Why Some Audiophiles Fear Measurements

[Ethan Winer]

the amount of information Ethan is provided is not enough, it is too generalised without specifics such as explaining the mechanisms involved

What exactly do you guys want from me? If someone writes a newspaper article about obesity in America, do you criticize it because it doesn't include every single potential contributor, or explain the precise way obesity leads to diabetes using medical terminology, or list 175 healthy recipes you can make in less than 20 minutes?

Paul Miller's test show two products that definitely sound different but using the usual standard type tests measure comparably

I just used the Search Posts function (thanks Amir) and found no link to any such article. If the comparisons were not done blind, I am not interested because they don't prove anything. Versus Nelson Pass's proper blind tests proving that most power amps sound the same, which I linked to.

I hope this post is not coming off vocally strong

Not at all. As long as you don't call me an a-hole as others have done, we're cool.

--Ethan

 

[amirm]

There's no magic in audio.

Maybe there is no magic left in audio. But I would say fair amount of "art" remains. And by that, I do not mean the way something looks.

I honestly don't understand your (and others) objection to my categorizing audio parameters. The reaction I sometimes get amazes me. All I'm doing is trying to make audio more understandable and accessible to non-engineers. Why all the hostility? This is a serious question!

I will give a serious answer!

My main objection is distinct from others here. I don't like oversimplification which reduces our understanding of the subject. One example would be if you said "digital is perfect." You will immediately get me to say not quite and go on to explain why it could be imperfect. So when you put even distortions that we have not discovered or we the two of us know about as something that is known, that is oversimplification to me and hence, unfair to be used as an argument to beat up the the other side.

Second is my personal observations which trouble the engineer in me. I cannot explain why in my personal double-blind tests I hear differences between interconnects. I can't quite explain why my $7000 dedicated DAC sounds different (both better and worse) when I mess with the frequency of the PS Audio power regenerator. I also remember a time when jitter was not anything people worried about or understood in the context of audio reproduction. All of this tells me that I might be able to properly analyze audio products to 90% or better with strict, objective tools. But the last bit is black art to me right now.

Note that there was a time when I could not hear any of the above differences. If you caught me then, I would be with you 100%. It is through years of testing audio that I have developed an opinion that leaves the door ever so slightly open for arguments that don't have a quick and immediate answer in science.

That said, as probably the only guy here with a $25K audio tester, I clearly see the value in measurements and if measurements tell me the story, you never catch me using my ears.

 

[Ethan Winer]

Great post Amir. I would never say that digital audio is perfect, though I think it's audibly perfect. Or so close as to not really matter.

I cannot explain why in my personal double-blind tests I hear differences between interconnects. I can't quite explain why my $7000 dedicated DAC sounds different (both better and worse) when I mess with the frequency of the PS Audio power regenerator ... if measurements tell me the story, you never catch me using my ears.

So have you measured the audio throughput with different interconnects and different PS frequencies? What did you find?

--Ethan

 

[Johnny Vinyl]

Maybe there is no magic left in audio. But I would say fair amount of "art" remains. And by that, I do not mean the way something looks.


I will give a serious answer!

My main objection is distinct from others here. I don't like oversimplification which reduces our understanding of the subject. One example would be if you said "digital is perfect." You will immediately get me to say not quite and go on to explain why it could be imperfect. So when you put even distortions that we have not discovered or we the two of us know about as something that is known, that is oversimplification to me and hence, unfair to be used as an argument to beat up the the other side.

Second is my personal observations which trouble the engineer in me. I cannot explain why in my personal double-blind tests I hear differences between interconnects. I can't quite explain why my $7000 dedicated DAC sounds different (both better and worse) when I mess with the frequency of the PS Audio power regenerator. I also remember a time when jitter was not anything people worried about or understood in the context of audio reproduction. All of this tells me that I might be able to properly analyze audio products to 90% or better with strict, objective tools. But the last bit is black art to me right now.

Note that there was a time when I could not hear any of the above differences. If you caught me then, I would be with you 100%. It is through years of testing audio that I have developed an opinion that leaves the door ever so slightly open for arguments that don't have a quick and immediate answer in science.

