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Interesting Observations about MQA and Tidal's software


bcwang
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With the Tidal release, we get to have access to many MQA files. With this, I started to notice some oddities which bring up some questions that may lead to interesting discussion.

 

1. Many MQA files are actually 1x sample rate (44.1 or 48khz), especially the modern pop albums. This is confirmed by the single blue light seen on the Explorer 2. Nothing wrong with that fact. However, the Tidal App will upsample these to 88.2 or 96khz as I can see in my Geek Pulse display. I wonder why it does that. Hmm...

 

2. I notice some files on Tidal don't seem to match the original source files it seems. For example, the album "Mozart Violin Concertos (MQA Remix) by Marianne Thorsen. On my Geek Pulse, it shows 88.2khz. But the original versions of the PCM files on the 2L site seem to be based on 48khz sample rates. Thus I would expect to see 96khz on the Geek Pulse. Strange... I wish I had an MQA Dac that could display the exact sample rate and bit depth so I could really confirm it's not some strange Tidal App bug doing sample rate conversion to non integer multiples.

 

3. Tidal by default will unfold files to high resolution in software before passing it to the DAC unless you select "Passthrough MQA". With a high resolution file, a non-mqa dac will get 44.1khz or 48khz sample rates if checked, and 88.2 or 96khz sample rates if unchecked. However, even if the box is unchecked (which should pass unfolded high resolution data) to the dac, the MQA capable dac will still get the blue light. I thought of a few ways this could happen:

 

a: Tidal detects the MQA capable dacs and ignores the checkbox, sending original bits to the MQA DAC.

 

b: There is a way to unfold the stream to higher resolution while maintaining MQA authentication as it is passed along to the DAC

 

sidenote: With a 44.1khz MQA file, when the "passthrough MQA" is unchecked, a non-MQA dac plays at 88.2khz, but the MQA Explorer2 still plays back at 1x 44.1khz. This leads to "a" being more likely what is happening.

 

4. It seems Tidal has some albums which have both the Master and HIfi versions. But there are also albums (notably the 2L catalog) which you can only find the MQA versions. So comparisons of versions won't be easy. However, on the iphone (and probably android), those same albums are playing back with the HIFI version without MQA. So that is one way to access them for now to compare. I'm not sure what will happen once the tidal app on the mobile devices get updated to support MQA files. I wonder if the reason they haven't released the mobile versions yet is because they want to enable higher sample rates and not only support MQA passthrough. I would think it could already play the MQA stream as plain PCM now if it wanted to.

 

5. Everyone talks about comparing 44.1khz CD files with high resolution MQA files and whether the MQA process sounds worse without a decoder. But there has been no discussion about whether a 44.1khz MQA file (final resolution) is going to be better or worse than a CD resolution version.

 

Supposedly the MQA process truncates the bit depth of and uses those to encode the high frequency parts in the noise floor. But with a 44.1khz final resolution MQA file, this isn't necessary right? So I wonder if it's still done. If not, then how different is the MQA file playback going to be from a CD file on non-mqa hardware? You don't have the advantage of higher sample rates unless somehow being in MQA mode, the DAC is operating at it's highest sample rates even when the input file is 44.1khz resolution to do the temporal response thing.

 

So it kind of brings up two questions.

a. Does a 44.1khz MQA file sound better than a CD quality file on a non-mqa DAC?

(The encode time deblurring helping maybe, but what about effective bit depth being possibly reduced)

 

b. Does a 44.1khz MQA file sound better on an MQA DAC compared to a CD quality file?

(Since you aren't getting the hi-res unfolding)

 

I'm not sure, I've seen no analysis done on this type of MQA file. Hope someone will eventually analyze these in detail and post about it.

 

6. I'm really interested to know how much difference a full MQA feature on a DAC makes to know how important it is to get hardware MQA. But with what I have at least, it is not possible to get an apples to apple test. If I compare a CD quality file with an MQA file, the deblurring process changes the sound so you are getting a culmination of improvements. If I try to play the same MQA file, one on an MQA dac and one on a non-MQA dac, now the DAC itself being different skews those results.

