MQA technical analysis

[PeterSt]

What air has to do with anything completely escapes me.

 

I did not read the texts implied, but what I get from it is that air itself will cause said blur, and probably MQA is (or should be) designed such that MQA does not cause more blur than 10m of air implies. A sort of : we sit closer than 10m to our speakers anyway.

[PeterSt]

Both claim better time domain accuracy.

 

Is that so ? I thought only the NOS guys do ?

Personally I don' see how long(er) filters can imply a better time accuracy.

[PeterSt]

Originally Posted by mansr

It was supposed to be silent. The purpose was to see if it actually detected the audio bits being tampered with while leaving the control bitstream alone. Apparently it does.

 

The report (of someone else) on this was wrong-ish. The blue light does come on, but only very briefly. Throughout this stream (of IIRC 30 seconds) the decoder keeps on resetting (I counted 24 times). Also IIRC it is a 24/96 originally.

 

I'm confused by this.

 

So very well observed.

[PeterSt]

5 hours ago, Ralf11 said:

It's been 21 pages now, so has anyone been able to do that?

 

Audibly you mean ?

Many.

[PeterSt]

11 minutes ago, jabbr said:

The other 1/2 the MQA promise seems to be per DAC corrections and you’ve shown this false.

 

Of course this was meant to say : the best filter (out of 32) for the DAC of concern.

Right ?

 

[PeterSt]

 

34 minutes ago, mansr said:

The DAC then applies what is allegedly its version of the indicated filter number on playback. From the official explanations, one is led to believe that the actual filters applied by the DAC are tweaked such that a given filter number provides the same analogue output response on every DAC (the "end-to-end" spiel). The measurements and firmware dumps we've done suggest that there is in fact no such per-device tuning.

 

This sort of guessing happens when we're not told the how and what.

Let's say that my info (ok, data) tells me that what happens in a last stage of "MQA licensing" is that the DAC where the license is given for, is made suit to MQA (this is 99,99% not guessing). Next it is my own assumption that the found 32 filters exist for that reason. For me it is a logical combination of matters (so this is 99,99% guessing but say 50% plausible). 

 

That this thus NOT suit dedicated filters or whatever people may have in mind "per track", only follows from logic for me. That you thus also can not see the reality in "32 filters for all" (tracks) is again logic hence probably correct.

However, What keeps on lacking in the stories is the "deblurring", which (for me) most obviously won't happen by any of these 32 filters - the contrary (they are not counteracting filters for track data). So the "deblurring" has to happen somewhere else, and I say that it already has been done in the file (track) which is handed to us (this follows from deduction and at this moment I 100% think this is so *assumed* it happens in the first place anywhere (!)).

 

If we combine all, then the steeper transient etc. blahblah MQA files handed to us, must counteract the DAC's blurry filtering (like any large tap filter so-called "blurs") and it is done by a. upsampling with b. one of the 32 filters. That this implies (huge) aliasing is just a decision (or Meridian hobby horse).

 

Do I make sense ?

[PeterSt]

 

On 2-11-2017 at 7:46 PM, mansr said:

On 2-11-2017 at 7:38 PM, GUTB said:

Just did another MQA vs non-MQA comparison through Roon with a DFR+Jitterbug to a TH900.

 

https://tidal.com/album/78913887

 

If you can't hear the MQA version is better I don't know what to tell you.

Is it the same master? Many of the MQA versions are made from better masters, which is why they sound better.

 

I did not listen but got intrigued by the fact that the MQA version compresses 3dB more than the normal Redbook; both taken from Tidal and both have the same track lengths to the 1/100 of a second. This is the normal Redbook : https://listen.tidal.com/album/78899595.

 

This album unveils a novelty to me : the compression ratios are different per track. And let's say that I never expected such a thing (never investigated it either).

With the remark that this will be opera and will be more dynamical because of it (average SPL is relatively low but close to full digital headroom is utiliized), a few tracks carry the same compression, some differ 3 dB, more differ 5dB and some even differ 10dB.

because the two longer tracks in there (8+ and 9+ minutes) coincidentally compress the same, the average that the MQA compresses more is only 3dB.

 

Since the "functional" masters as such won't differ (I am as far as being sure about that by now), the process of creating the MQA version (the "master" we receive) must be dynamical to the content it processes. Otherwise this wouldn't differ (so much) per track.

 

The difference is so large in some tracks that I can not imagine the MQA sounding better (this was the claim of @GUTBin that thread) and on some other hand the difference in SQ should somehow be huge. So although I am not into opera at all, I am curious how these compare.

