MQA Discussion

[still-one]

A very comprehensive Q&A with Bob Stuart regarding MQA has just been posted on the Computeraudiophile site. This is going to take some time to get through.

 

[es347]

..also a couple of lengthy articles in this months TAS. Harley is very high on it saying he thinks it will become the standard. We shall see..

 

[jfrech]

Wow, a lot to read through. I have a 3 hour flight tomorrow...will sort through the CA article and TAS. Hoping one of us gets to hear this soon...

Jim, you might be first up given your Meridian front end...

 

[Ken Newton]

I just skimmed through the interview and the MQA foundational AES paper published in 2014. MQA spans technological areas ranging from audio codec requirements to content distribution. However, a few technical details caught my eye as an amateur DAC designer. Stuart makes clear in that AES paper his conclusion that brickwall anti-alias and reconstruction filters blur transient information to a degree the can ear perceive. http://www.aes.org/tmpFiles/elib/20160408/17501.pdf

Along with specifying technical paramters for minimum sample rate, maximum bit-depth, noise-shaping, etc., the AES paper presents an integrated system (recording through to playback) which minmizes transient bluring, even capturing transient timing which occurs in less than one sampling interval. What Stuart proposes is to utilize non-ringing anti-alias and reconstruction filters. The example shown in the paper is a filter having a triangular impulse response (which has no ringing), as has a moving average digital filter. The triangular impulse response of the anti-alias filter at recording will convolve itslef with the triangular impulse response of the reconstruction filter at playback to produce an overall 3rd order B-spline function response (which still has no ringing yet has a higher order slope than a purely triangular impulse response filter. Being very much akin to an Bessel response analog filter.). What's the fly in this ointment? Well, triangular function filters are not near as sharp as SINC function filters. Which means that the MQA anti-alias filter will pass some alias products! If I correctly understood what was being claimed in the paper, any alias products are said to be held below the system noise floor.

On the DAC side, the paper essentially says that having no reconstruction filter provides the best transient resolution. Good news for NOS DAC fans, but that some filtering is prudent for reducing the fast slewing stair-step output signal of the DAC chip, so long as such filter adds none or minimal ringing of it's own.

 

[amirm]

MQA analyzes the spectrum of high-resolution music and will find per very little reaching out to the nyquist frequency but very low level noise. That is how it gets its efficiency. So other than pathological cases, I don't think there is any danger of aliasing.

 

[Rodney Gold]

well, meridian have predicted that everyone will own dsp active speakers , bet wrongly on dvd a , touted apodising as the next best thing , had a proprietary losseless packing scheme mlp which didnt take off, has their own bass thingy called EBA , and now MQA is the next best thing since sliced bread .. based on their record .. Im not so sure it will take off ..maybe thats why they hived it off from meridian itself

I have listened to the few available mqa encoded sample files and it does sound better than redbook played on a NON mqa dac.
Big problem for me is that you cannot do any digital manipulation of the signal at all .. so no DRC ...
MQA and a super limited library vs digital Room correction ... hmmm.... no contest for me

Make no mistake , I am a meridian fan.. had many of their speakers and units , still have a set of dsp actives etc

 

[vjayh]

I still think the big market for MQA ultimately is streaming. The much smaller file size relative to hi-res PCM or DSF files makes it much more practical (even with internet bandwidth available now). But of course same problem, we have to have the record companies buy in, and I'm sure that's an interesting negotiation to say the least. I've been playing around with the limited MQA files that are available on 2L (downloaded 4-5) and I've been impressed so far. The few that are available in multiple high res formats seem to be better in MQA than the other formats-- of course understanding that it's on a Meridian DAC (818v3) and doesn't do DSF so no way to compare there.

Anyway, I'm optimistic that this could get some momentum given the quality but agree with the prior comments it needs some momentum via record labels' support or I'm afraid it won't make it. BTW, I am doing DRC with my Meridian 818v3, but having to do A/D and D/A with outboard DRC unit-- as Rodney's post indicates, you can't to my knowledge manipulate an MQA digital file. Still better than no DRC at all for me, given I have some room limitations that I can only treat so much. As an aside, room correction is the one area in Meridian where I feel like they are falling behind the competition where they used to be leaders. Correction like DIRAC would be nice to have Meridian incorporate into their products, which tend to be more "proprietary". Here's hoping with their next generation of processor they improve...

