MQA explanations wanted - fundamentalists need not apply


(simon arnold) #81

Off course I compared and no your completely misunderstanding. The same album is on Qobuz as a hires master of 44.1/24 the same album on Tidal is an MQA master of 44.1/24 which in Roon unfolds to 88.2/24 and this sounds better than either the base 44.2/24 on both services. If you turn of MQA decoding you get the base 44.1/24 flac container and to me sounds the same as the 44.1/24 flac on Qobuz.


#82

If you look carefully, MQA is authenticated at 44.1k, not 88.2k. So this means the original recording master is done on 44.1k. MQA decoder always output at fixed 2x stream (88.2/96k) irregardless whether original recording (Master) is 44.1/48k or higher 88.2/96k or 176.4/192k.

It doesn’t mean the MQA decoder output at 2x stream (88.2/96k) is better SQ, in this case it is actually up-sampling.


(Mark) #83

LOL. Professional monitors are just as subject to the vagaries of speaker compromise as any other. They are optomised for a particular type of listening environment, but they’re rarely the type of speaker that would excel in the home environment. They are not “virtually transparent”, though.


#84

According to MQA, no.

Again, MQA would disagree with you and assert that studio monitoring is anything but transparent (and has always been flawed).

Here’s why:

MQA’s (at the time, Meridian’s) studio-based experiments revealed a tremendous amount of time-domain smearing with the simplest (very) high quality studio mic --> A/D --> D/A --> loudspeaker chain. In fact, the breadth of the impulse response was of an order of magnitude (10x) greater than the final MQA system, and with far more leading edge uncertainty.

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You may not think that this matters, but I do. That’s not to say that MQA-encoded recordings automatically sound better than the PCM master, but the potential is significant for great recordings and masterings, particular those made in a live acoustic.


(simon arnold) #85

Still sounds better to me. As we know SQ is very subjective. I prefer the SQ of the MQA I used to test compared to equivalent on Qobuz.But I have heard others that suck as I already mentioned on here, Does not mean I am correct or wrong or the same goes for you. But should we be making outright judgements and say MQA is better than the PCM or the other way around.

Overall its just an opinion as is yours. We will beg to differ as will countless others who argue network and power cables improve SQ when to me they have never made one bit of a difference. Perhaps i prefer the MQA filters and the upsampling involved here is better from my DAC which in ll honesty i normally can’t notice a difference when I have used upscaling.


(Jeremy) #86

This is a claim by Meridian. They happen to be trying to sell something. As far as I am concerned their claim is not supported by any evidence. 50 years of digital audio and nobody worried about this “smearing” because we don’t need to.

They appear to be using an apodizing filter or window (Hann or Hamming etc) to alter the amount of ringing of the impulse response. Nothing magic. I used these filters in a physics thesis 35 years ago - everyone did in time series analysis. Nothing was missed by Sony Philips engineers back in the late 70’s and early 80’s. For excellent reasons these engineers stuck to the mathematics at the time (same mathematics today) and did not time smear the audio with minimum phase and apodizing filters. Computational power has simply increased today so we can do better brick wall filtering. Clock accuracy/timing and elimination of jitter has also improved. 21 bit resolution is possible in analog electronics where 16 bit was more common back then. All to say, digital and analog technology has improved but there has been no fundamental advances. Absolutely NO change in our fundamental understanding of the physics - just better performance from the gear.

The pre-ringing of a brick wall filter isn’t actually audible because it sits just above 20KHz. So why do MQA proponents show an irrelevant picture of the sort you display above? (Picture is true but it isn’t relevant to audio as we can’t hear the ripples of the impulse since the frequency is too high) I can tell you Why: because they want to sell you the idea that we need to correct something that doesn’t need correcting to begin with. It is a technology in search of problem only there isn’t a problem.

Worse than that. MQA isn’t benign it is actually detrimental. Minimum phase filters (changes the pre-ringing to post rigging) and apodizing fillters (shortens the ringing) BOTH cause phase errors!!! Phase is something that Sony/Philips and any decent audio engineer have tried to preserve accurately for 50+years! Why? I can tell you why: changing phase is most definitely audible especially with harmonically related tones. So what you and others are probably hearing and subjectively liking is the added phase distortion. I know it is there because I can hear it and because I know the mathematics and can see from the shape of the impulse spectrum that they are mucking about with audio phase across the audible band. Just look at the width of the central frequencies in the impulse of the MQA spectrum - it is much broader than the well defined peak of the linear phase spectrum. This broadening is time smearing or blurring of the audio. Images of the impulse wavelet as marketed by MQA also tell us that it is using a minumum phase filter that will delay higher frequencies with respect to lower frequencies - damaging phase harmonic relationships critical to timbre.

The whole MQA concept is a step backwards for accuracy in high end audio. It is actually damaging music quality. Thankfully it seems to only degrade higher frequency stuff largely outside the mid range meat and potatoes of music - so I believe that most of the phase distortion is probably around 10KHz or so. Violin, percussion and ambience might be affected most. Presence region and up.


#87

I disagree with so much of your post, it’s hard to know where to begin. There is plenty of peer-reviewed evidence if you choose not to dismiss/ignore it. You have set out your stall. No point discussing this further.


