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In praise of AR3a's


Carlspeak

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Actually, I will not debate the quality of their ears, which were pretty great, but it should be pointed out that both Villchur and Allison were (and still are) strong advocates of a scientific approach to speaker design. Villchur has pointed out that his reference standard was live music, and one way he proved that was to present those 'live-vs-recorded" demonstration concerts back in the 1960s. The speakers used were AR-3 models (not the later AR-3a)

AR continued these demos at various hifi show venues well into tne mid-seventies, using the AR-3a and AR-10pi models after the 3 was discontinued. The live music for later demos was a solo guitarist rather than the original chamber music group.

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Interestingly, I recently finished reading a copy of Floyd Toole's new book on loudspeakers and rooms, and in there Toole basically dismisses the AR live-vs-recorded presentations as mostly being entertainment for people who were unsophisticated by modern audio standards. I think this is a preposterous claim, but it is obvious that if one embraces the validity of what Villchur did it invalidates much of what Toole says about speaker sound in his book.

Key to the Toole perspective is that we do not listen in the reverberant field, nor even a uniformly reflective one, either, which is the cornerstone of AR's "Max dispersion" designs.

They measure poorly both on- and off-axis, as Allison disclosed in a 1970 AES paper*, in which he argued that the energy was going SOMEWHERE in the room, and if it is measured at enough locations, it sums to a uniform response.

Toole has effectively demonstrated that measured response, both on-axis and over a narrow listening window, correlates highly with listening preferences, instead:

http://www.aes.org/e-lib/download.cfm?ID=1...amp;name=harman

*Presented October 12, 1970, at the 39th convention of the Audio Engineering Society, New York, and published in the AES Loudspeakers anthology Volume 1, p. 258, as "The Sound Field in Home Listening Rooms"

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Key to the Toole perspective is that we do not listen in the reverberant field, nor even a uniformly reflective one, either, which is the cornerstone of AR's "Max dispersion" designs.

They measure poorly both on- and off-axis, as Allison disclosed in a 1970 AES paper*, in which he argued that the energy was going SOMEWHERE in the room, and if it is measured at enough locations, it sums to a uniform response.

Toole has effectively demonstrated that measured response, both on-axis and over a narrow listening window, correlates highly with listening preferences, instead:

http://www.aes.org/e-lib/download.cfm?ID=1...amp;name=harman

*Presented October 12, 1970, at the 39th convention of the Audio Engineering Society, New York, and published in the AES Loudspeakers anthology Volume 1, p. 258, as "The Sound Field in Home Listening Rooms"

Toole is rediculous. Toole is not about high fidelity but about marketing which suits his boss Sidney Harman just fine since he is about making money. Toole is always talking about preferences. High fidelity is about reproducing the audible experience of live music. Ironically, when Leo Beranek talks about preferences for concert halls, that is an entirely different matter and is a legitimate object where preference plays a roll. Interestingly, both came to the same conclusions, that lateral reflections play a major roll in listener preference. In Beranek's web site, there is a link to a paper he wrote comparing the preferences of conductors and other golden ears with 20 measured parameters for 59 concert halls and a similar one for 29 opera houses. The number one correlation was BQI, Binaural Quality Index which is 1-IACC, inter aural cross correlation which expresses the degree of "stereophonicity" of the early reverberent field. Beranek makes a direct connection between this and early lateral reflections. The second most important parameter is bass response, a strong bass being more desirable. Interestingly, Revel which is Toole's baby changed the design of its flagship product the Salon by removing the rear firing tweeter that increases audible lateral reflections. You have to wonder if Toole is still calling the shots at Revel.

Based on my own mathematical modeling, all existing methods of acoustic measurement of loudspeakers (and concert halls) are conceptually badly flawed and will not correlate with subjective results. What's more, similar or even identical measurements invariably give subjectively very different results demonstrating that they are not based on reasoning which reflects the most salient aspects of how sound fields are experienced by the listener. AR engineers instinctively understood the limitations of AR3a. Despite having the widest high frequency angular dispersion by far of probably of any speaker ever sold commercially to that point, the development of LST showed that it was not sufficient for them. LST is about more than just increasing power handling capacity, it is about lateral dispersion especially at high frequencies. But the design was intuitive, not based on a scientific understanding of how to measure and assess the reflections within the listening room. In theory, LST should be at the pinacle of AR's efforts. AR9 betters LST in low frequency capabilities and in mid bass coupling having added an 8" LMR but as a wide angle disperser of sound above 200 hz, is not in LST's league. I think Allison also recognized this fact which may be why his speaker has two mids and two tweeters on angled panels. My own efforts go far beyond those points requiring most high frequency propagation directed away from the listener. This is similar to the way most musical instruments propagate sound and is consistent with my model.