 

 

On 2-11-2017 at 7:38 PM, GUTB said:

Just did another MQA vs non-MQA comparison through Roon with a DFR+Jitterbug to a TH900.

 

https://tidal.com/album/78913887

 

If you can't hear the MQA version is better I don't know what to tell you.

 

[PeterSt]

5 hours ago, Abtr said:

Hi Peter. Like @mansr said, nearly all MQA files on Tidal are created from compressed so called remastered versions of the original.

 

No Sir, they are not. The masters are often the same, but what we receive from them are processed by MQA. However, *if* other masters as such have been used for the MQA base (for processing) they are the better ones. At least this is my own consistent finding. Never they are worse, but with this one possibly as the exception. That's why I jumped on it.

 

Btw, I tried listening to it, but it seriously is nothing for me, this opera. Maybe an other day.

 

4 hours ago, Jud said:

So these MQA tracks may be louder during softer passages.

 

Yes, that should be the case.

 

Thanks,

Peter

[PeterSt]

4 hours ago, Abtr said:

Hm.. I wish that was true. The dynamic range of so called 'remastered' albums is almost always compressed relative to the original version.

 

I fully agree with that. Now with that as a base (do not forget it), try to hear what I am telling (you) :

 

a. The "remasters" MQA uses (*if* that is the case) are the BETTER ones, not the worse ones. A sort of : back to basics. This is a good thing because now we have a better master than we were used to. It is reason alone for the MQA version to sound better.

(read again what mansr said because he says the same)

 

b. I found that in many cases (which may end up to be all cases), no real remaster as such has been used. Instead it is a processed version of one of the versions hanging around on Tidal (which in the end is one of the versions hanging around at the owning labels).

Thus, we take a version, push it through some manipulating processor, and what comes out is the version we receive. This is not a remaster; it is a processed version of an existing master and maybe we should forbid that this exists.

 

c. In either case MQA processes the file/album. So what we see is an MQA'd version and we should not call it a master of any kind. It is the opposite because it has been processed - even in lossy fashion.

 

d. Another master as such would be some mastering (up to mixing !) engineer who takes all the raw data and processes it such that it will be more bassy or whatever to his skills and liking. Usually this is not really remixing, but often the separate tracks (like for the bass guitarist) are taken and blended in differently from before.

This is NOT what MQA is doing at all, as it is impossible for the amount of work. So MQA utilizes one of the other existing masters and to my finding the best = least compressed ones. This includes ones which were never produced on to CD.

 

e. That album of the subject is the rare occasion where I see that the MQA version as delivered to us, is more compressed than the original, of which I can find one version only : on Tidal again. They are by (my) guarantee from the very same master, which is proven by the track lengths. And *because* it is the same master, it is odd to notice that MQA makes it more compressed. But why not, it processes the file(s) one way or the other.

 

New to this thread is that this works out for the better as the original one is too dynamical to my finding. Therefore it shouts or the exhaling voice is too loud for the level it requires (Crime of the Century is also unplayable for that and thinking of it, here too MQA delivers a way more compressed version - this album in native version though, does not utilize even half of the digital headroom, so it is just wrong).

 

4 hours ago, Abtr said:

if a remastered version is available, then the MQA version sounds like the compressed remastered version

 

Explicitly not my finding, with the notice that this is my preselection (and I always have real time on screen what the compression ratio is of any album I play).

More compressed albums than the ones I am used to, I don't even play (I hear it right away as well).

So what seems to be wrong with your statement is that it should say : when a least compressed version is available, MQA uses that. Even if it never saw daylight (OK, that I could find). But there is more going on, and the persons who select the "base" masters for MQAs processing, must be intelligently looking at what version to use. So if it would be "just the least compressed" then they should have taken the original Crime Of the Century. But they didn't.

[PeterSt]

5 hours ago, mansr said:

Many of the MQA albums are from different masters than their non-MQA counterparts. I did a detailed analysis of one track here:

Among other differences, the MQA version is 8 seconds longer.

 

Yes, but that was not the answer. The answer is a few posts further in there (my post). We must compare apples with apples.

 

Anyway, the moral is that the masters indeed are often different. But as often they are not, but processed by MQA (say DSP) before they get to us.

[PeterSt]

8 hours ago, JensPH said:

I tend to think, that MQA probably requires a less clipped master than the loudness ruined ones

 

Hmm ... You can well be right there but with no reason for it other than I have been thinking the very same myself . This thinking was quite explicit, but by now I forgot the how or why. Something with expansion (like emphasizing high frequencies and the digital room required for that).