Question about filters - MQA vs Hi-Res?

[Taketheflame]

Hey all,

So - I posted a thread a couple of weeks or so ago inquiring about potential DAC choices if selling the one I have to fund an MQA-compatible DAC, as I was using Tidal. I'm now giving the free trial of Qobuz a try to decide which service I want to stick with (so far, Qobuz has a few desired titles that Tidal does not, which is a plus), but noticed that Qobuz streams FLAC 24/96 instead of MQA.

Doing a bit of side-by-side comparing, there were a few MQA versions I actually liked the sound of a bit more than the 24/96 streams, but with some others, there was no real audible difference I could detect - I realize this is purely subjective, but I thought the MQA versions of stuff I preferred sounded a bit "warmer", or more lively (but both being great).

I found a technical article about how MQA works, and what caught my attention was something about how MQA uses a filter that supposedly reduces a "ringing" effect caused in all other digital audio formats when the analog waveform is reconstructed.

This has me curious - is this simply BS/marketing jargon for MQA? Don't all DACs use a filter of some type when reconstructing the analog waveform? And therefore, shouldn't it be possible to do anything MQA can (and more, as MQA supposedly isn't a truly lossless format?) with standard Hi-Res files using a filter to suit one's taste?

Just hoping to gain a better understanding of how it all works, and if MQA is all hype?

Thanks!

 

[andreasmaaan]

This has me curious - is this simply BS/marketing jargon for MQA?

Hi @Taketheflame, it is BS, but like all the best BS it's built on fragments of truth.

Don't all DACs use a filter of some type when reconstructing the analog waveform? And therefore, shouldn't it be possible to do anything MQA can (and more, as MQA supposedly isn't a truly lossless format?) with standard Hi-Res files using a filter to suit one's taste?

Yes, in theory. However, what MQA claims to be doing is using specific filters for specific recordings based on inside knowledge of the anti-aliasing filter of the particular ADC used in the recording process in the first place.

This is generally an implausible claim, as it is unlikely that only one ADC was used in a given recording, and even if it was, if the recording was done half properly, the anti-aliasing filter will not be audible anyway. Moreover, the claim appears to be in fact false, as many have tried to find evidence that MQA does this and have failed.

Also, MQA is technically (or objectively if you prefer) an inferior format to non-lossily-compressed hi-res. This is because, unlike non-lossily-compressed hi-res (e.g. WAV, FLAC, etc.), MQA lossily compresses the audio (within particular frequency bands).

In other words, a 24/96 FLAC or WAV file is higher fidelity than a 24/96 MQA file. Of course, since the lossy compression in MQA occurs only above the audio band, there is not going to be any audible difference between the two (unless they are in fact two different masters, which is another question entirely). But I just point this out to emphasise that there is nothing about MQA that makes it technically better than, let alone equal to, non-lossily-compressed hi-res.

There's lots of useful info about MQA in this thread.

 

[Tks]

Hi @Taketheflame, it is BS, but like all the best BS it's built on fragments of truth.



Yes, in theory. However, what MQA claims to be doing is using specific filters for specific recordings based on inside knowledge of the anti-aliasing filter of the particular ADC used in the recording process in the first place.

This is generally an implausible claim, as it is unlikely that only one ADC was used in a given recording, and even if it was, if the recording was done half properly, the anti-aliasing filter will not be audible anyway. Moreover, the claim appears to be in fact false, as many have tried to find evidence that MQA does this and have failed.

Also, MQA is technically (or objectively if you prefer) an inferior format to non-lossily-compressed hi-res. This is because, unlike non-lossily-compressed hi-res (e.g. WAV, FLAC, etc.), MQA lossily compresses the audio (within particular frequency bands).

In other words, a 24/96 FLAC or WAV file is higher fidelity than a 24/96 MQA file. Of course, since the lossy compression in MQA occurs only above the audio band, there is not going to be any audible difference between the two (unless they are in fact two different masters, which is another question entirely). But I just point this out to emphasise that there is nothing about MQA that makes it technically better than, let alone equal to, non-lossily-compressed hi-res.

There's lots of useful info about MQA in this thread.

I sometimes can't find coverart for some of the records I need... And MQA claims they have inside knowledge of the original anti-aliasing filter of the ADC used in the first chain of recording?

Oh that's rich..

 

[Taketheflame]

Well, in addition to the posts here, I did some digging through the MQA thread that was shared, and have come up with the following thoughts

- Any audible differences I may have heard between an MQA version of a track on Tidal versus its Qobuz counterpart (using the same DAC) would more than likely be a difference in the masters used than anything else.

