How to Choose a Loudspeaker -- What the Science Shows - Page 22 - AVS Forum | Home Theater Discussions And Reviews
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post #631 of 3815 Old 01-12-2019, 12:29 PM
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Originally Posted by DS-21 View Post
I agree completely. However, that is a markedly different narrative from "Both KEF and TAD speakers suffer from Intermodulation Distortion since the woofer or mid cones are the waveguides. While it is true that their off-axis radiation it symmetrical, the design also limits dispersion at the highest frequencies, which is heard as a lack of "air.'"

Speculation of a long-standing Harman blind spot about concentric drivers is "idle chatter," I agree. But I heard similarly dismissive comments about concentrics due to IM distortion from ex-JBLer Greg Timbers last decade, so...

To be clear, I am NOT making the argument that concentrics are inherently better than a thoughtfully engineered multiway speaker with a waveguide-loaded tweeter that matches the dispersion of the next-driver-down at the crossover region. I'm merely pushing back on comments that they're inherently worse.

I'm also very skeptical of the IMD argument. Not that it's there. Clearly it is. But is it audible and consequential? Mitchco's earlier post includes a link to his article comparing the KEF LS50 and a JBL Pro speaker with a 15" woofer and compression driver tweeter. This review includes binaural recordings of the LS50 full range, LS50+subs, and JBL + subs. Can someone point out how the inarguably much higher IM distortion in the LS50 manifests itself in these recordings?

Lastly, there is one company selling a speaker line based on a concentric with flat midrange today: Technics. Within the limits of what one can discern from Stereophile's measurements - no sign JA's dumb practice of normalizing his off axis charts to the axial response will end, alas - the bookshelf model seems capably engineered if voiced very bright.

Listening window


Normalized horizontal





For those following along at home: Kindle Location 9362 (pg. 448).

And, yuck. The midrange level jump does make me wonder if the Alnico woofer had been partially demagnetized at some point. So glad we've moved beyond Alnico!



Business realities and IP law do get in the way of that to a large extent, of course.

Other companies and individuals have made a certain drivers a large and perhaps dominant part of their business identity, and as a practical matter following them would imply that they were "right" and the previous products were "wrong." Just look at what happened to Thiel when they abandoned some idiosyncratic design concepts. There were other factors involved there, but undeniably one of them is that "Thiel buyers" hated the upgraded design philosophy.

As for IP, to use a speaker example: if multiple-entry horns are a superior technology - I'm not saying they are, just using them as an example! - then other companies are limited more by their willingness to license technology (and the IP holder's willingness to license) or risk litigation on their patent workarounds.
Ah, yes, it was Technics that made, and I just learned, still makes flat concentric transducers. It has the potential to be an excellent design, and it seems that they did quite well at it. Thanks for the reminder.

Many years ago, engineers from both Pioneer and Technics visited me at the NRCC. One of them, I cannot remember which, brought large binders of my papers translated into Japanese. They had a camera and a tape measure and took enough data to go home and recreate my facility, which I am told was at least partially done. They believed in science.

That Andrew Jones should end up designing TAD and Pioneer loudspeakers was not at all surprising. He has now moved on and I wish him well. He is a "white hat" audio engineer
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post #632 of 3815 Old 01-12-2019, 06:07 PM
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Originally Posted by Floyd Toole View Post
He is a "white hat" audio engineer
Wasn't that a favorite expression of Peter Aczel, editor of the Audio Critic? He use to refer to Black Hats and White Hats in the audio industry and Dr. Toole was considered a "White Hat". You can see the article HERE and who he considered to wear which hats. Some of the Black Hats are obvious but some not so much. An interesting read.

Love him or hate him, he was not the friend of the subjective nonsense we have to read today in Stereophile or TAS.
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post #633 of 3815 Old 01-12-2019, 06:54 PM
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Originally Posted by audioguy View Post
Wasn't that a favorite expression of Peter Aczel, editor of the Audio Critic? He use to refer to Black Hats and White Hats in the audio industry and Dr. Toole was considered a "White Hat". You can see the article HERE and who he considered to wear which hats. Some of the Black Hats are obvious but some not so much. An interesting read.

