophile website.

 

John Atkinson

Editor, Stereophile

 

 

Is this the way to engage a technical exchange?

[mansr]

2 minutes ago, vl said:

Is this the way to engage a technical exchange?

No, it is how to avoid one.

[adamdea]

32 minutes ago, John_Atkinson said:

 

That is correct. I used an artificially generated, non-musical test signal with the necessary properties to investigate the subject in a repeatable and diagnostic manner. The use of such signals to investigate the behavior of audio components and infer the results of that behavior with music is routine. You can find myriad examples in the review archive at www.stereophile.com.

 

John Atkinson

Editor, Stereophile

 

Of course. But the claim that the results led to an incontrovertible conclusion about every actual musical event of a particular type is novel. You know this, why play act?

[FredericV]

16 minutes ago, mansr said:

So there we have it. No discussion, just another deflection.

Let's do the same.

Here's a good example where an MQA ADC would not be able to save the day. The audio is horrible:
 

And there was a microphone almost in front of him but still we got sh* audio.

[Jud]

43 minutes ago, mansr said:

The Mytek ADC is basically the inverse of an MQA "renderer." It records at some rather high rate (I have no way of knowing the exact number) and downsamples to the selected output rate using the super-leaky MQA filters. The output of this can be edited as usual and sent off for encoding when mastering is completed.

 

Are you certain the "super leaky" filters are used? I'm guessing someone has done a spectrum analysis of MQA-encoded stuff, but I haven't seen it myself.

[vl]

1 hour ago, John_Atkinson said:

 

The experimental evidence I presented is incontrovertible. That unless the user of an A/D converter is prepared to accept the possibility of some aliased image energy in order to use an antialiasing filter that preserves the time-domain behavior of the original analog signal, the resultant digital data will have sinc-function content at the Nyquist frequency accompanying every musical transient.

 

Reply: I understand your perspective.  In one case the use of brick wall anti aliasing and reconstruction filters can result in filter ringing.  In the other case the use of gentler filters that run the risk of aliasing may alleviate filter ringing.  I submit that your perspective may not be the only one that exists.  Consider this case: the analog signal is band limited by a non brick wall filter to LESS THAN half Fs before it enters the ADC.  There will not be brick wall filter ringing in the ADC and DAC.  The recording engineer has a choice of what anti aliasing filter to use.  He is not limited to the brick wall filters in your example.

 

1 hour ago, John_Atkinson said:

If the original data were captured at 2Fs and or 4FS rates, then the sample-rate converter used to prepare a CD master will introduce ringing at the new Nyquist frequency of 22.05kHz with every musical transient.

 

The "lazy" mastering engineer may do such a thing.  Other engineers can choose to use their choice of non brick wall LP filters to band limit the signal BEFORE sampling rate conversion.  Again you have presented a possible scenario but it is not the only scenario.

 

1 hour ago, John_Atkinson said:

Decoding these correctly band-limited digital data with a conventional sinc-function reconstruction filter will replace this ringing with its own, again at Nyquist, with every transient. A slow-rolloff reconstruction filter will not ring but will preserve the Nyquist-frequency ringing in the original data.

 

If the ADC and DAC designer does a design with little thinking, what you describe can happen.  For example if he designs the ADC with a brick wall 22.05 KHz anti aliasing filter and the DAC with a 22.05 KHz reconstruction filter, what you describe can indeed happen.

 

A smarter designer can use a brick wall anti aliasing filter at say 22.00 KHz and a reconstruction filter at 22.05 KHz.  The anti aliasing filter will ring at 22.00 KHz but the reconstruction filter will not ring on recordings made with the ADC mentioned above.

 

Another designer can use a non brick wall anti aliasing filter with good rejection at 22.00 KHz and a 22.05 KHz reconstruction filter.  This arrangement will not show any brick wall filter ringing.

 

Again your statement above does not represent the only scenario.