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Interestingly, Revel which is Toole's baby changed the design of its flagship product the Salon by removing the rear firing tweeter that increases audible lateral reflections. You have to wonder if Toole is still calling the shots at Revel.

What am I missing? Removal of the rear-firing tweeter would be consistent with Toole's advocacy, that axial reflections are the worst offenders, no?

[i guess I have to buy Toole's book and help him on his way to financial independence.... :D ]

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What am I missing? Removal of the rear-firing tweeter would be consistent with Toole's advocacy, that axial reflections are the worst offenders, no?

[i guess I have to buy Toole's book and help him on his way to financial independence.... :D ]

A single rear firing tweeter may not be the best arrangement but it's better than nothing. Lots of designers used it without having any technical understanding of how and why it does what it does. Among them besides original Revel Salon were Snell AIIIi, TOTL Vandersteen, and Wilson. I'm not sure but maybe Von Schweikert TOTL too. High frequencies directed backwards will undergo multiple reflections, some bouncing off the back wall and some scattered to the sides depending on how reflective surfaces are arranged. Not carefully modeled or thought out at all, it's kind of hit or miss. Many people like it including some designers but they don't have a clue as to why other than their subjective impressions. They do not have either an acoustic model or a model of hearing to expain its physical effect or the psychoacoustic consequences.

In my designs, over 95% of high frequency energy is directed away from the listener in many directions. If you consider carefully how musical instruments are constructed and played, you will conclude that the situation is similar. Most musical instruments are either close to being omnidirectional radiators or indirect radiators with respect to the audience most of the time. If someone pointed a trumpet in your direction and blew through it even from 40 or 50 feet away, you'd know what I am talking about.

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Okay, just a small peek under the tent so to speak.

"What is important is flat power input to the room

No. What is important is a flat acoustic energy field transfer function. It not only takes into account the direct field but must account for the reflections too which must arrive at the listener flat. That is how the speaker performace must accomodate itself to individual room acoustics. No loudspeaker ever commercially designed and marketed comes even remotely close to meeting this criteria. What is more, for musical instruments to have the same subjective timbre they would have if played in your listening room, the reproducing system must be flat right back to the microphones. Since the spectral balance of recordings varies all over the map from one recording to another, failure to compensate for each recording individually can rarely if ever sound accurate to critical ears. At the current state of the art, this is a long painstaking process, at least for me that relies on listening experience and memory.

To reproduce the timbre of musical instruments as they are heard at concert hall venues, the acoustic energy field transfer function of the hall must be duplicated as well. The subjective timbre of the sound at a live venue is inseparable from the reverberation of the hall because of the relative different rate of decay of each sound as a function of frequency characteristic of the hall. This can be understood by looking at RT's as a function of frequency for various halls. No recording or sound system within the current state of the art comes close to achieving this goal either.

The "secret" if you can call it that, behind my patent was the still unpublished mathematical model which describes this transfer function. Everything I have done with audio equipment for the last 35 years is the result of this discovery.

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As for your " No loudspeaker ever commercially designed and marketed comes even remotely close to meeting this criteria" statement, the very success of the Villchur AR concerts proves it as wrong

I don't think so. The AR demos placed live musicians and more or less anechoically recorded reproductions of those musicians into the same (concert or other demo) space. This is not the same as recreating the sound of a concert space in a different space, such as a home living room. For all the attempts that audio designers have made over the years, whether with wide dispersion speakers or multi-speaker surround sound, this has yet to be achieved at any "state of the art."

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In a way it is the same. It basically proved that for all intents and purposes, proper (and properly equalized) speakers set up in a given environment and given the right kind of recordings can behave basically as subjectively "perfect" reproducers. Yes, it is probably impossible to reproduce a true sense of concert-hall space in a small listening room, and two reasons for that are that the rooms themselves are not the "right kind of environment" and the recordings themselves are just not the "right kind." However, what the person was saying is that no recording or sound system can do the job, period. To counter that I pointed out that the recordings Villchur made and the sound systems he used DID do the job.

