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Topic: Is this digital bashing true or false? (Read 10543 times) previous topic - next topic
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Re: Is this digital bashing true or false?

Reply #25 –
Quote from: KozmoNaut on
The whole polarity inversion thing is bullshit as well, unless you're using speakers with severe excursion nonlinerarity.

When AM was a commonly used medium polarity really matters because minus going modulation is limited by the laws of physics to -100%, but positive going modulation is limited only by available power.  FM' limits are symmetrical.  Many natural sounds including many forms of the human voice are consistently asymmetrical, again with negative going peaks being  limited to 100%, but only practical limits to postive peaks.

Polarity is pretty audible with certain steady test signals that are wholly in the audible range.  For example  1F + 2F over a wide range. However, natural music and voice are not steady, and this seems to make a huge difference in audibility.

Of course anybody who bases judgement in this area with sighted evaluations is fooling themselves, and this is pretty easy to demonstrate as well.

Historical note: Vanderkooy and Lipshitz were introduced to ABX testing by our group here in Detroit as part of some polarity tests they wanted to run.  They had developed a randomized AB switcher which was pretty good all by itself. We jointly ddi ABX tests related to polarity, some of which may have shown up in their subsequenty JAES paper.  A few months later they showed up with a modified tester, that now could do ABX tests...  ;-)

Re: Is this digital bashing true or false?

Reply #26 –
Quote from: KozmoNaut on
Quote from: board on
I agree with this - which is also why I was surprised to actually hear a difference in that test with SOME CDs. Many CDs showed no difference at all. So if you keep trying this, maybe you will hear a difference eventually, although I am aware that you might not do this as you clearly find it pointless :-).

You should definitely ABX test this.
Sure, but I can't at the moment, as my belongings are in storage. In this case it would have to be a "human" ABX as well, as someone would have to change the speaker wires.
But believe me, it wasn't a small difference. I've done plenty of ABX tests, and I've passed several with 16 out of 16 correct, where I hadn't even thought I would be able to hear a difference, and I have failed several - for instance 320 kbps mp3 vs. wave, hi-res vs. CD quality and others. So I'm not an obsessive audiophile who pays silly money for placebo effects. I just want to find out what was going on :-).
So if you can get a hold of that Badly Drawn Boy soundtrack to "About a boy" you will probably also hear a drastic difference - unless of course my speakers are seriously broken, ha ha ha (but I doubt that) :-).
"What is asserted without evidence can be dismissed without evidence"
- Christopher Hitchens
"It is always more difficult to fight against faith than against knowledge"
- Sam Harris

Re: Is this digital bashing true or false?

Reply #27 –
I feel like adding my $0.02 to this, hopefully to increase understanding and not confuse you.

Quote from: board on
So, I just want to be competely sure I understand what both you, Arny, and the rest of you guys are saying:
On digital medias, there IS a phase shift, but it's never audible. And the phase shift is constant, so therefore there is no audible effect, as the phase shift manifests purely as a delay. Is that correct?
You first need to realize that the term "phase shift" implicitly assumes a reference, against which you could determine a shift. There is no "freestanding" phase shift, it is always relative to some reference. It is important to understand what the reference is, or else you can't understand the point being made. Since this reference is often tacitly assumed, there is ample chance for misunderstandings, and hence misinformation.

Another important point is that phase is a concept that relates to a periodic signal, which will always have a certain frequency. There is no sense in speaking about phase when the signal at hand isn't periodic. The only exception to this is a sloppy usage of the term in conjunction with a polarity reversal of the signal, which gets associated with a phase shift of 180 degrees. People usually know what is meant, but strictly speaking a phase shift by 180 degrees is not the same thing as a polarity reversal, a fact that becomes quite obvious once you deal with signals other than pure sine waves.

The term "phase distortion" usually implies that the reference is a different frequency component within the same signal. For example, if you take the phase of a 1 kHz frequency component as the reference, the phase of a 2 kHz component may be shifted against it. Since signals that are not pure sine waves contain multiple frequency components, such phase distortion may alter the looks of the signal waveform on a display quite clearly, even though this kind of waveshape distortion is usually inaudible.

