[KeithEmo]

When I read your post, I see many "assertions" - which is something quite different than facts.

For example, you assert that "filter ringing should be clearly inaudible".
Why do you assume that this would be the case?
Ringing produces clearly audible effects in some speakers; and its effects were clearly audible in old-style analog equalizer circuits with L-C filters.
In fact, many EQ plugins for DAWs offer the option of choosing "vintage EQ sound" - which includes filters that introduce ringing and other sorts of "vintage circuit sounds".
Many folks assert that "finally, now, it is inaudible in most modern equipment, unless it's put there intentionally" - but that is simply an assertion.

And, yes, most modern equipment measures frequency response over time.
However, the time constants used vary quite widely.
An oscilloscope trace, especially on a modern digital oscilloscope, will show that firecracker quite clearly - it you look for it.
But the standard spectrum measurements used to measure THD, and the sort of noise sidebands used to quantify jitter effects, are usually averaged over several seconds.
There's a good reason for this: time averaging allows greater accuracy, and helps eliminate random noise and other random fluctuations.
However, it also tends to ignore, or avoid showing, short-term effects like ringing on transients (because, FOR THAT PARTICULAR TEST, those are NOT what we're trying to measure, so they're considered to be "distractions".)
And, of course, any measurement done using steady state sine waves fails to experience or show anything whatsoever about transient performance.
In fact, in order to measure things like transient response, and filter ringing, you have to use special tests and test signals designed for that purpose.

And, yes, many of the microphones and other equipment used to record audio introduce various alterations to the sound; some of which are intentional, and some of which are not.
And, yes, some of them "can... produce greater amounts of artifacts than any well designed filter... and in ranges to which we are sensitive."
However, all of those are part of the music PRODUCTION process; somebody chose that microphone because they like the way it sounds, or because they consider its flaws acceptable, NOT because they imagine it's "perfect".
When REPRODUCING that music, our goal is to play it as it is provided to us, and to avoid introducing more and different alterations.
Van Gogh may have used cheap paint, scraped off old buildings, for one of his paintings; however, when I reproduce it, I still try to do reproduce his painting, original errors and all, just as he painted it, as accurately as possible.

One time one of my customers sent in a piece of equipment for repair of a "problem" he'd discovered.
He also included a copy of the file where he'd noticed it.
His particular piece of equipment would clip this particular test signal - quite obviously - even though we were unable to notice any odd sounds with any other music.
Would you suggest that "it doesn't really matter if that sound is clearly distorted - because it's not something you encounter very often in popular music"?
(That sound was included on that test disc, along with a few other odd sounds, specifically BECAUSE it stresses equipment, and so tends to emphasize flaws that might otherwise not be obvious.)
In fact, when designing tests, we often create specific unusual test signals, designed to maximize the visibility or audibility of certain flaws.
For example, when testing a camera lens for distortion, we use a black and white checkerboard or crosshatch pattern...and, when testing it for color accuracy, we use a checkerboard of accurately known colors.

This is not something that is limited to audio testing....
The very popular JPG image compression format was designed to work well with images with continuous tones - like human faces - for which it works VERY well.
However, it works very poorly with images that include lines or sharp edges - like cartoon images and text.
If you apply a high level of JPG compression to a variety of images, faces will look very good, but text will display obvious artifacts (little ghosts around the edges of the letters).
For this reason, JPG compression is often used for photographs, but would be a bad choice for "compressing an unknown mixture of images and pictures".
(Because, not only do we KNOW that it will perform badly on certain specific types of images, but, if we see artifacts on some of our images, we won't know if they were there originally, or if the JPG processing caused them.)
So, likewise, when attempting to accurately reproduce complex signals, we generally prefer to do so in ways that we KNOW won't alter them audibly, rather than in ways that we hope or assume will not.
(And, yes, one thing that differentiates "audiophiles" from "regular consumers" is that audiophiles are willing to expend more effort and money to avoid issues that occur infrequently or aren't especially annoying.)

