MQA technical analysis

[Archimago]

I would bring on several more writers like Mitch if I could find them. Good writers are incredibly hard to find.

 

Sounds good Chris... Bring it on!

[Miska]

Input signal is 19.1 kHz pure sine in 44 kHz?

 

Yes, just normal 19.1k sine at 44.1k sampling rate.

 

It is modelled signal? What is bit depth?

 

What you mean by modelled signal?

 

Should be at least 24-bit, but probably 32-bit. I use dithered 32-bit test signals, and sometimes just 64-bit float WAVs.

[audiventory]

What you mean by modelled signal?

 

Should be at least 24-bit, but probably 32-bit. I use dithered 32-bit test signals, and sometimes just 64-bit float WAVs.

 

As "modelled" I meant synthesed sine into audio file.

 

How you send direct to DAC 32- or 64-bit float? A DAC can receive integer formats only, as far as I know.

[Miska]

As "modelled" I meant synthesed sine into audio file.

 

Yes, that's of course the case.

 

How you send direct to DAC 32- or 64-bit float? A DAC can receive integer formats only, as far as I know.

 

It is automatically dithered by the player to DAC's resolution what ever that is, or converted to DSD when that is the output format.

 

It is practical for many cases, because there so many different DAC resolutions, 16, 18, 20, 24 and 32 bit.

[Jud]

LOL.

 

OMG Chris, I have "commercial interests"? Come on man... The amount of traffic I have on the blog *pales* to the commercial interests on any of the major audiophile blog and sites I've seen. To put it another way, I make a few bucks off Amazon if there's anything I talk about and readers buy, and another few bucks in AdSense. Notice that not all my posts are about audio, some about video as well; stuff that interests me and experiments that other hobbyists might find interesting.

 

Let me be honest as well. I make more money in my day job in one day than 2 years worth of what I'm getting off blog proceeds... I trust this puts into perspective the level of "commercial interest" I have.

 

I'm interested in truth. I'm interested in having audiophiles be educated in such truth as can be proven with evidence. Not every audio lover will care about a lot of this but I do want the material and measurements out there for reference if one days, an audiophile get to thinking about an alternative viewpoint other than the interests of the "mainstream" audiophile Industry-supported media.

 

Go ahead and do the same with your reviews by adding objective data and I will be a happy man because then I can look forward to answers rather than yet more testimony and opinions rather than facts. I would happily retire when that day comes!

 

I like being able to see the measurements and other information on your site, and other similar information here. They are very often very helpful.

 

I do happen to think better understanding leading toward what can objectively be called progress will actually come not solely from what you are referring to as facts, but also to some degree (it might be small, but some) from what you are referring to as "opinions" and "testimony." There are some things at which human perception is very bad in comparison to technical means of measurement, but yet there are certain areas where human perception is as yet superior to anything technology can provide. I think we ought to make use of each in its areas of superiority.

[Samuel T Cogley]

I like being able to see the measurements and other information on your site, and other similar information here. They are very often very helpful.

 

I do happen to think better understanding leading toward what can objectively be called progress will actually come not solely from what you are referring to as facts, but also to some degree (it might be small, but some) from what you are referring to as "opinions" and "testimony." There are some things at which human perception is very bad in comparison to technical means of measurement, but yet there are certain areas where human perception is as yet superior to anything technology can provide. I think we ought to make use of each in its areas of superiority.

 

While I agree with what you're asserting here, I still think we're not addressing the "business reality" and how a successful "business" with regards to "audiophile social media" pretty much depends on an overall favorable opinion from the vendors. Based on what I've seen on his blog, Archimago is not bound by that "red line" where perhaps Chris is.

 

When a certain other Audiophile Social Media Personality swaggers in here to take others to task, the clear motivation is to "protect" his business.