 

So I think the only way is for someone who has hardware that can turn MQA decoding on or off can do a real apples to apples comparison of how much improvement the "dac compensation" part of MQA makes. (compare 44.1khz MQA file to remove the hi-res from being a factor). They can also test how much MQA decoding added to a DAC can make to MQA files with full hi-res improvements using hi-res MQA files. This is a kind of test that can possibly show if it's worth it for hardware manufacturers to add MQA. I believe the Mytek Brooklyn has a way to disable the MQA decoding, so those of you who have that could try it out and report back to the rest of us. This would also help gauge how much non-MQA dac owners are losing with software MQA decoders without "dac compensation"

 

That's it for now! Continuing to enjoy MQA streaming through my system as I write this rather than do constant A/B compares.

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2. I notice some files on Tidal don't seem to match the original source files it seems. For example, the album "Mozart Violin Concertos (MQA Remix) by Marianne Thorsen. On my Geek Pulse, it shows 88.2khz. But the original versions of the PCM files on the 2L site seem to be based on 48khz sample rates. Thus I would expect to see 96khz on the Geek Pulse. Strange... I wish I had an MQA Dac that could display the exact sample rate and bit depth so I could really confirm it's not some strange Tidal App bug doing sample rate conversion to non integer multiples.

 

 

Oops, I just noticed there is a 352.8khz DXD version of this file which must be the original master version. I guess it's 2L doing the non integer sample rate conversion for most of their PCM downsampled versions. Only the DXD and MQA preserve the original sample rate.

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With the Tidal release, we get to have access to many MQA files. With this, I started to notice some oddities which bring up some questions that may lead to interesting discussion.

 

1. Many MQA files are actually 1x sample rate (44.1 or 48khz), especially the modern pop albums. This is confirmed by the single blue light seen on the Explorer 2. Nothing wrong with that fact. However, the Tidal App will upsample these to 88.2 or 96khz as I can see in my Geek Pulse display. I wonder why it does that. Hmm...

 

2. I notice some files on Tidal don't seem to match the original source files it seems. For example, the album "Mozart Violin Concertos (MQA Remix) by Marianne Thorsen. On my Geek Pulse, it shows 88.2khz. But the original versions of the PCM files on the 2L site seem to be based on 48khz sample rates. Thus I would expect to see 96khz on the Geek Pulse. Strange... I wish I had an MQA Dac that could display the exact sample rate and bit depth so I could really confirm it's not some strange Tidal App bug doing sample rate conversion to non integer multiples.

 

3. Tidal by default will unfold files to high resolution in software before passing it to the DAC unless you select "Passthrough MQA". With a high resolution file, a non-mqa dac will get 44.1khz or 48khz sample rates if checked, and 88.2 or 96khz sample rates if unchecked. However, even if the box is unchecked (which should pass unfolded high resolution data) to the dac, the MQA capable dac will still get the blue light. I thought of a few ways this could happen:

 

a: Tidal detects the MQA capable dacs and ignores the checkbox, sending original bits to the MQA DAC.

 

b: There is a way to unfold the stream to higher resolution while maintaining MQA authentication as it is passed along to the DAC

 

sidenote: With a 44.1khz MQA file, when the "passthrough MQA" is unchecked, a non-MQA dac plays at 88.2khz, but the MQA Explorer2 still plays back at 1x 44.1khz. This leads to "a" being more likely what is happening.

 

4. It seems Tidal has some albums which have both the Master and HIfi versions. But there are also albums (notably the 2L catalog) which you can only find the MQA versions. So comparisons of versions won't be easy. However, on the iphone (and probably android), those same albums are playing back with the HIFI version without MQA. So that is one way to access them for now to compare. I'm not sure what will happen once the tidal app on the mobile devices get updated to support MQA files. I wonder if the reason they haven't released the mobile versions yet is because they want to enable higher sample rates and not only support MQA passthrough. I would think it could already play the MQA stream as plain PCM now if it wanted to.

 

5. Everyone talks about comparing 44.1khz CD files with high resolution MQA files and whether the MQA process sounds worse without a decoder. But there has been no discussion about whether a 44.1khz MQA file (final resolution) is going to be better or worse than a CD resolution version.