Love him or hate him, he was not the friend of the subjective nonsense we have to read today in Stereophile or TAS.
“Today”? Stereophile and TAS have been spreading their subjective nonsense since each of their inception.

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post #634 of 3815 Old 01-12-2019, 06:56 PM
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Originally Posted by audioguy View Post
the subjective nonsense we have to read today in Stereophile or TAS.
Stereophile is also paradoxically one of the few publications that does meaningful measurements. The best entertainment is reading the creative wording used to dance around bad measurements, usually along the lines of:

This problematic measurement result suggests audible problems, but since the reviewer did not have anything bad to say (they never do), it's probably not a problem (because subjective impressions override objective measurements... wait, why are we doing measurements again?)

or

This behavior looks idiosyncratic. I suggest anyone considering buying this speaker to listen for themselves (instead of looking at measurements... wait, why are we doing measurements again?).
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post #635 of 3815 Old 01-13-2019, 12:07 AM
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Dr. @Floyd Toole

Related to comparisons done in mono, you mentioned that highest rated loudspeakers in mono have always been highest rated loudspeakers in stereo (over multiple tests done) . I assume yes but just to confirm, did they also retain the order ? And there was never a “surprise” entry into the highest rated stereo list from the sample group ?


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post #636 of 3815 Old 01-13-2019, 03:46 AM
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Originally Posted by tonygeno View Post
“Today”? Stereophile and TAS have been spreading their subjective nonsense since each of their inception.
But TODAY, there is no "The Audio Critic" to offer an opposing (and more realistic) view so TAS and Stereophile are the choices.

Stereophile's founder, Gordon Holt, was sort of a White and Black Hat (according to me, not The Audio Critic) as he said (as I noted previously but will say again here): "As far as the real world is concerned, high-end audio lost its credibility during the 1980s, when it flatly refused to submit to the kind of basic honesty controls (double-blind testing, for example) that had legitimized every other serious scientific endeavor since Pascal. [This refusal] is a source of endless derisive amusement among rational people and of perpetual embarrassment for me"
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post #637 of 3815 Old 01-13-2019, 09:07 AM
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Wilson Audio’s take on a speakers linear frequency response vs its ability to play a dynamic range, and its actual performance in a listners home. This is what I have been talking about, and am glad this has been responded to in this thread. Great learnings!

Skip to 3:35


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post #638 of 3815 Old 01-13-2019, 09:09 AM
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Originally Posted by Hifisound View Post
Dr. @Floyd Toole

Related to comparisons done in mono, you mentioned that highest rated loudspeakers in mono have always been highest rated loudspeakers in stereo (over multiple tests done) . I assume yes but just to confirm, did they also retain the order ? And there was never a “surprise” entry into the highest rated stereo list from the sample group ?
Excellent question!
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post #639 of 3815 Old 01-13-2019, 09:31 AM
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How did Dr. Amar Bose not make the white or black hat list? Good read, thanks for sharing.
Ah ha!

He discovered in his ABX testing that paper cones are good enough as long as their behaviour is well studied and controlled by an elaborate dynamic electronic EQ tightly coupled to them.

That makes him hated by both the White & Black hats alike, I guess.
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post #640 of 3815 Old 01-13-2019, 09:34 AM
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Originally Posted by chikoo View Post
Wilson Audio’s take on a speakers linear frequency response vs its ability to play a dynamic range, and its actual performance in a listners home. This is what I have been talking about.

Skip to 3:35

https://youtu.be/CBwSA0lcM-U
Looks to be a very nice speaker. The video introduced some new terms for speakers: "Harmonic Expression", "Dynamic Contrast", and deeper "Settling".
Will those be appearing in AES soon?


- Rich
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post #641 of 3815 Old 01-13-2019, 10:15 AM
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Originally Posted by Hifisound View Post
Dr. @Floyd Toole