That said, as probably the only guy here with a $25K audio tester, I clearly see the value in measurements and if measurements tell me the story, you never catch me using my ears.

With respect.... the bottom-dwellers in the audio loving community don't have that luxury, and even if we did....would you really tune out your ears? I don't necessarily trust them to provide the truest sound, but if the sound perceived by those ears is pleasing and pleasant then I think I'll go with my ears.

John

 

[kareface]

Everyone should use their ears. The problem with audiophiles isn't their ears, it's their eyes. If you really only used your ears, no one would be complaining. However very few audiophiles actually preform blind comparesons. I trust your ears to tell you what you like, I just don't trust your eyes.

 

[Orb]

What exactly do you guys want from me? If someone writes a newspaper article about obesity in America, do you criticize it because it doesn't include every single potential contributor, or explain the precise way obesity leads to diabetes using medical terminology, or list 175 healthy recipes you can make in less than 20 minutes?



I just used the Search Posts function (thanks Amir) and found no link to any such article. If the comparisons were not done blind, I am not interested because they don't prove anything. Versus Nelson Pass's proper blind tests proving that most power amps sound the same, which I linked to.



Not at all. As long as you don't call me an a-hole as others have done, we're cool.

--Ethan

Haha Ethan no worries about the last line, while I may not necessarily agree with your approach or conclusion just yet, there usually is always something for most to consider related to the subject raised.
The purpose we all should remember (not saying this has been done but it is in our nature to be competitive) is that posting should not about being to try and win an argument, but to make us think deeper on the subject raised.
For me this even got me going back to reading old papers on timbre and effects caused by various types of resonance and also timbre affects related to spectra, while also following up again on other cool stuff that we sometimes do not always remember and think about in its complete depth.

Anyway, Amir captured the essense pretty well that the hypothesis in our opinions is an oversimplification or generic definition for an incredibly complex set of mechanisms that to be validated will rely upon many different defined tests and measurements at higher resolution or different focus than the existing ones we only have to go by as a point of reference (which as I badly try to point out by going with an actual real life situation).

Those two products; the Nad and Arc require the magazine to be purchased (mentioned this a long time ago), but lets be honest.
In general I am yet to see anyone and I mean anyone say a tube preamp with zero feedback sounds exctly the same as a solid state cheap high feedback design (for the very good designs with exceptional performance behaviour and measurements)
The use of cheap does not mean it is crap (NAD are really well engineered and implemented but cost considerations do have an affect - Bruno Putzeys has touched on this in the past as well in relation to use of negative feedback)

It does seem like a lynch mob but it is not honest
Basically I would say those of us quering just want correlated data to go with the hypothesis, which would also explain how the mechanism works (in reality it would be multiple mechanisms due to the varied factors and parameters involved).
As an example look at some of Floyd's papers and he will match objective measurements to see how they trend with both listening and operational behaviour.
My mistake was to jump straight in with detail measurements of two like products that are fundamentally different, while discussing the challenges and implications these had on your proposal.
Although to be fair I was hoping to raise awareness for posters who may not be interested in measurements to also try and consider them, including how they possibly (some may feel it not/is relevent) to your own statement.

Amir, I feel myself and a couple of others agree with what you very succinctly said, I blame you for not posting much earlier hahaha

Cheers
Orb

 

[kareface]

Second is my personal observations which trouble the engineer in me. I cannot explain why in my personal double-blind tests I hear differences between interconnects.

One of the most interesting theories on IC's I've heard was magnetic coupling from return current traveling via. line cord ground instead of the IC's shield. With out the return current, coupling occurs, it'll be frequency dependent, and it'll vary depending on the IC and the ground impedance mismatch. I haven't had the opportunity to test it first hand but it makes a fair amount of sense.

 

[DonH50]

Amir -- Does your test unit have a network analyzer in it? Good LCR meter?

Curious - Don (only about $1k in test gear at home but $1M+ at work, and >>10x that at the home office, mostly at too high a frequency to be useful here!)

 

[amirm]

Amir -- Does your test unit have a network analyzer in it? Good LCR meter?

