John Atkinson: Yes, MQA IS Elegant...

[mansr]

1 hour ago, Shadders said:

Again, the point i was referring to is that ringing has been characterised - and the preference as given in the website.

The experiment discussed on that website has characterised ringing at 2 kHz. I'm not disagreeing with their findings.

 

1 hour ago, Shadders said:

If you are stating that the ringing at the higher frequencies do not correlate to the same preference at 2kHz, then ok.

Given what we know about human auditory perception, it does not appear valid to generalise the findings for 2 kHz so as to apply at the very extreme of our hearing ability.

[Shadders]

21 minutes ago, mansr said:

Given what we know about human auditory perception, it does not appear valid to generalise the findings for 2 kHz so as to apply at the very extreme of our hearing ability.

Hi,

So no evidence either way that it is, or is not, applicable.

Regards,

Shadders.

[Fokus]

It is not applicable, if you like that more.

 

For some people 'appear' seems to hold a 50% chance.

 

For others it is more like 90-99%, and words like 'appear' are used to avoid

an absolute.

 

[crenca]

1 hour ago, Shadders said:

Hi,

So no evidence either way that it is, or is not, applicable.

Regards,

Shadders.

 

The only evidence I know of about this audibility of this very low level, high frequency "ringing" is provided by audiophiles - and even they don't speak of terms of being able to directly hear it - rather they talk about how they can "hear" how transients are "smeared" and the like, and then they go on to reason a correlation between this "smearing" and impulse tests and the "ringing" these tests reveal.  

 

In the other words, it's all one big audiophile house of cards that in theory could be true (how would you test it outside of subjectivsed audiophiledom and its reliance on sighted listening "tests"?) but probably is not...

[Shadders]

16 minutes ago, crenca said:

 

The only evidence I know of about this audibility of this very low level, high frequency "ringing" is provided by audiophiles - and even they don't speak of terms of being able to directly hear it - rather they talk about how they can "hear" how transients are "smeared" and the like, and then they go on to reason a correlation between this "smearing" and impulse tests and the "ringing" these tests reveal.  

 

In the other words, it's all one big audiophile house of cards that in theory could be true (how would you test it outside of subjectivsed audiophiledom and its reliance on sighted listening "tests"?) but probably is not...

Hi,

OK, if you examine the ringing - it is not just a single frequency at a constant amplitude. The ringing has an envelope - this envelope has a frequency content predominantly less than the ringing frequency. It has to, else it would not be an envelope.

 

It is possible that this is what "audiophiles" are hearing, the effect of the ringing envelope.

 

Regards,

Shadders.

[crenca]

3 minutes ago, Shadders said:

Hi,

OK, if you examine the ringing - it is not just a single frequency at a constant amplitude. The ringing has an envelope - this envelope has a frequency content predominantly less than the ringing frequency. It has to, else it would not be an envelope.

 

It is possible that this is what "audiophiles" are hearing, the effect of the ringing envelope.

 

Regards,

Shadders.

 

Ah, intriguing question. The envelope itself is still very low level in amplitude is it not (honest question)?  In the video I posted above:

 

https://www.computeraudiophile.com/forums/topic/49609-john-atkinson-yes-mqa-is-elegant/?page=5&tab=comments#comment-864679

 

They force (through extreme Q EQ, gain, etc.) the ringing of a linear (0 phase) filter to be audible, and while it is a chirping sound it certainly is below 8000khz I believe.  Is this the envelope and and not the ringing frequencies themselves that have become audible?  

 

[Shadders]

7 minutes ago, crenca said:

 

Ah, intriguing question. The envelope itself is still very low level in amplitude is it not (honest question)?  In the video I posted above:

 

https://www.computeraudiophile.com/forums/topic/49609-john-atkinson-yes-mqa-is-elegant/?page=5&tab=comments#comment-864679

 

They force (through extreme Q EQ, gain, etc.) the ringing of a linear (0 phase) filter to be audible, and while it is a chirping sound it certainly is below 8000khz I believe.  Is this the envelope and and not the ringing frequencies themselves that have become audible?  

 

Hi,

I used Octave to analyse the envelope - frequencies are across the frequency range up to the ringing frequency.

 

I said earlier that ringing occurs in every waveform that has a transient change - the transient does NOT have to be at the ringing frequency - i said it was based on the rate of change of the signal, I should correct this - it is a second order effect - it is the rate of change of the rate of change of the signal, that causes ringing. The transient response.

