A Broad Discussion of Speakers with Major Audio Luminaries

[Floyd Toole]

I've heard hundreds of examples of the BBC LS3/5a. In a heavily acoustically treated control rooms. In these circumstances they were good and sometimes astonishingly good on voice reproduction.

In those treated control rooms you were listening mainly to direct sound - on axis response - and to a sound source, voice, that because of its limited spectrum and spectral density is not the best at revealing loudspeaker problems - see Figure 10.13 in the 4th edition. That said, the real problem for the consuming world was quality control. In our Canadian Broadcast Corporation monitor loudspeaker evaluations the LS5/8 did not do well because of its poor off-axis performance, which violated the BBC performance target. Sad.

You are right about there being some very fine minds in the BBC Research department in its prime. However, as I understood Harwood, it was progressive budget cuts that eventually forced an end to real research. I was fortunate to come along at that time and benefit from their work.

 

[PristineSound]

Dr. Toole,

I have so many questions. But something less technical and more fun.

1) I know you and Dr. Olive still do consulting in your retirement and are still very actively engaged in the field. But who do you think are the next generation of "new blood" in the field of acoustics and psychoacoustics?

2) When you started your career at the NRCC, have you ever thought that your work would lead you to Harman and ultimately impact an entire industry and shape it the way it has?

3) What is it that you enjoy the most and least as a researcher?

4) Do you see the future to be more multi-channel audio or do you see stereo audio to continue to be prevalence for music?

5) If you weren't a psychoacoustician (if that is even a word) what would you have chosen as a career?

Thank you for your time

 

[Newman]

Maybe Dr. Toole should consider writing a simplified book aimed at the general audience.

I think the '101' reader would be well served by looking at the contents section, ignoring topics that don't interest, and for those that do, read the first paragraph and the summary at the end. Floyd's book is well structured to reward such a reading.

Cheers

 

[Duke]

the first audience needing persuasion that science exists and is potentially useful are those designing loudspeakers. If that audience is convinced the result will be what we are beginning to see: increasing numbers of basically neutral loudspeakers.

Yes! The very first thing I look at when mulling over a speaker design is, what will the radiation pattern look like, particularly in the crossover region(s)?

Not only does what's happening off-axis matter a great deal at normal listening distances in any reverberant or semi-reverberant environment, but it is effectively impossible to fix the radiation pattern later on in the design process. So that's something the designer has to get right from the start. EQ can mitigate resonances and improve the frequency response to some extent later on, but it cannot fix a poor radiation pattern.

Ime the earliest decisions made in the design process tend to be the most far-reaching, especially regarding what the radiation pattern will be.

 

[mpw]

Would the recording industry be better served if they had these 'neutral monitors as there only speakers for the producers and the musicians listening to the 'mix of their recording sessions ?

It seems that recording studios have many monitors to listen to some more neutral then others. Maybe having monitors that are not totally neutral give the session 'character/uniqueness along with a certain 'sound that the musicians desire ?!

So in the future all recording studio will use these Harnan netrual monitors for sessions and mix-down to the desired medium then the user buys the product plays it through their colored components into the neutral speakers. Would the user enjoy the music more in the above system or from a variety of BBC Ls3/5 speakers that to the user just sounded 'right ?! Is music more enjoyable with a totally neutral system or with some degree of coloration?

 

[jmckay]

Interesting stuff, back around oh about 1982 the NRC and now 2026, modern design was enough to disengage my interest. Not sure I can go along with the idea of resonance as a target for me. My best designed systems were all extraordinarily disappointing as soon as room measurements were made. Then there was the issues of cost. To this day, my phase coherent systems are what I keep. ( as much as I also partially disagree with the science ) honestly, I just don’t think the ultra precision designs make the difference. Quality cabinets, nice cast frame drivers, a good tweeter and a phase linear approach …… heck, maybe even some designer colouration ( just to mess things up a bit ) value, a pair of quality speakers shouldn’t cost more than 5K. The consumer deserves value. Add people in the room and move around …… your measurements will be all over the place. I think , for me, simplicity and value have been a life lesson. I am not at all surprised by the recent trend towards consumers selecting open baffle systems. When you go down the path of resonance it complicates things.

