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The Computer Audiophile

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  1. MQA is Vaporware
    MQA is Vaporware
    30 minutes ago, esldude said:

    The whole MQA affair lacks transparency and honesty.  


    I think you’re being too charitable. They selected filters that no competent designer would choose for fidelity, because they knew many listeners subjectively preferred them, and said they corrected time domain errors in recordings, which these filters are incapable of doing. They used lossy compression that reduced fidelity, to try to protect their IP (while initially denying it was lossy). They gave a false impression of the original resolution of upsampled files. And they marketed it all as “Master Quality.”


  2. MQA is Vaporware
    MQA is Vaporware
    1 hour ago, Shadders said:

    Hi,

    I know this may be regressing, but, has MQA Ltd or the supporting Hifi press ever presented evidence of ringing in an audio file ? (by which i mean CD's)

     

    It has been claimed that the ringing of a filter causes blur, and everyone seems to have accepted this as fact, when those making these claims have never provided proof.

     

    Are the AES and Hifi press so lame in capability, that they believe everything that they are told ???, where the Hifi press repeat it as fact, and seem to not understand what they are saying.

     

    Surely the MQA Ltd website would have real world examples that people could, if they have the relevant CD, analyse and confirm the ringing. Why is this basic fact or prove, never been presented ?

     

    Regards,

    Shadders.

     

    Great comment @Shadders. Not "regressing" at all... Rather it strikes at the heart of the problem, doesn't it?

     

    In all these years of debates, pages upon pages spent on MQA, bad feelings on either side, real $$$ spent on implementation for Tidal, software like these Android/iOS players, decoders like Audirvana/Roon, the marketing hype, etc... What does this achieve?

     

    At best, MQA Ltd. made a few bucks (probably not). Some hardware manufacturers got a chance to claim that the next product refresh "Now decodes MQA!". Maybe a few in the music industry felt that their "crown jewels" were kept safer by not releasing a hi-res bit-perfect copy... Oh yes, of course it gave members of the audiophile press something to write about; eyeballs reading articles and clicks on a website are good for some revenue at least (perhaps some even got directly paid for MQA support... who knows).

     

    But beyond the commerce and dollars changing hands, what lies beneath? As your comment implies, all of this is built upon a fantasy. A salve for an ailment that either does not exist, or if it did, absolutely incurable using the MQA snake oil. It has been obvious for awhile now (thanks especially to @mansr and @Miska) that there is no reality-based foundation from which the company is building upon to truly benefit the music lover interested in sound quality or fidelity.

     

    There has never been demonstrations of MQA being able to "de-blur" because the "blurring" they speak of as if with authority itself is unfounded. They have never defended the value of "authentication" for end users. The "studio sound" they speak of is meaningless. They were coy about practical A/B demonstrations when they had the chance years ago at audio shows to the public. Bob Stuart started out strong making the rounds with articles in Stereophile, TAS and even here as I recall giving his spiel but has since retreated to silence (and presumably some level of embarrassment).

     

    In his stead, we are "treated" with innuendos, opinions, murmurs from questionable actors (specifically those who end up being banned). Undisciplined members of the second-rate audiophile press who appear unable or incapable of understanding basic scientific principles (or apparently even just being decent human beings in their level of discourse as the case may be). And ridiculous company officials who also cannot concede that they have lost the intellectual battle - but just the same are paid to vigorously maintain the hype.

     

    This whole sad episode has clearly demonstrated the general ineptness of the audiophile press to speak truth. At least when it comes to MQA, it appears that there is no journalistic integrity left; no ability to speak truth against the power of the Industry nor to independently explore the issue without dragging Industry members to comment. This has only made the hobby appear even more ridiculous than it already is with all its bizarre products, beliefs, and rituals.

     

    Well guys, I really hope MQA marks the nadir in some ways for this hobby. Or at least an interesting landmark signalling some kind of change. That maybe the proverbial "silver lining" is that out of this, audiophiles actually learn to take on a more skeptical position. To demand evidence. To recognize that some dude expressing his subjective opinion is the lowest of the levels of evidence - even if that dude has the initials BS and brings with him pages of irreplicable claims. Maybe the Industry takes note that indeed one cannot just come out and make unsubstantiated products without expecting significant scrutiny. Maybe as a community, audiophiles recognize that we are not sheep in a flock of "believers".

     

    It has certainly been fun reading these comments over the years . Wowzers, 493 thread pages. Epic... 🙂

     

     


  3. MQA is Vaporware
    MQA is Vaporware
    13 hours ago, Paul R said:

    unlike most here, I think they could actually deliver what they promised

     

    Hi Paul - 

     

    Here are the reasons why that's not possible:

     

    - The more the interpolation filter in a DAC cuts, the more it rings, or to use MQA's non-standard parlance, "blurs."  In order to avoid the DAC filter itself being a cause of "blurring," it can't cut much.