Many kinds of filters produce this kind of distortion as a side effect of their frequency-dependent behavior, particularly those in the analog domain. Digital filters of the linear phase type don't, but they have no equivalent in the analog domain, so digital technology is actually better than analog in this respect.

A pure delay causes a frequency-dependent phase shift with respect to the undelayed signal. It doesn't matter whether the delay was caused by digital circuitry or in another way. This is purely due to the fact that higher frequencies need less delay to accomplish a certain phase angle. The relaitionship is a simple mathematical one. It only becomes an issue when delayed and undelayed versions of the same signal get combined in a single signal, and the effect of this is known as comb filtering. Both analog and digital systems behave the same in this respect. The only difference is that it is more common to encounter some delay in a digital system than in an analog system. If you don't combine delayed and undelayed signal versions, you don't have a problem. In a pure playback situation, this shouldn't bother you.

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On analogue medias, there is even more phase shift, and it's not constant and doesn't manifest itself as a delay, so it can be audible. Is that also correct?
If the phase shift is caused by a delay, it can't be constant across the frequencies. If the phase shift is constant across the frequencies, it can't be caused by a delay. That's due to mathematics.

Analog circuitry or media, as soon as it has a bandwidth limitation (i.e. always) will distort phase to some extent. But whether that's audible is a very different question. Phase distortions are by themselves unlikely to be audible.

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Are you also saying that on analogue medias, the phase shift varies from left to right channel, which is when phase shift actually becomes audible, and to some, like David Robinson, this phasing effect actually sounds pleasing, whereas the lack of audible phase shift, sounds "flat" to his ears.
You probably mean slightly different delays between left and right. They can easily arise in analog media because of slight misalignments of tape heads or pickups. If you are fancy enough, try to calculate the relative delay between left and right channel in a stereo tape head depending on the angle between the head gap and tape motion. You will develop a feeling how sensitive to mechanical tolerances such a system is. Digital technology is close to ideal in this regard, beating practical analog systems by orders of magnitude.

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So, David Robinson's claim was partly true, partly false...?
It was mainly bullshit. It is hard to say whether he was right or wrong when it isn't very clear what he actually tried to say. My impression is that he referred to neither delay nor phase distortion, but to the effects of sampling frequency and signal frequency being asynchronous to each other, leading to time-varying sampling positions on the signal's waveform. It looks like a shifting phase of the sampling clock with respect to the signal. This kind of phase shift is completely bogus as it doesn't affect the signal at all in a correctly implemented sampling system. The exact point on the waveform where the sampling happens is of no consequence as long as the bandwidth limitation is adhered to, on which digital sampling depends. So if my suspicion is correct, he just doesn't understand sampling.

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I'm also partly asking about this, as Michael Fremer bascially SCREAMED at me a few months ago on Youtube that vinyl has better phase resonse than CDs (as well as screaming that CDs have never been more transparent than, or as transparent as, vinyl + vinyl has wider bandwidth, as it can go to 30 kHz, but of course I do know that the claim of transparency is bullshit, and the claim of bandwidth is mosltly irrelevant, and vinyl rarely goes above 20 kHz except for distortion in the form of harmonics).
If you compare CD with vinyl, you can do that fairly by recording a vinyl playback on a CD and then compare the vinyl playback with the CD recording. Or you can do the reverse and press the material found on CD on a vinyl disc, and then compare the two. It has been done several times. The result is as clear as the day: In the second case you can hear a clear difference, in the first case you can't. That has got to mean that the CD is the transparent medium and the vinyl disc isn't. That should be the end of the story, and in fact it was the end of the story 30 years ago. Nothing has changed since then.

If Fremer says anything that differs from that, it is bullshit. And if he's screaming it, it is screaming bullshit. He's full of it anyway, I wouldn't listen to it for a second.

Re: Is this digital bashing true or false?

Reply #29 –
Quote from: ajinfla on
Quote from: board on
Quote from: KozmoNaut on
You should definitely ABX test this.
Sure, but I can't at the moment
That would sink the boat

???
"What is asserted without evidence can be dismissed without evidence"
- Christopher Hitchens
"It is always more difficult to fight against faith than against knowledge"
- Sam Harris

Re: Is this digital bashing true or false?