Related to comparisons done in mono, you mentioned that highest rated loudspeakers in mono have always been highest rated loudspeakers in stereo (over multiple tests done) . I assume yes but just to confirm, did they also retain the order ? And there was never a “surprise” entry into the highest rated stereo list from the sample group ?
Ah yes, mono vs. stereo. I address this in some detail in Section 7.4.2 in my book and in the original JAES papers:
Toole, F. E. (1985). “Subjective measurements of loudspeaker sound quality and listener preferences”, J. Audio Eng. Soc., 33. pp. 2-31.
Toole, F. E. (1986). “Loudspeaker measurements and their relationship to listener preferences”, J. Audio Eng. Soc., 34, pt.1, pp. 227-235, pt. 2, pp. 323-348.
The interest was in the effect of loudspeaker directivity; all test loudspeakers had comparably good on-axis performance (normally an essential starting point), but differed significantly in off-axis performance. The answer to your question is that "it depends on the recording". The rendering of direction and spaciousness are major contributors to our impressions of sound quality and these factors are substantially determined by the recordings - how they were miked and mixed. These factors determine the amount of inter-channel uncorrelated information which in turn determines most of the sense of space, or envelopment.

The short answer, summarized in Figure7.14 is that monophonic tests yielded the strongest opinions and the clearest differentiation among test loudspeakers. Ratings and rankings in stereo were so influenced by spatial cues in the recordings that listeners ended up having essentially no opinion, averaged across all types of recordings. However, when ratings were separated according to music type, each type yielded different results, but the statistical scatter was so great that they generated little confidence. Except for popular music. That result was almost identical to the monophonic results. Why? Because such recordings are substantially mono: mono left (hard panned), mono right (hard panned) and double-mono for all amplitude panned phantom images between the speakers, including the featured artist. Most pop music and jazz has much less uncorrelated information (between left and right channels) than the classical repertoire where hall sound is strong.

So, the decision to employ monophonic listening tests was not a goal, but a result of exploring the options. When blind listening in mono, it is often noted that the highest rated loudspeakers "disappear" behind the screen - they do not draw attention to themselves.

Over the years a number of mono vs. stereo tests have been done, mostly to satisfy skeptics that mono tests don't overlook important sound quality factors. All have yielded the same rankings, but the statistical confidence is much higher in mono. Looking back, it is clear that the best of today's loudspeakers are much better than those in the original test (e.g. Figure 12.1) so it is essential to maximize the ability of listeners to discern small differences; hence the basic reliance on mono tests.
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post #642 of 3815 Old 01-13-2019, 10:19 AM
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Quote:
Originally Posted by chikoo View Post
Wilson Audio’s take on a speakers linear frequency response vs its ability to play a dynamic range, and its actual performance in a listners home. This is what I have been talking about, and am glad this has been responded to in this thread. Great learnings!

Skip to 3:35

https://youtu.be/CBwSA0lcM-U
My favorite line: "It silently kisses the top of the midrange driver and blends flawlessly."

Thanks for posting. What a hoot!
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post #643 of 3815 Old 01-13-2019, 10:24 AM
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Originally Posted by RichB View Post
Looks to be a very nice speaker. The video introduced some new terms for speakers: "Harmonic Expression", "Dynamic Contrast", and deeper "Settling".
Will those be appearing in AES soon?


- Rich


This. My first thought was, lots of words thrown around that I don't know what they mean. I wonder if they have actual meaning. Maybe they make a difference but it would be great to see a research paper that tested that.
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post #644 of 3815 Old 01-13-2019, 10:34 AM
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This. My first thought was, lots of words thrown around that I don't know what they mean. I wonder if they have actual meaning. Maybe they make a difference but it would be great to see a research paper that tested that.
We could create a new research category: "audio poetry".

It would likely have a high similarity to "wine poetry", for those of you who dip into wine reviews. For my part, I have found very low correlation with my own likes and dislikes. Who really knows what "forest floor" smells or tastes like?
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post #645 of 3815 Old 01-13-2019, 11:11 AM
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Originally Posted by audioguy View Post
Wasn't that a favorite expression of Peter Aczel, editor of the Audio Critic? He use to refer to Black Hats and White Hats in the audio industry and Dr. Toole was considered a "White Hat". You can see the article HERE and who he considered to wear which hats. Some of the Black Hats are obvious but some not so much. An interesting read.

Love him or hate him, he was not the friend of the subjective nonsense we have to read today in Stereophile or TAS.
I remember Peter Aczel well. We had a lot in common. I had a look back at the issue with a cartoon of me on the cover - drawn I think by Peter's son. I don't have a hat on

http://www.biline.ca/audio_critic/ma...ritic_28_r.pdf
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post #646 of 3815 Old 01-13-2019, 11:50 AM
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Originally Posted by Floyd Toole View Post
We could create a new research category: "audio poetry".

