[amirm]

OK.....

So, all DACs produce some ringing, which is exactly what it sounds like - the DAC continues to produce audio energy at its output after the input signal has stopped.
However, because it is a transient phenomenon, ringing only appears with non-steady-state signals, and so does not show up at all in standard frequency response, THD, or S/N measurements.

An impulse is an "illegal" audio signal. It is a pulse that goes from zero to max in one sample. This requires infinite bandwidth. Digital audio by definition requires that the source be bandwidth limited. An impulse is not bandwidth limited and therefore "can't happen."

Of course it is trivial to create one in digital domain using software. But again, it is not representative of what is supposed to be there.

The usefulness of an impulse is to characterize a linear system (e.g. a filter). That is the proper use of it. It is NOT characteristic of music reproduction and what we "hear." That ringing you see will vanish if make you limit the bandwidth for example.

The audio energy you talk about is ultrasonic and hence not an audible concern.

That said, pre-ringing can be an issue if its energy is in-band. But I don't want to get into that and confuse this issue.

 

[Phronesis]

this section is obviously focused around a few leading concepts. if you wonder why, it's in the TOS:
this section is the only place where we can really discuss such ideas instead of being stopped after 2 posts. so of course all the people with similar ideas about the dire need to stop calling a sighted test a "listening test", are gathering here. by force as much as by choice. you think the name of the section doesn't properly reflect this, go ask the admins to change the name. I didn't pick it nor did I make the rules of this forum.

now if you cooled down your philosoraptor arguments in a topic about testing stuff, and focused on one audio question or idea at a time, you may come to realize that there are plenty of things we can test, and plenty of knowledge to be had from those tests.
you may also notice how you preach for caution when drawing conclusions on the most skeptical section of the forum. you argue about flaws in methodology in pretty much the only section of the forum that tries to control variables in a test. I'm not trying to get away with all we do wrong, we have people of all kinds with opinions of all kinds and various ways of thinking. plus we're still just lowly humans, so BS will be claimed and hypocrisy will be used in stead of argument. but maybe instead of comparing what you read here with some ideology of ultimate proper science, you could just look at the rest of the forum and put things in perspective about claims and their legitimacy? just so that it doesn't look like you have a 2 tier kind of righteousness.
I don't mind that you hit me on the head when I do something wrong, TBH I hope you will do it because I can't learn if I don't know that I'm wrong. but I'll find it very frustrating if the guy next to me does much worst and you leave him be as if he did nothing wrong. and that's the vibe I've been getting for a while now. I haven't seen you posting tens of messages in the cable section to tell people about how to reach a conclusion correctly, or blaming them for some of the most ludicrous claims you'll ever get to read about electricity(did you know that gold sounds warm?^_^). anyway you got the idea, I don't think this section deserves to be the bad guy of your story. nor do I think that 3 guys with the same views represent the Sound Science section entirely.

also, modo again, stop it with the religious analogies. discussing religion is not allowed on Head-fi for the most obvious reasons.

Thanks for that info and context.

I do think Sound Science has value, and I do see much nonsense spewed in other parts of the forum. I don't talk about that latter much here, but I do talk it about it there - at least until they tell me I need to stop.

If I come across as too outspoken in Sound Science, it's because some things here have really surprised me, particularly the rigidity of some views. But if people are quite sure of their beliefs, I suppose that comes with the territory. I'm more of a 'degree of belief' person, rather than a certainty person. Don't get me wrong, I'd prefer certainty, but if we're truly skeptical, certainty is difficult and perhaps impossible to achieve.

If you take the 'average' what's said around here, I suspect that it's not too far from the truth, and there's probably more common ground than the debates suggest. IMO, it's when we take extreme positions - DACs never make any audible difference, cables and DACs make a huge difference, etc. - that we're probably off the mark.

I'm all for testing, but when the measuring device is the human mind, I think there are a lot more complications than when testing only involves objective measurements. For example, when I did my own blind testing and asked whether I can hear a difference between A and B, or can pick whether it's A or B, the answer was more often "I'm not sure" rather than Yes or No. A while back, I myself challenged some audiophiles to do blind testing to support their claim that expensive cables made a worthwhile difference. But after I did my own blind testing, I realized that it's not quite that simple.

Anyway, I've found the discussion to be stimulating, and will try to avoid making statements which unnecessarily aggravate or offend anyone. If I go out of bounds, don't hesitate to let me know (I've been a moderator also, and know it's not always an easy job).