 

Supposedly the MQA process truncates the bit depth of and uses those to encode the high frequency parts in the noise floor. But with a 44.1khz final resolution MQA file, this isn't necessary right? So I wonder if it's still done. If not, then how different is the MQA file playback going to be from a CD file on non-mqa hardware? You don't have the advantage of higher sample rates unless somehow being in MQA mode, the DAC is operating at it's highest sample rates even when the input file is 44.1khz resolution to do the temporal response thing.

 

So it kind of brings up two questions.

a. Does a 44.1khz MQA file sound better than a CD quality file on a non-mqa DAC?

(The encode time deblurring helping maybe, but what about effective bit depth being possibly reduced)

 

b. Does a 44.1khz MQA file sound better on an MQA DAC compared to a CD quality file?

(Since you aren't getting the hi-res unfolding)

 

I'm not sure, I've seen no analysis done on this type of MQA file. Hope someone will eventually analyze these in detail and post about it.

 

6. I'm really interested to know how much difference a full MQA feature on a DAC makes to know how important it is to get hardware MQA. But with what I have at least, it is not possible to get an apples to apple test. If I compare a CD quality file with an MQA file, the deblurring process changes the sound so you are getting a culmination of improvements. If I try to play the same MQA file, one on an MQA dac and one on a non-MQA dac, now the DAC itself being different skews those results.

 

So I think the only way is for someone who has hardware that can turn MQA decoding on or off can do a real apples to apples comparison of how much improvement the "dac compensation" part of MQA makes. (compare 44.1khz MQA file to remove the hi-res from being a factor). They can also test how much MQA decoding added to a DAC can make to MQA files with full hi-res improvements using hi-res MQA files. This is a kind of test that can possibly show if it's worth it for hardware manufacturers to add MQA. I believe the Mytek Brooklyn has a way to disable the MQA decoding, so those of you who have that could try it out and report back to the rest of us. This would also help gauge how much non-MQA dac owners are losing with software MQA decoders without "dac compensation"

 

That's it for now! Continuing to enjoy MQA streaming through my system as I write this rather than do constant A/B compares.

There won't be an apples to apples on/off switch, because such a thing would underline what a wasteful, vapid, and condescending lie MQA is.

 

Sent from my SAMSUNG-SM-G891A using Tapatalk

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7. Another observation, if your DAC does not support 88.2khz sample rates (like the oDAC), Tidal will switch from exclusive mode on your sound device of choice back to the Windows System Default if it encounters an MQA song with a sample frequency that is a multiple of 44.1khz. Thus you lose bitperfect playback for that song and subsequent songs until you switch it back to the proper DAC choice. But this required restarting the Tidal app to make the switch back to exclusive mode successful.

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3. Tidal by default will unfold files to high resolution in software before passing it to the DAC unless you select "Passthrough MQA". With a high resolution file, a non-mqa dac will get 44.1khz or 48khz sample rates if checked, and 88.2 or 96khz sample rates if unchecked. However, even if the box is unchecked (which should pass unfolded high resolution data) to the dac, the MQA capable dac will still get the blue light

 

There are two processes of MQA decoding that collectively comprise "complete decoding".

 

The Tidal desktop app is doing the "MQA Core" processing. A completely MQA-capable DAC will still perform the "MQA Renderer" function if passed the output of the "MQA Core" decoding. This is essentially why the blue light is illuminated in this example.

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There are two processes of MQA decoding that collectively comprise "complete decoding".

 

The Tidal desktop app is doing the "MQA Core" processing. A completely MQA-capable DAC will still perform the "MQA Renderer" function if passed the output of the "MQA Core" decoding. This is essentially why the blue light is illuminated in this example.

The actual point I was making with #3 is reflected in point A and B below it. The strange part is Tidal is sending 88.2khz data to the DAC when software decoding is on, but with an MQA dac connected, it shows a single blue light on the explorer 2 which means playback at 44.1khz rates. That is what led to point A and B as speculation to what is actually happening.

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There won't be an apples to apples on/off switch, because such a thing would underline what a wasteful, vapid, and condescending lie MQA is.

