MQA Deep Dive - I published music on tidal to test MQA

[John Atkinson]

while you are converting an analog source to digital, there is a need to cut frequencies of the incoming analog signal before reaching the Nyquist frequency (NF), 22.05 Khz in a Redbook. Otherwise, severe aliasing artifacts will occur in ADC. If as close as possible to 'Brickwall' filters are used for this, a much bigger increase of the time smearing problems in the frecuencies below will happen. If instead a gentler filter slope is used, either you will have signals remaining beyond that NF and won't eliminate those aliasing problems you are trying to avoid, or, by displacing the filter to a lower frequency, you will start having a poor high frecuency response in the audible band , as that NF in Redbook is quite close to the audible limit. And yet, still having phase problems to some degree. Every ADC process must balance these opposing problems, but it is not possible to get rid of them completely.

I examine the issues that are faced by A/D converters in this article I wrote for Stereophile in 2018:
https://www.stereophile.com/content/zen-art-ad-conversion

John Atkinson
Technical Editor, Stereophile

 

[voodooless]

All these mentions about the blue light and how it’s the main “advantage” of MQA. My streamer/DAC doesn’t have a blue light. It has no light at all, it just displays “MQA” on the screen. I feel cheated.

Imagine my luck: I even have blue light on my amp, and it's always on

 

[guenthi_r]

All these mentions about the blue light and how it’s the main “advantage” of MQA. My streamer/DAC doesn’t have a blue light. It has no light at all, it just displays “MQA” on the screen. I feel cheated.

Hey, my DAC also have a blue light, its the power-on light!
So, it must be much more lossless as before! wow.

 

[voodooless]

I admire you, you have a lot of patience to keep answering all this ongoing nonsense!

...

In this case, what he probably wants to achieve, with these many long posts is to impersonate an expert, so that MQA or Tidal customers ( the vast majority being unable to discern between meaningful technical talk and technical gibberish) looking at the thread will think that there is no agreement between "experts", so they can go on believing in MQA's claims (even if actually debunked):
One guy wrote , I think yesterday, something like: we are back at the beginning, nothing conclusive has been reached (thanks to Mieswall 's "technical arguments")...

So that is my major driver here. If we don't address the non-sense, it remains unchallenged, meaning that some people might conclude different things based on their observations of the conversations. Obviously, still engaging does also give more exposure, but at least it's clear that the statements are not simply accepted as fact.

Also, I like the pose counter questions, rather than only stating my view on the matter. It helps in getting to know the other viewpoint. Even if questions are not answered, or evaded, that says a lot, and people will notice.


But really.. I'm doing it for the likes

 

[sandymc]

Imagine my luck: I even have blue light on my amp, and it's always on

Meridian Audio will be around shortly to collect their license fee

 

[Zensō]

Greetings from Sydney, Australia.

Newbie here.

Could some one please post The Perfect Hi Res track for comparing the superiority of Qobuz vs Tidal?

Preferably, House, Jazz, Classical or Soundtrack?

I ask because I just purchased the THX Onyx - primarily to add some 'oomph' beyond the 2013 Mac Pro's onboard sound, to drive Audeze LCD-X's (2020 revision). Not for the MQA stuff, mainly for the convenience of a small device with punch. fwiw: Onyx delivers in the "plug it in and go" oomph department ;-)

View attachment 125145

I tried a quick A/B test on an (allegedly) identical track from both Qobuz vs Tidal, using their Mac desktop app(s) - on maximum settings. I know the track was 44.1 on Qobuz, and Tidal is doing its 'treatment' of the same source material. Hardly a comprehensive critical listening session, enough though.

The Tidal 'treatment' - upsampling? and other voodoo - was... subtle. Probably my own biases? But Tidal... seemed to have some, Mmm?, ethereal qualities. Spaciousness? Slightly different flavour, which I liked.

Anyway, does someone have a link to the ultimate slam dunk sample music track demonstrating Qobuz's superiority? Thanks in advance.

Be sure to volume match to 0.1 db or your comparisons won’t tell you much. When comparing subtle differences, even the slightest discrepancy in volume will almost always favor the louder track.

 

[mhardy6647]

Not quite unless your air conditioner operates on free energy.

yeah, yeah -- open, closed... whatever

Y'all know what I mean -- locally, it's easy to reverse entropy (well... it's straightforward) -- but the house always wins, and the universe always loses.
In my younger days, I used to quip that god (note the lower case g) is the Second Law (as opposed to vice versa); I'm not quite that cynical any more. Well... actually I am just as cynical, just in different ways.

 

[Harry1973]

Was the original 44.1 khz test file 24bit? (As it seems from the first page picture). Just wondering what happens to red book 16/44.1 music on tidal. Are they messed up with MQA stuff also (if they have a hires MQA version also available)?

 

[mansr]

I'm not quite that cynical any more. Well... actually I am just as cynical, just in different ways.

Cynicism is like entropy. It can never be reduced, only redistributed.

 

[Atanasi]

All these mentions about the blue light and how it’s the main “advantage” of MQA.

Blue light as a means to high definition is not actually a new invention. It was already popularized by BluRay.

 

[John Atkinson]

Interesting: the potential benefits of AAC vs MP3 seem obvious and your conclusion was clearly expressed, based on that test signal analysis.

That really demonstrates there is a double standard as far as MQA is concerned.

On one hand, the behavior MP3/AAC/OGG/etc...with test signals is worthy of investigation and publication and the results described as conclusive.