 

My point is that if there is a line between pro-vendor and pro-consumer in audiophile social media, it's not possible to make a successful business without being on the pro-vendor side of that line, period. Archimago is clearly on the pro-consumer side of that line, and has accepted the reality that he will not be rewarded by "business success" as a result. This clearly gives him a level of freedom that often invites scorn and even envy from some quarters of audiophilia.

 

I disagree that Archimago should consider subjective testimony when conveying information to his readers. There's far too much of that in the mainstream audiophile press and social media and it would only invite mistrust from his readers.

[Jud]

While I agree with what you're asserting here, I still think we're not addressing the "business reality" and how a successful "business" with regards to "audiophile social media" pretty much depends on an overall favorable opinion from the vendors. Based on what I've seen on his blog, Archimago is not bound by that "red line" where perhaps Chris is.

 

When a certain other Audiophile Social Media Personality swaggers in here to take others to task, the clear motivation is to "protect" his business.

 

My point is that if there is a line between pro-vendor and pro-consumer in audiophile social media, it's not possible to make a successful business without being on the pro-vendor side of that line, period. Archimago is clearly on the pro-consumer side of that line, and has accepted the reality that he will not be rewarded by "business success" as a result. This clearly gives him a level of freedom that often invites scorn and even envy from some quarters of audiophilia.

 

I disagree that Archimago should consider subjective testimony when conveying information to his readers. There's far too much of that in the mainstream audiophile press and social media and it would only invite mistrust from his readers.

 

Since this is OT in a valuable thread, I'll make a quick reply and we can take it to another thread to discuss further if required.

 

I do not think this divides neatly into pro-consumer and pro-industry. I, along with many other consumers, appreciate some opinions and testimony. I also see industry marketing geared toward consumers who think of themselves as objectivists.

 

I'm not questioning anyone's motives (I think there's far too much of that in our discourse as it is), simply saying opinions can be informative and measurements can be used by manufacturers as marketing.

 

 

Sent from my iPhone using Computer Audiophile

[Jay-dub]

User-supplied, no. The Bluesound applies bass/treble controls between decode and render. This involves sending the data another round through the MQA-provided software library to restore the control bitstream needed by the renderer.

 

Now this is interesting. Just to be clear, are you saying that the MQA library performs the EQ in the Bluesound player? How flexible are the EQ capabilities in the MQA library? I could imagine anywhere from a handful of boost/cut settings to a full three-parameter shelving filter, plus a parametric peaking filter that could be cascaded as many times as needed. If it's anything like the latter, then it sounds to me like you're very close to the point where you could write an MQA player that would perform fairly general room-correction DSP, incorporating the MQA library that you got off the Bluesound player.

[mansr]

Now this is interesting. Just to be clear, are you saying that the MQA library performs the EQ in the Bluesound player? How flexible are the EQ capabilities in the MQA library? I could imagine anywhere from a handful of boost/cut settings to a full three-parameter shelving filter, plus a parametric peaking filter that could be cascaded as many times as needed. If it's anything like the latter, then it sounds to me like you're very close to the point where you could write an MQA player that would perform fairly general room-correction DSP, incorporating the MQA library that you got off the Bluesound player.

The EQ itself is Bluesound's code (a simple biquad filter). All the MQA library does is copy the LSB carrying the renderer parameters.

[gabeg]

can someone explain the de-blurring process mqa claims to do. It doesn't show up in measurements...at least those I've seen.

[mansr]

can someone explain the de-blurring process mqa claims to do. It doesn't show up in measurements...at least those I've seen.

For all I know, it's a lie. It wouldn't be their first lie.

[Archimago]

Since this is OT in a valuable thread, I'll make a quick reply and we can take it to another thread to discuss further if required.

 

I do not think this divides neatly into pro-consumer and pro-industry. I, along with many other consumers, appreciate some opinions and testimony. I also see industry marketing geared toward consumers who think of themselves as objectivists.

 

I'm not questioning anyone's motives (I think there's far too much of that in our discourse as it is), simply saying opinions can be informative and measurements can be used by manufacturers as marketing.