- MQA doesn't appear to offer any real advantage to the consumer over existing digital formats, particularly as internet/phone technology improves and file size/download speeds become even less of an issue (if it's not that way already).

Would these be fairly sound conclusions? I'm starting to drop the idea of switching to a DAC that supports MQA - but would it still be worth having a DAC with more filter options? (Mine has 3).

 

[Tks]

Sound as sound can be. Toss high-res in there as well. In my book, so as long as you have a lossless fileformat, audible differences vanish between each format. Though I feel it's somewhat justified for piece of mind to purchase music at the format it was recorded in or produced. But aside from that. Lossless is all you will ever need. I can somewhat stomach higher res in the editing phase (having 24 bit to work with is much more forgiving than 16 bit), but in the consumer sphere, its meh.

Maybe when the need arises for 140db output at high fidelity, and Rob Watts isn't in the venue.. THEN I think 24 bit will be good to go, and no more need for dither.

Though we'll see if some of the bigger players will be able to muster a 140db SNR out of the latest chips like the 4499 in some fashion..

But in all honesty, it's just a silly curiosity on a technical level at this point. Ain't nobody outside of -300dB distortion sensitive Rob Watts that can tell any of this stuff apart. MP3 to FLAC, there are trained folks who can. FLAC CD quality vs High-Res? Haven't met a single confirmed case in all the years.

 

[BDWoody]

Would these be fairly sound conclusions? I'm starting to drop the idea of switching to a DAC that supports MQA - but would it still be worth having a DAC with more filter options? (Mine has 3).

You are on very solid ground with your conclusions.

I haven't managed to hear filter differences personally...i tried pretty hard for a while, then gave up worrying about it.

 

[maverickronin]

I haven't managed to hear filter differences personally...i tried pretty hard for a while, then gave up worrying about it.

The only one I can hear on my RME ADI-2 DAC is the NOS/AKM Super Slow.

 

[BDWoody]

The only one I can hear on my RME ADI-2 DAC is the NOS/AKM Super Slow.

I might actually be able to hear THAT...! Rolls off early enough that even my old ears might have a chance, but most start kicking in much later, at which point I'm dreaming if I think I'm hearing much...

 

[Billy Budapest]

Well, in addition to the posts here, I did some digging through the MQA thread that was shared, and have come up with the following thoughts

- Any audible differences I may have heard between an MQA version of a track on Tidal versus its Qobuz counterpart (using the same DAC) would more than likely be a difference in the masters used than anything else.

- MQA doesn't appear to offer any real advantage to the consumer over existing digital formats, particularly as internet/phone technology improves and file size/download speeds become even less of an issue (if it's not that way already).

Would these be fairly sound conclusions? I'm starting to drop the idea of switching to a DAC that supports MQA - but would it still be worth having a DAC with more filter options? (Mine has 3).

I have found ZERO audible difference between switchable audible filters on DACs that use them. Do they measure differently? Sure.

When I was a beta tester for Oppo, nobody could hear the difference between the “Steep” and “Slow” filter settings for the HA-1. Oppo ended up removing the choice in a firmware revision and just set the choice to “Steep” which was a traditional FIR filter. I don’t remember if it was a decision arrived at through discussion with the beta testers or whether Oppo just did it and nobody seemed to care.

During Oppo Sonica development, digital filters weren’t even discussed. I believe they just went with one of the minimum phase, slow roll off filters built into the ESS 9038PRO.

 

[andreasmaaan]

Well, in addition to the posts here, I did some digging through the MQA thread that was shared, and have come up with the following thoughts

- Any audible differences I may have heard between an MQA version of a track on Tidal versus its Qobuz counterpart (using the same DAC) would more than likely be a difference in the masters used than anything else.

- MQA doesn't appear to offer any real advantage to the consumer over existing digital formats, particularly as internet/phone technology improves and file size/download speeds become even less of an issue (if it's not that way already).

Would these be fairly sound conclusions? I'm starting to drop the idea of switching to a DAC that supports MQA - but would it still be worth having a DAC with more filter options? (Mine has 3).

Your conclusions are spot on IMHO

I don't bother with having DACs with different filter options. The only requirement is that at least one filter is transparent, and this is guaranteed be the case for virtually any filter in which the roll-off does not begin until above the audio band.

 

[Tks]

You are on very solid ground with your conclusions.

I haven't managed to hear filter differences personally...i tried pretty hard for a while, then gave up worrying about it.