 

1 hour ago, John_Atkinson said:

 

 

 

[tmtomh]

 

2 hours ago, John_Atkinson said:

 

It saddens me that so much of this thread has degenerated into personal attacks, from people who have not read what I have written or, if they have done so, have not understood it, as in the case of the post which I am responding. Too many posters have a greater confidence in their opinions than they do actual knowledge, driven by what appears to be antagonism toward those of us who earn our livings by what we publish and write.

 

[...]

 

The experimental evidence I presented is incontrovertible. That unless the user of an A/D converter is prepared to accept the possibility of some aliased image energy in order to use an antialiasing filter that preserves the time-domain behavior of the original analog signal, the resultant digital data will have sinc-function content at the Nyquist frequency accompanying every musical transient.

 

[...]

 

If a specific type of slow-rolloff antialiasing filter in the A/D converter is combined with a reconstruction filter in the D/A converter that behaves in a similar manner, you will have an analog-digital-data storage/transmission-digital-analog chain that will have an impulse response and top-octave rolloff equivalent to that of a small distance of air. As I wrote in my article, this was the stated goal of both Bob Stuart and the late Charley Hansen; I see no disrespect to the latter in pointing that out, especially as I instanced Charley's antipathy to MQA in the article.

 

[...]

 

Is the compromise in the frequency domain associated with using time-domain-perfect converters acceptable with real musical signals? Or is the possibility of image energy being aliased into the audioband too great? I have heard arguments on both sides of this question. I suspect the answer is that it depends on the type of music.

 

Does ringing at 22.05kHz even matter when it comes to sound quality? Again, I have heard arguments on both sides of this question, from people I respect.

 

@John_Atkinson, thank you for your thorough comment here (which I upvoted). I don't agree with all of it, but I certainly agree that some folks here are resorting to personal attacks and general snark, and in the process avoiding substantive debate.

 

I hasten to add, though, that while the debate you and @mansr are in is antagonistic in tone, I believe it's false to claim that he's making a personal attack. He's making a specific claim - which he's been consistent about in this and other MQA threads, and which he's been very specific about in multiple prior comments - that some of what you are claiming does not comport with his understanding of the relevant mathematical principles.

 

For my part, I don't have the level of technical expertise to weigh in on the specific issues up for debate. I will only say that I do think there's a specific issue with the ideas as you express them in your Stereophile article (which article I've praised earlier in this thread).

 

The issue is that you see to be inconsistent in how you write about the audibility of pre-ringing. In the piece, you cite a listening test that failed to turn up evidence that it's audible (except for the intentionally-poorly designed filter). But then you speculate, as you do in the comment above, that it might possibly cause problems - and then almost immediately thereafter in the article you strongly imply that it is indeed a problem.

 

It seems to me that the case for MQA - whether one calls it "a whole new world" or "elegant" or simply "good" or "important" - depends upon pre-ringing being a major issue. And your discussion seems to zig towards asserting this when you are discussing MQA and its beneficial/intriguing/elegant design, and then zag towards "who knows, maybe it's not an issue at all" when you are explicitly critiqued for your apparent editorial stance on MQA.

 

This is not a mathematical critique, but it's not a personal attack either. I'm making a rhetorical observation and objection, that to my eyes is about the way you have framed coverage of MQA. I'd welcome your response and thoughts. Thank you.

 

 

On 8/22/2018 at 5:35 PM, tmtomh said:

[...] I think his article is a very well-written, informative recitation of the case for minimizing pre-ringing (aka prioritizing time-domain accuracy) in digital filtering. Anyone who's not already well-versed in this issue (either by professional training or from doing a lot of reading) would, I think, benefit from it.

 

There does seem to be one major logical (or perhaps evidentiary) gap in the piece, though: He cites a listening test that failed to turn up audible evidence that pre-ringing causes problems (except in an intentionally worst-case filter where all the ringing is pre-ringing). Then almost immediately he nevertheless speculates that pre-ringing nevertheless could be an issue (by wondering if higher sample rates are pleasing to folks because they move ringing out of the audible range) - and then quickly moves on from there to strongly imply that pre-ringing is indeed a problem, despite the lack of evidence in the listening test mentioned just a couple of paragraphs above.