Why don't all speaker manufacturers design for flat on-axis and smooth off-axis?

[Juhazi]

Well, dipoles are often very poor in consistency of radiation pattern. Panels like Quad, ML, Soundlab etc. all have different patterns. Many multiway dipoles with dynamic drivers aren't actually dipole at all above 2kHz. And we don't even have measurements of backside radiation for most of them publicly available. Positioning may be very tricky.

Typical monopole speakers radiate very little energy backwards - above baffle step knee. Narrow baffles have this knee at a bit higher freq. The front wall (behind the speaker) makes cancellation typically around 300-600Hz depending on distance and below it bass gets boosted because of summation. Biggest problem for sound coloration and poor imaging are sidewall reflections, if speakers are too close to sidewalls - which happens very very often. In this scenario high directivity above 1kHz helps like Geddes has documented by research.

Here is KEF LS50 representing a typical naffow baffle speaker, horizontal disperion by Princeton 3D3a

If sidewalls are far away, listening window-directivity differencies loose importance and overall power response smoothness has higher role.

 

[amirm]

The point you make, that one risks testing for a specific test procedure rather than general speaker qualities, is as good as it’s an obvious one. Another point, made by @oivavoi recently, that findings from just one research group, would stand stronger if they were supported by other research groups, is also a good one.

One read of any research paper from Dr. Toole or Olive shows countless references from other researchers backing the same conclusions. There are some 270+ references in Dr. Toole's book for example. I have read countless ones of those before I formed my opinion of this research. Alas that work is beyond the reach of many audiophiles so the accusation is made that this is some sole research source. It is not. Yes, it is by far the highest quality version of such research given the extensive resources applied to it. But not the only one in this direction.

 

[Krunok]

If sidewalls are far away, listening window-directivity differencies loose importance and overall power response smoothness has higher role.

Sure.. I'm willing to bet that in average room sidewalls and back wall are really far away - app 0.5-1.0m far away.

 

[amirm]

Never became a negative to me in 12 years or so I owned them. I didn't find them to homogenize music either.

And that is how I was until I attended the Harman blind test. It instantly sensitized me to this issue. Now I notice it in every demo I listen to.

BTW, the Quad was tested in the AES paper I quoted earlier. Here is what the bypass test showed with them:

These speakers have serious resonances and other problems that are ignored when one falls in love with their diffused sound.

 

[Krunok]

Never became a negative to me in 12 years or so I owned them. I didn't find them to homogenize music either.

Among non-audiophiles speakers that play loud cleaner than they have usually heard and with real solid deep bass (not loose marshmellow wallowing bass) impresses them. And Quads impressed them. The Quads were cool looking and different, but it was the sound that drew non-audiophile's attention to them in the first place. Comments like, "it just sounds so real", or "it's like the music is here, you don't hear a stereo box". People would come in for other reasons and get transfixed sometimes when they weren't even there to listen to music.

One could attribute that to many things. I think it was lack of a box, and the quasi-point source nature of it.

There you go, you and your Quads..

 

[Purité Audio]

I am sure they were pretty special in 1957.
Grimm’s design white paper,
https://www.grimmaudio.com/wordpress/wp-content/uploads/speakers.pdf
Keith

 

[Juhazi]

And that is how I was until I attended the Harman blind test. It instantly sensitized me to this issue. Now I notice it in every demo I listen to.

BTW, the Quad was tested in the AES paper I quoted earlier. Here is what the bypass test showed with them:

View attachment 29638

These speakers have serious resonances and other problems that are ignored when one falls in love with their diffused sound.

Wrong conclusion! ESL and many other speakers like B&W show very strange and uneven directivity etc. problems on-axis or in listening window, but compensate those in a typical room with reflections. They are designed that way, by listening tests more than just measuring. This however makes positioning critical and with modern understanding and skill manufacturers can do better, like eg. MartinLogan has improved it's panels.

This ML Montis measures pretty well both on-axis and in a room - here room response by Stereophile. other measurements and review here
https://www.stereophile.com/content/martinlogan-montis-loudspeaker-measurements

 

[amirm]

Wrong conclusion! ESL and many other speakers like B&W show very strange and uneven directivity etc. problems on-axis or in listening window, but compensate those in a typical room with reflections.

B&W? How do you fix the directivity caused dip in the mid-range for B&W in room? Build a full padded cell with absorbers?