 

 

Sent from my iPhone using Computer Audiophile

 

Agree not to go off topic here. But quickly...

 

Regarding testimony and opinion, I can agree that at times they're valuable especially when it comes to ease of use, appearance, workmanship. Yes, it can be useful sometimes as well when it comes to sound quality when deficits are significant enough. But in my experience when it comes to "high fidelity" goods, sound quality has exceeded human perceptual ability already with reputable equipment we might be evaluating. As such when people talk about having preferences towards a certain type of filter, MQA vs. non-MQA, 16/44 vs. 24/96, etc... I would prefer non-sighted listening results to tease out the perceptible facts around sound quality.

[bcwang]

can someone explain the de-blurring process mqa claims to do. It doesn't show up in measurements...at least those I've seen.

 

You'd need a measurement of an impulse in the time domain to visualize and compare. I haven't seen measurements of that sort yet.

[mansr]

You'd need a measurement of an impulse in the time domain to visualize and compare. I haven't seen measurements of that sort yet.

 

And you never will. There is no way MQA would permit such a test to be published.

[jmudrick]

And you never will. There is no way MQA would permit such a test to be published.

They control the media and internet too? I'm surprised they haven't come for you. Yet.

 

Sent from my Nexus 5X using Tapatalk

[mansr]

They control the media and internet too? I'm surprised they haven't come for you. Yet.

 

They control the encoder.

[abrxx]

can someone explain the de-blurring process mqa claims to do. It doesn't show up in measurements...at least those I've seen.

 

Previously I posted this link:

 

https://www.google.com/patents/EP3029674A1?cl=en

 

This is more likely than not the DSP process they used for redbook archives. A different (or additional?) process may be used for existing hi-rez masters. I can't pretend to fully understand this approach, but reading the patent at least gives me some ideas about what they may be doing.

[bcwang]

And you never will. There is no way MQA would permit such a test to be published.

 

You'd have to look for musical material that exists from the same mastering to do the measurement. A cymbal hit maybe, or any sound with a fast transient edge.

[smartin]

They control the encoder.

You can buy one and do the test =).

[mansr]

You can buy one and do the test =).

 

It's not that simple. Even you could just go out and buy one, which you can't, the terms of use would most likely explicitly prohibit the publication of anything resembling test results. They wouldn't be the first do that kind of thing.

[smartin]

It's not that simple. Even you could just go out and buy one, which you can't, the terms of use would most likely explicitly prohibit the publication of anything resembling test results. They wouldn't be the first do that kind of thing.

 

Don't know about TOU, but you can buy one from Mytek (https://mytekdigital.com/brooklyn-adc/)

[mansr]

Don't know about TOU, but you can buy one from Mytek (https://mytekdigital.com/brooklyn-adc/)

That's just an ADC with some MQA filters. It's not an MQA encoder.

[crenca]

It's not that simple. Even you could just go out and buy one, which you can't, the terms of use would most likely explicitly prohibit the publication of anything resembling test results. They wouldn't be the first do that kind of thing.

 

Exactly - this is how NDA's lead otherwise competent engineers and physicists into be impressed with MQA prematurely - they get told what it is but can not actually test/confirm it so they end up trusting an "audio savant" like Bob who is very likely bamboozling them, or at least selling them something that however true "in theory" and seems to make a big difference but in reality does not because of confounding factors (such as speakers, etc.).

[SMG]

For all I know, it's a lie. It wouldn't be their first lie.

 

They say that during MQA encoding they employee DSP to delay the preresponses cause by the linear filters previously used in the recording process. Do you know this not to be the case? Have you tested (and could you test) any of the MQA 2L files against originals to try to determine whether they employed this "debluring?"

[Miska]

It's not that simple. Even you could just go out and buy one, which you can't, the terms of use would most likely explicitly prohibit the publication of anything resembling test results. They wouldn't be the first do that kind of thing.

 

But if you get someone to encode test signals for you and then you publish the results...