 

[Newman]

Would the recording industry be better served if they had these 'neutral monitors as there only speakers for the producers and the musicians listening to the 'mix of their recording sessions ?

Yes, that is the process or closing the Circle of Confusion, when the industry and consumer base both do so.

It seems that recording studios have many monitors to listen to some more neutral then others. Maybe having monitors that are not totally neutral give the session 'character/uniqueness along with a certain 'sound that the musicians desire ?!

True, but it also seems that there is a trend towards studios using neutral monitors. Dr Toole's work, and others, deserves some of the credit for the emergence of this trend.

So in the future all recording studio will use these Harnan netrual monitors for sessions and mix-down to the desired medium then the user buys the product plays it through their colored components into the neutral speakers. Would the user enjoy the music more in the above system or from a variety of BBC Ls3/5 speakers that to the user just sounded 'right ?! Is music more enjoyable with a totally neutral system or with some degree of coloration?

See my first point above.

The LS3/5a is pretty much irrelevant to this discussion: a historical footnote. That, of course, is despite some audiophile media and hobbyists persisting with the notion that it still represents some sort of pinnacle.

Despite your trepidation mentioned earlier, I still commend to you Dr Toole's book for purchase and perusal to whatever level you feel comfortable doing.

cheers

 

[RexrothPigeon]

it also seems that there is a trend towards studios using neutral monitors.

There very definitely is. Mastering rooms even moreso.

 

[MaxwellsEq]

In those treated control rooms you were listening mainly to direct sound - on axis response - and to a sound source, voice, that because of its limited spectrum and spectral density is not the best at revealing loudspeaker problems - see Figure 10.13 in the 4th edition. That said, the real problem for the consuming world was quality control. In our Canadian Broadcast Corporation monitor loudspeaker evaluations the LS5/8 did not do well because of its poor off-axis performance, which violated the BBC performance target. Sad.

You are right about there being some very fine minds in the BBC Research department in its prime. However, as I understood Harwood, it was progressive budget cuts that eventually forced an end to real research. I was fortunate to come along at that time and benefit from their work.

Thanks Dr Toole. I am in broad agreement. In the heavily treated control rooms that were home to most of the LS3/5a-s, LS3/7s , LS5/8s and LS5/9s I encountered, side wall reflection was greatly reduced and so off-axis (miss)behaviour was less critical. Like all budget-constrained environments, the designers worked to a specific use case: acoustically dead rooms where the room-width is normally greater than the room-depth (so side walls are a long way from the speaker) and where there is a large mixing desk between the listener and the speaker. They certainly were not designing for acoustically untreated spaces nor domestic use-cases!

They were also not treated as pairs - the underlying principle was an elderly faulty unit could be swapped with a more recent production unit without there being a change in frequency balance or central image location. Often a room might contain two speakers with a large gap between their serial numbers. The fact that you measured run-to-run variation would have been disturbing for the designers.

 

[Wesseling Audio Lab]

I have a pair of LS3/5A and performed some measurements. There was discussions about them on another forum

One older well respected British fellow had many details including what's in my attachment

 

[Wesseling Audio Lab]

A version of LS3/5A outside measurements and inside measurements with grilles on and off at 3 distances.

Subjectively - no bass(can't get past this fact) but had so called "magic"(drivers well integrated exposing recorded detail). There were worse speakers in the early 80's from my experience as far as what was being pushed from local retailers.

 

[Floyd Toole]

I have so many questions. But something less technical and more fun.

1) I know you and Dr. Olive still do consulting in your retirement and are still very actively engaged in the field. But who do you think are the next generation of "new blood" in the field of acoustics and psychoacoustics?

2) When you started your career at the NRCC, have you ever thought that your work would lead you to Harman and ultimately impact an entire industry and shape it the way it has?

