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#271727 - 2018-01-12 12:26 Stereophile MQA appraisal (MQA Tested Part 2: Into the Fold)
Registered: 2008-02-29
Posts: 1,810
Asa Post Offline
Knows where his towel is
Asa Post Offline
Knows where his towel is

Registered: 2008-02-29
Posts: 1,810
Loc: Devon, UK
The Stereophile MQA appraisal series makes for essential reading for anyone interested in understanding how MQA works and what benefits it may bring. It has the considerable merit of bringing science to the debate though this has not reduced the emotive and abusive comments on their own site. Here is a link: MQA Tested Part 2: Into the Fold

This article raises a number of important issues: MQA is indeed lossy but this may not matter.

Also, some early MQA files were encoded sub-optimally. This makes me wonder whether MQA decoding could also be improved, perhaps via a firmware update for our 8x8s, DSP SEs etc. Some people have told me that Bob has said that MQA does not fully unfold. I do not know whether this is true and unfortunately do not have a link to Bob's alleged statement. In any case, Meridian seem to be so emasculated by the development of MQA and the Roon divorce as to render them moribund, so I do not expect to see any upgrades soon (just look how long it took them to launch the UHD722).

I am also intrigued that MQA encoding chooses from 2000 algorithms. As simple solutions are usually the best this seems alarmingly complex. I am also suspicious of the round number (rather than 1948 algorithms for example).

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#271739 - 2018-01-12 16:27 Re: Stereophile MQA appraisal (MQA Tested Part 2: Into the Fold) [Re: Asa Post]
Registered: 2011-02-02
Posts: 2,153
Hector Offline
Senior Shouting Officer
Hector Offline
Senior Shouting Officer

Registered: 2011-02-02
Posts: 2,153
Loc: Midlands, UK
Originally Posted By Asa Post
I am also intrigued that MQA encoding chooses from 2000 algorithms. As simple solutions are usually the best this seems alarmingly complex. I am also suspicious of the round number (rather than 1948 algorithms for example).
To be fair Asa the article you misquote from states "more than 2000 algorithms".

Would it be reasonable to assume that the author is not party to the real number?

Hector


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#271761 - 2018-01-13 08:25 Re: Stereophile MQA appraisal (MQA Tested Part 2: Into the Fold) [Re: Hector]
Registered: 2002-02-14
Posts: 8,349
ncpl Offline
President of the Imperial Galactic Government
ncpl Offline

President of the Imperial Galactic Government

Registered: 2002-02-14
Posts: 8,349
Loc: Surrey, UK
The alogorithms will cover profiles for mics, desks, tape machines, ADC and DAC, and all sorts of measured and profiled hardware in the recording chain.

It really isn’t hard to work out that the permutations would result in a large number of profiles to best match the chain associated with each master.

Where the chain info isn’t known, generic profiling is used based on analysis of the “fingerprints” found in the data.


Rgds,
Nick

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#271811 - 2018-01-13 19:49 Re: Stereophile MQA appraisal (MQA Tested Part 2: Into the Fold) [Re: ncpl]
Registered: 2004-10-20
Posts: 1,378
GMT Offline
Working on the ultimate question
GMT Offline
Working on the ultimate question

Registered: 2004-10-20
Posts: 1,378
Loc: Cambridge, Cambs, UK
Does it also cover new source equipment that will be used for playback as they are moved through the certification process?
Cheers
Tom


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#271963 - 2018-01-18 07:47 Re: Stereophile MQA appraisal (MQA Tested Part 2: Into the Fold) [Re: GMT]
Registered: 2013-05-07
Posts: 92
Dappad Offline
Hitchhiker
Dappad Offline
Hitchhiker

Registered: 2013-05-07
Posts: 92
Loc: Solihull, UK
Hi Tom,

From what I understand, yes it does cover new source equipment.

To release an MQA enabled product, any manufacturer new or old, need to send their new D.A.C chip to MQA.

MQA then create a new algorithm specific for that D.A.C chip. This is to ensure the output signal from the new D.A.C matches that of the input signal, thus enabling the authentication to be carried out at the end user.

All these D.A.C specific algorithms are stored below the noise floor of each recording, so it can be authenticated on any MQA enabled device.

As there are currently over 2000 algorithms, that must take up some space, only time will tell how many algorithms can be embedded into each and every song.

With the advancements in internet speeds, at some point the file size will become less of an issue....but still the D.A.C chip correction is one of the key elements that I'm sure will remain.

This is just my understanding from what I have read.


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#271965 - 2018-01-18 08:58 Re: Stereophile MQA appraisal (MQA Tested Part 2: Into the Fold) [Re: Dappad]
Registered: 2002-02-14
Posts: 8,349
ncpl Offline
President of the Imperial Galactic Government
ncpl Offline

President of the Imperial Galactic Government

Registered: 2002-02-14
Posts: 8,349
Loc: Surrey, UK
I don't think that MQA stores the DAC profile in each track. That wouldn't any make sense at all.
The DAC profile is measured by MQA and stored in the MQA code in the DAC.


Rgds,
Nick

#15SE
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