 

[KeithEmo]

An impulse is indeed an invalid signal - at least in a digital audio file. Impulses are used in audio measurements for two very different reasons.
1)
In certain types of measurements, the desired output is "the response of the system to an impulse".
In those measurements, certain calculations are performed on "the output signal you get when you send in an impulse".
One very popular such test is to apply an "impulse" to a room, then analyze the returning audio signals over time.
Therefore, for those sorts of measurements, the proper test signal is "as close as you can practically get to a real impulse".
2)
The same exact logic applies when testing DACs.
The impulse signal itself is invalid in a digital audio file.
However, how the DAC responds to that signal tells us a lot about its filter and time response.
(And, whether technically valid or not, it's a nice standard test signal, so it's simple to compare the results you get with it.)

HOWEVER, there are quite a few natural sounds that resemble an impulse... such as a drumbeat.
Virtually all natural transient sounds involve some ringing - which we might hope a DAC can reproduce accurately.
But some DACs may add enough ringing to significantly change the ringing that belongs there....
And some DACs may do the opposite...
For example, DACs that have extra processing to eliminate pre-ringing might actually remove pre-ringing that BELONGS there.
Seeing the transient response with an impulse lets us predict pretty accurately what will happen with music.

The other thing to remember is that ringing isn't generally extra added energy.
It is energy that has been "moved" from somewhere else.

To pick the simplest possible example......
If I start with a 10 mSec pulse with a roughly rectangular envelope.... than add 20 mSec of ringing to its beginning, and 20 mSec of ringing to its end, I now have a 50 mSec pulse containing as much energy as the original 10 mSec pulse. This new pulse will have a very different envelope shape than my original pulse, and that difference may well be audible.

The ringing will NOT vanish when you limit the bandwidth.
In fact, ringing will appear as a RESULT of limiting the bandwidth.
The only question is whether alteration of that ringing will be audible or not.

An impulse is an "illegal" audio signal. It is a pulse that goes from zero to max in one sample. This requires infinite bandwidth. Digital audio by definition requires that the source be bandwidth limited. An impulse is not bandwidth limited and therefore "can't happen."

Of course it is trivial to create one in digital domain using software. But again, it is not representative of what is supposed to be there.

The usefulness of an impulse is to characterize a linear system (e.g. a filter). That is the proper use of it. It is NOT characteristic of music reproduction and what we "hear." That ringing you see will vanish if make you limit the bandwidth for example.

The audio energy you talk about is ultrasonic and hence not an audible concern.

That said, pre-ringing can be an issue if its energy is in-band. But I don't want to get into that and confuse this issue.

 

[amirm]

HOWEVER, there are quite a few natural sounds that resemble an impulse... such as a drumbeat.

Well, let's look at that. Here is a Chesky reference drum track. I have selected the attack of one such note:

Looks like an impulse as you say. But let's zoom in and see what is really there:

As you see, it is nothing like an impulse, i.e. zero sample to max.

It has to look the way because it is frequency limited. The enemy of impulse is lack of high frequencies. Take those away and the change cannot be sudden.

Spectrum analysis of that segment shows this clearly:

We see that the energy drops like a rock as frequencies increase.

The net results is that this does NOT generate the ringing you see in measurement graphs. Those impulses again assume infinite bandwidth (and energy).

And oh, the above is from a 192 kHz audio sample so it has a lot more high frequency content than a CD would (sadly much of it is wasted due to noise shaping).

 

[amirm]

The other thing to remember is that ringing isn't generally extra added energy.
It is energy that has been "moved" from somewhere else.

Nobody said it was. Indeed the cause is that you are removing energy from an infinite energy signal, i.e. impulse, and hence, it can no longer have its infinite slew rate. That is what a DAC reconstruction filter does. It is supposed to create that "ringing." To the extent that removal is above your hearing range, then what it looks like on a scope is immaterial.

The point was that if you don't stick that infinite energy into your filter, then you don't have that large ringing that you see in your graphs.

 

[KeithEmo]

I agree with your observations...

Excessive generalizations are often a disservice for several reasons.
First, simply because they're sometimes wrong, which can cause errors to occur, and can lead to bad decisions.
And, second, because, when they're found to be wrong, they tend to raise doubt about the validity of science in general.