 

If the music content contains transients then ringing will occur - it is difficult to see once the waveform is non-zero - it is embedded in the music signal - low level.

 

If you have a play with Octave, or Matlab - you can see the effect. Whether this is the smearing that they are talking about - who knows.

 

Regards,

Shadders.

[crenca]

37 minutes ago, Shadders said:

 

If the music content contains transients then ringing will occur - it is difficult to see once the waveform is non-zero - it is embedded in the music signal - low level.

 

If you have a play with Octave, or Matlab - you can see the effect. Whether this is the smearing that they are talking about - who knows.

 

Regards,

Shadders.

 

Just to be clear Shadders, when you say you can "see the effect" you mean with an impulse or impulse like "transient" that comes out of 0dBFS?  You don't mean you can see the effect in the middle of an otherwise normal musical signal/waveform?

 

 

[mansr]

42 minutes ago, Shadders said:

frequencies are across the frequency range up to the ringing frequency

Of course they are, that's the definition of an impulse. Step functions have similar properties.

 

[Shadders]

30 minutes ago, crenca said:

 

Just to be clear Shadders, when you say you can "see the effect" you mean with an impulse or impulse like "transient" that comes out of 0dBFS?  You don't mean you can see the effect in the middle of an otherwise normal musical signal/waveform?

 

 

Hi,

I initially used a sine wave at 1kHz which was gated - started from zero and finished at zero, and saw the pre and post ringing. I analysed the ringing from that to see the envelope. I examined the initial ramp of the sine - the ringing continued to appear (as it should) embedded here too. Essentially the amplitude of the sine signal was modulated for 256 samples assuming a 512 tap filter, reducing in level of modulation as the sine waveform progressed.

 

I then examined a ramp signal from 0volts to 1volts, which took 1 second to reach 1 volt, using a sample rate of 192kHz, and examined the pre-ringing. It appears even in this signal at an extremely low level.

 

This is obvious - if you look at the coefficients of the filter - you can see that it will present the +ve/-ve values accordingly.

 

The filter will have a steady state response and transient response. The steady state response is just that - when a signal is passing through such as a sine wave - steady state (after N+1 samples for an N tap filter) - the output will have an attenuation and phase characteristic. Same for a step change - the steady state response is the final settled output which will be the step voltage.

 

For the transient response - the ringing will depend on the amplitude and rate of change of the transient. The ringing is small - in many cases, and music by its very nature has many transients, negative and positive - where they will oppose or reinforce . You will not see obvious examples of ringing through a continuous (unbroken waveform) of music - since it is embedded, and small in amplitude.

 

Use Octave/Matlab - to examine the ringing in waveforms - as the waveform starts to build from zero, ringing is still in the waveform - embedded - but very low level.

 

Regards,

Shadders.

[mansr]

42 minutes ago, Shadders said:

I initially used a sine wave at 1kHz which was gated - started from zero and finished at zero, and saw the pre and post ringing.

This is not a band limited signal.

[Shadders]

37 minutes ago, mansr said:

This is not a band limited signal.

Hi,

Yes, i know. It demonstrates the ringing to analyse the envelope.

There will be transients in music from minimal to a maximum - and the envelope amplitude will be proportional to the transient.

 

If you examine a 1volt peak sine wave at 1kHz which reaches 0.5volts and then jumps to 1volt in the next sample, it will be a transient and you will see ringing.

 

In the next test, the 1volt peak is reached in 2 samples (0.5v, 0.75v, 1.0v). You will see ringing. Then the 1volt peak is reached in the next 4 samples (0.5v, 0.625v, 0.75v, 0.875v, 1.0v) you still see the ringing - reduced in amplitude.

 

If you keep doing this, you will eventually have a tangent to the sine curve from 0.5volts - no ringing at the 0.5volts sample.

 

So, from the worst case which is next sample at 1.0volts, to the tangent, the ringing occurs, but reduces to zero at the tangent test. This shows that ringing is inherent in the waveform, and appears at every transient, where that transient does not need to be band limited.

 

Regards,

Shadders.

[mansr]

7 minutes ago, Shadders said:

Yes, i know. It demonstrates the ringing to analyse the envelope.

There will be transients in music from minimal to a maximum - and the envelope amplitude will be proportional to the transient.