     

    - A filter that doesn't cut much doesn't remove frequencies in the near ultrasonic, which has two effects: (1) It cannot remove ringing caused by the ADC filters, which occurs in the low ultrasonic range; and (2) it allows low ultrasonic frequencies to intermodulate with themselves and with audible frequencies, causing harmonic and intermodulation distortion.

     

    - If you don't want your technology copied, and don't want to spend time and money chasing down alleged patent violations, you must somehow obscure the precise effect of the technology.  Therefore you cannot use lossless compression, since simple decompression will reveal the effect of the technology.  You must use lossy compression, which obscures the effect of the technology at the cost of unrecoverably throwing away information from the original file.

     

    - Since your DAC filters don't cut in the low ultrasonic, with the potential bad effects we've described, if you don't want those bad effects realized, you must remove the low ultrasonics from what you are feeding the DAC filters, and the only place you can do this, other than mics that don't have any ultrasonic response, is in the decimation filtering in the ADC.

     

    - If you use an ADC filter with a strong cut, it will ring ("blur"), and we know that the DAC filter can't remove this (cannot "deblur"), or it will ring itself.  So the only thing you can do is cut gently, but start in the audible range so that you have sufficient cut by the time you reach ultrasonic frequencies.

     

    - Therefore you will either be feeding your DAC filter a file with rolled-off highs, or one with ringing and ultrasonics it can't remove, which will cause distortion.  And you will be applying lossy compression to this file as well.

     

    Thus what one might call the "central dogma" of MQA is itself impossible; it isn't just this particular implementation that is bad, any attempt to apply the principles MQA advertises itself as built on will inevitably, due to sheer mathematics, have the same set of problems.

     

    There are ways to do filtering well, and wind up with a product that doesn't have a great deal of ringing, or IM or harmonic distortion.  And of course it isn't necessary to use lossy compression.  But it's not possible through application of "MQA technology."


  4. MQA is Vaporware
    MQA is Vaporware

    Some additional points about MQA:

     

    1 - Why can't MQA be done "better"? 

     

    a -- To put what I said in my long post in different terms, every filter must strike some mathematical balance between "frequency distortions" (aliasing, imaging) and "time distortions" (ringing).  https://en.wikipedia.org/wiki/Conjugate_variables  This has been known for the better part of two centuries.  https://en.wikipedia.org/wiki/Fourier_transform#History

     

    b -- It is the essence of MQA that it seeks to absolutely minimize time distortions.  If you don't have this, you don't have MQA.  This extreme approach to filtering inevitably means mathematically that it *must* maximize imaging and aliasing.  And this is indeed what we see in the frequency responses of all MQA filters.

     

    c -- As noted by me and others, lossless compression cannot satisfactorily protect how MQA processing works, its intellectual property.  In order for MQA to make money in the way it is intended to do, by utilizing proprietary processing that protects its IP and allows the labels to hold back full resolution digital files (since they are still convinced, or at least trying to convince their bosses and investors, that piracy is the reason they aren't more successful), it must use lossy compression.

     

    d -- As Miska has mentioned and mansr has confirmed, MQA uses part of the 24- or 16-bit word length to hold information about MQA decoding.  Thus, although the full dynamic range of 16 bit material is never used (let alone 24-bit, which is pretty well impossible, since you're into the heat noise of the electronics by that point), MQA does limit potential dynamic range versus RedBook material in particular.

     

    e -- Combine filtering that must produce distortion with lossy compression and a higher noise floor with RedBook material, and the result *must* to a mathematical certainty be further from the original than better filtering and lossless (if any) compression, i.e., genuine hi res or RedBook played back with a reasonably good DAC or software player.

     

    f -- Now you may not hear the distortion, or the losses due to compression, or you may not mind them if you do hear them, but MQA is not marketed as "We screwed up your music, but not so badly you can actually hear it."  It's marketed as closer to the original, which as we've just seen can't be true on a sheer mathematical basis.  No real room for argument, this is as plain a mathematical fact as 2+2=4 (though I do love the T-shirt that says "2+2=5, but only for higher values of 2").

     

    2 - So why might people like it?

     

    a -- We've gone through a variety of reasons - subjective predisposition, subconscious pressure of social expectations, a liking for a very slightly warmer, more exciting sound that distortion might produce.  But I want to add one more, that was first brought to our attention by @firedog.  It is that many MQA DACs do not stop using their MQA filters once MQA material is no longer being played.  Giving a DAC the ability to stop means extra expense and complexity.  So what many people who think they're comparing MQA and normal hi res are actually doing is comparing material that may have been prepared specifically for MQA's DAC filters (it may have the highs and low ultrasonics rolled off by the ADC) to material that doesn't play well with those same filters (real hi res, that has response in the low ultrasonic, causing intermodulation and harmonic distortion when used with MQA's filters).  In that situation, you would in fact be hearing more distortion with genuine hi res.


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