"Peanuts are NOT poisonous"; tell that to my buddy who's allergic to peanuts.
"All speaker wires sound the same"; except that, if you attach a set of Vampire Wires to a Threshold 400b amplifier, it will blow its fuse.
It's more accurate to say: "Peanuts are healthy for most people, except for the few who happen to be allergic to them".
And to say: "Most normal modern amplifiers don't sound any different with different speaker cables - unless there's something really odd about the cables".

I might even go a bit further on that last one.....
"Most modern amplifiers have a relatively low output impedance, and are relatively insensitive to the amounts of capacitance and inductance found in a typical piece of wire."
"Therefore, with most modern amplifiers, most speaker wires, made with regular wire, and having typical amounts of capacitance and inductance, all sound the same".

Interconnect cables are even more entertaining...... with both sides acting more like sports fans than either scientists or intelligent humans in general.
- The capacitance of MOST interconnect cables falls into a certain range.
- MOST modern preamps have a very low output impedance; and will sound the same when connected to an amplifier using interconnects whose capacitance falls within that range.
(I consider a preamp with a high output impedance to be "badly designed" - but that's just my opinion. Most people would agree with me today; in 1950 most would not.)
- MANY vintage tube preamps had a much higher output impedance; and their frequency response WILL vary significantly depending on the capacitance of your cables.
- MANY modern passive preamps share this characteristic, and their frequency response WILL also vary significantly depending on the capacitance of your cables.
- And, finally, moving magnet phono cartidges are usually sensitive to cable capacitance, and their frequency response WILL also vary significantly due to cable capacitance.

Therefore, if you make a generalization about interconnect cables sounding the same, without properly qualifying it, then you are spreading false information.
(Your claim may help more people than it hurts - but it could be more helpful, to more people, if you qualified it more carefully.)

If the purpose of this thread is to discuss "testing audiophile myths"........
Then the validity of claims in both directions is surely fair game.......

Thanks for that info and context.

I do think Sound Science has value, and I do see much nonsense spewed in other parts of the forum. I don't talk about that latter much here, but I do talk it about it there - at least until they tell me I need to stop.

If I come across as too outspoken in Sound Science, it's because some things here have really surprised me, particularly the rigidity of some views. But if people are quite sure of their beliefs, I suppose that comes with the territory. I'm more of a 'degree of belief' person, rather than a certainty person. Don't get me wrong, I'd prefer certainty, but if we're truly skeptical, certainty is difficult and perhaps impossible to achieve.

If you take the 'average' what's said around here, I suspect that it's not too far from the truth, and there's probably more common ground than the debates suggest. IMO, it's when we take extreme positions - DACs never make any audible difference, cables and DACs make a huge difference, etc. - that we're probably off the mark.

I'm all for testing, but when the measuring device is the human mind, I think there are a lot more complications than when testing only involves objective measurements. For example, when I did my own blind testing and asked whether I can hear a difference between A and B, or can pick whether it's A or B, the answer was more often "I'm not sure" rather than Yes or No. A while back, I myself challenged some audiophiles to do blind testing to support their claim that expensive cables made a worthwhile difference. But after I did my own blind testing, I realized that it's not quite that simple.

Anyway, I've found the discussion to be stimulating, and will try to avoid making statements which unnecessarily aggravate or offend anyone. If I go out of bounds, don't hesitate to let me know (I've been a moderator also, and know it's not always an easy job).

 

[upstateguy]

Not at all, I wouldn’t waste any of our time by doing that, and am not a fan of needless aggravation of anyone. I’m trying to understand the dynamic of the forum, since it doesn’t fit my expectations of a science forum. The dynamic is more like if this was called a religion forum, but the regulars are all atheists who attack any whiff of a religious idea because it lacks their definition of ‘proof’ (ps - I'm not religious). Nothing wrong with having an atheism forum, just don’t call it a religion forum. That said, I struggle to come up with a good alternate name for this forum. It’s anti something, but hard to put a name to it.

From it's inception, this is and always has been the Objectivist Forum. Early on, as Big Shot said, objectivists views were banned from the main forum because it upset the prevailing subjectivistism. There were many discussions about what to do with us. Ultimately, it was decided to corral us in the Ghetto you are now posting in and the name "Sound Science" was chosen to represent the Objectivist point of view, that was allowed to be spoken only here. In retrospect I guess it would have been better to just call it the "Objectivist Forum", because if that was the case you wouldn't have a problem understanding what goes on here.

 

[bigshot]

I've changed the way I think about the banishment. I see us as the "outside" and the rest of HeadFi as being "in a box". When you limit what can be discussed, you limit what you can do.

