Reference

"It's Time" ........... Imagine Dragons :-) .............

...in fact, usually, very little knowledge is what is exhibited by people who are dilettante A-holes with strong opinions about audio that disagree with you, John.

MQA is rather brilliant. While I understand why it’s not being universally adopted, most people who aren’t engineers who have strong opinions about it don’t even understand basic audio recording and engineering.

Give them the credence they deserve (none).

What footnote 4 appears to indicate, is that all that is required to eliminate the "time smear" introduced by the A/D process is the use of an apodizing filter in the playback DAC. Problem solved without all the additional expense and nonsense of MQA. BTW, one can implement an apodizing filter by oversampling lower sample rate content via the DSP capabilities incorporated into ROON or the use of iZotope oversampling incorporated into Audirvana Plus, all in real time, during playback. All this shows there is no need for, or reason for MQA and its requirement for the audiophile to purchase new hardware with MQA. Just oversample in ROON, or implement an apodizing filter in iZotope using Audirvana Plus and you have solved the "time smear" problem yourself without the need for (purchasing a new DAC with) MQA.

"Satori"? ...............
Zen leading to satori :-) ................

I find little to complain about these days with all the 2496 recordings I can make that sound superb with only average recording equipment and I can complain about nothing. Music reproduction has never been better, but why people would listen to MP3 quality in 2018 and beyond me is still a sad thing to us as music lovers. All I every wanted was a better turntable and cart., better speakers so I could hear more and now for all too many less is just fine. We will never get it.

I make MP3 files for specific applications from 192,96,44.1 CD-Res, that are listenable.

in all things audiophile at the down of the 21th century? Well, fine-tuning and convenience aside, absolutely nothing whatsoever. Therefore MQA or something HAS to be fresh and exciting – somehow, anyhow..

Analog vs digital ....... tubes vs solid-state ........ hi-res vs mp3 ......... you choose ........ whatever floats your boat ......... Enjoy the music ........

It seems as though everybody is commenting on everything other than the article at hand.

So how about pristine 44.1 red book with no low-pass filter whatsoever and merely letting our ears cut off ultrasonic aliases? Rumors of wideband amplifier oscillation have never been confirmed for that matter as far as I know. I presume file size/bitrate is not actually an issue in the days of real-time HD video streaming..

...Their Unprocessed State as Performed by Three Groups — Expert Listeners

This paper aims to examine perceived clarity in MQA encoded audio files compared to their unprocessed state (96-kHz 24-bit). Utilizing a methodology initially proposed by the authors in a previous paper, this study aims to investigate any reported differences in clarity for three musical sources of varying genres. A double-blind test is conducted using three groups—expert listeners, musicians, and casual listeners—in a controlled environment using high-quality loudspeakers and headphones. The researchers were interested in comparing the responses of the three target groups and whether playback systems had any significant effect on listeners’ perception.
***Data shows that listeners were not able to significantly discriminate between MQA encoded files and the unprocessed original due to several interaction effects.***

Authors: Generale, Mariane; King, Richard; Martin, Denis
Affiliations: McGill University, Montreal, Quebec, Canada; The Centre for Interdisciplinary Research in Music Media and Technology, Montreal, Quebec, Canada
AES Convention: 144 (May 2018)
http://www.aes.org/e-lib/browse.cfm?elib=19396

I think it's silly for anyone to question whether or not MQA is elegant or not and it IS a brilliant innovation in my mind. The issue, for me, is ultimately traction and the very difficult path to making it matter to anyone other than producers/engineers and the high end community.

Most in my social circle are lifelong music fanatics but have zero interest in something like MQA and there's no use trying to convince them they need new stuff when they are enjoying music so much as is (via streaming, local files or records).

Surprising ......... Nobody mentioned or opined about Bluetooth :-) .........

Bob Stuart's comments leave some questions still to be resolved. Even so just looking at the electrical performance of the digital chain is overlooking other real system constraints.

First, real-world recordings made with real microphones have intrinsic low pass filters with the attendant phase response in front of any recording system. I don't know of any recording microphones with useful response to 60 KHz or anywhere near that. Measuring mikes that can respond that high have way too much noise. Plus the short wavelengths make every physical element near the mike have an impact where the longer wavelengths are much less perturbed. Same physics for recording mikes. Some have 1/2” diaphragms but the most desirable ones have 1” diaphragms and are hard pressed to get to 20 Khz. Still it would be valid to add (convolve) the impulse response of a microphone that has that response to 50 KHz to the impulse response of the digital recording chain and see what you get. Same for a Neumann U47.

I would really like to see some real impulse and tone burst measurements through the complete MQA system.

The concept of conjugate filters and dynamic sync of the encode/decode parts of the chain were first introduced by Keith Johnson and Pflash Pflaumer in the HDCD system. Along with encoding a marker to flag the content as HDCD. It has many of the same features as MQA and was compatible with 16 bit CD. However, it never had real marketing clout.

Any chance you could compare those impulses as reproduced by the speaker of your choosing?

About microphones ............ Some of the readers may not be familiar with Ehrlund triangular diaphragm microphones ......... Search for Ehrlund microphones on Google .......... Ehrlund claims that their triangular diaphragm microphones are superior compared to round diaphragm microphones because they have better impulse response ........... hence, low latency, less time smearing, low IMD ......... Very desirable properties ...........
Since JA is a recording engineer, he may be interested in these microphones ........... JA may be interested in making some recordings with these microphones .............

How can Stereophile see MQA as the solution to poor digital recording/replay sound quality? All these words, but nowhere any reason for pushing another lossy packing app. when the world does not need one. Lossless is available already, has been available for a long time, and data rates + storage are no issues in our time for those who want lossless quality. Lossy is ubiquitous, and has been for a long time - for people who want to pack a lot of music on to their portable devices, at the expense of some compromise of quality. MQA has been around quite a while now and has made close to zero impression anywhere except in Stereophile.

I was pleased to read that you acknowledge that Charley Hansen (i) had his head screwed on and (ii) was a strong critic of MQA. Charley and I exchanged a lot of emails and he was indeed very knowledgable and sensible, and delivered fine products. However it is disrespectful to his memory to say: "Charley Hansen was a vociferous critic of MQA. However, if you compare what I've written in the paragraph above with my earlier description of the goal of MQA's developers, they are, in essence, identical!"

The conclusion is idle talk when it comes to justifying MQA as a finished product rather than talking about the goal of its designers. Donald Trump has "goals" of making America great again and to establish world peace. Great "goals" few would choose to take issue with - but the practicalities end up less easy than the statement of a "goal". MQA is fundamentally a lossy packing app., albeit a clever one which should sound better than mp3 - but nonetheless lossy and consequently fundamentally flawed. Where is Stereophile's listening test evaluating the losses MQA imposes on a lossless original recording? Has anyone independent of MQA Ltd. done any such test? If you subtract the MQA'd version of a 192k/24 source file from the lossless original, what do you hear? The big question remains - who needs MQA lossy packing if the pursuit is audiophile transparency?

When will this dead parrot be laid to rest?

I've not been able to hear an A / B demonstration with MQA and non MQA digital recordings so I have no opinion yet. However any format that can compress 24/96 so you can stream it and replace 16/44 bit would be welcome. For me 24/96 is the sweet point, IF you can get it. Too many on line resellers just give you upsampled 16 bit. Until then i'm all about working on my music collection and kinda believe in the Mike Moffat thinking on music collections. Buy gear for the music you have. Regardless, if I listen to vinyl or digital or streamed digital, I find the original recording and mastering quality is the absolute pivotal factor in listening enjoyment.

..:-}

Are people still seriously talking about MQA?
When it was first announced, the USP was enabling HD streaming at standard definition bit rates. That is now firmly ancient history, I've been streaming Qobuz up to 24/192 for several years and all you lucky audiophiles in the USA will be able to do so when they launch Stateside in the next month or so.

Ever since it's been looking for a reason to exist and has yet to find one. At the most basic level, when the CD was brought to market in the early 1980s anyone who was semi-conscious with some residual hearing capacity could tell the difference between vinyl and CD. It did not matter whether the listener preferred one or the other and, bizarrely, that argument still whimpers on. All that matters is that there was a difference to justify the new format, besides a quantum change in practicality and durability. Most listeners of classical music left emotion out of the debate on entering the digital world and never looked back.

The fact that several blind listening tests have been carried out and that it has not been shown with statistical validity that MQA and non-MQA can be told apart should be enough to consign it to the dustbin of audio history. Reference above to "expert listeners" is enough to raise my blood pressure to a level at which the only release is to grab the largest kitchen knife available and murder the nearest sofa. Any mass-market product must have perceived benefit to the average punter (the man on the Clapham omnibus), and if your market is limited to expert listeners then the audio dustbin should be close at hand.

Which gets me to the article. Finnegans Wake was an easier read, made more sense and was funnier. I hope the article made sense some people, it made none to me, I thought someone was having fun publishing an article in Ethiopian Coptic. If MQA requires understanding at this level to convince people to adopt it, then I suggest Bob Stewart could spend his time better introducing ice hockey into Namibia. He'll make as much money as he'll make out of MQA (none), but will realise the error of his ways a lot quicker (due to the lack of ice).

On the subject of Namibia, I was there recently with my Mojo DAC, Mr Speakers headphones and about 50gb of offline Qobuz HD downloads on my phone. I was at one lodge with no services at all - water was filtered from a dry riverbed, solar electricity, occasional wifi as they'd installed a few repeaters, the nearest road was 2 hours away and the nearest mobile signal a further 3 or 4 hours. As I sat on a sand dune listening to Bach, all was peace and I couldn't have been happier. The sound was sublime. Try convincing me I need another format.

FWIW (as they say these days), my unit from Devialet turns anything that hits it, including analogue, to 24/192 and does it's jiggery-pokery on that, including BBC Radio 3 that is the bastion of broadcast technology and civilisation as we know it, and broadcasts at mp3 or lower.

Thanks, JA, and kudos for your fine article on A-to-D conversion in the September 2018 issue!

After all the widespread handwringing about evil commercial interests foisting an MQA monopoly on innocent music lovers, it's a relief and boon to see your careful, objective, fully substantiated demonstration of how:

- Typical digital audio recorders (from which come the hi-res PCM files many regard as the best digital audio can do) introduce time smear and ringing during A/D conversion which typical playback systems can't and don't fix, and to which those playback systems' D/A converters typically add;

- A/D converters following a particular unusual design approach don't introduce significant time smear or ringing during recording; and

- Recordings made that way can then show substantially perfect impulse responses if D/A conversion in playback is also done following a particular unusual design approach.

Your final paragraph then calmly pointed out that if MQA can indeed reach upstream into existing PCM files and remove the time smear and ringing caused by typical A/D converters during recording, then MQA encoding could permit those existing PCM files to be able to be played back with substantially perfect impulse response.

You neither endorsed nor dismissed MQA. You did show that substantially perfect impulse response can be attained in a digital audio system if both A/D and D/A operations follow specific but not typical approaches. You left room for MQA to demonstrate it can not only provide the necessary D/A conversion but also remove time smear in existing recordings not made with suitable A/D converters (i.e., nearly all, though not the ones you've made with the Ayre A/D, thank you!).

Those of us who especially value the time-domain performance of audio systems welcome the prospect of routinely hearing music reproduced with all attacks, rim shots, and other interesting transients delivered without smear (at least until the speakers make their contribution).

Please persevere in measuring and presenting impulse responses for digital gear, step responses for speakers, and fast square wave responses for analog electronics. We can hope manufacturers begin to recognize the value of improving all those.

Thanks again!

... has been solved. You design a DAC with a much higher tap count such as Chord and iFi have done. The problem is, we're still stuck in the past with DACs that haven't changed design in over a decade, with lousy built-in filters, leading MQA to come along and try and "solve" a problem that should have been solved by manufacturers. Unfortunately now the "solution" is to run all the music through some kind of compression so they can say "Listen! It sounds better!" which wouldn't have worked if it were just compressed high-res music. To me, the whole b-spline etc. discussion is just to avoid the fact that they can no longer say they are reproducing the studio master, as that has been shown, very comprehensively, not to be true.

Regardless, the discussion in this article on digital ranges, as I understand things, from out-of-date at the very least, to wrong. Infinite slope impulse responses, don't exist in music, as they contain out-of-bandwidth frequencies, so using the ringing caused by a DAC's response to out-of-bandwidth signals to explain what is going on is nonsense. Show me an in-bandwith signal that has ringing using a conventional filter! I'll bet that you can't!.