You really do need to differentiate between "fixing problems that really don't exist" and "fixing problems that ARE quite real, but aren't bad enough that MOST PEOPLE care about them".

That is virtually never the case. For example, what "you DO hear" is some external soundwaves hitting your eardrums plus a rather large amount of heartbeat sound, the sound of blood moving though blood vessels and even the sound of your nervous system. What we think we hear is typically NOT closely related to what "you do hear" because, except for some rare circumstances, we never think we hear these constant, relatively loud body function sounds because our brain eliminates them from our perception, and this is just one of many similar examples. The reality of the situation is that almost never is what we think we hear "closely related" to what we do hear, the best we can truthfully say is that occasionally, what we think we hear aligns quite well with what other people think they hear.



1. True but in this particular case we're talking about filter ringing, something which should be clearly inaudible, unless it's been specifically designed to be audible.
1a. OK, let's run with your analogy. By orders of magnitude, the most common type of equipment used to examine sound is the graphical representation of sample data over time (in say a DAW/audio editor) and graphical representations of frequency content over time, both of which would blatantly obviously "reflect how audible the firecracker really is". In fact, you'd have to doctor the firecracker recording in the case of the SPL measurement or use a measurement type specifically designed not to report amplitude variations (only an average), all while avoiding the almost unavoidable other types of measurements. In other words, one would need to be deliberately trying to avoid a measurement that would "accurately reflect how audible that firecracker really is"!



1. The controlled tests I'm aware of used standard type filters, with a transition band of around 2kHz or so. What about the inverse of the question, how steep were the filters used in controlled tests where a difference could be detected? As far as I'm aware the answer is either: Steeper than is ever found in consumer equipment or extremely shallow and well into the audible range (for some "warmth" or other lower audible fidelity and supposedly subjectively better result).

2. A very good point and one often omitted in the arguments made by audiophiles (or marketed to them). How many pieces of music do you know that were NOT recorded by mics and had no EQ (or other ringing/phase inducing effect) applied during mixing or mastering? All of which can not only produce far greater amounts of ringing/phase related artefacts than any well designed/standard reconstruction filter but also in a freq range to which we're actually sensitive!



We're trying to determine scientifically/factually whether there is any audible difference between DACs designed for high-fidelity conversion when reconstructing commercial digital audio.

Why would anyone be trying to "determine, scientifically, if there is ANY audible difference between different DACs, even if it can only be detected with certain test signals"? Of course there is, that's already been determined scientifically, decades ago! It's easy to deliberately make a DAC sound different with certain test signals and there are actual, commercially released, deliberately obvious examples of this. For example there were some which did not oversample and had no reconstruction filter (the NOS/Filterless DACs) and it's simple to design a test signal which would result in the DAC producing alias images which are clearly audible or at least, easily differentiated from a DAC with a competent filter.

The thread is: "Testing audiophile claims and myths". What audiophiles are we talking about? How many audiophiles are there who listen exclusively to test signals and are not interested in fidelity? Even if there are some, the audiophile claims and myths clearly relate to reproducing commercial audio.

The above points are all misrepresentations or obfuscations, although I can't be sure if they're deliberately so or inadvertent but they are obfuscations, as per my last post (#9650), and I fail to see how any of this makes your "interest more scientific". If anything, it demonstrates to me "less scientific" or at least, less factual.

G

 

[Joe Bloggs]

When I read your post, I see many "assertions" - which is something quite different than facts.

For example, you assert that "filter ringing should be clearly inaudible".
Why do you assume that this would be the case?

Because the frequencies through which the ringing occurs is supersonic. Certainly supersonic to you and me, if not to most everybody old enough to play with a DAC.

Ringing produces clearly audible effects in some speakers; and its effects were clearly audible in old-style analog equalizer circuits with L-C filters.
In fact, many EQ plugins for DAWs offer the option of choosing "vintage EQ sound" - which includes filters that introduce ringing and other sorts of "vintage circuit sounds".
Many folks assert that "finally, now, it is inaudible in most modern equipment, unless it's put there intentionally" - but that is simply an assertion.

