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MQA is Vaporware


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3 hours ago, mansr said:

I wonder why they even bother recording in anything above 96 kHz. There's nothing but noise at those high frequencies.

This comment jogged my memory regarding something Charles Hansen said:

Quote


Q: Can you discuss the cause and effect of Pre-Ringing and Pre-Echo?

 

A: It's really quite simple. Any filter steeper than 6 dB/octave (first order) will ring when a transient event comes along. The ringing can be minimized to any arbitrary degree by making the transition as gentle (as opposed to a sharp transition) as desired.

 

It is not practical to have a gentle transition with single-rate audio (such as found on CDs). You only have 2 kHz (20 kHz to 22.05 Hz = Fs/2) to get at least 96 dB (16 bits) of attenuation, so there will always be a lot of ringing. We can minimize it by letting the rolloff start at (say) 18 kHz instead of 20 kHz. Already that cuts the problem in half as now you have twice the bandwidth to perform the filtering, which means half as much ringing. There are additional compromises that can be made, but they will always be compromises.

On the other hand, by the time you get to quad-rate sampling (176.4 kHz or 192 kHz), the compromises are practically non-existent. One can have flat frequency response to 40 kHz or 50 kHz, and still have a filter with little or no ringing (in the case of the moving-average filter).

 

 

 

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51 minutes ago, Dr Tone said:

 

It seems the MQA discussion also has the following:

 

Buy Meridian

Think Bob Stewart is god.

Read MQA isn't all that Bob says it is, simply refuse to believe it.

Must attach all posters against MQA and fight to death in Bob's honor even when Bob knows better than try to defend his own $invention$ in a technical discussion.

 

It happens in all areas of human discussion. Why we still have anti-vaxxers out there even though the preponderance of proof says their idea doesn't hold any water. I know someone who still believes the Apollo missions to the moon were staged by the 'secret state'. It is what it is. 

 

http://exisleempowerment.com/avoid-being-judgemental-the-principles-of-opinion-forming/

 

https://digest.bps.org.uk/2018/04/20/our-brains-rapidly-and-automatically-process-opinions-we-agree-with-as-if-they-are-facts/

 

Hence why many places now, opinion is stated as fact. 

Current:  Daphile on an AMD A10-9500 with 16 GB RAM

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Pre-amp - Rotel RC-1590

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10 minutes ago, mansr said:

spacer.png

 

 

Exactly.....

Current:  Daphile on an AMD A10-9500 with 16 GB RAM

DAC - TEAC UD-501 DAC 

Pre-amp - Rotel RC-1590

Amplification - Benchmark AHB2 amplifier

Speakers - Revel M126Be with 2 REL 7/ti subwoofers

Cables - Tara Labs RSC Reference and Blue Jean Cable Balanced Interconnects

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8 minutes ago, mansr said:

He's right about 44.1 kHz sample rate requiring a steep filter. Everything else is wrong or misleading. Charley had an obsession with slow roll-off filters. Rob Watts is equally obsessed with super-steep filters. They can't both be right.

 

The point is that there *is* a reason to record >96 kHz even if *you* disagree with Hansen's filtering decision.

 

What is "wrong or misleading" in Hansen's statement?

Roon ROCK (Roon 1.7; NUC7i3) > Ayre QB-9 Twenty > Ayre AX-5 Twenty > Thiel CS2.4SE (crossovers rebuilt with Clarity CSA and Multicap RTX caps, Mills MRA-12 resistors; ERSE and Jantzen coils; Cardas binding posts and hookup wire); Cardas and OEM power cables, interconnects, and speaker cables

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1 hour ago, mansr said:

He's right about 44.1 kHz sample rate requiring a steep filter. Everything else is wrong or misleading. Charley had an obsession with slow roll-off filters. Rob Watts is equally obsessed with super-steep filters. They can't both be right.

 

From an earlier post of mine August 2018

 

Actually Jud I believe and have stated most of the time linear filers work best, sometimes a minimum phase works and sometimes an intermediate filter like Archimago's is best. I'm in the category of agreeing with Julius O Smith of Stanford. Charles Hansen and I were friends so I heard a lot about why minimum phase filters worked but he didn't live long enough to experiment with intermediate phase filters. And Rob Watts has made compelling arguments to me in our discussions as have several others. I keep saying one size does not fit all.

 

But I have a lot doubt about anything but linear filters when you are assembling songs from tracks.  And I would rather listen to an old iPod than my iPhone X with a minimum phase filter. 

 

The doesn't occur in nature isn't a convincing argument to me. 

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43 minutes ago, mansr said:

 

The ripples occur at the corner frequency of the filter with an intensity proportional to the signal content at that frequency....