Ive heard that ringing stuff on the NOS filter on my ADI 2. Heard it with only one Pop track though, also might've been Equalizer APO causing it (I know this software for whatever reason messes up things, sadly had to dump it after I started hearing this sort of odd wobbly ringing stuff out of the blue one day).

 

[MRC01]

...
I haven't managed to hear filter differences personally...i tried pretty hard for a while, then gave up worrying about it.

I have found ZERO audible difference between switchable audible filters on DACs that use them. Do they measure differently? Sure. When I was a beta tester for Oppo, nobody could hear the difference between the “Steep” and “Slow” filter settings for the HA-1. ...

The differences may or may not be audible, depending on the filter response and the source material you use when listening to differentiate them. Regarding the latter, I've found that square waves are pretty revealing, enabling me to differentiate filters that I could not differentiate with music. Also, high quality recordings of jangling keys. However, even when filter differences are revealed with these kinds of signals, the differences are still subtle, I can't express a preference or say which sounds more "real" or "natural" (what kind of square wave sounds natural?!), and I find even these subtle differences disappear at higher sampling rates.

That said, I don't usually listen to square waves or jangling keys for musical enjoyment. So even if one can hear the difference with certain test signals (which is satisfying and fun), the extent to which this matters for music is dubious.

 

[Count Arthur]

Some more stuff about MQA: https://www.audiosciencereview.com/forum/index.php?threads/an-interesting-talk-about-mqa.12070/

 

[Mnyb]

Why would not all DAC manufacturers just stick with what’s theoretically best ffs ?

Instead they offer a tweak menu with a dozen filters and the default filter is usually not the optimal one ?

It’s a design choice that should be made by the engineer imho , if audiophiles want knobs to twiddle why not useful ones such as tone controls

 

[MRC01]

Why would not all DAC manufacturers just stick with what’s theoretically best ffs ? ...

With 44.1 kHz sampling, the filter transition band is narrow: 20 kHz to 22.05 kHz. The standard "sharp" linear phase filter having flat FR up to 20 kHz induces some amplitude ripple in the passband. No filter is perfect, but alternative implementations can eliminate or reduce that amplitude ripple at that cost of phase shift, or non-flat FR (rolling off early). Most DACs have several different filter choices built into the chip itself, so the implementer/designer can pick one. In the few DAC chips whose data sheets I've read out of curiousity, a standard linear phase "sharp" filter is always one of the choices, along with a few alternatives. The alternatives are typically linear vs. minimum phase, with fast or slow rolloff, making 4 combinations.

PS: here's some home-grown measurements I made with my DAC. It uses the WM8741, which has 5 digital filter choices, and the DAC has a switch you can select "fast" or "slow". My goal was to see if I could figure out which of the 5 digital filters the switch was selecting. I don't have any fancy measuring equipment, just a sound card, so my resolution is limited. But I think it was sufficient to figure it out.
http://mclements.net/blogWP/index.php/2019/12/24/corda-soul-wm8741-dac-filters/

 

[Count Arthur]

I haven't managed to hear filter differences personally...

I can, but it's pretty subtle. If someone changed it while I was out of the room, I wouldn't notice when I came back in, but I can hear a slight change as I switch between them. I set it to sharp when I first got the DAC and haven't bothered with it since.

 

[maverickronin]

Why would not all DAC manufacturers just stick with what’s theoretically best ffs ?

Instead they offer a tweak menu with a dozen filters and the default filter is usually not the optimal one ?

It's all marketing specifically to cater to audiophile myths. It's so bad that all those different filters are built into the DAC chips themselves. Management is making the engineers include technically inferior options as features because (they think?) it will sell more chips

Most DACs that let's you change filters like that now are just sending a signal to the DAC chip and telling it to use a different built in filter.

 

[Veri]

Most DACs that let you change filters like that now are just sending a signal to the DAC chip and telling it to use a different built in filter.

Well of course

 

[Mnyb]

There must be some optimum for each samplerate ?
Would not remove all aliases be no 1 prio while keeping flat fr in the audible range ? Is not ringing pre or post a red herring as it all take place above human hearing .

Now ripple inside the audible spectrum will be an issue, but does it exist since the 80’s

 

[Jimbob54]

I can, but it's pretty subtle. If someone changed it while I was out of the room, I wouldn't notice when I came back in, but I can hear a slight change as I switch between them. I set it to sharp when I first got the DAC and haven't bothered with it since.

My wife can hear a filter change before I push the button. She can also hear when I press ALT TAB. Not good.