And, yes, most modern equipment measures frequency response over time.
However, the time constants used vary quite widely.
An oscilloscope trace, especially on a modern digital oscilloscope, will show that firecracker quite clearly - it you look for it.
But the standard spectrum measurements used to measure THD, and the sort of noise sidebands used to quantify jitter effects, are usually averaged over several seconds.
There's a good reason for this: time averaging allows greater accuracy, and helps eliminate random noise and other random fluctuations.
However, it also tends to ignore, or avoid showing, short-term effects like ringing on transients (because, FOR THAT PARTICULAR TEST, those are NOT what we're trying to measure, so they're considered to be "distractions".)

And, of course, any measurement done using steady state sine waves fails to experience or show anything whatsoever about transient performance.
In fact, in order to measure things like transient response, and filter ringing, you have to use special tests and test signals designed for that purpose.

Do you understand sampling theory enough to know that the amount of ringing is fixed for a given filter frequency response, and that you can only move it around in front or behind the impulse, never remove it given the same frequency response?

This is such an immutable law that whenever I see a 44.1kHz or 48kHz player / DAC / recording system with no ringing in response to the Kronecker delta, I immediately turn my eye away, for it goes without saying that stupid audiophool things have been done to the lowpass filter, either an apodizing filter that suppressing inaudible ringing at the 20-24kHz supersonic transition band (which was the "cushion area" intentionally left in the formats, to LET brickwall filter ringing happen and be inaudible) at the cost of quite audible dulling of audible high frequencies 15-20kHz; severe compromise of stopband attenuation; or complete omission of the filter.

The one smart thing to be done within the confines of linear filtering, given sensible filter frequency response, is to decide on minimum phase or linear phase filtering, or some intermediate choice. Given that for audible frequencies masking occurs before and after a signal, but mostly after, if we extrapolate these tests results from audible frequencies to inaudible 20-24kHz ultrasonics the preferred binary choice would be the minimum phase filter, with the optimum choice being a hybrid filter somewhere between minimum and linear but leaning towards minimum.

One time one of my customers sent in a piece of equipment for repair of a "problem" he'd discovered.
He also included a copy of the file where he'd noticed it.
His particular piece of equipment would clip this particular test signal - quite obviously - even though we were unable to notice any odd sounds with any other music.
Would you suggest that "it doesn't really matter if that sound is clearly distorted - because it's not something you encounter very often in popular music"?
(That sound was included on that test disc, along with a few other odd sounds, specifically BECAUSE it stresses equipment, and so tends to emphasize flaws that might otherwise not be obvious.)
In fact, when designing tests, we often create specific unusual test signals, designed to maximize the visibility or audibility of certain flaws.
For example, when testing a camera lens for distortion, we use a black and white checkerboard or crosshatch pattern...and, when testing it for color accuracy, we use a checkerboard of accurately known colors.

And yet, in another post:

However, my point was not what to call it...
My point is that it is something which is clearly audible, at least under some circumstances, but will not show up on traditional frequency response, THD, IMD, or S/N measurements.
It is only detectable, or measurable, with certain specific types of test signals and test equipment... however, those test signals are quite characteristic of music, which pure sine waves are not.
(And anyone versed in science knows that, when devising a test, it must be designed to approximate the actual usage conditions as closely as possible, and not be chosen "because it's easy to measure".)

It really seems like in your imagination the scientific method is whatever you imagine to be convenient for your argument at the time?

For the record I side more with the test signals side of the argument, especially as it is basic psychoacoustic fact that humans can detect distortion in pure tones much more easily than in regular music material. And on that note... When playing sine sweeps on "vanilla" DACs I do often hear a "harmonic" crawling down from the Nyquist frequency as the actual sweep crawls up to meet it, presumably caused by IMD between the signal frequency and its ultrasonic image generated when the DAC oversamples and which is not fully removed by the reconstruction lowpass filter. So it would seem that these DACs would audibly benefit from even steeper filtering... at the cost of more ringing.