 

[Fitzcaraldo215]

well, meridian have predicted that everyone will own dsp active speakers , bet wrongly on dvd a , touted apodising as the next best thing , had a proprietary losseless packing scheme mlp which didnt take off, has their own bass thingy called EBA , and now MQA is the next best thing since sliced bread .. based on their record .. Im not so sure it will take off ..maybe thats why they hived it off from meridian itself

I have listened to the few available mqa encoded sample files and it does sound better than redbook played on a NON mqa dac.
Big problem for me is that you cannot do any digital manipulation of the signal at all .. so no DRC ...
MQA and a super limited library vs digital Room correction ... hmmm.... no contest for me

Make no mistake , I am a meridian fan.. had many of their speakers and units , still have a set of dsp actives etc

Rodney, I agree completely. I have not seen a Stuart comment on peaceful coexistence between MQA and digital room correction. So, I might be wrong. I have a hunch it might be possible, if MQA's unzipping of its file compression were made available in software for use before the DRC. I think it would still need an MQA-enabled DAC to take full advantage of MQA on the playback side. Otherwise, through an ordinary DAC, we would only gain its correction of the a-d during recording production. Still, half a loaf might be better than none. Time will tell.

 

[still-one]

Rodney, I agree completely. I have not seen a Stuart comment on peaceful coexistence between MQA and digital room correction. So, I might be wrong. I have a hunch it might be possible, if MQA's unzipping of its file compression were made available in software for use before the DRC. I think it would still need an MQA-enabled DAC to take full advantage of MQA on the playback side. Otherwise, through an ordinary DAC, we would only gain its correction of the a-d during recording production. Still, half a loaf might be better than none. Time will tell.

Look at Question 65.
His answer is yes, it works with Room Correction.

 

[jfrech]

Jim, is their a upgrade path for your 808? A new card or something? Are you considering this? Looking forward when our WBF members can hear it...

 

[still-one]

Jim, is their a upgrade path for your 808? A new card or something? Are you considering this? Looking forward when our WBF members can hear it...

Yes there is a upgrade path for my 808 that will allow for MQA. The upgrade from v3 to v6 also includes the v5 changes to a linear power supply, swap to ID41 card plus a new digital in card, new digital out card and new analog out card. I have been waiting to see what MQA content will be released and whether Tidal will be streaming MQA as planned. I am hoping for new releases and not the SOS we see from other hi-rez and DSD sites.

 

[Fitzcaraldo215]

Look at Question 65.
His answer is yes, it works with Room Correction.

I read the Stuart response, and I thought he was eloquent and fairly forthright at this juncture, when obviously many product details are still under development by MQA and its licensees. He is an impressive dude, and I think the technology is equally impressive. There will always be naysayers, as with this as its still in a somewhat nebulous, early anticipation stage. Much of that antagonism comes from DSD afficianados, who can abide nothing else, and for whom MQA might become a serious threat.

There are still questions about how exactly it can work with Room Correction in terms of marketable products. Conceptually, it appears to be in line with my speculation. But, I need the phase 1 MQA processing to be in software on my PC as opposed to being in a separate hardware box. It is still not clear which way they are planning to go. Maybe they will do it both ways.

Or, Maybe, they will design it such that both Phase 1 and Phase 2 MQA processing can only be done inside a closed box MQA-enabled A/V processor, where the processors' own DSP EQ is internally performed in between the two MQA stages. This seems most likely, at least at the outset. So, probably we will see Denon, Marantz, Onkyo, etc. Mch AVRs and prepros as some of the initial products that support MQA plus EQ. Those guys love to be able to put yet another logo'ed feature on their front panels and their spec sheets. Yes, Meridian, Datasat, Trinnov, etc. will likely do it, too, likely more slowly, except for Meridian. But, that will not help me or others who do EQ on their PC, unless they split out the phase 1 processing in PC/Apple/Linux software versions.