It would likely have a high similarity to "wine poetry", for those of you who dip into wine reviews. For my part, I have found very low correlation with my own likes and dislikes. Who really knows what "forest floor" smells or tastes like?
Nothing like "buttery flavor" and "hints of cedar"....
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post #647 of 3815 Old 01-13-2019, 11:56 AM
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Originally Posted by Floyd Toole View Post
Ah yes, mono vs. stereo. I address this in some detail in Section 7.4.2 in my book and in the original JAES papers:
Toole, F. E. (1985). “Subjective measurements of loudspeaker sound quality and listener preferences”, J. Audio Eng. Soc., 33. pp. 2-31.
Toole, F. E. (1986). “Loudspeaker measurements and their relationship to listener preferences”, J. Audio Eng. Soc., 34, pt.1, pp. 227-235, pt. 2, pp. 323-348.
The interest was in the effect of loudspeaker directivity; all test loudspeakers had comparably good on-axis performance (normally an essential starting point), but differed significantly in off-axis performance. The answer to your question is that "it depends on the recording". The rendering of direction and spaciousness are major contributors to our impressions of sound quality and these factors are substantially determined by the recordings - how they were miked and mixed. These factors determine the amount of inter-channel uncorrelated information which in turn determines most of the sense of space, or envelopment.

The short answer, summarized in Figure7.14 is that monophonic tests yielded the strongest opinions and the clearest differentiation among test loudspeakers. Ratings and rankings in stereo were so influenced by spatial cues in the recordings that listeners ended up having essentially no opinion, averaged across all types of recordings. However, when ratings were separated according to music type, each type yielded different results, but the statistical scatter was so great that they generated little confidence. Except for popular music. That result was almost identical to the monophonic results. Why? Because such recordings are substantially mono: mono left (hard panned), mono right (hard panned) and double-mono for all amplitude panned phantom images between the speakers, including the featured artist. Most pop music and jazz has much less uncorrelated information (between left and right channels) than the classical repertoire where hall sound is strong.

So, the decision to employ monophonic listening tests was not a goal, but a result of exploring the options. When blind listening in mono, it is often noted that the highest rated loudspeakers "disappear" behind the screen - they do not draw attention to themselves.

Over the years a number of mono vs. stereo tests have been done, mostly to satisfy skeptics that mono tests don't overlook important sound quality factors. All have yielded the same rankings, but the statistical confidence is much higher in mono. Looking back, it is clear that the best of today's loudspeakers are much better than those in the original test (e.g. Figure 12.1) so it is essential to maximize the ability of listeners to discern small differences; hence the basic reliance on mono tests.
Interesting ! Assuming that classical recordings ( and similar realistic stereo recordings ) would still be varied in the way they are miked/mixed, in normal everyday stereo , better off axis behavior (as per mono) won’t necessarily translate to better reproduction ? The differences would be glaring in mono, but we wouldn’t be listening that way in normal use.
( let alone multi channel setups )

Unless I misunderstood....
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post #648 of 3815 Old 01-13-2019, 12:15 PM
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Quote:
Originally Posted by Floyd Toole View Post
Ah yes, mono vs. stereo. I address this in some detail in Section 7.4.2 in my book and in the original JAES papers:

Toole, F. E. (1985). “Subjective measurements of loudspeaker sound quality and listener preferences”, J. Audio Eng. Soc., 33. pp. 2-31.

Toole, F. E. (1986). “Loudspeaker measurements and their relationship to listener preferences”, J. Audio Eng. Soc., 34, pt.1, pp. 227-235, pt. 2, pp. 323-348.

The interest was in the effect of loudspeaker directivity; all test loudspeakers had comparably good on-axis performance (normally an essential starting point), but differed significantly in off-axis performance. The answer to your question is that "it depends on the recording". The rendering of direction and spaciousness are major contributors to our impressions of sound quality and these factors are substantially determined by the recordings - how they were miked and mixed. These factors determine the amount of inter-channel uncorrelated information which in turn determines most of the sense of space, or envelopment.