 

[KeithEmo]

I guess I'm a little bit confused... I'm not sure that your point is here.

You seem to be agreeing that filters with different responses will have different amounts and types of ringing...
And there are obviously an infinite number of filter variations that will yield a response that is "arbitrarily very flat between 20 Hz and 20 kHz and down a lot of dB at 24 khz".
(Not to mention that, as you did point out, a lot of DAC designers are willing to forego those semi-obvious requirements in pursuit of other specific characteristics they're convinced are important.)
And, yes, if everybody used the same filter, then the ringing on every system that used it would be the same.
(And, if all the other parameters were the same, then I would expect them to sound the same.)
However, everybody does NOT use the same filter.

For example, the Wolfson WM8741 DAC offers a choice of 21 different filters.
Many of them are "arbitrarily quite flat from 20 Hz to 20 kHz"...
Yet they have significant differences in other characteristics...
Some have more or less out-of-band suppression; others have more or less out-of-band ripple; others have different amounts of phase shift...
And some seem to sound different than others...
And, no, they do NOT say "filter #14 is the right one - and we've provided the others just for fun".
So, yes, there are choices, and there are differences.
And, clearly, not everyone agrees with you about "the best and most optimal choices".
(And, to be honest, "a hybrid filter somewhere between minimum and linear but leaning towards minimum" seems to offer a lot of leeway for variations too.)

Your other assertion is probably correct - but also obviously limited.

Yes, steady state levels of THD and IMD tend to be most audible with pure sine waves.
However, it's also obvious that it isn't going to work to try and test the audibility of distortions that ONLY occur during transients using steady state sine waves.
(You cannot test the audibility of something that isn't there... and distortions related to transients simply will not occur while playing steady state sine waves.)

And, yes, I certainly agree that, if a certain design exhibits audible aliasing with sine wave sweeps, then it probably would benefit from better filter design

Because the frequencies through which the ringing occurs is supersonic. Certainly supersonic to you and me, if not to most everybody old enough to play with a DAC.



Do you understand sampling theory enough to know that the amount of ringing is fixed for a given filter frequency response, and that you can only move it around in front or behind the impulse, never remove it given the same frequency response?

This is such an immutable law that whenever I see a 44.1kHz or 48kHz player / DAC / recording system with no ringing in response to the Kronecker delta, I immediately turn my eye away, for it goes without saying that stupid audiophool things have been done to the lowpass filter, either an apodizing filter that suppressing inaudible ringing at the 20-24kHz supersonic transition band (which was the "cushion area" intentionally left in the formats, to LET brickwall filter ringing happen and be inaudible) at the cost of quite audible dulling of audible high frequencies 15-20kHz; severe compromise of stopband attenuation; or complete omission of the filter.

The one smart thing to be done within the confines of linear filtering, given sensible filter frequency response, is to decide on minimum phase or linear phase filtering, or some intermediate choice. Given that for audible frequencies masking occurs before and after a signal, but mostly after, if we extrapolate these tests results from audible frequencies to inaudible 20-24kHz ultrasonics the preferred binary choice would be the minimum phase filter, with the optimum choice being a hybrid filter somewhere between minimum and linear but leaning towards minimum.



And yet, in another post:


It really seems like in your imagination the scientific method is whatever you imagine to be convenient for your argument at the time?

For the record I side more with the test signals side of the argument, especially as it is basic psychoacoustic fact that humans can detect distortion in pure tones much more easily than in regular music material. And on that note... When playing sine sweeps on "vanilla" DACs I do often hear a "harmonic" crawling down from the Nyquist frequency as the actual sweep crawls up to meet it, presumably caused by IMD between the signal frequency and its ultrasonic image generated when the DAC oversamples and which is not fully removed by the reconstruction lowpass filter. So it would seem that these DACs would audibly benefit from even steeper filtering... at the cost of more ringing.

 

[bigshot]

For the record I side more with the test signals side of the argument, especially as it is basic psychoacoustic fact that humans can detect distortion in pure tones much more easily than in regular music material.