Not directly. The box in question is from Audio Precision: http://www.audioprecision.com/. My box is a generation or two old. It has both a digital side and an analog side. The analog side performs typical level, phase and distortion measurements. It has a high-performance sweep generator which automates measurements. The digital side has a pair of programmable high-performance ADC where you can make trade offs between performance and bandwidth. It is all optimized for audio measurement as opposed to being a standard analyzer such as an HP box might be.

Curious - Don (only about $1k in test gear at home but $1M+ at work, and >>10x that at the home office, mostly at too high a frequency to be useful here!)

There is really nothing else like the above box. It is totally optimized for audio analysis and despite its obscure interface, it is still a lot easier than trying to use standard measurement boxes.

They have a newer box which I wished I had which has HDMI input and can measure jitter across that.

 

[amirm]

With respect.... the bottom-dwellers in the audio loving community don't have that luxury, and even if we did....would you really tune out your ears?

Of course. The instrument is repeatable and positive proof to anyone that what it measures is well, what it measures . In sharp contrast, if I said I heard something, at least 50% of the world wouldn't believe me. Worse yet, at least 20% of the time I would not believe myself!!! Seriously, having fallen in a ditch imagining things sometimes, I can say that people's hearing is not perfect. So picking between a perfect instrument and an imperfect one becomes easy.

I don't necessarily trust them to provide the truest sound, but if the sound perceived by those ears is pleasing and pleasant then I think I'll go with my ears.

John

You can do that. In my case, my job depended on being right so as you can imagine, that makes one look more openly at the issues . As I have said before, I use my ear a lot, almost as much as many of you do to judge things. It is imperfect to be sure but it is lightning fast and lot more fun to use. Setting up a measurement or double-blind test is extremely time consuming and boring. But time permitting, and test existing, I prefer to go that way given the fact that the results cannot be doubted as much.

 

[amirm]

So have you measured the audio throughput with different interconnects and different PS frequencies? What did you find?

--Ethan

I did not have the AP when I did the PS audio test so no, I don't have that data but can run it now. Time permitting, I will do so.

I did test the interconnects. I compared three ICs, one video coax, one generic audio cable, and last, Transparent Audio. The frequency sweep is up to 200K or about 10X CD frequency response:

Kind of what an engineer would expect: no difference whatsoever. All three traces are on top of each other.

I then ran the same test, this time changing the output impedance from 20 ohns to 600 ohms:

We now see a high frequency roll of in Transparent Audio. If you look at their web site, they confirm the same that they filter out ultrasonic frequencies.

So the audiophile cable has a filter, and the others do not. Now you know why I am conflicted .

 

[FrantzM]

Hi

The Thread original subject has moved somewhat, which is fine with me...

Looking at Amirm last post. I can only be by the contradiction in the Transparent Audio Cable and some of the ost basic tenets Orthodox Audiophilia philosophy: Leave the signal untouched.. So no Room correction, no EQ. Leave the signal alone in all its purity ... Meanwhile Audiophiles do pay serious money for a cable which clearly messes up with the signal, much more so that a generic but good (or so I think) pro audio cable... I think Transparent also have a$30K speaker cable.. Which likely messes more withe the signal since it has their filter attached ..Interesting , very interesting ..
Will wonders ever cease ?

I am starti

 

[microstrip]

Hi

The Thread original subject has moved somewhat, which is fine with me...
Leave the signal untouched...

Frantz,
You are moving it much more than you thing. Who said that we are members of the rigid Orthodox Audiophilia?
Why not "since it is not possible to leave the signal untouched, touch it in a proper way". Now we can discuss what it is "proper way"!

BTW, I do not have the Transparent 30K speaker cable, but this weekend I am guilty of borrowing the 20K one!

 

[Ethan Winer]

I then ran the same test, this time changing the output impedance from 20 ohns to 600 ohms:

Most audio devices have a higher input impedance than 600 Ohms. I think 10K to 100K is more typical. So if that one cable is down 0.1 dB at 20 KHz at 600 Ohms compared to 20 Ohms, it could be down much more into 100K. And that of course would account for a different sound. Versus believing we are somehow affected by frequencies higher than 20 KHz.

If you get a chance, I'd like to hear / read more about changing the PS frequencies too, and what you hear versus measure.

--Ethan

 

[FrantzM]

Microstrip


No one. You can't deny however that leaving the signal untouched and unspoiled is not an ideal oh hi-fi though, one by the way to which I subscribe although not rigidly ... It is an ideal and the fact that we can reach it perfectly doesn't mean we should not try to approach it, else we would have stopped at the Edison Wax cylinder for High Fidelity sound reproduction.

 

[Orb]

Most audio devices have a higher input impedance than 600 Ohms. I think 10K to 100K is more typical. So if that one cable is down 0.1 dB at 20 KHz at 600 Ohms compared to 20 Ohms, it could be down much more into 100K. And that of course would account for a different sound. Versus believing we are somehow affected by frequencies higher than 20 KHz.

If you get a chance, I'd like to hear / read more about changing the PS frequencies too, and what you hear versus measure.

--Ethan

May be useful for the discussion, I checked out several preamps and digital sources, info from Stereophile.

CD/Transport:
Ayre C-5xe Output Impedance: 93ohms unbalanced, 187ohm balanced.

Boulder 1021 Output Impedance: 100ohms balanced.

Esoteric SA-60 Output Impedance: 94 to 114ohms across audioband unbalanced, and 80 ohms balanced

Bryston BCD-1 Output Impedance: 74 to 106.5ohms across audioband unbalanced, and balanced exactly double.

Preamps:
Boulder 810 Input Impedance: 86k to 74kohms across audioband (not stated if balanced)
Output Impedance: 50ohms unbalanced, 100ohms balanced

Simaudio Moon Evolution P-8 Input Impedance: 11k to 4.3k ohms across audioband unbalanced, 22k to 9.7k ohms across audioband balanced.
Output Impedance: 50ohms unbalanced, 100ohms balanced

Ayre KX-R Input Impedance: 1m ohm for unbalanced and balanced.
Output Impedance: 312ohms balanced

So the output Impedance does fit well within the boundaries of what Amir tested, but maybe run some more tests with the above values.

Cheers
Orb

 

[FrantzM]

Orb

I do not agree with some of Ethan assertions. For the record I am of the opinion that electronics sound different ... If one looks at the figures you stated however Ethan's last points remain and you corroborated it. In High End Audio 600 ohms of input impedance is very rare ...

 

[amirm]

Most audio devices have a higher input impedance than 600 Ohms. I think 10K to 100K is more typical.

As I mentioned, 600 was the *output* impedance of the generator, not the input of the analyzer. Orb post some samples and I would add that output impedance of sources is often frequency dependent, rising at higher frequencies.

 

[amirm]

May be useful for the discussion, I checked out several preamps and digital sources, info from Stereophile.

Thanks for posting these. Here is another useful reference: http://www.stereophile.com/cdplayers/207naim/index4.html per my earlier note of frequency dependence:

"The player's output impedance was very low at midrange and high frequencies: 17 ohms at 1kHz and 28 ohms at 20kHz. However, its impedance at 20Hz was 378 ohms, presumably due to the use of an output coupling capacitor. Though this is still a low source impedance in absolute terms, the contrast between it and the lower impedance at higher frequencies will result in premature bass rolloff if the CD555 is used with a preamplifier of very low input impedance."

So the output Impedance does fit well within the boundaries of what Amir tested, but maybe run some more tests with the above values.

This is hard to do. My analyzer only has those two settings. Anything else requires building a test fixture to simulate that impedance.

 

[DonH50]

As Amir has implied, most specs are frequency dependent, one of the reasons the spec sheet is barely a start.

While I have used an older AP unit, most of my measurements in the past were with an HP (Agilent now) audio test set (about $30k now, I think, for the latest version). Supplemented with a VNA, spectrum analyzer, generators etc. About $500k in equipment. Testing is not for the poor! Unfortunately for me and my participation here, my current company is microwave-oriented and I don't have access to as much low-frequency gear as I did a few years ago. Just when I get back into audio... - Don

p.s. Amir -- Have you thought about building a lo-Z output buffer for your AP unit?