Article: MQA: A Review of controversies, concerns, and cautions

[crenca]

1 hour ago, John_Atkinson said:

 

Not correct, as you can see from reading my article on Listening to MQA:

https://www.stereophile.com/content/listening-mqa

"I scored four out of seven correct; though this is insufficient to prove formal identification, I feel that it is relevant information," adding in the comments that "it was the Steely Dan track that I got wrong—twice. Without it I would have scored 4 out of 5."

 

The reason I misidentified the Steely Dan track was that under blind conditions I preferred the sound of the 24/96 PCM version  and assumed it must have been MQA, based on my experience with the other blind comparisons.

 

 

Ok, I stand corrected.  Interesting how your bias and preconception played out - of course the subject of preference testing is a large one.

[John_Atkinson]

54 minutes ago, eclectic said:

do you still stand by this?

 

I have not yet read anything that would convince me to change my mind. Much of the most virulent criticism comes from non-technical people and where it comes from technically astute commentators, I have serious issues with much of what is written. But something that I might have to rethink is the sound of undecoded MQA datastreams, which is what Tony Faulkner was discussing in his Strreophile letter. I admit that I have done very little auditioning of undecoded MQA data and need to do more.

 

And @Doug Schneider Yes, some of the files of mine from which Bob Stuart produced MQA versions for me were made with the Ayre QA-9 ADC, others with a dCS 904 ADC and a Metric Halo MIO2882 ADC. There is something unique about that Ayre ADC, BTW, which increases my respect for the late Charley Hansen even further. But people will need to wait for the August issue of Stereophile to discover what.

 

John Atkinson

Editor, Stereophile

[John_Atkinson]

7 minutes ago, crenca said:

Ok, I stand corrected. 

 

Thank you.

 

7 minutes ago, crenca said:

 

Interesting how your bias and preconception played out - of course the subject of preference testing is a large one.

 

Indeed it is. And again I refer CA posters to my 2011 Richard Heyser Memorial Lecture for a discussion on this subject.

 

John Atkinson

Editor, Stereophile

 

[mansr]

1 minute ago, John_Atkinson said:

I have not yet read anything that would convince me to change my mind. Much of the most virulent criticism comes from non-technical people and where it comes from technically astute commentators, I have serious issues with much of what is written.

Really now?

[crenca]

2 minutes ago, John_Atkinson said:

 

I have not yet read anything that would convince me to change my mind...

 

John Atkinson

Editor, Stereophile

 

Oh boy...

 

I don't envy your position - how do you back away from such a statement?  Fact is, most don't have it in them...

[Doug Schneider]

10 minutes ago, John_Atkinson said:

And @Doug Schneider Yes, some of the files of mine from which Bob Stuart produced MQA versions for me were made with the Ayre QA-9 ADC....

 

Hi John,

 

Thanks for replying. I talked to Charles for many hours in 2017, to just a couple weeks before his death. We all knew what he thought of MQA, which was played out on Audio Asylum. But this topic was also there and two very important things came up from him (there and in the phone conversations):

1) That you had sent Bob not your fully mixed or mastered files, but the recording tracks and MQA basically re-mixed them. Correct me if he was wrong here.

 

2) The one thing he definitely not wrong about, though, is how his ADC works -- it has no anti-aliasing filter. When talking about ideal format sample rates, I told him I thought 24/88.2 and 24/96 would suffice, where he wanted 24/176.4 and 24/192 because at these high frequencies no sound will get into the signal chain anyway and, therefore, ADCs could be designed filterless, as he did. In any event, the key about this is there is no "blurring" for MQA to correct. So what you would've heard from these recordings had nothing to do with any of that -- unless, of course, as Archiamago's tests show, MQA actually worsens timing accuracy, or it's some other effect.

 

Doug Schneider
SoundStage!

[Archimago]

31 minutes ago, John_Atkinson said:

 

I have not yet read anything that would convince me to change my mind. Much of the most virulent criticism comes from non-technical people and where it comes from technically astute commentators, I have serious issues with much of what is written. But something that I might have to rethink is the sound of undecoded MQA datastreams, which is what Tony Faulkner was discussing in his Strreophile letter. I admit that I have done very little auditioning of undecoded MQA data and need to do more.

...

John Atkinson

Editor, Stereophile

 

Well, I'm sure we're looking forward to your technical evaluation of MQA, @John_Atkinson.

 

As for Tony Faulkner's comment, it certainly does not seem like he was talking about only undecoded MQA. From the first sentence, he admonishes you to:

"Please edit the rubbish out of these pseudo-technical articles before publication."

 

The reader has to simply look at that letter and his various concerns to see that he was addressing all kinds of issues from the non-sense of MQA being the answer to "record company need stock only a single inventory" all the way to why MQA delivers "none" (his emphasis even!) of what he believe high-resolution audio is about!

 

When a man speaks like that and references the political context with his "Age of Trump" sentence and being "gullible 24 hours per day", I think it's pretty evident that he wants nothing to do with MQA decoded or not!

 

[asdf1000]

2 minutes ago, Archimago said:

 

Well, I'm sure we're looking forward to your technical evaluation of MQA, @John_Atkinson.

 

As for Tony Faulkner's comment, it certainly does not seem like he was talking about only undecoded MQA. From the first sentence, he admonishes you to:

"Please edit the rubbish out of these pseudo-technical articles before publication."

 

The reader has to simply look at that letter and his various concerns to see that he was addressing all kinds of issues from the non-sense of MQA being the answer to "record company need stock only a single inventory" all the way to why MQA delivers "none" (his emphasis even!) of what he believe high-resolution audio is about!

 

When a man speaks like that and references the political context with his "Age of Trump" sentence and being "gullible 24 hours per day", I think it's pretty evident that he wants nothing to do with MQA decoded or not!

 

 

I'm no MQA fan and I like Kal's take in this latest issue (we don't need it) but I give JA credit for actually including that letter in the publication - he could have chosen not to include it.

[Archimago]

8 minutes ago, Em2016 said:

 

I'm no MQA fan and I like Kal's take in this latest issue (we don't need it) but I give JA credit for actually including that letter in the publication - he could have chosen not to include it.

 

True, and I don't not give him credit. I appreciate he's even here. It's great that there are various voices being represented in Stereophile as I noted in a previous comment that this is a good start.

 

But what Mr. Faulkner says seems pretty clear...

 

[Doug Schneider]

26 minutes ago, Archimago said:

But what Mr. Faulkner says seems pretty clear...

 

Faulkner sounds like a lot of people I talked to over the last couple of years about this -- frustrated over what they quickly saw as looking like a lot of B.S.

 

As far as I can tell, in the professional community, hardly anyone has heard of MQA, and of those who have, no one is waiting for it. It's basically a niche thing, promoted by handful of audiophile writers (that number appears to be shrinking now), known only to audiophiles. I would guess that at least 9 of 10 Tidal users don't even know what the Masters tab is.

Doug
SoundStage!

 

 

[beetlemania]

1 hour ago, Doug Schneider said:

he wanted 24/176.4 and 24/192 because at these high frequencies no sound will get into the signal chain anyway and, therefore, ADCs could be designed filterless, as he did. In any event, the key about this is there is no "blurring" for MQA to correct. So what you would've heard from these recordings had nothing to do with any of that -- unless, of course, as Archiamago's tests show, MQA actually worsens timing accuracy, or it's some other effect.

 

This is very interesting and, I think, further explains Hansen's disdain for MQA. I would love to hear Mr. Atkinson's PCM files through, say, a QX-5 and the MQA version (assuming the same master) decoded with a Meridian. Hmm, actually there  *is* someone who could perform that trial.

[MikeyFresh]

23 hours ago, Archimago said:

"Lossless music registration"? Anyone use this kind of terminology? Is this even a "thing"?

 

No, it is not even a thing. It's sheer nonsense.

[HalSF]

26 minutes ago, Doug Schneider said:

It's basically a niche thing, promoted by handful of audiophile writers (that number appears to be shrinking now), known only to audiophiles. I would guess that at least 9 of 10 Tidal users don't even know what the Masters tab is.

Doug
SoundStage!

 

 

I recently started a Tidal Hi-Fi trial so I could listen to a bunch of MQA, and to see how the MQA renderer in my brand-new iFi Nano iDSD Black Label DAC/amp sounds.

 

If I wasn't highly attuned to all of the controversy and hype about MQA on forums like this one, I would have no reason to know or care about MQA's presence on Tidal. It's hardly mentioned and mostly buried throughout the sign-up and set-up process, and the Mac desktop app is free of any reference to MQA apart from its implicit use on those Masters tab albums (which currently features a fairly mediocre selection). I had to do a lot of vigorous digging just to make sure I was actually zeroing in on MQA content.

 

I was quite surprised how aggressively downplayed MQA is on Tidal.

[Currawong]

I couldn't help noticing on the "Bob Talks" web site that it doesn't mention studio masters at all, but a "studio preview".

 

Quote

The MQA file can be fully unfolded to recover the exact sound of the studio preview using a Full Decoder. To add convenience, unfolding can proceed step by step, enabling a number of intermediate quality steps, each of which can be previewed in the studio and Authenticated.

 

[crenca]

delete

[Doug Schneider]

3 hours ago, John_Atkinson said:

There is something unique about that Ayre ADC, BTW, which increases my respect for the late Charley Hansen even further. But people will need to wait for the August issue of Stereophile to discover what.

 

John Atkinson

Editor, Stereophile

 

I'm just going to go out on a limb and guess -- it shows none of the filter artifacts typical of ADCs. That's just a guess. But if so, it's not a surprise because Hansen has stated for a long time that it has no filter.

 

If it's something else, I'll be surprised because in the talks I had with him over the summer months, he told me what was special about it and many of his other designs -- and almost all of it, he took little or no credit for, as a long of it was done by other people long before.  He just felt that it was the best way to go and used those ideas (btw, to me and in AA a couple of times, he credited John Curl with inspiring basically all the work in his analog designs).

Doug

SoundStage!

[beetlemania]

9 minutes ago, Doug Schneider said:

it shows none of the filter artifacts typical of ADCs

 

It appears that Ayre discontinued the QA-9. Must not have sold well? Sign me up for the parallel Earth where all albums are recorded by such a device and the end user can play it back on the DAC and format of their choice .

 

10 minutes ago, Doug Schneider said:

in AA a couple of times, he credited John Curl with inspiring basically all the work in his analog designs

 

 IIRC, he wrote something to the effect of: "if I have seen further than others it is because I have stood on the shoulders of John Curl".

[Doug Schneider]

Just now, beetlemania said:

 

It appears that Ayre discontinued the QA-9. Must not have sold well? Sign me up for the parallel Earth where all albums are recorded by such a device and the end user can play it back on the DAC and format of their choice 

 

I believe they did discontinue it. In one of those conversations, he mentioned that despite how good it might've been, it didn't sell well.

 

Doug

[Archimago]

3 hours ago, MikeyFresh said:

 

No, it is not even a thing. It's sheer nonsense.

 

Yeah, that's what I thought... Someone should let Hans know.

[mansr]

1 hour ago, Doug Schneider said:

I'm just going to go out on a limb and guess -- it shows none of the filter artifacts typical of ADCs. That's just a guess. But if so, it's not a surprise because Hansen has stated for a long time that it has no filter.

It's a sigma-delta ADC. Of course it has a filter.

[FredericV]

4 hours ago, Doug Schneider said:

2) The one thing he definitely not wrong about, though, is how his ADC works -- it has no anti-aliasing filter. When talking about ideal format sample rates, I told him I thought 24/88.2 and 24/96 would suffice, where he wanted 24/176.4 and 24/192 because at these high frequencies no sound will get into the signal chain anyway and, therefore, ADCs could be designed filterless, as he did. In any event, the key about this is there is no "blurring" for MQA to correct. So what you would've heard from these recordings had nothing to do with any of that -- unless, of course, as Archiamago's tests show, MQA actually worsens timing accuracy, or it's some other effect.

 

Doug Schneider
SoundStage!

 

In digital photography, the same idea is used. Camera's with extreme megapixel counts, such as Nikon's D850 don't have an AA filter.

https://www.outdoorphotographer.com/photography-gear/cameras/can-you-go-no-low-pass/

They do not expect content to max out the actual resolution of a 40+ megapixel sensor, as the content is already band limited by the lens which acts as a resolution limiter.