If you're generally listening to music and not pure tones, then getting good sound using tones is probably overkill. That's fine if you want to go the extra mile, just as making sure your response goes beyond the range of human hearing, or your noise floor that is way below what you actually need, or your distortion specs are an order of magnitude or more below the threshold of hearing. But doing all that doesn't mean that you'll hear better sound when you put on a nice Vivaldi CD in your living room. Your dog might appreciate it though!

I don't find minuscule differences in specs are generally the problem because in practice they just aren't audible. A lot of what gets discussed in audiophile forums are like that. There are bigger fish to fry that actually do matter, but they aren't as ego gratifying I guess.

 

[Davesrose]

I've also heard rumors that some art experts were actually able to tell a real Rembrandt from a cheap forgery, and be correct at least some of the time, before colorimeters and mass spectrometers were invented.

You do realize that colorimeters and mass spectrometers don't tell you who the original artist is? What it tells you is the materials used and can help identify time period. With the "great masters", it's even harder in which they had a studio with their cheaper painting being derived from their apprentices and main commissions being from the recognized artist. Even now, there is a lot to be said about assessing a particular style. Rembrandt set a style for paintings, photography lighting, and etchings. We have seen that there were questionable "Rembrandt"s from school of or wannabes. An interesting documentary to watch for art is "Who the $&% Is Jackson Pollock?" The premise is that a retired truck driver happens on a painting that *might* be a Jackson Pollock. It's not in the quintessential period of Jackson's drip period...but may be earlier. With forensics, it's determined that the paint does exist in Pollock's studio....but that is not conclusive as many folks were expanding to these paints. Pollock's friend sees the painting and says he's not sure...that it may or may not be. An art critic looks at the painting and says he's certain it is not a Pollock. I have some fine arts background, and my opinion is that the painting seems busy for "quintessential" drip painting. So even this example...a painting that forensically has some indication of same materials, does not show quintessential composition.

 

[bigshot]

In the fine art world authenticity doesn't always matter. Some Arab sheik bought a painting purported to be a DaVinci that even to my ordinary eyes was clearly not a DaVinci. All it took was buying off one "art expert" to get him to say it MIGHT be a DaVinci.

 

[old tech]

Having read some of these recent posts, I thought I'd brush the dust off my CD player and have a play with its adjustable filters.

It is a NAD unit with three levels of filter adjustment, normal, gentle and aggressive.

For the life of me, I cannot hear a difference between any of these settings. Could it be because at 53 years of age I can't hear frequencies higher than 15khz?

 

[TheSonicTruth]

Having read some of these recent posts, I thought I'd brush the dust off my CD player and have a play with its adjustable filters.

It is a NAD unit with three levels of filter adjustment, normal, gentle and aggressive.

For the life of me, I cannot hear a difference between any of these settings. Could it be because I can't hear frequencies higher than 15khz?

Splitting hairs. Just enjoy the music.

Different masterings, or just moving one or more speakers one inch any any direction, or changing your seated listening position, will make more of a difference than filters, cables, or anything else.

 

[old tech]

Splitting hairs. Just enjoy the music.

Different masterings, or just moving one or more speakers one inch any any direction, or changing your seated listening position, will make more of a difference than filters, cables, or anything else.

I know. This is more tongue in cheek.

Whether these effects of filtering and potential artifacts like ringing can be audible or not, it always amazes me that those debating it are not 20 year olds with highly developed listening skills.

Btw - I'm not referring to anyone here in particular...

 

[bigshot]

Having read some of these recent posts, I thought I'd brush the dust off my CD player and have a play with its adjustable filters. It is a NAD unit with three levels of filter adjustment, normal, gentle and aggressive. For the life of me, I cannot hear a difference between any of these settings. Could it be because at 53 years of age I can't hear frequencies higher than 15khz?

It might be a placebo button with descriptive words like that. I have a Philips SACD player that has a button to "improve the sound quality and take full advantage of SACD sound". I can't hear any difference at all between on and off. I searched everywhere- through the manual, reviews, online, etc.- to figure out what it did and could never find any specific information at all. I think it is just a button to light up a nice calming blue light on the faceplate.