Reply #30 –
Quote
If Fremer says anything that differs from that, it is bullshit. And if he's screaming it, it is screaming bullshit. He's full of it anyway, I wouldn't listen to it for a second.


Yup! Those that shout the loudest, usually have the least to say...
 

Re: Is this digital bashing true or false?

Reply #31 –
Thanks for your lengthy response, Pelmazo. It did indeed help me understand the issue better :-).

It's too bad that for panel debates like that there are no people present who actually understand the technologies. When people like those on the panel are allowed to speak freely, they often spread bullshit just to further their own agenda, and people who don't know enough about the technical issues (like myself) just assume it must be true, because these people have authority (although I'm a lot more suspicious than the average guy in the crowd).
Unfortunately, up until recently I've taken Framer and certain other audiophiles seriously. I agree with some of the things he says (not in the panel debate), but I could probably also say that of the most dispicable person I could think of. But I suppose dealing with a guy who thinks a $5000 power cord makes an audible difference, and then refuses to take any kind of blindtest to back up that claim as well as all his other claims, should probably have tipped me off a long time ago to ignore anything coming from him. Alas! What a life, eh?
"What is asserted without evidence can be dismissed without evidence"
- Christopher Hitchens
"It is always more difficult to fight against faith than against knowledge"
- Sam Harris

Re: Is this digital bashing true or false?

Reply #32 –
Quote from: board on

It's too bad that for panel debates like that there are no people present who actually understand the technologies.

You have to understand that most of these events are sales events. Anything that make people think twice about their impulse buys has to be kept away.

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When people like those on the panel are allowed to speak freely, they often spread bullshit just to further their own agenda, and people who don't know enough about the technical issues (like myself) just assume it must be true, because these people have authority (although I'm a lot more suspicious than the average guy in the crowd).

Exactly right, and by the way I totally agree with your positive comments about  P's great post.

The more you know about real technology, the more high end sales events can irritate you. As a rule, people who actually know what's happening in audio avoid them like the plague.  Its like over a decade later and I still remember the two days I spend perusing HE2005.  Executive Summary: I came away very sad contemplating how many $millions are wasted on overpriced stuff that might even be pretty good, but is still vastly overpriced, and then there was the immense pile of outright snake oil and garbage.

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Unfortunately, up until recently I've taken Framer and certain other audiophiles seriously. I agree with some of the things he says (not in the panel debate), but I could probably also say that of the most despicable person I could think of.

He's definitely close to The Edge, emotionally and way over The Edge intellectually.

He's a very powerful man in High End Audio it would seem, and as they say: Great Power corrupts greatly.

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But I suppose dealing with a guy who thinks a $5000 power cord makes an audible difference, and then refuses to take any kind of blindtest to back up that claim as well as all his other claims, should probably have tipped me off a long time ago to ignore anything coming from him. Alas! What a life, eh?

I should point out that Real Working Audio Technology is both vastly different and also can be a lot of fun. It is more frustrating for most because in Real Reality things don't always work out the first time you try them.  Some times they don't work out at all!

However, if you can enter a state of Zen where the value of the occasional reward is enhanced by the hard work and frustration it always seems to involve, it is very good.

Re: Is this digital bashing true or false?

Reply #33 –
Quote from: Arnold B. Krueger on
The more you know about real technology, the more high end sales events can irritate you. As a rule, people who actually know what's happening in audio avoid them like the plague.  Its like over a decade later and I still remember the two days I spend perusing HE2005.  Executive Summary: I came away very sad contemplating how many $millions are wasted on overpriced stuff that might even be pretty good, but is still vastly overpriced, and then there was the immense pile of outright snake oil and garbage.
What's also a bit funny/sad is that when I found the 2005 debate on Youtube (haven't watched it though), I saw an equal split in the comments between "That Atkinson guy should really shut up! He's ruining it for everybody" and "That Krueger guy should really shut up! He's ruining it for everybody" :-D :-(.