3) What is it that you enjoy the most and least as a researcher?

4) Do you see the future to be more multi-channel audio or do you see stereo audio to continue to be prevalence for music?

5) If you weren't a psychoacoustician (if that is even a word) what would you have chosen as a career

1) I know you and Dr. Olive still do consulting in your retirement and are still very actively engaged in the field. But who do you think are the next generation of "new blood" in the field of acoustics and psychoacoustics? I no longer consult, unless you consider my contributions to ASR as such. Sean and Todd Welti both still consult. It is difficult to speculate on who will "follow" because these days money is limited and few researchers have access to the necessary facilities to do proper subjective/objective investigations. Universities are intellectually willing, but rarely have the equipment. Besides, it is my opinion that in terms of linear performance we have reached the point of diminishing returns and the meaningful measurements of non-linear distortions are still not widely used. The problem is that all the distortion products that are measured are not heard because of various forms of perceptual masking. There has been work, but I have not followed the subject closely of late.

2) When you started your career at the NRCC, have you ever thought that your work would lead you to Harman and ultimately impact an entire industry and shape it the way it has? Not at all, in fact as described in Chapter 1 my career has had a few significant turns before it settled down. I thought I was to be a transistor circuit designer after my BSc EE in Canada, but Imperial College in London prevented that when they refused my (already approved) entry into the post graduate program (the locals had filled the seats and "colonials" had to find something else to study). I was crestfallen, but decided that I would persevere - I was on an all-expense-paid scholarship. By pure luck I ran into Colin Cherry, inventor of the term "cocktail party effect" (binaural localization of multiple sources), and I ended up using my circuit design skills to create elaborate test signals to interrogate the binaural hearing system. That research, using headphones, was successful, three published papers before graduation, still referenced, and I was hired by the National Research Council of Canada to continue the research using their anechoic chamber to move the experiments closer to real rooms. For those experiments I needed technically accurate loudspeakers to deliver contrived sounds to the ears. I could not find an accurate loudspeaker among numerous highly rated HiFi products and conducted a "Friday afternoon experiment" in 1966 to see if they sounded as bad as the measurements looked. They did, but in the blind, equal-loudness, multiple-loudspeaker comparisons most listeners liked the same loudspeakers (where were the personal preferences that were supposed to exist?), and the one they like best had the flattest, smoothest on-axis frequency response (obviously measurements mattered). So, why did the other crummy ones exist? People even disliked their own loudspeakers proudly submitted to the tests, indicating that adaptation is part of our perceptual process - we learn to listen through problems in loudspeakers we live with, but instantly recognize superior sound in comparisons. Everyone was surprised. Here was a large international industry that needed basic scientific guidance, and a course change in my research was approved. More such testing simply confirmed the original observations, and the rest is history. Interpreting the right set of measurements is a more reliable method of identifying accurate, timbrally-neutral, loudspeakers than the normal modes of subjective evaluations that yield opinions biased by factors other than the sound.

3) What is it that you enjoy the most and least as a researcher? The satisfaction of adding to new knowledge and the disappointment of being wrong (from which one learns, of course - don't do it again).

4) Do you see the future to be more multi-channel audio or do you see stereo audio to continue to be prevalence for music? Placing several loudspeakers around a domestic listening space does nothing positive for the decor, so stereo wins even if it is demonstrably limited in its capabilities. A dedicated home theater or media room is a luxury few can afford. So stereo has become the default format, and now that much (most?) listening is done through headphones the channel count is a convenient match, and "spatial" upmixing/encoding adds interest if not accuracy.

5) If you weren't a psychoacoustician (if that is even a word) what would you have chosen as a career? It is a word, and I have contributed to the psychoacoustic knowledge base, but under it all I am the engineer that I set out to be. Engineers, and those like me who become research scientists, are motivated to identify and solve real world problems. In my case my formal education really taught me how to think critically, and learn what is necessary to solve problems. My books contain information I mainly learned after graduation. Working among some of the world's best acousticians at the National Research Council of Canada for 27 years was a remarkable opportunity to exchange information and to learn.