 

If you examine a 1volt peak sine wave at 1kHz which reaches 0.5volts and then jumps to 1volt in the next sample, it will be a transient and you will see ringing.

 

In the next test, the 1volt peak is reached in 2 samples (0.5v, 0.75v, 1.0v). You will see ringing. Then the 1volt peak is reached in the next 4 samples (0.5v, 0.625v, 0.75v, 0.875v, 1.0v) you still see the ringing - reduced in amplitude.

 

If you keep doing this, you will eventually have a tangent to the sine curve from 0.5volts - no ringing at the 0.5volts sample.

 

So, from the worst case which is next sample at 1.0volts, to the tangent, the ringing occurs, but reduces to zero at the tangent test. This shows that ringing is inherent in the waveform, and appears at every transient, where that transient does not need to be band limited.

I don't understand what you're trying to prove. Nobody is saying that filters don't "ring" when applied to impossible signals.

[Shadders]

1 minute ago, mansr said:

I don't understand what you're trying to prove. Nobody is saying that filters don't "ring" when applied to impossible signals.

Hi,

If this is in regards to the gated sine, i agree - was not band limited.

 

The following text in the post demonstrates that it does not need to be an out of band signal to cause ringing.

 

Ringing is inherent in the filter - see my previous post on transient response and steady state response.

 

Music is full of transients, and they do not need to be out of band to cause ringing. That ringing is embedded in the signal - difficult to see, and does not look like the pure ringing as seen by an out of band signal response.

 

Regards,

Shadders.

[mansr]

4 minutes ago, Shadders said:

Music is full of transients

Not in the mathematical sense.

[Shadders]

1 minute ago, mansr said:

Not in the mathematical sense.

Hi,

I am not sure what you are trying to prove here.

https://en.wikipedia.org/wiki/Transient_(oscillation)

There does not seem to be a stated bound for a transient.

 

I will assume you mean that a transient has to represent energy outside the bandwidth of the the system.

 

Can you provide the definition of a transient ? Thanks.

 

Anyway, if you disagree with the presented example, description, or whatever, then ok  - i am happy to read your thoughts.

 

Regards,

Shadders.

[John_Atkinson]

18 minutes ago, mansr said:

Nobody is saying that filters don't "ring" when applied to impossible signals.

 

You can see from the article of mine that triggered this thread an example where a perfectly legal, band-limited impulse nevertheless excites the DAC reconstruction filter's sinc-function ringing.

 

John Atkinson

Editor, Stereophile

 

[mansr]

30 minutes ago, John_Atkinson said:

band-limited impulse

Ain't no such thing. Please use standard maths/engineering terminology if you want to be taken seriously.

[John_Atkinson]

6 minutes ago, mansr said:

  36 minutes ago, John_Atkinson said:

band-limited impulse

 

Ain't no such thing. Please use standard maths/engineering terminology if you want to be taken seriously.

 

Okay, a very short unidirectional waveform, sampled at 44.1kHz, that has no spectral content above 22.05kHz.

 

John Atkinson

Editor, Stereophile

[Le Concombre Masqué]

I've read Jim Austin's literature on Stereophile and it made me wanna puke.

How can a publication advocate for the voluntary distribution of a voluntarily degraded format so that "jewels of crown" are preserved ?

Furthermore, instead of promoting calibration (ie so yo don't have a funny x dB bump between say 1 and 1.5 K because a moron is mastering/approving etc with monitors with a dip in said region....) MQA as is is not even compatible with dsp hence room correction etc etc

 

Legal paid for streaming is winning, for movies or music, large enough bandwidth is available in the remotest places : even on DRM and content distribution MQA is dinosaur

 

Plus I'm bored yet with the MQA flavor of poly sinc filter in HQP when upsampling Redbook ; Closed form 16 M is so much better...

 

I'll never buy a DAC MQA colluded, will turn to another brand   ; will you ?

 

[Fokus]

12 hours ago, John_Atkinson said:

You can see from the article of mine that triggered this thread an example where a perfectly legal, band-limited impulse nevertheless excites the DAC reconstruction filter's sinc-function ringing.

 

 

John, seriously: if it does do that, you have done something wrong in preparing the stimulus and/or in capturing the DAC's output.