We apparently read that differently. As I read it, "the job" soundminded was talking about not being able to do was reproducing the sound of instruments as heard in concert hall venues in other environments. (hopefully he will correct me if I read him wrong).

Yes, the Villchur recordings and playbacks successfully reproduced the sound of instruments as heard in their original recorded environments, but only because they were recorded in environments that had been specifically configured to be as close as possible to no environment at all. About the only application I can think of that such a reproduction technique might be useful for would be something akin to a player piano that is intended to simulate the presence of the live performers in the listener's own space.

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Well, if you are talking about the room and speaker working together to deliver flat energy to the listener, wel, then, sure. Flat in that way is vital. Your use of the phrase "flat acoustic energy field transfer function" seems to be a bit presumptious, however. You seem to have made up a parameter and then worked to satisfy the requirements of that parameter with your own design. Note that "flat power input to a room" as I initially phrased it has very little to do with the direct field as you implied. It basically equals what you indicated with your "flat acoustic energy field transfer function" terminology, and I do not see a difference in terms of practical needs, other than what you wrote makes a rather simple concept seem to be considerably more complex. What is required is that the reverberant field be as large as possible, and to do that we have to have speakers that can put maximum wide-bandwidth energy into the room, and do so as smoothly as possible.

However, rooms vary, and so all any good speaker designer can do is see to it that his product delivers flat energy to the listening room. That is basically what Villchur did with his concerts. The deal was to record properly (taking into account the variability between the radiation patterns of the various instruments) and then adjust the output of the speakers (using the anechoically recorded material) to get the speakers to generate the same spectral balance as the instruments. (According to Roy Allison, all that contouring involved was a few dB of boost by the treble control of the Dynaco preamp what was used with the playback gear.) That done, the concerts were a success. As for your " No loudspeaker ever commercially designed and marketed comes even remotely close to meeting this criteria" statement, the very success of the Villchur AR concerts proves it as wrong as those same concerts proved what Toole has said as wrong before he ever said it.

I would be very interested in just what products you have come up with during your 35 years of research. One would think that so much work would have resulted in some stellar results. (As a past product reviewer I am interested in any kind of breakthrough components.) I'd also be interested in knowing just who you are, because real people with real accomplishments are more than happy to tell people who they are. After all, I am using my real name, and so you know who I am. One good turn deserves one in response.

PS: While listening experience is very nice, memory about how certain things can sound can be tricky. I would prefer a bit more measurement work in addition to memory techniques when designing gear.

Howard Ferstler

"Your use of the phrase "flat acoustic energy field transfer function" seems to be a bit presumptious, however. You seem to have made up a parameter and then worked to satisfy the requirements of that parameter with your own design. "

Well I did make up the term because it describes the criteria set forth in my mathematical model. Since no other such model exists as far as I know, new terminology had to be invented to describe many aspects of it.

"Note that "flat power input to a room" as I initially phrased it has very little to do with the direct field as you implied. It basically equals what you indicated with your "flat acoustic energy field transfer function" terminology"

Not really. You could have a speaker that radiates its bass omnidirectionally similarly to the way AR9 does and beams all of its high frequency energy directly at the listener and it would still have flat power input into the room. But it would sound very different from one that radiated the same energy differently by propagating it multidirectionally. Also failure to take into account the difference of absorption/reflection as a function of frequency of the room boundaries would make even a pulsating sphere with flat frequency response deliver less than flat acoustic energy field transfer to the listener because the reflections would not be flat.

"However, rooms vary, and so all any good speaker designer can do is see to it that his product delivers flat energy to the listening room."

That's a lame excuse for bad engineering. Let's be honest about it, few real "brains" have actually worked on this problem which BTW is not an electrical engineering problem (this is coming from an electrical engineer.) All electrical aspects of audio meaning the transmission, storage and retrieval, control, and amplification of electrical analogs of music have been solved a long time ago. High end manufacturers can try to re-invent those wheels at ever escalating prices but it will never get any rounder. Acoustics, the study of acoustical energy propagation is a problem in fluid dynamics, the fluid being air. It's actually a branch of mechanical engineering. The surface of it has barely been scratched.

"I would be very interested in just what products you have come up with during your 35 years of research."