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

Can you elaborate on your quote? Where's the wasteful, vapid and condescending lie of MQA? May make for a good discussion :)

PC/NAS/JRiver/Roon - PS Audio P5 Regenerator - KEF LS50 Nocturne - Rel 328 subwoofer - PS Audio AC5 Power cables 

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The actual point I was making with #3 is reflected in point A and B below it. The strange part is Tidal is sending 88.2khz data to the DAC when software decoding is on, but with an MQA dac connected, it shows a single blue light on the explorer 2 which means playback at 44.1khz rates. That is what led to point A and B as speculation to what is actually happening.

 

I've seen some similar things in my experimenting as well. Either MQA Core is behaving differently in software and hardware, or the Explorer 2's lights are wrong.

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  • 2 weeks later...

Looks like with the latest tidal update, the explorer2 doesn't detect as an mqa dac and the "pass through" option being deselected will cause tidal to send a 2x rate (88.2, 96) data stream from mqa files, which will not turn the blue light on anymore.

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Can you elaborate on your quote? Where's the wasteful, vapid and condescending lie of MQA? May make for a good discussion :)

Hmm check out the multiple threads with MQA bashers talking to themselves. Let's not get a perfectly good thread off track.

 

Sent from my Nexus 5X using Tapatalk

FLAC -> Jplay-> Jkeny Mk3 -> Audio-GD Ref 5->Hornshoppe Truth -> Music Reference EM7-> Hornshoppe Horned Heils

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Hmm check out the multiple threads with MQA bashers talking to themselves. Let's not get a perfectly good thread off track.

 

Sent from my Nexus 5X using Tapatalk

 

I agree, but your quote did just that. The OP stated that they like MQA for the most part and had some interesting questions that they thought maybe answered. Then you say "There won't be an apples to apples on/off switch, because such a thing would underline what a wasteful, vapid, and condescending lie MQA is." To me, and I could have read the meaning in your sentence wrong, were putting down the technology and company. I thought you were bashing MQA also like the other threads. So my apologies if I miss took you stance or meaning in your response. :)

PC/NAS/JRiver/Roon - PS Audio P5 Regenerator - KEF LS50 Nocturne - Rel 328 subwoofer - PS Audio AC5 Power cables 

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It doesn't.

 

You may want explain before you confuse more posters. Like it's no longer lossless it's lossy or what ever your reason is. This will help clear the confusion, thanks.

 

 

Sent from my iPad using Computer Audiophile

PC/NAS/JRiver/Roon - PS Audio P5 Regenerator - KEF LS50 Nocturne - Rel 328 subwoofer - PS Audio AC5 Power cables 

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You may want explain before you confuse more posters. Like it's no longer lossless it's lossy or what ever your reason is. This will help clear the confusion, thanks.

 

In its undecoded form, MQA definitely falls short of CD quality with considerable noise upwards of 15 kHz less than 15 bits of resolution. The first-stage decoding (as done by the Tidal player) improves things but still falls short of the original simply downsampled to 88.2 or 96 kHz. The "rendering" available only on compatible DACs actually makes things even worse by introducing severe aliasing and high-frequency noise. See this thread for more in-depth discussion: http://www.computeraudiophile.com/f8-general-forum/mqa-technical-analysis-31311/

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In its undecoded form, MQA definitely falls short of CD quality with considerable noise upwards of 15 kHz less than 15 bits of resolution. The first-stage decoding (as done by the Tidal player) improves things but still falls short of the original simply downsampled to 88.2 or 96 kHz. The "rendering" available only on compatible DACs actually makes things even worse by introducing severe aliasing and high-frequency noise. See this thread for more in-depth discussion: http://www.computeraudiophile.com/f8-general-forum/mqa-technical-analysis-31311/

 

Just to add/clarify - mansr here is using a technical definition of "resolution" as applied to digital audio (essentially a mathematical one). Other posters here use "resolution" primarily in a euphonic way, or even in a marketing sense.

 

Noting this before all the talking past one another begins... ;)

Hey MQA, if it is not all $voodoo$, show us the math!

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