With my D750 an AA filter is required. My lenses easily outperform the D750's resolution. Even very old lenses from the 90's can max out the 24 megapixel resolution of my camera, so an AA filter in this case is needed.

 

[Doug Schneider]

51 minutes ago, mansr said:

It's a sigma-delta ADC. Of course it has a filter.

You are right, but I wish I could go back and talk to him more. And you know a lot more about A/D and D/A than most. But I swear in one of his conversations he was talking about a lack of a filter at 24/192. I will look more as he described this in pieces on AA, but here's part. But it's not everything.

 

https://www.audioasylum.com/forums/pcaudio/messages/16/167848.html

 

EDIT: As I said, above I could've sworn what he said on the phone about the filter. But I'm certainly OK to be corrected because in that above link he talks about the filter used at 2X and 4X conversion, so there's something there. What he claims, though, remains the same -- that there are no timing issues to correct with the QA-9 Here's a little more:

 

https://www.audioasylum.com/cgi/t.mpl?f=critics&m=87523

Doug

[mansr]

42 minutes ago, Doug Schneider said:

You are right, but I wish I could go back and talk to him more. And you know a lot more about A/D and D/A than most. But I swear in one of his conversations he was talking about a lack of a filter at 24/192. I will look more as he described this in pieces on AA, but here's part. But it's not everything.

 

https://www.audioasylum.com/forums/pcaudio/messages/16/167848.html

 

EDIT: As I said, above I could've sworn what he said on the phone about the filter. But I'm certainly OK to be corrected because in that above link he talks about the filter used at 2X and 4X conversion, so there's something there.

A sigma-delta ADC doesn't need an analogue anti-aliasing filter since the sample rate (typically 128x or more) is far higher than required by Nyquist for any audio signal. To produce a PCM output, at any sample rate, a digital low-pass filter must be used to remove the modulator noise. Presumably this ADC uses Ayre's signature slow roll-off minimum phase filters.

 

42 minutes ago, Doug Schneider said:

What he claims, though, remains the same -- that there are no timing issues to correct with the QA-9 Here's a little more:

 

https://www.audioasylum.com/cgi/t.mpl?f=critics&m=87523

I'd say no reasonable ADC has any timing issues. Here's a square wave with 5 ns rise time recorded at 192 kHz on a Tascam UH-7000:

Sure, there's a little overshoot and ringing, but real audio signals don't have such short rise times so it doesn't matter.

[Doug Schneider]

14 minutes ago, mansr said:

A sigma-delta ADC doesn't need an analogue anti-aliasing filter since the sample rate (typically 128x or more) is far higher than required by Nyquist for any audio signal. To produce a PCM output, at any sample rate, a digital low-pass filter must be used to remove the modulator noise. Presumably this ADC uses Ayre's signature slow roll-off minimum phase filters.

 

I should've been more specific. He was talking about anti-aliasing filters. And, yes, it makes sense from what I've read about that piece, it used their slow roll off filters.

 

Which brings up another thing related to MQA. I have no doubt that people ARE hearing differences -- and Charles had no doubt either. What's "better" versus was more "accurate" can be two different things. But when it comes to these slow-roll-off filters, which Charles preferred, too (his Listen versus Measure filters), what ARE people hearing? MQA would like to tell you it's timing accuracy, but that doesn't seem to be the case. Yet people are hearing something and this is where some interesting testing could/should be done.

 

Doug
SoundStage!

[mansr]

22 minutes ago, Doug Schneider said:

I should've been more specific. He was talking about anti-aliasing filters. And, yes, it makes sense from what I've read about that piece, it used their slow roll off filters.

Of course it's about anti-aliasing. That is the purpose of any filter in an ADC. In a sigma-delta ADC, the AA filter is digital. If you somehow managed to build a 22-bit flash ADC operating at 192 kHz or higher, you wouldn't need any filters at all. Unfortunately, that is highly unpractical, if at all possible. Although the audio signal has essentially no content above 100 kHz, the output of the sigma-delta stage does, in the form of modulator noise. For this reason, PCM output, even at 192 kHz, requires a digital anti-aliasing filter. Otherwise the audible range would be swamped in aliased modulator noise.