I am the inventor of Electronic Environmental Acoustic Simulation which was a direct consequence of my math model. I was unable to get any of 20 audio equipment manufacturers interested in it at the 1983 AES convention. In 1987 I became aware of the Yamaha DSP-1 which may have a similar processor to the one in your amplifier. DSP-1 just meets the minimum criteria for a critical circuit in my invention. Two patent attorneys advised me not to sue Yamaha because of the time and cost and because of the degree of difficulty in proving my case. After re-examining my patent, DSP-1 seems to expoit a loophole I inadvertently left between the abstract and the claims. It should be easy to show that inferring this circuit from the abstract would be obvious to anyone skilled in the art (that's the legalese terminology in patent law) after examining the claims and the description. However, after carefully considering it, I decided not to pursue it and now the patent expired.

"I am pretty sure that even Mr. Soundminded, with all of his 35 years of work on the issue, is not going to be able to come up with a system design that will work to that kind of perfection in typical home-listening rooms."

Don't be so sure. I'm not given to hyperbole because for one thing, there's been so much of it in the audio industry that any claims no matter how well founded have to be laughed at. If half the things audio manufacturers have advertised over the decades had been true, man would have traveled to the Andromeda galaxy and back already.

It was several years after I began tinkering with AR9 in the late 1980s that I realized I was applying the same equations I'd used in my other idea, only I was applying it to a different aspect of the problem.

In its current state, the prototypes I've built are not suitable to be marketable products. The difficulty of building a working simulator around DSP-1 and operating it satisfactorily are extraordinarily tedious even for me and I invented it. It's seems to me right now well beyond the skills of even advanced audiophiles. I'm working on that problem now. There will have to be much further R&D before this could be commercially exploited and then not in a manner familiar to the way products in this industry have been usually marketed. I've got some ideas about whom best to approach (not what you'd call audiophile type companies at all) but I'm not quite ready yet. Meanwhile another patent attorney wants me to apply for more patents. I don't think that's the best route this time having been burned once already.

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Incredible what Vilchur and Kloss did with their ears as measurement equipment :D

Shacky,

This characterization of Villchur and Kloss isn't truly accurate. Both of these speaker pioneers certainly did use subjective techniques to evaluate the results of their testing, listening sessions and so forth, and Kloss probably used that means as a primary testing methodology once he had done initial measurements at the start of KLH in 1957. Villchur used the AR-3 Live-vs.-Recorded concerts as a subjective validation of his objective-measurement techniques, and these concerts demonstrated conclusively that his AR designs -- which measured extremely well -- were also very accurate reproducers. Perhaps this was not to everyone's "taste," but these AR speakers were accurate reproducers, and that is the very definition of "high fidelity." Moreover, Villchur felt that loudspeakers were really not different from any other audio device with respect to objective-measurement techniques; i.e., you could measure a loudspeaker just as you could measure an amplifier, preamp or pickup cartridge in the turntables of the day. It was more difficult, for sure, but he rigorously measured every parameter of loudspeaker performance that could be measured during that period in history, and he published every detail of that information -- the first for any loudspeaker manufacturer. AR loudspeakers were primarily designed and refined using laboratory measurements, and then the final results were put to the subjective test establishing their accuracy -- probably the main reason for the continued popularity of AR speakers after fifty years.

--Tom Tyson

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Key to the Toole perspective is that we do not listen in the reverberant field, nor even a uniformly reflective one, either, which is the cornerstone of AR's "Max dispersion" designs.

They measure poorly both on- and off-axis, as Allison disclosed in a 1970 AES paper*, in which he argued that the energy was going SOMEWHERE in the room, and if it is measured at enough locations, it sums to a uniform response.

Toole has effectively demonstrated that measured response, both on-axis and over a narrow listening window, correlates highly with listening preferences, instead:

http://www.aes.org/e-lib/download.cfm?ID=1...amp;name=harman

*Presented October 12, 1970, at the 39th convention of the Audio Engineering Society, New York, and published in the AES Loudspeakers anthology Volume 1, p. 258, as "The Sound Field in Home Listening Rooms"

Zilch,

"They measure poorly both on- and off-axis, as Allison disclosed..." What are you referring to here, "AR's 'Max dispersion' designs?" What speakers measure poorly on- and off-axis? I must be missing a link or something.