On a different note, and to return to topic, I was told that ringing and phase are basically the same thing. Can you (or anybody) else say how "important" or "audible" ringing is in properly made digital audio? I was thinking maybe you could say it was -100 dB or -60 dB down, or perhaps you could even link to some files specifically made for the purpose that has increased the level of ringing so it's clearly audible (you once posted files like that with and without jitter so we could hear the difference).
"What is asserted without evidence can be dismissed without evidence"
- Christopher Hitchens
"It is always more difficult to fight against faith than against knowledge"
- Sam Harris

Re: Is this digital bashing true or false?

Reply #34 –
Quote from: board on
Quote from: Arnold B. Krueger on
The more you know about real technology, the more high end sales events can irritate you. As a rule, people who actually know what's happening in audio avoid them like the plague.  Its like over a decade later and I still remember the two days I spend perusing HE2005.  Executive Summary: I came away very sad contemplating how many $millions are wasted on overpriced stuff that might even be pretty good, but is still vastly overpriced, and then there was the immense pile of outright snake oil and garbage.
What's also a bit funny/sad is that when I found the 2005 debate on Youtube (haven't watched it though), I saw an equal split in the comments between "That Atkinson guy should really shut up! He's ruining it for everybody" and "That Krueger guy should really shut up! He's ruining it for everybody" :-D :-(.

Scientific facts are not established by means of public opinion polls. I'm surprized the split was 50-50, since my experience is that the pro-science, anti-audio-snake oil view is more generally unpopular.  The pro-snake oil forums seem to outdraw the scientific ones by large margins.

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On a different note, and to return to topic, I was told that ringing and phase are basically the same thing.

I'd say that one is a cause and the other is an effect in real-world situations, but which is the cause and which is the effect flip=-flops a lot. ;-)

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Can you (or anybody) else say how "important" or "audible" ringing is in properly made digital audio?

In real world, mainstream, well-engineered gear, such ringing and phase shift as exists is not audible.

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I was thinking maybe you could say it was -100 dB or -60 dB down, or perhaps you could even link to some files specifically made for the purpose that has increased the level of ringing so it's clearly audible (you once posted files like that with and without jitter so we could hear the difference).

Any ringing that is -100 or -60 dB down is wayyy into inaudible. You can have just about any artifact that exists or is imaginable at -100 dB and it is highly unlikely to be audible.  At -60 dB down the story changes from "Highly unlikely" to "Pretty Unlikely". 

Audibility depends on things like the regularity of the effect and percentage of time affected.   For example you can have a ringing-induced but damped peak that is +3 dB for one cycle right below the 22.05 KHz Nyquist for 44/16 and its not audible.  If it rings all of the time @ +3 dB at 13 KHz, then it might be audible.   Ringing much of the time at + 3 dB at 3 KHz is going to be audible unless the range of frequencies that stimulates it is very narrow so it rarely happens.  

Re: Is this digital bashing true or false?

Reply #36 –
Stephen, thanks for the suggestion. I actually watched that video more than once. I'm a fan of Ethan's :-). But it might have been too long since I watched it, although I was in touch with Ethan before making my post here, and he did direct me to this video and the part about phase shift. Still, I was in doubt about the issue at hand (hence this topic).

Arny, again, thanks for your help. My 50-50 comment was just a shot from the hip, so the real number might be very different. But yes, the scientific approach seems less popular overall.
Just to make sure I understand you correctly: The way I understand ringing in digital audio is that it's pretty much present constantly, but that it's always around the Nyquist frequency, so if there's a +3 dB spike around 22 kHz (or even at 20 kHz) it won't be audible due to it being at such high frequencies. But is your example of ringing at lower frequencies something you would actually find in real life?
As for the level, on a general level would you say the level of ringing in properly made digital audio is closer to -100 dB or -60 dB (if that's possible for you to say)?
In one of JJ's online powerpoint presentations he mentioned that he had looked at thousands of CD tracks and the anti-imaging filtering were questionable at best. I don't know if that's related to ringing.
"What is asserted without evidence can be dismissed without evidence"
- Christopher Hitchens
"It is always more difficult to fight against faith than against knowledge"
- Sam Harris