#88

Again this is based on their claims, another one from MQA. Time domain correction is NOT making the recording transparent but it reduces the effects of ‘ringing’ and improve transients response. However, the downside to this is it creates aliasing and intermodulation distortion (frequency domain) effects in the audio range due to use of ‘leaky’ MQA filter (minimum phase slow roll off) These artifacts will effect the music we hear.

My question to you is why MQA sounds so much different from the original master? MQA advertised as ‘Studio Sound’ then it should sound virtually the same. So what is reason behind all these? Is the de-blurring effect, lossy compression or aliasing plus intermodulation distortion causing it? Until this can be proven, I will always stick conventional way of doing proper recording and playback; using linear phase sharp cut-off filter for both ADC and DAC.

We need keep an open mind on claims until another independent panel can prove this otherwise.


(Henry) #89

Hi, where is the evidence that MQA sounds, in your own words, so much different? Bearing in mind few of us here have ever heard a real studio master at a mixing desk or anywhere for that matter.


#90

You don’t have to be in the mixing desk to do the comparison. We have original master as well as MQA downloads of the same album. A good place to try out is…

I tried the same album from original master DXD vs MQA, both have different SQ. For MQA, I’ve tried on a Mytek Brooklyn (Full MQA decoding) and also Holo Spring DAC (No MQA) with Roon own MQA decoding. In almost all the subjective listening sessions done by me and my few colleagues, we are able to consistently hear the difference. This is done at the highest sampling available at 352.8k.

Having said in my last few posts, MQA has a typical sound signature that is almost not present in the original recording, in this case DXD. My assertion is to not argue which one sound better but why it sounds different.


(Henry) #91

OK, it was a genuine enquiry. I have personally made similar comparisons and not had that same experience but I will revisit them and listen again. It is always possible my reproduction chain was lacking as my only full MQA DAC is an Explorer 2, but I do have an ace or two I didn’t have back then.


(Jeremy) #92

No worries. You may disagree in that you prefer the sound of MQA processed music. A preference there would be a matter of taste. However if you have an understanding of physics, mathematics and audio engineering then I welcome any critique or correction for the factual aspects in my comments.

Note I did not say that the manipulation by MQA is false. What they do is fairly clear (minimum phase and apodizing filter). What is false are the claims that this is beneficial to what we hear. We are talking about corrections to inaudible frequencies and in exchange they are willing to introduce phase shift in the audible band. Phase distortion is actually detrimental to harmonically related signals. I did not discuss the lossy aspect but I know that compression algorithms if correctly designed can be mostly inaudible so I don’t have much of a beef with that aspect of MQA.


(Jeremy) #93

Two words: Phase shift.

I don’t think the lossy aspect of MQA is much of a problem with most digital CD music. It is a technical shortcoming that probably doesn’t matter in any pop or rock.


(simon arnold) #94

Well I just bought Etta James’ At last tonight in 192/24 from Qobuz with the current 3 month trial of Sublime+. I also compared some tracks to the MQA 192/24 on Tidal which I am familiar with they will unfold to 96/24 as I don’t have MQA dac. And I have to say I prefer the MQA. The one from Qobuz is a tad too bright and the strings come across a bit harsh and overall its a bit thin.MQA is fuller and more balanced…Make of this what you will.


#95

Overall your description of the original master from Qobuz 192/24 is, it is devoid of any coloration; it is exactly what ‘studio sound’ should sound like; high level of transparency, clean and accurate representation of the original recording.

On the other hand, the original master to a processed MQA actually alter the overall sound signature, so your description here is accurate. I’m hearing the same thing. That’s why in my previous posts I’m trying to get the message out that both will never sound the same.
When it come down to personal preference, it all depend on individuals liking. For vocals like Jazz MQA will make it sounds more ‘analogue’ with thicker midrange and warmer sound. For orchestra music which emphasis on the highs, I prefer the original master, it is more dynamic, livier, more ‘air’, better sound staging and imaging.

My take is the sonic signature difference between both has to do with the type of filters used; MQA uses minimum phase slow roll-off while original master uses linear sharp cut-off filter. Do note, MQA is derived from the original master which is termed ‘processed’ MQA.


(simon arnold) #96

Your right MQA feels more analogue which my ears respond to better. I could not listen to the PCM version for long it was to fatiguing.


(Henry) #97

This is an interesting recording for a couple of reasons. Firstly there are cues which suggest she or the engineers didn’t know enough about what they were doing. The microphone craft is poor in places with lots of pops and plops when she releases too much air towards the microphone which seems to be under damped. Clearly audible, even on the CD version. Secondly I feel this was never intended for consumption in its mastered form, rather it was mastered in a way that was designed with the knowledge that it would lose something in the transfer to vinyl, taking some of that edginess off the final record. So is what we are hearing a straight MQA transfer or has some amount of licence been taken in the process of that transfer?


(simon arnold) #98

I also listened to the Doors LA Woman again last night on Qobuz and MQA on Tidal. What I thought was artefacts on the MQA are actually present on the master on Qobuz too. I never noticed this on my vinyl copy so must be the digitzation of the original master. These I did not prefer one over the other and found them both not very pleasant it listen to over the length of the album. So will stick to vinyl for this one.


(Dan Herrmann) #99

I’ve read through most all the posts here. Simple question - is an MQA DAC worth the $$$?


(Peter Lie) #100

There is a very large price range of MQA DAC, starting from USD99.