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Learning more about the science of sound - Page 10

post #136 of 395
Quote:
Originally Posted by jaddie View Post

But, why would anyone doubt that less distortion is preferable?

Indeed, this hobby is called High Fidelity, where the key word is fidelity - faithfulness to the source.
Quote:
We're trying to reproduce sound, why would adding distortion resulting in harmonics not otherwise present be a good thing?  The Aphex case is special, and not universally positively accepted.

Yes again. When creating sounds anything goes. Once the recording engineers and producers have sculpted the sound to their liking, from there on through to the end-listener's loudspeakers, the goal should be accuracy.

--Ethan
post #137 of 395

Mr Winer, what is your favourite speaker? biggrin.gif Or what brand do you think produces objectively fantastic speakers at a very reasonably price?


Edited by uchihaitachi - 5/3/13 at 11:33am
post #138 of 395

My favorite speaker is Mr. Winer. 

post #139 of 395
Quote:
Originally Posted by jaddie View Post

My favorite speaker is Mr. Winer.

LOL, thanks.

I usually avoid recommending speakers (and microphones) because there are literally hundreds of models and I'm familiar with only a few. That said, I'm a big fan of the Mackie HR series because they're very flat and have low distortion, yet they don't cost an arm and a leg. They're also self-powered and bi-amped. Five of my friends have the original Mackie HR824s in their home studios, and I have HR624s in my living room home theater. The 624s don't play to as low a frequency as the 824s, but I have a killer subwoofer so the 624s are perfectly adequate and cost less.

--Ethan
post #140 of 395

Thank you sire!

 

On another note Mr Winer, what is the potency of the placebo effect when it comes to speakers. Is it more powerful or weaker compared to say portable audio?


Edited by uchihaitachi - 5/5/13 at 1:15pm
post #141 of 395
Quote:
Originally Posted by uchihaitachi View Post

 

On another note Mr Winer, what is the potency of the placebo effect when it comes to speakers. Is it more powerful or weaker compared to say portable audio?

Not directed at me, but I'll respond anyway.

 

Take a look at this:

post #142 of 395

God I love the sound science forum! darthsmile.gif

post #143 of 395

Perhaps I might add an anecdote.  In the early 1990s I was hired as an "expert witness" by a law firm defending a client in a suit against them, a speaker company (or at least a seller of speakers).  The issue was that the seller's product was accused of being sub-standard relative to other products of the same price class.  I believe there may have been some questionable sales and marketing practices as well, but that was never made clear.  

 

The testing I did was exactly what was shown in this video, except I had 8 pairs of speakers, including the ones in questions.  I had no knowledge of which speakers belonged to the defendant.  The tests were done over a period of several weeks, with somewhere around 35 testers of a wide spectrum of demographics.  I built a high quality speaker switcher, and wired everything with what was, at the time, considered high-performance speaker wire (it was a Monster product) just to be sure my data would withstand challenges. Testers were allowed to compare speakers A&B, and choose a preference, then I scrambled the choices and tried a different set. Testers ran through the test program in groups of 4, there was a wide variety of program material, and there was also an acoustically transparent screen to hide the speakers.   The data collected was a bit massive, but once sorted through I found that the preference was overwhelmingly for the most neutral sounding speakers.  Unfortunately, the defendant's speakers scored dead last (which I didn't know at the time), so the test evidence wasn't used in the case, which was settled out of court.  What was interesting was the overwhelming preference, which was unexpected.  I expected a sort of bell curve to the results, with preferences clustered in the middle, but that's not what we got.  I guess the Harmon lab found the same thing.

post #144 of 395
Quote:
Originally Posted by jaddie View Post

David Clark did some extensive ABX testing using his "chamber of horrors" distortion generator back in the 1980s.  He found two things: 1, we can't hear distortion as well as we thought.  He could introduce some rather high levels without reliable detection.  2, distortion was never preferred.  The data is in an old AES paper.

 

But, why would anyone doubt that less distortion is preferable?  We're trying to reproduce sound, why would adding distortion resulting in harmonics not otherwise present be a good thing?  The Aphex case is special, and not universally positively accepted.  

