Why Do People Come To Computer Audiophile To Display Their Contempt For Audiophiles?

[pkane2001]

2 minutes ago, Jud said:

 

By the way - As esldude has found in doing some of his difference measurements, timing may need to be adjusted between files to achieve the closest match (deepest “null” when reversing polarity of one file to get a difference signal).  How certain can you be that you aren’t washing out real phase differences when doing this?

 

As certain as the mathematics would allow  There are better mathematical ways to match signal phases than by adjusting for the smallest difference between them. 

 

[mansr]

7 minutes ago, Jud said:

By the way - As esldude has found in doing some of his difference measurements, timing may need to be adjusted between files to achieve the closest match (deepest “null” when reversing polarity of one file to get a difference signal).  How certain can you be that you aren’t washing out real phase differences when doing this?

Are you referring to slight clock differences between devices and run to run? For comparing two amps, this can be avoided entirely by recording both simultaneously on two channels of the same ADC.

[Jud]

1 minute ago, mansr said:

Are you referring to slight clock differences between devices and run to run?

 

 

Yes.

 

1 minute ago, mansr said:

For comparing two amps, this can be avoided entirely by recording both simultaneously on two channels of the same ADC.

 

Thank you.

[mansr]

2 minutes ago, pkane2001 said:

As certain as the mathematics would allow  There are better mathematical ways to match signal phases than by adjusting for the smallest difference between them.

When comparing files, I always start by doing a cross correlation over a few seconds at the start and a few seconds near the end. If the offset of the strongest correlation differs between the start and the end of the recordings, I know there has been some clock drift. If this is the case, it must be compensated for before some types of comparisons can be done with any validity.

[Jud]

10 minutes ago, pkane2001 said:

 

Jud, you are changing the subject. My post was in response to @jabbr about measuring differences between two amps to determine which one is more accurate.

 

Yep, let's take amps.  My speakers, as my sig says, are Vandersteens.  Let's assume for the moment that Vandersteen's marketing about the impact of time and phase "correctness" (including linear phase crossovers) on imaging and localization is true.  I'm looking at a Class D amp, say something NCore-based.  I assume (someone please correct me if I'm wrong) that some circuitry in a Class D amp must in effect do filtering to get the analog electrical waveform as output, and that this filtering has phase characteristics.  Are there published measurements for the NCore amps that will tell me this?  When people do measurements on Class D (or other) amps, is this something they commonly measure?  Is the phase behavior of an amp something you have bothered to measure in the past?

 

[pkane2001]

2 minutes ago, mansr said:

When comparing files, I always start by doing a cross correlation over a few seconds at the start and a few seconds near the end. If the offset of the strongest correlation differs between the start and the end of the recordings, I know there has been some clock drift. If this is the case, it must be compensated for before some types of comparisons can be done with any validity.

Yup, correlation is what I was referring to.

[Jud]

6 minutes ago, mansr said:

If this is the case, it must be compensated for before some types of comparisons can be done with any validity.

 

I'm supposing "strongest correlation" and compensation for clock drift can involve judgment, though my assumption (not having done such measurements myself) is that where the correlations fit is pretty obvious, so I don't want to make overmuch of the judgment aspect.

[pkane2001]

3 minutes ago, Jud said:

Yep, let's take amps.  My speakers, as my sig says, are Vandersteens.  Let's assume for the moment that Vandersteen's marketing about the impact of time and phase "correctness" (including linear phase crossovers) on imaging and localization is true.  I'm looking at a Class D amp, say something NCore-based.  I assume (someone please correct me if I'm wrong) that some circuitry in a Class D amp must in effect do filtering to get the analog electrical waveform as output, and that this filtering has phase characteristics.  Are there published measurements for the NCore amps that will tell me this?  When people do measurements on Class D (or other) amps, is this something they commonly measure?  Is the phase behavior of an amp something you have bothered to measure in the past?

 

You are still trying to take this into a direction that is orthogonal to the original discussion. Regardless of what speakers you use, amplifiers will add some distortion to the signal. Measuring which one adds less distortion before the speakers is measurable. Measure this into an 8Ω resistor. Or, measure this into an actual speaker. As long as the load remains the same (same resistor or the same speakers) and you swap amplifiers, you can measure the differences between them.

[pkane2001]

3 minutes ago, Jud said:

 

I'm supposing "strongest correlation" and compensation for clock drift can involve judgment, though my assumption (not having done such measurements myself) is that where the correlations fit is pretty obvious, so I don't want to make overmuch of the judgment aspect.

 

No, correlation is a well-defined mathematical procedure, not at all judgment-based. Something I've used to automatically match other types of signals, including the noisy 2D images in the frequency domain, as well periodic error of telescope tracking mounts. It's much more robust in the presence of large differences and noise than the nulling procedure you mentioned.

 

[Jud]

13 minutes ago, pkane2001 said:

You are still trying to take this into a direction that is orthogonal to the original discussion. Regardless of what speakers you use, amplifiers will add some distortion to the signal. Measuring which one adds less distortion before the speakers is measurable. Measure this into an 8Ω resistor. Or, measure this into an actual speaker. As long as the load remains the same (same resistor or the same speakers) and you swap amplifiers, you can measure the differences between them.

 

Hi Paul -

 

I don't think it's actually orthogonal.  Here's why: We don't listen to amps, we listen to systems, and how an amp works with our speakers is important in determining which will produce a sound we hear as closest to the original.  Granted thus far?

 

If yes: You are comparing two amps.  They have different phase behavior - let's say one is good at maintaining absolute or linear phase, while the other uses circuitry that operates in effect as a minimum phase filter.  (I don't even know whether such descriptions make sense in the context of amplifier operation and measurement.  Do they?)

 

If these descriptions of phase behavior in amps do have some validity: In your comparison of "frequencies and amplitudes" between two amps, is this an important variable, or is frequency response across the audible spectrum really what you are looking for?  Because for example a plus or minus .35dB variation in frequency response across the spectrum may not be audible to me, but perhaps the two amps might have different impacts on imaging and localization when combined with my speakers.

 

So that's what I'm after here: What tends to show up and be looked for as significant when comparing measurements of two amps, versus what may be significant when those two amps are placed into a system and music is played through that system.

 

Edit: By the way, I agree, as I mentioned in Bill's thread, that all the characteristics I'm talking about *can* be measured, and that in principle every characteristic important to what we hear can be.  So I'm not talking about measurability, but about what characteristics are highlighted by common measurements versus what may be significant in the context of a particular system.

[Jud]

3 minutes ago, pkane2001 said:

 

No, correlation is a well-defined mathematical procedure, not at all judgment-based. Something I've used to automatically match other types of signals, including the noisy 2D images in the frequency domain, as well periodic error of telescope tracking mounts. It's much more robust in the presence of large differences and noise than the nulling procedure you mentioned.

 

 

The nulling procedure seems pretty popular, which is why I mentioned it.

[pkane2001]

3 minutes ago, Jud said:

So that's what I'm after here: What tends to show up and be looked for as significant when comparing measurements of two amps, versus what may be significant when those two amps are placed into a system and music is played through that system.

 

OK, sure, that's a topic as well  

 

But, what you are driving towards is that it's impossible to really measure any component in isolation. All have to be measured in the complete system that will be used for playback, otherwise measurements are not useful. I don't think that's true.

You can certainly measure phase performance of the amplifier independent of your own system. You can measure frequency response and gain into a fixed or variable load. You can measure clipping, slew rates, etc. And, if you know the characteristics of your speakers (that can also be measured), you can even predict with some degree of accuracy how well this amp will work in your system. I know this is not a popular thought among audiophiles, as it implies that you don't need to keep evaluating different components in your own home system 

 

Personally, I use measurements as the primary guide to component selection. After I pick a component, I evaluate it in my system to confirm that it works as expected, measure it if possible, and listen to it.

[Jud]

9 minutes ago, pkane2001 said:

And, if you know the characteristics of your speakers (that can also be measured), you can even predict with some degree of accuracy how well this amp will work in your system. I know this is not a popular thought among audiophiles, as it implies that you don't need to keep evaluating different components in your own home system 

 

I don't know that it's necessarily an unpopular thought.  I think positions can often tend to become more polarized on forums (whooda thunk, right?).  I'm happy to find that stuff out (as far as I can, not having the equipment or knowledge personally), and I'm guessing a lot of "audiophiles" feel the same.  But of course you can't discount the fun of listening.

 

I do something similar when buying cars.  I look at measurements that matter to me, but it's also nice to take a test drive.   

[AJ Soundfield]

45 minutes ago, pkane2001 said:

if you know the characteristics of your speakers (that can also be measured), you can even predict with some degree of accuracy how well this amp will work in your system.

Reality is full of traps for believers, because they are blissfully unaware of so many technical issues when they carry on their "hearing" sessions (aka "tests, listening, etc").

For example, take a speaker with highly erratic polar response:

 

(keep in mind the off axes curves are normalized to the (averaged curve above) on, so they are not as smooth as shown near zero axis).

What this means is that even the slightest head movement can result in a change is sound reaching the ears, in rather critical bands.

Unless a head vice is used, getting up even when listening to same amp, could sound different. Good luck getting up and actually inserting another!

 

[The Computer Audiophile]

23 minutes ago, AJ Soundfield said:

Reality is full of traps for believers, because they are blissfully unaware of so many technical issues when they carry on their "hearing" sessions (aka "tests, listening, etc").

 

Nothing like talking to potential customers like they are idiots. Glad to see you design speakers without listening, contrary to the best designers in the industry. I'll stick with my TAD CR1s that Andrew designed first by measurements and finally be ear. Oh that terrible thing called the ear can produce such crazy results when used in conjunction with measurements. 

[AJ Soundfield]

13 minutes ago, The Computer Audiophile said:

Nothing like talking to potential customers like they are idiots.

"Unaware" and "idiot" are 2 different things entirely. Smart people in one area can make silly mistakes in another...outside their area of expertise. The true dichotomy here.

Quote

Glad to see you design speakers without listening, contrary to the best designers in the industry.

That is false, I listen..with awareness of fallibility.

Quote

I'll stick with my TAD CR1s that Andrew designed first by measurements and finally be ear. Oh that terrible thing called the ear can produce such crazy results when used in conjunction with measurements.

Oddly enough, I use the same method as the AJ that designed your loudspeakers, who I have met in person and had nice chats with about just that.

Very different from those who can only do one thing, listen...no measurements. 

[jabbr]

 

8 hours ago, Sal1950 said:

 

"The output impedance was relatively high for a solid-state design, at 0.5 ohm from 20Hz to 20kHz. As a result, the response with our standard simulated loudspeaker varied by ±0.35dB (fig.1, gray trace)."
Read more at https://www.stereophile.com/content/first-watt-j2-power-amplifier-measurements#QmWDdAB35Yr3QP9B.99

 

Right. So you are saying that you would read Stereophile to find out what is best. Ok then.

 

3 hours ago, pkane2001 said:

 

True. My point was that it's easy to throw up your hands and to say that the differences cannot be measured. In reality, anyone can measure equipment with a little imagination and some inexpensive (and often, free) tools.

 

Actually anyone can just listen. No you can't just make a few random measurements with cheap equipment (well unless you build or repair the equipment yourself in which case, yes it can be expensive)

 

Who would measure an amp with an ADC that is less accurate than the amp?

Who would measure a recoding at the same bitdepth and rate as the recording?

 

It should be basic that the measurement tools need to be substantially more accurate than the device under test. Or if not, then special care needs to be made in the measurement. That's why real measurement tools are expensive. I picked two very highly respected amplifiers which are in many respects very similar (case, power supply etc) and which have known and well documented differences. What you propose is off the mark (first of all measuring close to a speaker puts the directionality of the speaker elements in play). Second the speaker forms part of the circuit of an amplifier, so using an 8 ohm resistor just doesn't cut it. You need to measure at the speaker output with the speakers in position. So aside from the easy "level" you fail to control for many things. Your description of phase is confusing. What would short segment comparisons tell you??? What if parts are bass drums and different parts are violins???

Probably you are best off using a complex Fourier transform and looking at both the real and imaginary parts.

In any case real accurate measurements take real work.

 

Its far easier to just listen. Bad measurements don't help anyone. Or just read Stereophile...

[pkane2001]

49 minutes ago, jabbr said:

Who would measure an amp with an ADC that is less accurate than the amp?

Who would measure a recoding at the same bitdepth and rate as the recording?

 

It should be basic that the measurement tools need to be substantially more accurate than the device under test.

 

So, you think that an inexpensive, quality ADC will be less accurate than a power amp? I highly doubt that. But that's not the point.

 

The point is that the comparison is done with the same ADC, but with different amps, which means only the differences between the amps will be measured.

 

I think your other objections were already addressed by using the same ADC fed by the preamp output as the reference signal.

[Sal1950]

1 hour ago, jabbr said:

Right. So you are saying that you would read Stereophile to find out what is best. Ok then.

I've been a subscriber since the early 70's. But about the only redeeming quality for reading Stereophile today are JA's  (John Atkinson) measurements.  Of course you have to understand that he must temper his comments about many components failures on the test bench. Can't let any bad measurements reflect on the subjective reviewers glowing prose. First and foremost can't let the failures potentially hurt a advertisers sales or cut into the magazines income from advertisers. This dance can be found quite often where John finds problems but the reviewer thinks the piece "sounds great".

(IMHO it's very sad that the number one reason JGH started Stereophile, to escape advertiser control over content, has been so lost in the last few decades.)

 

The below amp is still a $6K Recommended Component.

KM very much liked the sound of the Spec RPA-W7EX. I, however, was disappointed by its measured performance—modern class-D amplifiers, especially those using one of the Hypex modules, measure very much better than this. And with its low input impedance, its dislike of load impedances below 4 ohms, and its high levels of radiated noise, this not an amplifier that can be universally recommended, I feel.—John Atkinson
Read more at https://www.stereophile.com/content/spec-rpa-w7ex-real-sound-power-amplifier-measurements#sVOVYGVILrPrv4S6.99

 

AJ / JA,  between Soundfield, Jones, and Atkinson it's getting hard to keep up.  LOL

[The Computer Audiophile]

14 minutes ago, Sal1950 said:

The below amp is still a $6K Recommended Component.

 

I believe every component that's written about in Stereophile makes it to the recommended lists. There are so many classes and categories that need to be filled. 

[Kal Rubinson]

11 minutes ago, The Computer Audiophile said:

I believe every component that's written about in Stereophile makes it to the recommended lists. 

Not quite but we do not choose what to review randomly.  I will not review anything that does not have promise. Although that may constitute a selection bias, not all live up to that hope.

[Sal1950]

21 minutes ago, The Computer Audiophile said:

 

I believe every component that's written about in Stereophile makes it to the recommended lists. There are so many classes and categories that need to be filled. 

There are other opinions why the "Recommended Component" list has grown to what it is today.

Some very good ones IMO

http://www.high-endaudio.com/RR-STEREOPHILE.html#REC

 

7 minutes ago, Kal Rubinson said:

Not quite but we do not choose what to review randomly.  I will not review anything that does not have promise. Although that may constitute a selection bias, not all live up to that hope.

 

Kind of stacking the deck. As I said, can't upset a advertiser. 

[mansr]

8 minutes ago, Kal Rubinson said:

Not quite but we do not choose what to review randomly.  I will not review anything that does not have promise. Although that may constitute a selection bias, not all live up to that hope.

It would be useful to readers if less than stellar results were published as well. Under the current model, which is apparently how all the publications operate, failure to find a review of a component one is considering could be down to any of three reasons:

1. It's new and nobody has had time to review it yet.
2. It's crap and nobody wants to upset the advertisers.
3. It has simply escaped the attention of reviewers.

If reviewers dared publish negative assessments more often, a lot of bad purchases, or at least wasted time, could potentially be avoided. Even buying exclusively from recommended lists isn't safe since often clearly inferior (as shown in measurements) products get glowing praise.

[The Computer Audiophile]

21 minutes ago, Kal Rubinson said:

Not quite but we do not choose what to review randomly.  I will not review anything that does not have promise. Although that may constitute a selection bias, not all live up to that hope.

 

Ah thanks for the clarification. I thought everything made it to the list, just in  different category.

[The Computer Audiophile]

18 minutes ago, Sal1950 said:

There are other opinions why the "Recommended Component" list has grown to what it is today.

Some very good ones IMO

http://www.high-endaudio.com/RR-STEREOPHILE.html#REC

 

Holy crap, that guy has some serious time on his hands and serious issues with Stereophile and its personnel. Life is short, perhaps he should stop reading the magazine he now hates and do something he enjoys.