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Hey JimiAustin: MQA Enabled ADCs

162.250.145.187
Posted on October 30, 2016 at 22:49:49
Isaak J. Garvey
Industry Professional

Posts: 1207
Location: Hollywod, CA
Joined: January 7, 2016
 Hey Jim:

When I asked:

"Why didn't Meridian produce an ADC that does all the SO CALLED "de-blurring" and time domain correction RIGHT from the get go?"

You replied:

"Your question doesn't even make sense. It's clear you don't understand the technology."

So it is YOU who clearly do not understand the technology.

From a Q&A with Bob Stuart on CA:

"Q23. It has been stated that MQA enabled ADCs will be available for the pro market (think Mytek):

Will these ADCs be delta-sigma based with decimation for PCM output?
If yes, where in the conversion stage will be MQA participating withits de-blurring technology: is
it in the decimation stage?

As a summary: what will be the main technological difference between a top-notch MQA
certified ADC and the already existing top-notch non-certified ADCs like Meitner, Merging,
Metric Halo or Apogee.

What are the technical requirements for a certified A/D converter?

A23. MQA ADCs comply with the triple goals of: i) specific, complementary and compact kernel; ii) very low modulation noise; iii) losslessly reversible archive metadata. Yes, delta-sigma architecture is acceptable but not required. The key differences are in the signal processing which can, in many professional designs, be updated in software. Further details on this are confidential and provided to our licensed partners.

Q28. Can you explain the difference between adding MQA during mastering process vs recording?

A28. MQA is involved in recording if an MQA ADC is used. In mastering the tools can optimise the stems or mix according to the producer's wishes and previews. MQA can be used in mastering as described in Q18."

So when I said get your story straight, I meant it. You also continue to claim that MQA was not intended as archival tool yet there are numerous questions and answers about MQA being used during tracking, mixing, and mastering.

 

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RE: Hey JimiAustin: MQA Enabled ADCs, posted on October 31, 2016 at 18:09:21
13th Duke of Wymbourne
Audiophile

Posts: 2794
Location: Orange Co., Ca
Joined: September 19, 2001
 Isaak,

in one of the numerous MQA threads I posted that the biggest problem with MQA is that it is too clever for most to understand.
The real problem with MQA is that is, IMO, really two functions:
1. An end-to-end temporal response with minimal 'blurring', to use Bob Stuart's phrase.
2. An encoding scheme that reduces the file size/bit-rate to below that of conventional 'hi-res' files.

Maybe the implementation of the two functions are so intertwined that they are one thing. It certainly seems that all interviews and publicity treat it as one thing (maybe to its detriment?)

An ADC is still an ADC. The answer in the linked interview does not state there is anything special about the ADC function for MQA except 'low modulation noise', i.e. it should be a good ADC. So, in those terms, Jim was correct, your original question does not make sense.
What I think the talk of an MQA-enabled ADC is about is, at minimum, having a defined temporal response or, at maximum, building the encoding process into the ADC so that output data rate is already reduced and the metadata included for the decoder to know what reconstruction filter response to adopt to compliment the ADC without the need to add that during mastering.

Regards
13DoW

 

RE: Hey JimiAustin: MQA Enabled ADCs, posted on November 1, 2016 at 15:40:10
Jim Austin
 There is one other consideration, which is at least slightly relevant to this discussion. MQA has implemented a procedure where, during recording, they basically collect a fingerprint of the ADC, if you're doing the ADC conversion in anticipation of transcoding to MQA. Not sure if this is just an impulse response test, but that would make sense. Anyway, that information makes it very simple for MQA to decide what needs to happen in terms of time-smear adjustment during the decoding.

Speaking of, WMG is doing this with all those analog masters they're in the process of recording. I'll leave it to you folks to decide whether that does or doesn't imply that MQA transcoding is a major motivation for digitizing all those master tapes. In my opinion, it pretty clearly does imply that, but I know some folks are a bit cynical when it comes to all things MQA.