 

If you want conceptual proof then a safer and cleaner approach is this:

 

1) work only in the digital domain

 

2) prepare the stimulus as an impulse at a very high sample rate, downsampled to a much lower Fs by using a blameless minimum phase SRC, like iZotope.

This gives you a truly band-limited 'impulse' with a clean leading edge, but obviously with the post-ringing of the MP SRC.

 

3) send this through a linear-phase reconstructor (i.e. the DAC, or rather a model of it).

You will see that no pre-ringing will be added to the output signal if the original filtering was done to a frequency not higher than slightly below Fs/2.

 

4) do so at high numerical accuracy, as any truncation or rounding will generate out of band signal.

 

 

[Fokus]

16 hours ago, Shadders said:

I said earlier that ringing occurs in every waveform that has a transient change - the transient does NOT have to be at the ringing frequency -

 

 

Take a  'ringing' Sinc-like low-pass filter with a transition frequency F.

 

If the spectrum of the stimulus is non-zero at F, then the output signal will visually exhibit filter ringing. If the spectrum of the stimulus is zero at F, then the output signal will not show ringing.

 

It is as simple as that.

 

 

As for the ringing envelope occupying frequencies below F ... consider that a filter is a linear operator, and think this through.

[Fokus]

13 hours ago, John_Atkinson said:

You can see from the article of mine that triggered this thread an example where a perfectly legal, band-limited impulse nevertheless excites the DAC reconstruction filter's sinc-function ringing.

 

This here, on page 2 of your article:

" To answer this question, I took the 96kHz pulse captured by the Ayre QA-9 in Listen mode and used the highest-quality sample-rate converter in BIAS Peak to downsample it to 44.1kHz.

...

Note that the digital data has already been band-limited to half the 44.1kHz sample rate, thus is a "legal" signal."

 

Did you verify the nature of the BIAS Peak SRC? The two versions documented at http://src.infinitewave.ca/ are clearly half-band, allow aliasing, and therefore do not provide legal band-limiting.

 

 

Isn't it the audio press's task to be thorough in its search for the truth? To avoid publishing half-truths and lies? And does this not imply a certain level of understanding of the subject? Is this not your responsibility?

 

Once more Stereophile is letting us down.

 

 

 

As an aside, the entire article, once you see through the confusing style and presentation, and with ignoring the more farcical parts, brings us nothing new at all.

 

 

 

 

 

[Shadders]

56 minutes ago, Fokus said:

Take a  'ringing' Sinc-like low-pass filter with a transition frequency F.

 

If the spectrum of the stimulus is non-zero at F, then the output signal will visually exhibit filter ringing. If the spectrum of the stimulus is zero at F, then the output signal will not show ringing.

 

It is as simple as that

Hi,

This seems to be a mantra on this site. People seem to be stuck on boundary conditions/effects.

 

If you examine my example of the sine wave with a discontinuity when it is 0.5volts going to 1.0volts at the next sample, and you relax the discontinuity until it is a tangent to the curve, ringing is always there, but it reduces in amplitude.

 

Examine my ramp example - easy to implement in Octave/Matlab - ringing is always there no matter how small a change, but the ringing is extremely small.

 

Examine the filter action in the time domain, look at the coefficients, and recall the convolution theorem where each input sample to the filter produces a scaled impulse response, which are summed together in time, each have the relevant delay. This should give you some insight to what is actually occurring.

 

Examine the DSP books and look up the aspects of transient and steady state responses. Every DSP book has this discussion and analysis. Every electrical engineering book has this discussion when dealing with filters, or any other circuit where a transient is applied - usually studied using Laplace transforms, most people just use spice now when analysing.

 

OK - in saying this - i know this will be ignored or scoffed at, and the mantra will win through.

 

1 hour ago, Fokus said:

As for the ringing envelope occupying frequencies below F ... consider that a filter is a linear operator, and think this through.

Not sure what you are saying here. A linear system will pass the envelope if the frequencies are in the passband as per the filter transfer function.

 

Regards,

Shadders.

[Fokus]

3 minutes ago, Shadders said:

Not sure what you are saying here.

 

That is abundantly clear.

 

Once more ... you claim that you investigate the ringing in isolation, and you claim that the ringing envelope emcompasses frequencies down in the passband. In other words, you claim that the ringing itself has audible content all over the passband. This means that the filter creates new spectral content, well below the filter's transition frequency.

 

Now tell us the main properties of a linear operator.