Also, I want to make it clear that I don't get angry with people here. I just don't have the patience for tortured logic like "we can't know everything so we can't know anything", so at some point I won't entertain discussions like that any more. I don't waste my time adding footnotes to everything I say because everything I talk about is in relation to listening to recorded music in the home. That is the context we are discussing- home audio. Sometimes people interpret the science aspect to mean that they have to split atoms and consider things that can't be heard in a normal home music listening environment. I'm too busy improving audible sound to spend my time on thinking about theoretical sound. It isn't that I'm not aware of this stuff. I just don't care about it because it has no use to me.

A lot of people wander in here from the inside of HeadFi. Perhaps they believed the subjective poetry they heard in there and got burned buying a high end DAC or fancy cable that didn't make any real difference. When they hear objective opinions for the first time, I think it's important to keep your eye on the prize. Doubling down on details just muddies the water and accomplishes the same thing that snake oil salesmen do when they dump a carload of irrelevant technical information on clueless customers- complex charts and diagrams illustrating jitter or distortion at levels that they never reveal are totally inaudible. I don't see a purpose in confusing people with too much useless information.

 

[upstateguy]

I've changed the way I think about the banishment. I see us as the "outside" and the rest of HeadFi as being "in a box". When you limit what can be discussed, you limit what you can do.

+1

 

[KeithEmo]

I agree.... you see much less.
The purpose of using that extreme test signal is in part to exaggerate the results to make them easier to see.
As an excessively broad generalization, with a sine wave signal, errors and distortions must reach several percent before a human can even see them on an oscilloscope screen.
That's one reason why we use things like spectrum analysis and various types of numerical analysis to make certain distortions easier to visualize.

However, I'll bet that, if you feed that same signal through a Wolfson 8741 DAC, and select each of its 21 different oversampling filters in turn,
you'll see a slightly different result with each one.... then we're right back where we started.... to the question of which of the differences between them will be audible.
(With music, I'll also bet it would be much more difficult to see the differences with the naked eye, but it would still measurably exist.)

Also, I'm looking at your spectrum plot.....
The most energy seems to be at a relatively low frequency .... and to hit -35 dB.
Interestingly, it doesn't hit the point that's 60 dB below that (-95 dB) until about 36 kHz.
So, at least to me, it sure looks like there is significant energy there well past 20 kHz.
(I also wonder why they used such aggressive noise shaping... it seems excessive for a 24/192k file... unless that one was upsampled.)

Please note that I am NOT making an assertion as to which filter responses would be audibly different from which others.
I would also note that, very often, the characteristics of various filters are too complex to allow for simple audible comparisons.
For example, many "apodizing" filters that exchange pre-ringing for post-ringing ALSO include a slow high roll-off.
Because of this, the fact that their response is - 3 dB at 20 kHz makes it difficult to determine whether you're hearing the time effect of the filter or just the HF roll off.
This is why I suggest that a LOT more testing would be necessary to "make complete sense" of what's going on with DACs and filters (in terms of audibility).
(And, sadly, as I've said, I don't think anybody has the incentive necessary to do it properly.)

Nobody said it was. Indeed the cause is that you are removing energy from an infinite energy signal, i.e. impulse, and hence, it can no longer have its infinite slew rate. That is what a DAC reconstruction filter does. It is supposed to create that "ringing." To the extent that removal is above your hearing range, then what it looks like on a scope is immaterial.

The point was that if you don't stick that infinite energy into your filter, then you don't have that large ringing that you see in your graphs.

 

[bigshot]

As far as I'm concerned if timing is good enough to create a perfect 20kHz tone, it's more than good enough to reproduce the fastest transient in music... by several magnitudes.

 

[Zapp_Fan]

As far as I'm concerned if timing is good enough to create a perfect 20kHz tone, it's more than good enough to reproduce the fastest transient in music... by several magnitudes.

The fastest transient in music is an illegal signal / dirac impulse as others have pointed out, so for those of us who bother with electronic music, the quality of the transient response even out of "realistic" boundaries is a material question. this song is one I really actually enjoy listening to, but it also happens to be a very difficult stress test for audio codecs as well as transient response in a system, it's chock full very sharp transients.

I guess since I spent so much of my life listening to almost nothing but "IDM" I don't see "within the boundaries of music" being a useful distinction, since those guys will commit pretty much any sound that CAN be synthesized to a record and call it music - as do their fans. In other words, almost all conceivable signals count as "music" if your taste happens to run that way.