Jim

 

RE: MQA Enabled ADCs, posted on November 1, 2016 at 09:29:45
John Atkinson
Reviewer

Posts: 4045
Location: New York
Joined: November 24, 2003
 >An ADC is still an ADC. The answer in the linked interview does not state
>there is anything special about the ADC function for MQA except 'low
>modulation noise', i.e. it should be a good ADC.

There are 2 strategies for designing an ADC with a very short impulse
response of the type desired by the MQA system. One is to use a true DSD
converter running at 128Fs or higher with a first-order low-pass
antialiasing filter set well above the desired passband. The other is to do
what Ayre has done in its QA-9 converter at 192kHz, where it uses a
moving-average low-pass filter, of the type described by Keith Howard at
the article linked below.

John Atkinson
Technical Editor, Stereophile

 

RE: MQA Enabled ADCs, posted on November 2, 2016 at 18:15:35
13th Duke of Wymbourne
Audiophile

Posts: 2794
Location: Orange Co., Ca
Joined: September 19, 2001
 Hi John,

I'll stick with my broad-brush 'an ADC is still an ADC' if only to back-up Jim's original statements and not to suggest that Isaac is in any way correct. Now, pretty much all (or just plain all?) ADCs are over-sampled types and the modulators are essentially similar, at least in my way of thinking. All highly-oversampled with a few bits of resolution. How those bit-streams are later decimated, with whatever resulting temporal response, is, to me, secondary.
As you mention DSD, I find it ironic that a recording format was developed to support 1-bit converters only for the converter industry to move away from 1-bit designs because they don't work that well.

When I see some of the arguments that have spun out of MQA related posts I am reminded of the New Yorker cartoon you told me about at the Newport Beach show in June!

Regards
13DoW

 

RE: MQA Enabled ADCs, posted on November 1, 2016 at 20:18:49
bjh
Audiophile

Posts: 18614
Location: Ontario
Joined: November 22, 2003
 I thought this thing could raise the dead, or at least make a Toscanini / NBC Symphony Orchestra recording sound half decent ... now it's just these two things that put out what is desired by the MQA system ???

Better get those MQA samples examined for something else hiding in the origami ... seems to be scrambling the minds of the audio press.

;)




 

RE: Hey JimiAustin: MQA Enabled ADCs, posted on October 31, 2016 at 18:00:31
Jim Austin
 from my review of the Mytek Brooklyn DAC:

Footnote 4: Over time, I've grown skeptical of the notion that a component can reproduce precisely what's on the recording—how can we know what that is? Jurewicz has an excellent answer: codesign a pair of companion converters, a DAC and an analog-to-digital converter (ADC). Now he can send a file through the DAC and on to the ADC. "The DAC and ADC are then fine tuned until the result is as close as possible to [the] original. This approach, unique to Mytek R&D, guarantees the highest transparency and fidelity to the original recorded content." The Mytek Brooklyn ADC will ship sometime this fall, and will include an MQA kernel so that you can set up your own MQA recording studio at home, though you'll need an audio workstation and an MQA plug-in. The ADC will cost the same as the Brooklyn DAC: $1995. No word yet—I've asked—on whether you'll need to pay royalties to MQA Ltd.
Read more at http://www.stereophile.com/content/mytek-hifi-brooklyn-da-processor%C2%96headphone-amplifier#EZ5kI48m9dfM6IKy.99

But the way you asked the question did not, in fact, make sense. It was unrecognizable.

I can't quite tell if you're having the time of your life attracting all this attention or perched on the edge of some high rooftop or windowsill trying to get up the courage. Perhaps both. Either way, you've made your impression here. Good day.

 

Ah, posted on November 1, 2016 at 05:44:44
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 the arrogance and rudeness of some reviewers!

 

RE: Ah, posted on November 1, 2016 at 15:46:16
Jim Austin
 I start out treating people courteously, until they prove they don't deserve it. Not speaking of you.

 

ADCs, posted on October 31, 2016 at 03:21:00
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 And when they get rid of coupling capacitors (smearing) from ADCs, there will be a step forward in preserving the original SQ integrity of the masters.

 

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