The short answer, summarized in Figure7.14 is that monophonic tests yielded the strongest opinions and the clearest differentiation among test loudspeakers. Ratings and rankings in stereo were so influenced by spatial cues in the recordings that listeners ended up having essentially no opinion, averaged across all types of recordings. However, when ratings were separated according to music type, each type yielded different results, but the statistical scatter was so great that they generated little confidence. Except for popular music. That result was almost identical to the monophonic results. Why? Because such recordings are substantially mono: mono left (hard panned), mono right (hard panned) and double-mono for all amplitude panned phantom images between the speakers, including the featured artist. Most pop music and jazz has much less uncorrelated information (between left and right channels) than the classical repertoire where hall sound is strong.



So, the decision to employ monophonic listening tests was not a goal, but a result of exploring the options. When blind listening in mono, it is often noted that the highest rated loudspeakers "disappear" behind the screen - they do not draw attention to themselves.



Over the years a number of mono vs. stereo tests have been done, mostly to satisfy skeptics that mono tests don't overlook important sound quality factors. All have yielded the same rankings, but the statistical confidence is much higher in mono. Looking back, it is clear that the best of today's loudspeakers are much better than those in the original test (e.g. Figure 12.1) so it is essential to maximize the ability of listeners to discern small differences; hence the basic reliance on mono tests.


Fascinating.

So, what is the best way to push a signal through that test system? Are mono recordings used or is stereo downmixed to mono? Or a combination?


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post #649 of 3815 Old 01-13-2019, 12:29 PM
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I believe the case being made by Dr. Toole was with regards to -width- of dispersion, not -linearity- of it.
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post #650 of 3815 Old 01-13-2019, 12:30 PM
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Toole Talk

Here's a very illuminating lecture given by Dr. Toole that comments on many of the topics being discussed here, including charts & graphs and provides a fairly concise summary of of the audio theories he has developed over the years.
http://www.youtube.com/watch?time_co...&v=zrpUDuUtxPM

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post #651 of 3815 Old 01-13-2019, 12:57 PM
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Originally Posted by Floyd Toole View Post
Who really knows what "forest floor" smells or tastes like?
For what I can tell, it must mean the smell of dirt and manure. Not sure about the taste part...,,

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post #652 of 3815 Old 01-13-2019, 01:26 PM
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Perhaps also of interest to some of the people here, the white paper on the new KEF R series - showing (semi/modified?) spinorama sets for each of the models. It seems they did not measure the rear of the loudspeakers, so the early reflections and sound power averages are incomplete (hence the 'front hemisphere' reference). There appears however to be enough data to see that the models behave well in terms of linearity of dispersion.

http://us.kef.com/media/doc/r2018_whitepaper_en.pdf
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post #653 of 3815 Old 01-13-2019, 02:33 PM
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Originally Posted by TimVG View Post
Perhaps also of interest to some of the people here, the white paper on the new KEF R series - showing (semi/modified?) spinorama sets for each of the models. It seems they did not measure the rear of the loudspeakers, so the early reflections and sound power averages are incomplete (hence the 'front hemisphere' reference). There appears however to be enough data to see that the models behave well in terms of linearity of dispersion.

http://us.kef.com/media/doc/r2018_whitepaper_en.pdf
Yes, they appear to have backed away from showing a full spinorama, as they did in section 4.1.5, figure 12 in:
http://www.kef.com/uploads/files/THE...ath_200514.pdf

It does make the directivity look better. Still there is enough information to get a preview of sound quality potential. That is so-o-o-o much better than most loudspeaker specs.
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post #654 of 3815 Old 01-13-2019, 02:52 PM
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Originally Posted by DS-21 View Post
...dismissive comments about concentrics due to IM distortion...
As I think you or somebody said later, there must be IM, but how serious is it? But the tweeter in a moving cone should also induce modulation of the frequency response itself which is a different problem. I never had a chance to try and measure that on a driver where the excursion was significant-did that ever happen at Harman or anywhere else? How much does the cone moving back and forth actually change the loading on the tweeter and thus the response?
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post #655 of 3815 Old 01-13-2019, 03:06 PM
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How did Dr. Amar Bose not make the white or black hat list? ...
If not prior to the following quote from Dr. Bose in 2007, certainly reason number 1 alone would have qualified him for placement on any update of the earlier black hat list:

Quote:
I decided on a philosophy at the time. We would cut out specifications because of two reasons. We decided to make each product that came out superior to what was out at the time. If it was superior, the public would appreciate it. That’s why we don’t give any measurements on any product today.