On the other hand, when that method is applied to MQA, reactions range from "oh, but you can't do that" to "this shows you don't understand anything".

There is no "double standard" as there is a significant difference between the tests of low-bit-rate codcs that I discussed and GoldenOne's test of MQA. I used "legal" test-tone signals - legal in the sense that they were appropriately band-limited and were at levels well below 0dBFS. The differences between how the MP3 and AAC codecs handled the test tones at lower and higher bit rates was therefore meaningful.

By contrast, GoldenOne's high-level ultrasonic test tones were not "legal," in that they didn't conform to the >20kHz spectral space typical of real music recordings. They therefore "broke" the encoder. See Amir's postings on this to which I was responding.

BTW: to make it easier for readers to access Stereophile's coverage of MQA since 2014, we have created an article category with all the relevant links: https://www.stereophile.com/category/mqa

John Atkinson
Technical Editor, Stereophile

 

[guenthi_r]

Blue light as a means to high definition is not actually a new invention. It was already popularized by BluRay.

"Blue light-emitting diodes were first reported in 1971"
Solid-State Electronics

"The term high definition once described a series of television systems originating from August 1936"
High Definition

 

[usersky]

All these mentions about the blue light and how it’s the main “advantage” of MQA. My streamer/DAC doesn’t have a blue light. It has no light at all, it just displays “MQA” on the screen. I feel cheated.

My DAC has 4 blue lights and no MQA. Can I get any better?

 

[guenthi_r]

My DAC has 4 blue lights and no MQA. Can I get any better?

Yes, with 8 purple lights -> "Ultra High Lossless"! Better than "High Lossless", "Lossless", "Less Lossless" and at least "MQA".

 

[mieswall]

You’re making a huge assumption. You are assuming that ADCs don’t follow basic Nyquist-Shannon sampling good enough to have a proper filter implementation. Filtering at both ADC and DAC level should be straightforward if following basic theory. Filter design has to be only reduced to the most effective brickwall filter at outside the wanted passband in order to limit out-of-band interactions that occur when not following the sampling theorem. I don’t see ADCs struggling with this nowadays.

You’re making a huge assumption. You are assuming that ADCs don’t follow basic Nyquist-Shannon sampling good enough to have a proper filter implementation. Filtering at both ADC and DAC level should be straightforward if following basic theory. Filter design has to be only reduced to the most effective brickwall filter at outside the wanted passband in order to limit out-of-band interactions that occur when not following the sampling theorem. I don’t see ADCs struggling with this nowadays.

Not sure if I'm making it (I'm basing this comment precisely because of N-S in fact).

The only way for a Redbook to have a flat FR up to 20Khz is to apply filters above that 20 khz. The space left for that before reaching Nyquist Frequency (NF) is 20Khz-22Khz. In that space of less than 1/3 octave, the only possibility for the filter not to go beyond the NF (that is: to reach 0 db @ 22 Khz) is to be of brickwall- type, ie: of some 300 db/octave or so! (remind: most people here seems to believe that MQA need to handle the full 16bit amplitude even at 20 kHz: 96 db, as they are horrified that they can't reconstruct a square wave in the test tones). Besides the fact that this (a perfect brickwall filter in analog domain) is quite difficult if not impossible, do you know an analog brickwall filter that doesn't mess the phases of the incoming signal? The steeper the filter is, the more it shift phases of the incoming signal. Or we are going to question that, also?

As this is problem that can't be solved perfectly, it think it is unavoidable that some degree of aliasing is present in Redbook files, because a tail of signal trespass the NF limit. It is also a obvious that, as ADC is trying to make this tail as short as possible, very steep filters are in fact applied, and so, phases of the harmonics in the PCM has some (big, according Meridian) anomalities embedded in it.

That's why HR files, having this problem shifted to a much higher frequency and with much more room to avoid steep filters, DO sound better (or at least have cleaner information stored if we are not able listen that difference [and we do, according Meridian]). And this is one of the foundational elements in MQA's theory.

 

[pjug]

I examine the issues that are faced by A/D converters in this article I wrote for Stereophile in 2018:
https://www.stereophile.com/content/zen-art-ad-conversion

John Atkinson
Technical Editor, Stereophile

There is a TI graphic in the post linked below showing a -100dB Aliasing Free zone. If an ADC gives -100dB aliasing free to 20KHz, aren't we pretty much good?
https://www.audiosciencereview.com/...r-mirror-images-short-study.20318/post-679066

 

[mansr]

Besides the fact that this (a perfect brickwall filter in analog domain) is quite difficult if not impossible, do you know an analog brickwall filter that doesn't mess the phases of the incoming signal?

Nobody uses analogue anti-alias filters for 44.1 kHz sampling. Take your red herring elsewhere.

 

[voodooless]

the steeper the filter is, the more it shift phases of the incoming signal. Or we are going to question that, also?

Yes!

 

[KeithPhantom]

Modern sigma-delta ADCs sample at several MHz, then apply a digital low-pass filter to produce the selected output sample rate. A choice of linear or minimum phase is sometimes available. There are no issues with aliasing or phase shifts.

That’s what pretty much said in the post below, even though I forgot to include references to DS. But thanks anyways.

 

[Kal Rubinson]

Thanks, That's already obvious as all DSP is digital, I think? (EYE ROLL) I asked based on previous comments from Rich B and TKS. I'm considering buying something with Dirac. I'll refrain from asking such stupid questions in the future.

Sorry for the attitude but I was just confirming your contentions.