 

[TheSonicTruth]

It might be a placebo button with descriptive words like that. I have a Philips SACD player that has a button to "improve the sound quality and take full advantage of SACD sound". I can't hear any difference at all between on and off. I searched everywhere- through the manual, reviews, online, etc.- to figure out what it did and could never find any specific information at all. I think it is just a button to light up a nice calming blue light on the faceplate.

Not intending to p- you off, but good production values at all steps of the making of an album will beat the pants off of any CD Vs SACD comparison.

 

[bigshot]

This wasn't a button to switch between the CD layer and the SACD layer, it was some sort of vague "enhancer" button that doesn't appear to do anything at all.

 

[analogsurviver]

There is one CD/SACD player that does sport a "button" for CD playback - and it is VERY audible. That's why I chose it some 10 years ago - because I prefer its less than brickwall filtering called Legato Link. Here a brief description https://www.techradar.com/reviews/a...yers-and-recorders/pioneer-pd-d6-95169/review.

 

[bigshot]

I just went and looked this deck I have up. (It's in a box in the closet now.) It's the Philips 963SA. I misremembered what the magic button was for... it's a super fancy upsampling gizmo for CDs. It makes absolutely no audible difference. But the light lights up real pretty. I think at the time this deck came out they were not only trying to convince people that SACDs sounded better on this deck, they wanted to claim that CDs did too. It was a crock o' bull. I did a careful comparison test when I got it and determined that neither SACDs or CDs on this deck sounded any different than on a $125 budget CD player. It was a serviceable SACD player, but home burned CDs and DVDs skipped like crazy on it so I replaced it.

 

[gregorio]

In fact, many EQ plugins for DAWs offer the option of choosing "vintage EQ sound" - which includes filters that introduce ringing and other sorts of "vintage circuit sounds".
Many folks assert that "finally, now, it is inaudible in most modern equipment, unless it's put there intentionally" - but that is simply an assertion.

Not just vintage EQs but many uses of all EQs, plus various/numerous other effects besides, which are used almost ubiquitously in every mix and typically numerous times. I am not arguing that ringing is not audible, I'm arguing that the ringing caused by transparently designed reconstruction filters when reconstructing commercial audio is inaudible!

[1] And, yes, many of the microphones and other equipment used to record audio introduce various alterations to the sound; some of which are intentional, and some of which are not.
And, yes, some of them "can... produce greater amounts of artifacts than any well designed filter... and in ranges to which we are sensitive."
[2] However, all of those are part of the music PRODUCTION process; somebody chose that microphone because they like the way it sounds, or because they consider its flaws acceptable, NOT because they imagine it's "perfect".
When REPRODUCING that music, our goal is to play it as it is provided to us, and to avoid introducing more and different alterations.

1. You think it's reasonable that small amounts of mainly ultrasonic ringing (from a decently designed recon filter) can be audible in the presence of the far greater amounts of ringing (and other phase effects) already in the mix/music, which also covers the audible range? Is that just your assertion or is it a fact?

2. Clearly that is NOT true! Engineers/Producers CANNOT listen to how a microphone or anything else sounds! When we listen to a microphone we are listening to the ringing of the anti-alias filters in our ADC and any other deliberately applied effects, all of which are/will be in the recording. IN ADDITION however, we are also listening to the ringing and phase effects of our DAC, speakers and room, NONE of which is in the recording. We do not expect our recordings to EVER be played-back without a DAC, on perfect speakers in a perfect anechoic chamber, we ALWAYS expect our music to be reproduced with "introduced alterations"!

But the standard spectrum measurements used to measure THD ...

Who examines a multiple hour recording with ONLY a THD measurement? Again, you'd have to be deliberately trying not to detect the firecracker transients in order not to detect them!

When I read your post, I see many "assertions" - which is something quite different than facts.

And when I read your response, I see it packed with obfuscations (as I predicted) - which is something almost diametrically opposed to honestly representing facts!

G