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Stereophile Series on MQA Technology


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8 hours ago, Rt66indierock said:

I've walked into glass doors

 

I did just that in a restaurant in Big Sur.

Now you know. O.o

 

Hard to behave expensive in such a situation.

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10 hours ago, Ralf11 said:

all personal attacks should be done by using song lyrics

 

But with MQA encoding. Makes them steeper. More direct. And more personal of course.

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21 minutes ago, Fokus said:

he recorded the MQA and PCM outputs of a DAC in to an ADC, and afterwards put one channel of each file side by side. That should be obvious.

 

Apart from it being very easy to make mistakes and thinking errors and what not, you see one here yourself - your quote.

So how would a resampling system which tries to catch dirac pulses of 1 sample width (where they ?) NOT land randomly by this means ?

From the article :

 

while MQA's approach may improve the shape of the impulse response, its sampling method—and the resulting, presumed increase in aliasing—introduce randomness in precisely when those impulses occur.

 

Jim must be talking about a means of digital resampling, applied by MQA. During the process of decimation or whatever.

What I'd like to head for is a virtual conclusion of Jim that this was nothing much MQA'd (hence no random sample landing). Also, there *is* not such a thing as possible improvement of a dirac pulse; only worse is possible (and otherwise I am curious about an idea about how the dirac pulse can be improved upon (band limit it is not allowed for a solution, I'd say)).

So the general consensus : something ain't right here.

 

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FWIW :

 

@John_Atkinson, what Jim should do is provide MQA with a dirac pulse train with varying distance.

If MQA is right with their promises, it should show what I could show you (not sure whether this is a good idea to do this in advance of matters). It will also show what a normal DAC with decent filtering will make of it : a mess (as in : no dirac pulse anywhere and one pile of distortion).

Best is to have a train of e.g. 20 pulses in a row, then a space of 50 or so "nothing" then 20 pulses again, 5 spaces with nothing - and so on for a nice 30 seconds. The "5 spaces" can be longer but must cover for the filter length to bridge the gap (and show the mess).

 

If this works out, all it will show is what I expect : anyone can do this as long as the filter has been made for it. But also : how such a filter overrules the in-DAC filter.

And regarding "starting in the middle" ... still only starting from there (the digitally generated file). The main part happens in the music file and the MQA encoding (means).

 

Regards,

Peter

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  • 5 months later...
1 minute ago, Galileo365 said:

That comment was originally made in reference to MQA, which claims to use B-spline interpolation but indirect evidence suggests is not true

 

I don't follow the (ultra negative) MQA hoopla any more. Fact is that 95% of what we know about MQA comes from minds on this forum. 50% of that could be wrong because it is (has to be) often derived from half-truths like not telling the complete story. Example :

 

If someone name Bob Stuart somewhere tells that there's B-spline interpolation "involved" he can be correct. Btw on this matter I'd like to see him say that himself. Meanwhile, any other means of filtering behind that B-spline interpolation can be just as well in order. Now he spoke the truth, right ? Yes, he did and it all depends on how the question was asked and how he may beat around a bush to come up with the response. Say that I know me ...

 

Again depending on the question, if he tells that interpolation is in order, I believe it. But I also believe that further filtering is behind that, which btw can only happen in a DAC for the purpose. This means :

 

That the B-spline interpolation (again, if there at all) happens at the e.g. Tidal servers. And, it would be the most logical thing to do, looking at MQA's objectives.

 

On a side note, where happens what in MQA is my thang. How it really happens is for others like Mansr. Together we form the picture.

 

Regards and welcome,

Peter (developer of some of these filters and producer of MQA decoding software (shht) BUT being complete neutral to it).

 

 

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13 minutes ago, Galileo365 said:

Yes, precisely. Interpolation is never performed with a filter.