 

Not so much about doubting why. Was just wondering if it was also researched (I'm guessing logically it has to be since it's what science is based on). Was just curious if there was any published research which backed that up. Thanks for sharing.

post #145 of 395
Quote:
Originally Posted by SunshineReggae View Post

 

Not so much about doubting why. Was just wondering if it was also researched (I'm guessing logically it has to be since it's what science is based on). Was just curious if there was any published research which backed that up. Thanks for sharing.

David demonstrated the distortion chamber of horrors to AES chapters and other audio groups around the country.  I'm not sure if an AES paper on distortion audibility came out of it or not, but the use of a distortion generating circuit along with Clark's ABX test system in an effort to determine the threshold of distortion audibility in music is mentioned in Mr. Clark's paper, "High Resolution Subjective Testing", Journal of the AES, Vol. 30, Number 5, May, 1982.  With his specific distortion circuit, the best lowest level that could be reliably detected was 3%.  The paper did not focus on distortion audibility, however, and a preference for lower distortion was not mentioned.  There are many papers written about the audible thresholds of specific types of distortions.  But there's no simple way to generalize, since every distortion mechanism and resulting spectra is different.  

 

It should be noted that audio devices have always been designed with lower distortion as a goal, and those with higher distortion have it as an undesired or unintentional by-product of a design compromise.  

 

A cursory search through the AES database revealed dozens of papers about measuring distortion, reducing distortion, correcting distortion, the audible thresholds of different types of distortion, correlation (or lack thereof) of mathematical predictions of distortion vs measured levels, and so on.  I found not one paper that attempted to analyzed if higher or lower distortion was preferred by listeners.  It's almost as if it is a given that lower distortion is a goal because it's always preferred. There is no logical reason why this should be otherwise, as a distortion product adds spectra that does not exist in the original.

 

This doesn't specifically isolate distortion, but the findings seem to support the general preference for neutral undistorted sound:

http://seanolive.blogspot.com/2012_05_01_archive.html


Edited by jaddie - 5/5/13 at 11:51pm
post #146 of 395

http://www.jhaudio.com/collection/freqphase

 

Is this legit? I mean, should it really provide a day/night difference or is the sonic difference negligible? Every reviewer seems to be so blown away by this 'freqphase' but it seems to me like a marketing hype more than anything.

post #147 of 395

The overall slope doesn't matter, what matters is the rate of change of the phase. We'd know a lot more if they plotted the group delay, but instead they put up these phase plots and a wrong description...

 

From a quick look the competitor "piece" has higher group delay ("is slower") around 1 kHz and 3 kHz.


Edited by xnor - 5/6/13 at 6:16am
post #148 of 395
Quote:
Originally Posted by uchihaitachi View Post

http://www.jhaudio.com/collection/freqphase

Is this legit? I mean, should it really provide a day/night difference or is the sonic difference negligible? Every reviewer seems to be so blown away by this 'freqphase' but it seems to me like a marketing hype more than anything.

I am not saying the difference is negligible, but take reviewers words with a grain of salt. They usually see "night and day" differences everywhere.
post #149 of 395
Quote:
Originally Posted by jaddie View Post

Part of the problem is that tubes operate at fairly high impedances, and have output impedances from hundreds to thousands of ohms.  In order to drive a low impedance load like a speaker or headphone, an output transformer is required...

 

Output transformer is one way.  Cathode follower is another.

post #150 of 395
Quote:
Originally Posted by uchihaitachi View Post

http://www.jhaudio.com/collection/freqphase

 

Is this legit? I mean, should it really provide a day/night difference or is the sonic difference negligible? Every reviewer seems to be so blown away by this 'freqphase' but it seems to me like a marketing hype more than anything.

If the only difference between the product and competitor was the phase plot, they'd sound identical to each other.  

Quote:
Originally Posted by xnor View Post

The overall slope doesn't matter, what matters is the rate of change of the phase. We'd know a lot more if they plotted the group delay, but instead they put up these phase plots and a wrong description...

 

From a quick look the competitor "piece" has higher group delay ("is slower") around 1 kHz and 3 kHz.

Same data, different window.  The phase plot in his case shows all we need to know, and it's an insignificant difference.  Frankly, if that's all the phase shift we're dealing with (and in many cases it's not) that would be easy to comp out with an allpass filter, but there's really no point.

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