There are two reasons we cut out the specifications:

1) We don’t know of any measurements that actually determine anything about a product, and 2) Measurements are phony, in general, as they are printed.
techcrunch.com/2007/09/19/dr-bose-tells-all-company-sercrets-why-they-dont-publish-specs-and-more/
SDX-LV and unretarded like this.
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post #656 of 3815 Old 01-13-2019, 03:06 PM
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I remember Peter Aczel well. We had a lot in common. I had a look back at the issue with a cartoon of me on the cover - drawn I think by Peter's son. I don't have a hat on

http://www.biline.ca/audio_critic/ma...ritic_28_r.pdf
For me, The Audio Critic was required reading in the late 70's early 80's.
I know he alienated the tube adherents.

Reading TAS was too exhausting, trying to decipher the cliches the writers made up.
Stereo Review gear reviews had a boring, predictable sameness but excellent music reviews.

Always liked J. Gordon Holt.
Back in like 2000(?), I read his take on 5.1 surround music and how it was the future of audio.
I totally poo-poo'd it until I heard a mediocre 5.1 system shortly thereafter and was convinced.
I should've known better.

IME, the best favor an audiophile can do for themselves is to be open minded, listen for yourself, don't be a fool or a slave to any single dogma & measurements matter.
I try to take my own advice.

 
This isn't Nam Smokey, there are rules here!

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post #657 of 3815 Old 01-13-2019, 03:54 PM
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Quote:
Originally Posted by Floyd Toole View Post
I remember Peter Aczel well. We had a lot in common. I had a look back at the issue with a cartoon of me on the cover - drawn I think by Peter's son. I don't have a hat on

http://www.biline.ca/audio_critic/ma...ritic_28_r.pdf
Excellent read!

"Urban Legend:
1. Fancy parts improve sound (ca-
pacitor dielectric, DACs, etc.).
2. Fast bass (small woofers are more
linear than big ones).
3. Rhythm and pace (a playback
component can change tempo).
4. Low bass is impossible in a small
room.
5. Fancy cables improve sound
quality.
6. Non-audio tweaks improve
sound (change placed on the
speaker, tiptoes, green ink, at al.).
7. DVD players sound inferior to
CD players.
8. LP sounds better than CD.
9. Data reduction always lowers
sound quality.
10. Small amplifiers burn out
tweeters.
11. Equalization is bad.
12. Negative feedback is bad.
13. Short signal paths are good.
14. Multichannel is a step backward.
15. Auto sound is bad.
16. Film sound is bad."
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post #658 of 3815 Old 01-13-2019, 03:55 PM
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Originally Posted by Hifisound View Post
Interesting ! Assuming that classical recordings ( and similar realistic stereo recordings ) would still be varied in the way they are miked/mixed, in normal everyday stereo , better off axis behavior (as per mono) won’t necessarily translate to better reproduction ? The differences would be glaring in mono, but we wouldn’t be listening that way in normal use.
( let alone multi channel setups )

Unless I misunderstood....
This is really the topic of Chapter 7 in the book. In general listeners prefer some amount of laterally reflected sound, and the more that sound resembles the direct sound in timbre, the better it sounds. Raw stereo is, as I keep on saying, a directionally and spatially deprived format, so some room reflections are almost always preferred, just as a tasteful multichannel up mix can be a useful enhancement.
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post #659 of 3815 Old 01-13-2019, 04:00 PM
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Quote:
Originally Posted by Floyd Toole View Post
Yes, they appear to have backed away from showing a full spinorama, as they did in section 4.1.5, figure 12 in:
http://www.kef.com/uploads/files/THE...ath_200514.pdf

It does make the directivity look better. Still there is enough information to get a preview of sound quality potential. That is so-o-o-o much better than most loudspeaker specs.
It's also a prime example of taking the research Harman has done and embracing it to design the best speakers they can, as opposed to denying the science as many posters in this thread have done.
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post #660 of 3815 Old 01-13-2019, 04:05 PM
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This is still my favorite tweak, and no one will ever convince me it isn’t working...

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