 

As how things tend to go in here, "of course everything is performed via a filter" because ... that's the language of speak even for those who think they read a lot. 9_9 So easy enough, if you never made an interpolating filter (hey !) you don't know that it is not a filter at all because ... the real filter is (software wise) set up very differently.

 

Challenge :

Can someone make an interpolating roll off filter with coils and caps and resistors etc., for a speaker ?

(let's have it, but I don't think this is possible)

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4 minutes ago, Audiophile Neuroscience said:

Yep, subjective interpretation of test results has been a recurrent bone of contention  around here

 

That's because the interpretation is merely interpolated.

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1 minute ago, Galileo365 said:

it would undermine my credibility even more than it already is.

 

All you need to do is investigate a bit who you address and never think you have "the" answer (not without context anyway). Of course this is rather impossible mostly, but most people have a history and you can't just know better. Oh, you can towards the person himself, but the others will be against you. Anyway about the interpretation :

 

A good example is the age of someone named Mansr. 19xx it was said. Beautiful interpretation makes that is is 19 or so. Interpolation should make that between 19 and ~364 days more.

But for me he could be 118 because he is from the 1900's.

 

You still have all of your 100 credit points all right.

 

 

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1 minute ago, Audiophile Neuroscience said:

FYI Peter is this guy http://www.phasure.com/

Being Dutch he will metaphorically knock you down with a bicycle before you see him even coming

 

Thank you for that introduction. You will recognize me by my tandem bike, double dutch being my partner.

 

24 minutes ago, PeterSt said:

Yes, he did and it all depends on how the question was asked and how he may beat around a bush to come up with the response. Say that I know me ..

 

I said it ...

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But seriously, does someone have a link to that Youtube or text where Bob Stuart tells about the B-spline interpolation ? At least I like to have some fun in laying out how it could be interpreted.

Thanks !

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52 minutes ago, Galileo365 said:

You must know Peter Qvortrup ..

 

From my Audio Note, yes.

But I don't adhere his "no filtering" ideas. So my (designed) DAC would be pure NOS/Filterless (and R2R) and the first thing to do was ...

creating a filter in software for it.

Ha ! readily make the mistake again, because it interpolates only (today this is a bit different but with the emphasis on "no ringing").

So you see ? I am all MQA ready. But let's change the subject because MQA is from the past. swoon.gif.d7a989fc3b686b42ab339433484180df.gif

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6 minutes ago, FredericV said:
2 hours ago, PeterSt said:

Again depending on the question, if he tells that interpolation is in order, I believe it. But I also believe that further filtering is behind that, which btw can only happen in a DAC for the purpose. This means :

 

That the B-spline interpolation (again, if there at all) happens at the e.g. Tidal servers. And, it would be the most logical thing to do, looking at MQA's objectives.


This is not the case. The Tidal servers are based on a CDN with a simplistic token system

 

I meant : in advance of further filtering (like the MQA DAC's renderer does it). I surely didn't mean to say that on any Tidal server some processing is being done in real time or so (when you ask for the file). Sorry to be vague about this.

 

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16 hours ago, The Computer Audiophile said:

For the most part people here love facts and data when it comes to MQA. So far 99% of this information seems to make MQA look bad. If you have any info on either side of the issue, it's very welcome here.

 

Yes, and might you put some emphasis on the pro-MQA side, then you will be called an MQA shill.

And for the rest of your life you will be one. That's how it works in here.

Just observing.

 

18 hours ago, Galileo365 said:

This is supposed to be Computer Audiophile, not We Hate MQA, or so I thought.

 

Ehmm

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Hahahaha, I posted two posts - of reading further - too early. So :

 

17 minutes ago, PeterSt said:

Yes, and might you put some emphasis on the pro-MQA side, then you will be called an MQA shill.

 

True !

 

Quote

And for the rest of your life you will be one.

 

Also true.

 

 

17 minutes ago, PeterSt said:
18 hours ago, Galileo365 said:

We Hate MQA

 

 

Also true. But not relevant. :o

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