 

[MSNWatch]

Audiophiles are always expecting surprises. But is it not the case that a speaker's Spin-o-Rama characteristics are already fundamentally set by what drivers it uses and the dimensions of the box they're put in? A slim floorstander based on a 5" woofer and a 1" tweeter cannot deviate very far from a defined characteristic, and all the designer can do to change that is to make a mess of it. The most expensive 5"/1" slim floorstander in the world will measure - and sound - very similar to the cheapest if they're both designed sensibly. And that sound will not be good:


Which seems to be why the Grimm people, for example, created a different speaker; not slapping something together and then measuring it, hoping for a miracle, but predicting in advance the simple (for them) characteristics of driver beaming and baffle step and creating the nice response they desired before starting to build anything. And then using DSP to make everything clean and neutral.

I own this pair among others and they sound pretty good to me. And they are slim at 6.75 inches wide.

https://www.soundandvision.com/cont...st-supertower-speaker-system-ht-labs-measures

 

[amirm]

Wrong conclusion! ESL and many other speakers like B&W show very strange and uneven directivity etc. problems on-axis or in listening window, but compensate those in a typical room with reflections. They are designed that way, by listening tests more than just measuring.

What listening tests? Where they controlled and blind? Or did they let the listener fall in love with the look of that B&W tweeter?

 

[MattHooper]

- the Grimm paper talks about the "ghostly brass section" and recorded audio as an "ill-posed problem".

Yes, I read that part of the Grimm paper with some puzzlement. It says of an omni speaker: "The sound stage may be quite con-vincing but the brass section sounds ghostly, as if it’s pointing in all directions. Well, it is. Not in the re-cording, but during replay. "

I'm not sure exactly what they are talking about there.

I have MBL omnis and there is nothing particularly odd-sounding about brass sections. In fact, they can sound disconcertingly life-like from the seated position. One of my favourite demos using those speakers centers specifically on some brass section-heavy pieces, for the realism of the sound of those brass sections. And they don't sound at all like they are "pointed in all directions" but pointed at the listener, as with any of my other non-omni speakers.

Perhaps they are referencing the idea that if you are walking around the omnis, the instruments (and soundstage to a degree) track you, sort of still pointing your way. Well...sure. But presumably what we care about is the way we tend to listen to speakers, and the Grimms are designed also to sound best from the usual listening position, in front of the speakers.

(As for out-of-seat listening, the omnis do the "sounds live from outside the room" better than any more direct radiating speaker I've owned).

 

[svart-hvitt]

One read of any research paper from Dr. Toole or Olive shows countless references from other researchers backing the same conclusions. There are some 270+ references in Dr. Toole's book for example. I have read countless ones of those before I formed my opinion of this research. Alas that work is beyond the reach of many audiophiles so the accusation is made that this is some sole research source. It is not. Yes, it is by far the highest quality version of such research given the extensive resources applied to it. But not the only one in this direction.

@amirm , I am not saying that kind of research is faulty. However, in many cases that research is called «HK» or «Toole» research, and in that process one often forgets the nuances and the breadth, idolising one camp in the same process.

Idolising is not a good thing. It makes you less curious and critical. One example:

@Floyd Toole calls room correction an «enticing marketing story». Olive’s paper on the same issue showed that room correction software could be of benefit. For some reason, many on ASR fail to see this inconsistency, maybe out of fear of questioning their idols?

I think it’s strange that Harman/Samsung affiliated researchers on the one hand dismiss room correction, while their only paper on this issue say room correction may be beneficial. And why have Harman/Samsung affiliated researchers not spent more resources on this theme in the many years after Olive found that room correction could be beneficial?

In another line of Harman/Samsung research, the same researchers use preference based tests to draw a «most preferred» frequency curve for headphones, which resembles what room correction software designers do when they make a «target curve». In defining this «most preferred» frequency curve, the Harman/Samsung researchers bypass the fact that every individual has his or her own unique HRTF, a bypass process which resembles, again, what room correction software does when it makes a target curve for every room.

Again, I am not saying that a particular group of researchers delivered faulty research. I am simply surprised that so many on ASR put so much weight on what one research group says - despite examples of lack of logic in that research - instead of keeping a more open mind and a willingness to read other researchers’ findings.

 

[svart-hvitt]

Yes, I read that part of the Grimm paper with some puzzlement. It says of an omni speaker: "The sound stage may be quite con-vincing but the brass section sounds ghostly, as if it’s pointing in all directions. Well, it is. Not in the re-cording, but during replay. "

I'm not sure exactly what they are talking about there.

