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Misleading Measurements


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On 7/20/2020 at 10:56 PM, bluesman said:

When I asked if you'd tested ("validated", a term at which you mysteriously took offense) your app to be sure it was not adding any distortions or other effects besides the desired one, you offered no answer other than that "DISTORT will construct a nonlinearity and that the same non-linearity will generate HD when applied to a single tone, and IMD when applied to multiple tones".  And you may well have said this "at least a dozen times" - I didn't count. 

 

You also ignored my request for any explanation, no matter how simple, of how you could generate harmonic or intermodulation distortion by adding a nonlinear transfer function to the signal path without producing any other effects on the signal.  Again, you ignored my question and gave the same answer.  Today, SoundAndMotion offered what I believe is a more accurate response - that "...if you want to add anomaly X, you have to be aware that the compression comes with it".  I, too, believe that you cannot add harmonic distortion to a signal without other secondary effects on it, e.g. compression, frequency response alteration, phase shift, etc depending on the exact transfer function used.  BTW, y=f(x) can be a linear equation depending on the function. That’s why I asked how you do what you do with your app.

 

I still do not understand how you can add a nonlinear transfer function to a signal chain with no resultant change in the signal except the production of harmonic / IM distortion.  You still haven't explained it, if it's even possible (which, from what I know, is not the case).  And compression is only the first unintended "side effect" that came to mind - there are many more. 

 

I'd hoped to learn something new from you - but that hasn't happened yet.  I still live in hope, but I'm not as optimistic now.  I'm sorry you choose to take umbrage at what I truly think are reasonable questions that are also very relevant to deciding if a measurement is useful or misleading.  

 

@bluesman, you clearly misunderstand what a non-linear transfer function does and how HD or IMD is produced by audio devices. I suggest you look into it, read about it. Plenty of textbooks, on-line courses, or even simple white papers and tutorials, some even have been mentioned in the new DISTORT thread by others. I'm not going to continue to try to explain the basics to you while being verbally abused.

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1 hour ago, Summit said:

For me, it is not the measurements that are misleading, it is what they are said to have for actual (SQ) effect that can be misleading. All measurements must be interpreted by someone and interpretations are based on preconceived ideas of what is audible and what is not.

 

 

Sure and I think it's Computer Auduophile's position too.

 

Measurements by themselve are not misleading. People that present them can have hidden agenda or personnal goals different than teachning and sharing neutral informations. There's people who use science badly (we have a couple of exemple here, as well as on ASR forum.

 

I do agree that we have to do something about this. But removing the data available is not a good solution, this would be a step back.

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8 hours ago, John Dyson said:

Whether the intermod happens in 'air' or in a 'string', the underlying math is essentially the same as software & electronics emulations of the effects.  I am NOT claiming that precise emulation of the real world is simple, but I don't think that is what we are worrying about.

 

 

What we're worrying about is whether recording the interplay of musical instruments, and then replaying that capture "doubles up" on some, nebulous, thing ...

 

Assuming adequate accuracy of the devices used, the answer is ... that it doesn't.

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  • 1 month later...
On 9/22/2020 at 12:01 PM, Blake said:

Speaking of the topic of this thread, I'm not sure if this has been posted about and discussed here on AS, but I found it to be an interesting read as I have always had some suspicions about ASR:

 

https://www.superbestaudiofriends.org/index.php?threads/audio-science-review-review.9827/

 

 

Well, I do understand how ASR can rub people the wrong way. I remember when the fine peeps at ASR were losing their shit over the Yggy glitch....  Kept looking at the graphs and was thinking "well, this is obviously beyond any human's hearing thresholds - what is the big deal?" - yet well, it was a big deal over at ASR... ah well  - nobody's perfect, but all in all, we need ASR - they help keep manufacturers honest...

 

v

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On 7/4/2020 at 6:17 PM, semente said:

 

This particular case is not so much that measurements are misleading but whether a couple of measurements are enough to characterise audible performance; I defend that they're not.

Life would be very easy if a spinorama could characterise loudspeaker performance in full and predict preference. But this is the real world...

Agree. I don't think measurements at ASR tell the whole story: For instance, does my -110db SINAD DAC sound audibly different from a -114db SINAD DAC of similar design from same company? I doubt it.  Bruno Putzeys talked about how he thinks measurements can tell you what you need to know about an amp, but you have to run many different meaurements, and not just the standard ones, to see how an amp actually behaves. Some of the people at ASR seem caught up in the numbers for the numbers sake. Others seem to just be looking for good values - units that seem to have near state of the art performance - at least for basic parameters - and that aren't wildly expensive. They are appreciative of the engineering success. 