 

[Cote Dazur]

Most audible resonances in most loudspeakers originate in transducers.

Looking at the graphs in Amir speakers reviews where can we see those audible resonance originating from transducers?

 

[Floyd Toole]

Looking at the graphs in Amir speakers reviews where can we see those audible resonance originating from transducers?

I explain it in my books, on a few occasions in ASR forums, including this reference that allows you to download a PowerPoint slide show that summarizes the core story of the books and explains how to interpret spinoramas from Amir or any other trusted source. Even this summary contains a lot of information, requiring a certain attention span, but the explanation of spinorama begins at slide 62. Earlier slides explain how we got to this point. Watch it in slideshow mode to see the animations.

You can download it at: https://www.audiosciencereview.com/...on-book-is-coming-discount.63666/post-2579817

 

[Cote Dazur]

Thank you, very educative, not at all what I was understanding by "resonance" this morning.
Amazing, what can be seen (heard) by looking at those curves.
@Floyd Toole happy Canada day.

 

[PristineSound]

I thought I was to be a transistor circuit designer after my BSc EE in Canada, but Imperial College in London prevented that when they refused my (already approved) entry into the post graduate program (the locals had filled the seats and "colonials" had to find something else to study). I was crestfallen, but decided that I would persevere - I was on an all-expense-paid scholarship. By pure luck I ran into Colin Cherry, inventor of the term "cocktail party effect" (binaural localization of multiple sources), and I ended up using my circuit design skills to create elaborate test signals to interrogate the binaural hearing system. That research, using headphones, was successful, three published papers before graduation, still referenced, and I was hired by the National Research Council of Canada to continue the research using their anechoic chamber to move the experiments closer to real rooms.

I can only imagine your heartbreak at that moment, but in the oddest way that life can throw at you, great things in life sometimes happens by accident and the audio industry owes Imperial College in London, your perseverance and Colin Cherry a debt of gratitude.

I know you feel that we have accomplished a lot in the field of acoustic and psychoacoustics research and anything further is likely diminishing return; I still feel uneasy not having a standard bearer after so many decades of your steady leadership in this field and with Dr. Olive's recent retirement.

But in the end, your legacy has left us a treasure trove of groundbreaking knowledge in this field.

Thank you.

 

[Multicore]

You can download it at: https://www.audiosciencereview.com/...on-book-is-coming-discount.63666/post-2579817

Hi Floyd, excellent, thoroughgoing slide presentation. Thank you for sharing it. Does this YouTube present roughly the same slide deck?

 

[Floyd Toole]

Hi Floyd, excellent, thoroughgoing slide presentation. Thank you for sharing it. Does this YouTube present roughly the same slide deck?

There are several slides in both shows, but the ASR download one is more useful when it comes to interpreting spinorama data.

 

[Jukebox]

I explain it in my books, on a few occasions in ASR forums, including this reference that allows you to download a PowerPoint slide show that summarizes the core story of the books and explains how to interpret spinoramas from Amir or any other trusted source. Even this summary contains a lot of information, requiring a certain attention span, but the explanation of spinorama begins at slide 62. Earlier slides explain how we got to this point. Watch it in slideshow mode to see the animations.

You can download it at: https://www.audiosciencereview.com/...on-book-is-coming-discount.63666/post-2579817

Thank you for providing this information! I found the material very clear and easy to understand, and I particularly appreciated the new graphs that were not included in the third edition of your book.

I would like to mention one minor detail: on page 119 of the slides, the spinorama shown is for a 3-way floor-standing speaker (not 4-way); As it is my dream speaker, I am very familiar with its specific spinorama profile and recognized the model immediately

 

[Floyd Toole]

I would like to mention one minor detail: on page 119 of the slides, the spinorama shown is for a 3-way floor-standing speaker (not 4-way);

OOPS! A typo, because I certainly know better. I think I know how it happened, but that is no excuse. Thanks for noticing - it has been corrected.