 

[upstateguy]

A lot of people wander in here from the inside of HeadFi. Perhaps they believed the subjective poetry they heard in there and got burned buying a high end DAC or fancy cable that didn't make any real difference.

When they hear objective opinions for the first time, I think it's important to keep your eye on the prize.

Doubling down on details just muddies the water and accomplishes the same thing that snake oil salesmen do when they dump a carload of irrelevant technical information on clueless customers- complex charts and diagrams illustrating jitter or distortion at levels that they never reveal are totally inaudible.

I don't see a purpose in confusing people with too much useless information.

+1

 

[Phronesis]

From it's inception, this is and always has been the Objectivist Forum. Early on, as Big Shot said, objectivists views were banned from the main forum because it upset the prevailing subjectivistism. There were many discussions about what to do with us. Ultimately, it was decided to corral us in the Ghetto you are now posting in and the name "Sound Science" was chosen to represent the Objectivist point of view, that was allowed to be spoken only here. In retrospect I guess it would have been better to just call it the "Objectivist Forum", because if that was the case you wouldn't have a problem understanding what goes on here.

I get that, but if you limit the scope of the forum to objective stuff (physics and technology) and ignore subjective aspects, you have a limited definition of sound science, and issues of psychoacoustics, blind testing, etc. have no relevance. From what I've seen so far, the discussions aren't by any means limited to objective aspects.

 

[analogsurviver]

I agree with your observations...

Excessive generalizations are often a disservice for several reasons.
First, simply because they're sometimes wrong, which can cause errors to occur, and can lead to bad decisions.
And, second, because, when they're found to be wrong, they tend to raise doubt about the validity of science in general.

"Peanuts are NOT poisonous"; tell that to my buddy who's allergic to peanuts.
"All speaker wires sound the same"; except that, if you attach a set of Vampire Wires to a Threshold 400b amplifier, it will blow its fuse.
It's more accurate to say: "Peanuts are healthy for most people, except for the few who happen to be allergic to them".
And to say: "Most normal modern amplifiers don't sound any different with different speaker cables - unless there's something really odd about the cables".

I might even go a bit further on that last one.....
"Most modern amplifiers have a relatively low output impedance, and are relatively insensitive to the amounts of capacitance and inductance found in a typical piece of wire."
"Therefore, with most modern amplifiers, most speaker wires, made with regular wire, and having typical amounts of capacitance and inductance, all sound the same".

Interconnect cables are even more entertaining...... with both sides acting more like sports fans than either scientists or intelligent humans in general.
- The capacitance of MOST interconnect cables falls into a certain range.
- MOST modern preamps have a very low output impedance; and will sound the same when connected to an amplifier using interconnects whose capacitance falls within that range.
(I consider a preamp with a high output impedance to be "badly designed" - but that's just my opinion. Most people would agree with me today; in 1950 most would not.)
- MANY vintage tube preamps had a much higher output impedance; and their frequency response WILL vary significantly depending on the capacitance of your cables.
- MANY modern passive preamps share this characteristic, and their frequency response WILL also vary significantly depending on the capacitance of your cables.
- And, finally, moving magnet phono cartidges are usually sensitive to cable capacitance, and their frequency response WILL also vary significantly due to cable capacitance.

Therefore, if you make a generalization about interconnect cables sounding the same, without properly qualifying it, then you are spreading false information.
(Your claim may help more people than it hurts - but it could be more helpful, to more people, if you qualified it more carefully.)

If the purpose of this thread is to discuss "testing audiophile myths"........
Then the validity of claims in both directions is surely fair game.......

Finally some reason in this thread ... - you've missed one or two applications for cables in audio that are at least as critical as those mentioned, but, it is a start.

Without this post, practically everything else by other members defending the almost blind faith - not science - conforms to the below intentionally caricatured generalizations that went way beyond any reason many full moons ago :

" 20-20k/infinitely low source impedance / pure resistive load / perfect digital filters / perfect everything / zero audible differences / mp3 is enough / CD is overkill / .... - everything else is heresy / everything else is snake oil and rip-off / our Sacred Duty is to prevent people from buying anything not sanctioned by our Blind Faith "

The fitting graphic comment to the above would be a farm of ostriches, each and every one of them trying to outdo the other just how deep he/she can stick the head into the sand ...