I think such measurements are useful if they reveal something like high levels of distortion, as has been found with some high end/well regarded DACs and amps. People or reviewers may like how they sound; I'd prefer to find a unit that measures well and sounds good - and not spend my money on euphonic distortion. 

Main listening (small home office):

Main setup: Surge protector +>Isol-8 Mini sub Axis Power Strip/Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>Stack Audio Link II>Kii Control>Kii Three (on their own electric circuit) >GIK Room Treatments.

Secondary Path: Server with Audiolense RC>RPi4 or analog>Cayin iDAC6 MKII (tube mode) (XLR)>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup.
Living Room/Kitchen: Ropieee (RPi3b+ with touchscreen) + Schiit Modi3E to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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13 hours ago, vmartell22 said:

 

Well, I do understand how ASR can rub people the wrong way. I remember when the fine peeps at ASR were losing their shit over the Yggy glitch....  Kept looking at the graphs and was thinking "well, this is obviously beyond any human's hearing thresholds - what is the big deal?" - yet well, it was a big deal over at ASR... ah well  - nobody's perfect, but all in all, we need ASR - they help keep manufacturers honest...

 

v

 

But, was there really a glitch?  That was the subject of debate as well.

 

https://www.superbestaudiofriends.org/index.php?threads/yggdrasil-a2-measurements-deconstructing-asr-amirs-hack-job.6442/

 

 

Speaker Room: Lumin U1X | Lampizator Pacific 2 | Viva Linea | Constellation Inspiration Stereo 1.0 | FinkTeam Kim | Revel subs  

Office Headphone System: Lumin U1X | Lampizator Golden Gate 3 | Viva Egoista | Abyss AB1266 Phi TC 

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Quote

Objectivists believe they know the threshold or level of audibility with respect to measurements.

Rob Watts (Chord) had noted in his talks (RMAF, etc .... see YouTube), that it is only when he began pushing metrics WAAAAAAAAAYYYY above and beyond -- limits of measuring instruments (> 300db s/n, etc)-- that he finally began to notice subjective improvements (which, as he claims, above all, is depth perception). 

There are likely to more measured parameters added to scientific toolkit ... yet to come. Eg.,  (to test labs) linearity and data jitter came in well after the CD format was released to consumer. 

Also, known (measured ) parameters and unknown/unmeasured ones my well significantly matter if they are found to synergistic or interactive. In crude words, the pac-man exits the left side of the arcade screen and simultaneously pops in on the right. 

I am still a bit unclear on why certain D-S dacs, as their specs get more and more "unmeasurable",  (esp. AKM), and the sound gets softer and smoother, but NOT more music or exciting. Or the NOS vs. OS crowd. You get the idea.

Hard-core objectivists have very little genetic imagination ... so, eg., they can't IMAGINE a world outside the box of, say, a Univ. Physics textbook publ'd in 2008.... that even basic equations and laws will change or be added to in an edition a few decades from now.

Think of all the "basic" science questions of day -- dark matter, dark energy, the "Hard Problem", etc. -- and then work back to how absurd objective complacency is in audio. 

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18 minutes ago, wbh said:

I am still a bit unclear on why certain D-S dacs, as their specs get more and more "unmeasurable",  (esp. AKM), and the sound gets softer and smoother, but NOT more music or exciting. Or the NOS vs. OS crowd. You get the idea.

Hard-core objectivists have very little genetic imagination ... so, eg., they can't IMAGINE a world outside the box of, say, a Univ. Physics textbook publ'd in 2008.... that even basic equations and laws will change or be added to in an edition a few decades from now.

Think of all the "basic" science questions of day -- dark matter, dark energy, the "Hard Problem", etc. -- and then work back to how absurd objective complacency is in audio. 

 

It's actually very simple ... no-one measures how robust audio systems are to resisting the influence of electrical interference, noise factors - these are just thrown into the "good enough to get a sticker meaning that it meets some EMC standard" box, and that's the end of it.

 

Highly "over-engineered" components actually do enough to mitigate these effects - they that shall never be mentioned, 🙂 - and the SQ, works.

 

The refusal of objectivists to take interference mechanisms seriously is a key factor of why so much nonsense exists in the audio world - at a practical level, this has to be dealt with, to get accurate reproduction of what's on a recording, irrespective of whether a rig costs $500, or $500,000 ...

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