 

[bmoura]

I still think the big market for MQA ultimately is streaming.

Meridian is saying that in their demos these days. Namely that Streaming is the headline with MQA due to its reduction in file size vs. sound quality.
From a sound quality perspective, my listening to MQA encoded material at Meridian's MQA demo reveals that you can get better sounding music from the DSD 64 and 24/96 music files vs. their MQA encoded editions.

 

[jkeny]

I heard an MQA demo today

First off, I think the setup was sub-optimal - The Bluesound device (which was the MQA decoder) had an internal disk from which some of the songs were being played but others were being streamed from Tidal. I think some of the MQA files played were streamed but I don't know for sure. They were using the internal DAC of the Bluesound - ESS, maybe? They were also using vol control on the Bluesound device - digital vol control?

Anyway, I couldn't hear any obvious difference with one track - Sultans of Swing track but on another track - an Ella & Louis track (can't remember which one) stood out as very noticeably better in MQA (don't believe there were any sample rate differences between these tracks!). Non-MQA sounded by comparison slightly thin-sounding, slightly sibilant, a bit white-washed. MQA version was full sounding, deeper soundstage, more textured, more believable

I guess one needs to live with it for a while to be sure - as always using it on your own system over an extended period is the only way to finally judge

 

[vjayh]

From a sound quality perspective, my listening to MQA encoded material at Meridian's MQA demo reveals that you can get better sounding music from the DSD 64 and 24/96 music files vs. their MQA encoded editions.

I've not been able to listen to a direct comparison of the same material in MQA vs. DSD 64. Is there a DAC that would do both? My Meridian 818v3 will do 192/24 and of course MQA, but not DSD. So you would have to listen on 2 different DACs I think? Which would introduce other variables. I have listened to some of the the 2L files in MQA vs. 192/24 and I thought MQA was superior, but still very limited ability to demo given lack of MQA encoded material.

 

[still-one]

I've not been able to listen to a direct comparison of the same material in MQA vs. DSD 64. Is there a DAC that would do both? My Meridian 818v3 will do 192/24 and of course MQA, but not DSD. So you would have to listen on 2 different DACs I think? Which would introduce other variables. I have listened to some of the the 2L files in MQA vs. 192/24 and I thought MQA was superior, but still very limited ability to demo given lack of MQA encoded material.

Just to clarify according to the current 808v6 sheet the unit will play DSD via DOP, is that the same for your 818v3 or has the update not been released as of now?

 

[Jeff Fritz]

Here is Doug Schneider on MQA in his latest editorial:

http://www.soundstagehifi.com/index.php/opinion/954-myriad-questions-about-mqa

Thanks,

 

[amirm]

Here is Doug Schneider on MQA in his latest editorial:

http://www.soundstagehifi.com/index.php/opinion/954-myriad-questions-about-mqa

Thanks,

Very good article! Answering Doug's question, MQA is perceptually lossless. Not mathematically. If done perfectly, it should be equiv. to mathematically lossless.

 

[Rodney Gold]

Certainly , DRC will not work in the way we do it nowdays
My DIRAC or Acourate or simple PEQ RC wont work at all as far as I can see

 

[das]

Very good article! Answering Doug's question, MQA is perceptually lossless. Not mathematically. If done perfectly, it should be equiv. to mathematically lossless.

Hi Amirim,

Though some might disagree with me, I would never called "perceptually lossless" lossless. Lossless means you don't lose anything -- and in this case you do. Now, one could argue that you can't tell, but it is still, on a bit-for-bit comparison, not truly lossless, which is what I was talking about. And if you encode perceptually lossless over and over again, you'll lose more and more. So I think using the term lossless is misleading. If something is grey, it's not black or white -- it's grey. It's either truly lossless or not.

For those wondering what "perceptually lossless" means, this video (which uses it in a video context) gives a good enough explanation.

Doug Schneider
SoundStage!