I have MBL omnis and there is nothing particularly odd-sounding about brass sections. In fact, they can sound disconcertingly life-like from the seated position. One of my favourite demos using those speakers centers specifically on some brass section-heavy pieces, for the realism of the sound of those brass sections. And they don't sound at all like they are "pointed in all directions" but pointed at the listener, as with any of my other non-omni speakers.

Perhaps they are referencing the idea that if you are walking around the omnis, the instruments (and soundstage to a degree) track you, sort of still pointing your way. Well...sure. But presumably what we care about is the way we tend to listen to speakers, and the Grimms are designed also to sound best from the usual listening position, in front of the speakers.

(As for out-of-seat listening, the omnis do the "sounds live from outside the room" better than any more direct radiating speaker I've owned).

I am not so sure I would take everything Grimm researchers say about audio without a pinch of salt. Here’s how the Grimm researchers talk about their new digital audio player:

https://www.grimmaudio.com/blogs/the-mu1-speeches/

Does what Grimm researchers say about their digital audio player make sense in 2019? When they use such a flowery language on a €10k digital audio player, what should one expect when they write white papers in other areas?

 

[edechamps]

@Floyd Toole calls room correction an «enticing marketing story». Olive’s paper on the same issue showed that room correction software could be of benefit. For some reason, many on ASR fail to see this inconsistency, maybe out of fear of questioning their idols?

I think it’s strange that Harman/Samsung affiliated researchers on the one hand dismiss room correction, while their only paper on this issue say room correction may be beneficial. And why have Harman/Samsung affiliated researchers not spent more resources on this theme in the many years after Olive found that room correction could be beneficial?

My understanding is that both @Floyd Toole and Olive, like many others, fully acknowledge that room correction is beneficial at low frequencies, to eliminate room modes at a single listening position. This is quite uncontroversial and Toole describes such techniques in his book. As far as I know, both of them are much more sceptical of the benefit of room correction products at higher frequencies, especially if the loudspeaker is already good. I don't think there's much inconsistency there. They might disagree slightly on a matter of degree, I don't know.

In another line of Harman/Samsung research, the same researchers use preference based tests to draw a «most preferred» frequency curve for headphones, which resembles what room correction software designers do when they make a «target curve». In defining this «most preferred» frequency curve, the Harman/Samsung researchers bypass the fact that every individual has his or her own unique HRTF, a bypass process which resembles, again, what room correction software does when it makes a target curve for every room.

The most preferred curve is meant to represent the average listener. Obviously, when it comes to headphones, listener variations are inevitable because of their individual HRTFs. Olive never claimed this curve was universal. In fact, he even wrote a whole paper describing the differences in preferred curves depending on listener demographics. Another paper he wrote acknowledges significant inter-listener variation in the preferred response of in-ear headphones.

Again, I am not saying that a particular group of researchers delivered faulty research. I am simply surprised that so many on ASR put so much weight on what one research group says - despite examples of lack of logic in that research - instead of keeping a more open mind and a willingness to read other researchers’ findings.

The main problem is that there is little published research that is as relevant, detailed and thorough as Toole & Olive when it comes to consumer audio reproduction. If you can provide examples of "other researchers' findings" from studies that are as rigorously conducted and yet contradict Toole/Olive, I would love to hear about them. (I'm very serious, by the way. I'm as concerned as you are about the lack of knowledge base diversity.)

 

[amirm]

I think it’s strange that Harman/Samsung affiliated researchers on the one hand dismiss room correction, while their only paper on this issue say room correction may be beneficial.

This is a myth created by people who go by sound bytes rather than reading the full texts. THe statement against room EQ is in regards to attempting to fix directivity problems with a speaker. This is something that cannot be done since any electric manipulation impacts both direct and indirect sound. No such position is taken at all against usefulness of EQ.

Everyone at Harman including Dr. Toole are completely in favor of EQ for fixing room modes. This is so without exception.

 

[amirm]

Idolising is not a good thing. It makes you less curious and critical. One example:

I have not idolized any one individual. I have praised the research that goes miles and miles beyond anything that the rest of the industry has done combined. Credit is of course given where it is due. But no one has made any appeal to authority here. In every argument research data is provided to stand as proof, not someone's opinion.

In reverse, you keep displaying this irrational allergy to this work in post after post. That is not data. Put forward contrary research and we can examine that. Without it, constantly objective is of no value and actually does damage to people who want to get through these topics and have to sort through these emotional posts.