--Tom Tyson

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Zilch,

"They measure poorly both on- and off-axis, as Allison disclosed..." What are you referring to here, "AR's 'Max dispersion' designs?" What speakers measure poorly on- and off-axis? I must be missing a link or something.

--Tom Tyson

http://www.audiokarma.org/forums/showthread.php?t=215006

The drivers measure well standing alone, but once they are in the cabinet and playing concurrently, all bets are off. Allison disclosed this in his 1970 AES presentation and published the curves, which are very similar to my findings here forty years later.

His paper is also an exposition of the AR design approach, based upon a rationale that home listeners listen in the reverberant field, and that the direct field frequency response is largely irrelevant; what matters is the integrated power response in the reverberant field.

He also stated that a directivity "Q" of 2 is ideal, with the speaker(s) against the wall (effectively, a 180° beamwidth for all drivers,) reflecting what I call the "Max Dispersion" design philosophy a popular pursuit at the time, further suggesting that speakers with Q = 4 and above were mediocre performers.

I surmise this is the reason AR never published performance measurements for their systems, rather, only the drivers individually, on test baffles.

Toole subsequently exposed the fallacies, namely, that we do not listen in the reverberant field, that the reflectivity in typical listening spaces is not uniform, and that, while our brains do quite a bit of integration of what we hear, flat axial frequency response, minimized early reflections and a uniform power response over a defined listening window correlate most highly with listener preferences in the typical small-room environment, which can best be achieved with controlled directivities Villchur and Allison would likely dismiss as definitive of truly terrible speakers.

In all of this, it's important to keep in mind that AR's design objective was to replicate the reverberant character of the concert hall, NOT the defined imaging and soundfield contemporary loudspeaker design strives to achieve; all of the cues should be in the program, including the ambiance of the performance venue, (they're not, always,) and it is therefore not desirable or necessary to artificially generate an acoustic listening field.

Much of this is far more significant when we depend upon the phantom imagery of two-channel than in multi-channel program presentation, which renders it all but moot....

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I am going to reproduce sections of your commentary below, with my comments interjected.

"Well I did make up the term because it describes the criteria set forth in my mathematical model. Since no other such model exists as far as I know, new terminology had to be invented to describe many aspects of it."

Unfortunately, you still have not adequately described just what it is. Perhaps you can describe it better with more than just a short phrase. You have made some points to that effect with your comments about Yamaha, up ahead.

> "Note that "flat power input to a room" as I initially phrased it has very little to do with the direct field as you implied. It basically equals what you indicated with your "flat acoustic energy field transfer function" terminology"

"Not really. You could have a speaker that radiates its bass omnidirectionally similarly to the way AR9 does and beams all of its high frequency energy directly at the listener and it would still have flat power input into the room. But it would sound very different from one that radiated the same energy differently by propagating it multidirectionally. Also failure to take into account the difference of absorption/reflection as a function of frequency of the room boundaries would make even a pulsating sphere with flat frequency response deliver less than flat acoustic energy field transfer to the listener because the reflections would not be flat."

Sure. It is easily possible for a directional speaker to deliver flat power. Indeed, it is done all the time, and even Consumer Reports magazine has shown test curves illustrating directional speakers inputting flat power to a test area. However, if it does that then the direct-field signals will be "hot" in the midrange and treble, so to speak, in order to have them generate enough energy to equal the output of the more wide-dispersing signals being radiated by the speaker at somewhat lower frequencies. A beamy speaker like that would run into the kind of problems that Mark Davis outlined decades ago. (Davis and Jim Brinton did some revealing comparisons between wide-dispersing speakers like the LST and more conventional models, and found that it was the different radiation patterns that allowed two flat-power equal speakers to sound different.) The angled-panel Allison IC-20 units I have in my main system do radiate widely well into the treble, and, yes, they do sound more spacious and enveloping that more directional speakers like the Dunlavy Cantatas I owned for a time, and even than the home-built speakers in my middle system that use Allison tweeters, but only with single forward-facing panels. However, some listeners like that kind of beamy sound, and under some conditions (say, what Villchur was working with during his live-vs-recorded sessions) a beamy sound might even be technically advantageous. Much will depend upon the room size, shape, and absorptivity, as well as the distance from the speakers to the listener. Incidentally, I covered this subject fairly well in both my last record-review book, "The Digital Audio Music List" and my last book on AV, "The Home Theater Companion." I also harped upon it aplenty in a number of my "The Sensible Sound" commentary columns and product reviews. In any case, you have kind of changed the subject from speaker performance to full system performance with more than two channels. Note that I am a huge advocate of surround sound with music reproduction and always use the surround processors when listening to two-channel materials. I also make use of a center channel that derives a faux, but speaker generated center from the phantom-center part of the mix.