 

What's the proportion of the ripples to signal?  It's based on the order of the filter I assume, so what is the level of the ripple (vs. signal) of a 2nd order and a 3rd order as examples?

 

On another note, I am so proud of you guys!  This so called "ringing" or "time smear" problem is the final technical nail in MQA's coffin as far as I can see.  Jim Austin and John Atkinson have their straws poked out of this coffin trying to suck in air around this issue, but the hammer is coming down...

Hey MQA, if it is not all $voodoo$, show us the math!

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21 minutes ago, crenca said:

What's the proportion of the ripples to signal?  It's based on the order of the filter I assume, so what is the level of the ripple (vs. signal) of a 2nd order and a 3rd order as examples?

The impulse response is the worst case.

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4 minutes ago, John Dyson said:

I 'upvoted' your comment -- but only one VERY MINOR modification -- I agree that the FIR filters used for LPF dont 'ring'.   it isn't that all filters don't ring (IIR or analog filters can ring -- store energy and continue with usually decayed oscillation.)   I didn't read the URL in the message, but the 'Gibbs effect' which is a residual from a series truncation is what people sometimes mistake for 'ringing' on waveform displays.  That 'Gibbs effect' doesn't result from energy storage in the same way that true ringing does -- Gibbs effect is simply a residual from a truncation of a series of sine functions (sometimes comprising something like a square wave) that leaves a left-over of 'undulations' that look a little like sine waves.  That 'truncation' of 'sine functions' is basically a constant delay low pass filter.

 

There can also be a difference in sound between a minimum phase vs. constant-delay-vs.-frequency filter, but it is a matter of relative time of arrival of the various signal components, not 'ringing' at all.

 

I suspect that the combination of the 'sine-like' residual signals (Gibbs effect), and the slight difference in sound character of filters with different kinds of time delay behaviors can trick non-technical people into believing that they are hearing the effects of 'ringing.'

 

John

 

I think it is mostly the pictures of "ringing" in magazines and then the marketing BS to pretend they are a problem that makes people think they hear it.  They don't.  

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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16 minutes ago, John Dyson said:

I 'upvoted' your comment -- but only one VERY MINOR modification -- I agree that the FIR filters used for LPF dont 'ring'.   it isn't that all filters don't ring (IIR or analog filters can ring -- store energy and continue with usually decayed oscillation.)

That is correct, I just didn't think the digression into IIR filters was necessary since we weren't discussing those.

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20 minutes ago, esldude said:

I think it is mostly the pictures of "ringing" in magazines and then the marketing BS to pretend they are a problem that makes people think they hear it.  They don't.  

You are probably right, but people do hear slight differences from filters, and seem to sometimes prefer one over the other. They might not “hear” as many differences without being prompted by he pictures, or the might actually prefer different filters if not being shown before hand how they should sound. 

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All absolute statements about audio are false :)

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20 minutes ago, firedog said:

You are probably right, but people do hear slight differences from filters, and seem to sometimes prefer one over the other. They might not “hear” as many differences without being prompted by he pictures, or the might actually prefer different filters if not being shown before hand how they should sound. 

 

It is hard to divorce the what is heard from what is 'thought' to be heard in most cases. Only way to separate the real from the not real is double blind listening session :D 

Current:  Daphile on an AMD A10-9500 with 16 GB RAM

DAC - TEAC UD-501 DAC 

Pre-amp - Rotel RC-1590

Amplification - Benchmark AHB2 amplifier

Speakers - Revel M126Be with 2 REL 7/ti subwoofers

Cables - Tara Labs RSC Reference and Blue Jean Cable Balanced Interconnects

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22 minutes ago, firedog said:

You are probably right, but people do hear slight differences from filters, and seem to sometimes prefer one over the other. They might not “hear” as many differences without being prompted by he pictures, or the might actually prefer different filters if not being shown before hand how they should sound. 

If anything, they are hearing early roll-off or phase effects within the audible range.

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5 hours ago, mansr said:

Even if you could hear the 20 kHz "ringing" by itself, it would be masked by lower frequency sounds whenever it actually occurs.


I have always thought this was the reverse of the way the subject should be conceptualized. I’d think we should be more concerned with how much low level signal (music) is masked by the noise.

 

The answer could well be “nothing one would hear in any case,” but at least I think it’s the proper question.

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

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5 hours ago, mansr said:

The ripples occur at the corner frequency of the filter with an intensity proportional to the signal content at that frequency.


Would it be correct to assume this intermodulates, same as any other component of the output?

One never knows, do one? - Fats Waller

The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. - Einstein

Computer, Audirvana -> optical Ethernet to Fitlet3 -> Fibbr Alpha Optical USB -> iFi NEO iDSD DAC -> Apollon Audio 1ET400A Mini (Purifi based) -> Vandersteen 3A Signature.

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