John Atkinson: Yes, MQA IS Elegant...

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7 hours ago, NOMBEDES said:

A new audio term: Ugly, Vile, Disgusting, Toad. (UVDT) 

 

So:

 

MQA = UVDT

 

Got it, thanks! 

 

 

 

SQAM

 

MQA denotes the lossy process with phase anomalies

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6 minutes ago, Jud said:

Way beyond my first year high school calculus (which unfortunately I don't remember anyway - 46 years ago), but on a layperson's level, I was just wondering: Is the straightline waveform resulting from the rectangular gating/windowing anything like those square waves at e.g. 10kHz you sometimes see "proving" only DSD is capable of correct reproduction of audible frequencies?  In other words, the straight vertical rise and fall times show you there's "illegal" (above Nyquist) bandwidth, regardless of frequency.

It has to be smooth to be band limited.  Maybe it is easier to think in mechanical terms?  Say Y axis is transducer position, for example. A function that is not smooth has infinite + or - acceleration.

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This really doesn't have to be very complicated, at least for the gated sine example.  As @mansr pointed out, you have a step in the dV/dt.  So this example is not band limited. 

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9 minutes ago, Shadders said:

Hi,

If you disagree with the analysis, state why the two unit steps do not cancel.

Regards,

Shadders.

Why don't the steps cancel in a square wave?

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I am not following you... are you maintaining that your example is band limited?

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14 minutes ago, Shadders said:

Hi,

I am stating that the positive and negative unit steps discontinuities at the point (5pi/2) cancel, and contribute no spectrum.

 

Regards,

Shadders.

still not following... are you saying there are + and - steps in the dV/dt of the gated sine that occur at the same time?

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55 minutes ago, Shadders said:

Hi,

For the equation :

y(x) = [u(x)-u(x-5pi/2)].sin(x) + u(x-5pi/2)

 

The negative unit step multiplied by the sin function occurs at (5pi/2). The positive unit step at (5pi/2) cancels this negative unit step.

 

The positive unit step [u(x)] multiplied by the sin(x) occurs at x=0, not at (5pi/2).

 

Regards,

Shadders.

OK now I'm following you better.  I didn't realize you were adding a step function at the close of the gate.  But you see derivatives show that this is not a smooth function at 5*pi/2 even though you don't see a "corner" there?

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16 hours ago, John_Atkinson said:

It seems incontrovertible, therefore that that ringing will excite the playback DAC's reconstruction filter, which will impose its own ringing on musical transients.

 

 

It would be incontrovertible if you show some hi-res captures of 16/44 DAC output showing the musical transients with all the ringing.

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3 minutes ago, John_Atkinson said:

 

This was shown in the article.

 

John Atkinson

Editor, Stereophile

 

I just looked at all the figures - all I see are impulse response plots.  By "musical transients" I mean recordings of music.

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On 9/3/2018 at 4:17 PM, mansr said:

For a solution to be elegant, there must first be a problem.

That really sums it up.  MQA  says the problem is temporal smearing, but they don't do the obvious and show examples of DAC output where ringing can be seen in properly recorded music (Archimago shows examples where ringing can be seen - in recordings with clipped peaks).  If they are talking about a different issue they don't explain what it is.  They want to claim that they are on to a whole new era of signal processing and have given this a name: post-Shannon.  And then MQA's solution to temporal smearing applies leaky filtering with phase shift, so that it actually introduces smearing.  It's not elegant. It's Orwellian.  Really sad or hilarious, depending on whether MQA succeeds or not.

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I do like the idea of calling a weed a flower, though, as an analogy for MQA.  But first you have to decide that your already established flower garden is a bunch of weeds.

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7 hours ago, Miska said:

 

Certainly ringing exists on CD's and not enough attention is paid for that...

And no it is not below the noise floor, it certainly is clearly seen.

 

Please show some examples so it can be discussed.  I don't mean to sound like I'm challenging you,  just want to see something.

7 hours ago, Miska said:

But luckily that, as many other source filter problems is fixable by using apodizing filters for DAC, while non-apodizing ones will pass the source's ringing through as-is.

Are you saying you always prefer apodizing reconstruction filters?  You consider ringing a worse problem than the phase error problem introduced by apodizing (or alternatively, ringing is worse than the problems introduced by slow rolloff filter).