 

[amirm]

In another line of Harman/Samsung research, the same researchers use preference based tests to draw a «most preferred» frequency curve for headphones, which resembles what room correction software designers do when they make a «target curve». In defining this «most preferred» frequency curve, the Harman/Samsung researchers bypass the fact that every individual has his or her own unique HRTF, a bypass process which resembles, again, what room correction software does when it makes a target curve for every room.

This is completely false. I have explained it in other threads but seemingly you don't pay any attention so why repeat.

Bottom line is this: the cornerstone of the research is controlled listening tests. People vote with their ears and then researchers attempt to correlate measurements with this data. Nothing is gamed in controlled testing. And no better data is put forward by anyone else saying differently.

 

[March Audio]

This is a myth created by people who go by sound bytes rather than reading the full texts. THe statement against room EQ is in regards to attempting to fix directivity problems with a speaker. This is something that cannot be done since any electric manipulation impacts both direct and indirect sound. No such position is taken at all against usefulness of EQ.

Everyone at Harman including Dr. Toole are completely in favor of EQ for fixing room modes. This is so without exception.

Indeed, the position AFAIK is that minimum phase issues can be addressed, non mp cannot.

 

[svart-hvitt]

My understanding is that both @Floyd Toole and Olive, like many others, fully acknowledge that room correction is beneficial at low frequencies, to eliminate room modes at a single listening position. This is quite uncontroversial and Toole describes such techniques in his book. As far as I know, both of them are much more sceptical of the benefit of room correction products at higher frequencies, especially if the loudspeaker is already good. I don't think there's much inconsistency there. They might disagree slightly on a matter of degree, I don't know.



The most preferred curve is meant to represent the average listener. Obviously, when it comes to headphones, listener variations are inevitable because of their individual HRTFs. Olive never claimed this curve was universal. In fact, he even wrote a whole paper describing the differences in preferred curves depending on listener demographics. Another paper he wrote acknowledges significant inter-listener variation in the preferred response of in-ear headphones.



The main problem is that there is little published research that is as relevant, detailed and thorough as Toole & Olive when it comes to consumer audio reproduction. If you can provide examples of "other researchers' findings" from studies that are as rigorously conducted and yet contradict Toole/Olive, I would love to hear about them. (I'm very serious, by the way. I'm as concerned as you are about the lack of knowledge base diversity.)

Thanks for good reply. My point is not to win arguments, just to raise issues that strike my mind.

On the one hand, people say that Floyd (and) Olive cannot be understood as one entity, that their research is mirrored, supported and reproduced (?) by other researchers (cfr. @amirm ’s point that Toole’s book has so many references). On the other hand, in other instances, the persons Floyd and Toole are used as aurhorities as if the research was their work alone. My point is: Maybe we should be clearer to distinguish between Mr X says and «science says» or «research shows». Do you see my point?

Olives room correction paper didn’t specify if the benefits of room EQ came from bass or higher frequency corrections. So one can only speculate what drove the results in favour of room EQ.

In my line of work I must alway ask who benefits? And I cannot but think about the fact that room EQ is a hassle for someone who wants to optimise logistics when pushing boxes to end customer. And a box pusher doesn’t want to talk too much about unique HRTFs too from a logistics point. So I could make a case that Harman/Samsung got the research that their funding wanted all the time. In the meantime, proponents of room EQ are ridiculed and those who talk about unique HRTFs are told they don’t get the point.

Don’t you find it curious that @Floyd Toole on the one hand ridicules room EQ while his research group stopped researching/publishing room EQ research after their one article from over a decade ago on the subject leaves the room open for room EQ?

As you say, the finer print of Olive’s research is more nuanced (in the headphones case), but the debate on ASR is not as nuanced, is it?

After I opened a thread on other factors than frequency response on perceived sound quality (I chose the punch factor for exploring), I was met with ridicule by some ASR members. My point being: Are we fully aware of lifting certain researchers to guru status, in the process reducing sound quality to frequency response, frequency response and frequency response.

And may I add: This is not a critique against @Floyd Toole , Olive and Harman/Samsung for promoting their research. @Floyd Toole is AES’s most merited member. I am talking here about their followers that do the idolising which means curiosity and an open mind may get lost. To me, curiosity and open mindedness are big drivers of fun too

 

[RayDunzl]

Superior and socially-acceptable wide dispersion JBL LSR 308 vs inferior MartinLogan hybrid only suitable for hermits and other deplorables as measured at the listening position in my room without averaging and with spawn of satan flat equaliztion applied to both: