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Great article by Mr. Austin on why measurements are important.

24.20.10.236

Posted on November 19, 2020 at 08:48:15
viridian
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But what happens if measurements do not characterize the real world performance of the DUT?

Stereophile currently does steady state amplifier power measurements. Long ago, they used the Miller Research Amplifier Profiler to characterize the short term peak performance of an amp. Presumably, these measurements more closely correlate with the transient nature of music. Hi-Fi News still uses the Miller profiler.

It seems that a test regimen should be an evolving process that seeks to correlate subjective sonic impressions with test results.

 

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RE: Great article by Mr. Austin on why measurements are important., posted on November 20, 2020 at 05:50:20
geoffkait
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Ah, the age old question, which is more important - measurements or listening tests? And if measurements have evolved so haven't listening skills?

 

Renewed the subscription.., posted on November 20, 2020 at 23:50:33
Bill the K
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to Stereophile for two more years. I think JA Two is getting close to One

Bill

 

RE: Renewed the subscription.., posted on November 21, 2020 at 09:12:23
PAR
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" I think JA Two is getting close to One "

Talking of One, you may enjoy this link ( especially if you can grab a beer):



"We need less, but better" - Dieter Rams

 

Yes- Measurements and listening go hand in hand, posted on November 21, 2020 at 17:33:26
Ross
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Listening can tell us what we hear, and measurements can tell us why we hear what we hear.

Wave forms and bandwidth can tell us why an amplifier sounds muddy in deep bass, or exhibits grain in high treble, or sounds warm/rolled off. Measurements can tell us an amplifier's dynamic range and power output into varying loads, which can be useful when matching to speakers.

Tonearm resonance and cartridge compliance can tell us much about how a cartridge will sound. So will a FR that changes with cartridge loading.

With speakers, linearity of FR, along with impedance swings can tell us much about how a speaker will sound in room and how it will couple to an amplifier.

Ying and Yang; Right Brain and Left Brain.

SP gets the balance right, and other mags that eschew measurements in favor of full subjectivity often have to struggle to explain why a reviewer hears or does not hear something.

 

RE: Renewed the subscription.., posted on November 21, 2020 at 18:59:05
Bill the K
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Thanks PAR. But I am too far away from Brooklyn and Long Island to grab a good beer!

Cheers

Bill

 

Ross, you bring up an interesting point..., posted on November 21, 2020 at 22:37:14
viridian
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...in that folks are focused on the primary tonearm/cartridge resonance, which is below the audible range. However the secondary, bell like, tonearm resonances, fall within the audible range and actually define the sound quality of the moving system. But the former are easier to measure, whereas the later are much more difficult to measure. So all of the hand wringing done by audiophiles centers around primary resonance.

 

A dissenting comment, posted on November 22, 2020 at 06:46:31
geoffkait
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The primary resonance of the cartridge and tonearm affects the sound, even though it's below the audio range. The problem is that the resonance at 8-12 Hz distorts the signal in the wire, and the signal of course is not the audio waveform, it's the current and voltage. It's not the audio waveform until the speakers generate it into the room. Case solved!

 

And..., posted on November 22, 2020 at 09:50:44
E-Stat
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Listening can tell us what we hear, and measurements can tell us why we hear what we hear.

why some like THD or SINAD have little to no correlation with what we hear.

 

RE: And..., posted on November 26, 2020 at 18:16:11
Archimago
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E-Stat said:
"why some like THD or SINAD have little to no correlation with what we hear."

True, while the human perceptual system has a wide tolerance to THD and SINAD, let's not get too extreme and suggest "little to no correlation". As per the blind test results using purposely distorted audio linked below, the overall results based on 55 respondents who felt they could hear a difference, there was a preference for distortion less than 0.3% (-50dB) being "better" sounding. While DACs and most good amplifiers can achieve better than this, many speakers would not be able to claim this level of low distortion (across the whole audible spectrum).

While it's not necessarily the end-all-and-be-all of technical measurements, it's good to keep in mind that low THD/high SINAD does correlate with low nonlinear distortion and in general I think it's nice to aim for <0.1% (-60dB) as a reflection of a "transparent" source device which will likely be well received as being good sounding. Obviously formal blind testing recommended to better understand/verify this.

Obviously this is a generalization. As with most human characteristics distributed over a "normal" curve, some audiophiles might actually prefer more distortion, while others demand even lower distortion.
-------
Archimago's Musings: A 'more objective' audiophile blog.

 

You're most welcome, posted on November 26, 2020 at 19:45:46
E-Stat
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To believe that artificially added distortion bears any resemblance to the far more complex reality of reproducing music.

Enjoy your parlor games. :)

 

Can you expand..., posted on November 27, 2020 at 07:07:09
Steve O
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...on why you believe the described experiment and results are a "parlor game" (deception)?

 

Sure, posted on November 27, 2020 at 07:38:54
E-Stat
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Such a test proves what it proves but bears little resemblance to actual qualitative factors in music reproduction. Harkens back to the irrelevancy of the THD wars in the 70s. What may look great on paper reduced to a single metric tells you very little - unless your favorite tunes are uncorrelated sine waves!

I have an Ncore amplifier that is highly rated in terms of SINAD but fails horribly at high frequency reproduction and imaging. It has a curious lack of center fill.

 

RE: You're most welcome, posted on November 28, 2020 at 22:31:33
Archimago
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E-Stat said:
"To believe that artificially added distortion bears any resemblance to the far more complex reality of reproducing music.

Enjoy your parlor games. :)"


Not sure if this is a fair assessment, man... Kinda rude in fact. Maybe you can provide some decent intellectual discussion?

Surely you must think at some high level, like say 3% or 5% THD actually is audible, right? If so, then there must be some kind of threshold whereby audiophiles do care about high-enough-fidelity playback?
-------
Archimago's Musings: A 'more objective' audiophile blog.

 

Do you ever , posted on November 29, 2020 at 05:25:53
E-Stat
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evaluate audio gear by listening to high quality recordings?

I find that approach provides far more insight to understanding how a DUT fares reproducing live, unamplified music than simplistic numerically based tests. It's easy to score well on THD based tests-just dial in boatloads of corrective feedback! Which to these ears results in compromised real world performance.

Years ago, there was a jerk here (since banned) who referenced a distortion perception test he referred to as "audiophile repellent". He posted his results and assumed no one would accept his challenge. I bettered his ability using the headphone output of a basic laptop and modest Shute IEMs. The THD threshold was in the several percent range IIRC.

Boring recording. Boring test. Been there, done that. Wasted time.

edit: I located that post here. -36 db relates to 2.5%.

 

That was definitely above the threshold of rudeness :) (nt), posted on November 30, 2020 at 22:15:25
Posts: 1978
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nt

 

Might be worth reading..., posted on December 2, 2020 at 05:24:04
Doug Schneider
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"Dare, even today, to extol the virtues of an amplifier as having really low
distortion and some know-it-all will stand up and say "you know measurements
don't say it all; remember the 80's when we were flooded with amps that had 0.00001% distortion and sounded all screechy", bystanders nodding vigorously"

Might be worth reading via the link below.

As well, you might want to ask yourself this: If a product can't perform well on "simple" sine-wave tests, how is going to perform well under supposedly more complex conditions?

Doug Schneider
SoundStage!

 

RE: Might be worth reading..., posted on December 2, 2020 at 06:34:20
E-Stat
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Might be worth reading via the link below.

I am quite familiar with Putzeys and his work - along with using one of his Ncore amplifiers for the garage system. Arguably, his designs are the best switchers available today. While it has a wonderful midrange, I find the top end is compromised as compared with the VTLs. But it works great with New Advents and having 300 watts/channel on hand provides nice headroom. Lots of bang for buck but have no interest with it driving the stats in the main system.

As well, you might want to ask yourself this: If a product can't perform well on "simple" sine-wave tests, how is going to perform well under supposedly more complex conditions?

It's not a case of inherently linear design not performing well on sine wave tests. Rather - how many zeroes to the right of the decimal point actually improve the listening experience? Nelson Pass has demonstrated that such an assertion has reality bass-ackwards. Designs using boatloads of cascaded feedback do downright poorly on complex conditions. Here is a visual from the referenced article:

As for me, I'll pass (pun intended!) on introducing complex distortion products for which the ear is more sensitive. Some feedback can be good, but lots is not necessarily better when the objective is determined by what you hear - as opposed to what you see on paper.

Which is likely why I am not a fan of op amp based designs as they have complex topologies and rely upon large amounts (>40db) of corrective feedback. Have you ever replaced such with discrete FETs and compared the differences? I found them very enlightening with a Music Hall DAC where I replaced three TI chips almost three years ago with Burson FETs.

My home theater/MC system uses Emotiva and Oppo products with TL072 and 5532 op amps, respectively. The result is neutral, but opaque sounding as compared with the Audio Research combination used upstairs which are zero feedback, class A designs using matched JFETs and triodes in the case of the SP20.

 

Apparently, posted on December 3, 2020 at 18:43:40
E-Stat
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you never listen to gear. Just look at numbers on paper.

To each his own I guess. :)

 

RE: Might be worth reading..., posted on December 5, 2020 at 08:31:00
CG
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You might enjoy this book. Yes, it's technical but not loads of math. Dr. Kolinummi has sections describing in engineering terms why steady state distortion measurement is hardly a complete examination of audio performance.

 

Thanks, posted on December 5, 2020 at 15:32:37
E-Stat
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As Nelson observes, it differs from other analyses of distortion by looking at open loop linearity - an area in which switchers and op amps are weak.

They require heroic amounts of correction to behave properly.

 

RE: And..., posted on December 5, 2020 at 18:30:03
Doug Schneider
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>>>>why some like THD or SINAD have little to no correlation with what we hear.

Very weak arguments They have a lot to do with what you hear. Raise them up high enough, you'll hear them. You'll be able to correlate them and all that stuff.

The thing is, good engineering has brought the levels down so they don't matter -- but only because the engineering has got them that way. Lower them anymore and it really doesn't matter -- but that doesn't mean they don't matter at all.

Doug Schneider
SoundStage!

 

RE: And..., posted on December 5, 2020 at 19:56:07
E-Stat
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They have a lot to do with what you hear. Raise them up high enough, you'll hear them.

If you're referring to Electrophonic brown goods gear, sure. Which is what I started with in 1970 as a kid. ;)

The tests performed by the "deceitful sorcerer", however, have little to do with what you actually hear with high end gear.

Lower them anymore and it really doesn't matter.

Once again, we agree.

What my experience tells me, however, is those who pursue extreme levels on paper compromise overall sound quality in the real world. Switchers and op amp based devices are not yet ready for prime time in the highest quality systems.

 

RE: And..., posted on January 10, 2021 at 14:57:13
j.sautter
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I think that Stereophile includes measurements more as a way for them to differentiate themselves from their competition than because such measurements are often truly significant. Gives the magazine one more thing to print and thus occupy space.

 

RE: Might be worth reading..., posted on February 6, 2021 at 14:48:50
A.Wayne
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Thats some pretty low distortion numbers by 80's standard .. :)

 

RE: And..., posted on February 6, 2021 at 16:29:11
A.Wayne
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No not really ...!

Stereophile started doing measurements as away to keep up as it was Standard for the industry back then , this was way before opinionated mags became the norm like today ..

Objective and subjective reviews were standard , Magazine of choice for me was "Audio" with Bascom King ..

With amplfiers you can basically tell everything from a complete set of bench testing , Stereophile while extensive is not complete or consistent in application , some protection of the innocent is necessary ...

:)

Regards

 

A component or speakers or cables sound different in different rooms to different people. Hel-loo! Nt, posted on February 14, 2021 at 13:22:36
geoffkait
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Nt

 

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