> "However, rooms vary, and so all any good speaker designer can do is see to it that his product delivers flat energy to the listening room."

"That's a lame excuse for bad engineering. Let's be honest about it, few real "brains" have actually worked on this problem which BTW is not an electrical engineering problem (this is coming from an electrical engineer.) All electrical aspects of audio meaning the transmission, storage and retrieval, control, and amplification of electrical analogs of music have been solved a long time ago. High end manufacturers can try to re-invent those wheels at ever escalating prices but it will never get any rounder. Acoustics, the study of acoustical energy propagation is a problem in fluid dynamics, the fluid being air. It's actually a branch of mechanical engineering. The surface of it has barely been scratched."

Maybe. However, given the customer living-space environments manufacturers have to deal with it is probably pointless for speaker manufacturers to get into a twist about what you are concerned with. The solution, once the speakers are essentially perfect in terms of flat power, radiation pattern, and distortion, is to put together proper surround-sound hardware. However, even that is going to be a partial solution at best, given the multitude of different playback environments out there. Some are good (go look at the pictures of my large and smaller systems in the Allison section of this site), but most are just not so good.

> "I would be very interested in just what products you have come up with during your 35 years of research."

"I am the inventor of Electronic Environmental Acoustic Simulation which was a direct consequence of my math model. I was unable to get any of 20 audio equipment manufacturers interested in it at the 1983 AES convention. In 1987 I became aware of the Yamaha DSP-1 which may have a similar processor to the one in your amplifier. DSP-1 just meets the minimum criteria for a critical circuit in my invention. Two patent attorneys advised me not to sue Yamaha because of the time and cost and because of the degree of difficulty in proving my case. After re-examining my patent, DSP-1 seems to expoit a loophole I inadvertently left between the abstract and the claims. It should be easy to show that inferring this circuit from the abstract would be obvious to anyone skilled in the art (that's the legalese terminology in patent law) after examining the claims and the description. However, after carefully considering it, I decided not to pursue it and now the patent expired."

I believe that the DSP-A1 integrated amp in my smaller system and the RX-Z1 receiver used in my main system do indeed make use of at least some of the original DSP-1 simulations. Of course, they also have updated other areas beyond that provided by the DSP-1 considerably. I am impressed that you came up with something like what Yamaha did. I was under the impression that they did basic research on the issue and essentially measured assorted halls in special ways, and then just applied the criteria discovered by those measurements to their processors. I assume you did some measuring yourself to prove that your concept not only works, but also is similar to what Yamaha did. Incidentally, the Yamaha approach is not the only one. Lexicon, led by David Griesinger, has come up with some pretty advanced surround simulations for music playback itself. I did get a chance to review their DC-1 device some time back.

In any case, what we are dealing with here are surround-sound concepts and not speaker performance, per se. Obviously, good surround sound requires good speakers to do the job, but even here we have different opinions, with people like Toole, David Rich, David Fabricant, John Dunlavy (John is not with us any more, unfortunately) having opinions that stand in contrast to those of Roy Allison, Mark Davis, John Strohbeen, and Ed Villchur. My main point at the beginning of this discussion was that Villchur proved that with good speakers it is possible, in a proper space, with proper recordings, to very closely simulate the spectral balance, spaciousness and realism of live music.

> "I am pretty sure that even Mr. Soundminded, with all of his 35 years of work on the issue, is not going to be able to come up with a system design that will work to that kind of perfection in typical home-listening rooms."

"Don't be so sure. I'm not given to hyperbole because for one thing, there's been so much of it in the audio industry that any claims no matter how well founded have to be laughed at. If half the things audio manufacturers have advertised over the decades had been true, man would have traveled to the Andromeda galaxy and back already."

I agree, especially when it comes to stuff like amps, power conditioners, isolation devices, and wire, and to digital playback devices, too.

"It was several years after I began tinkering with AR9 in the late 1980s that I realized I was applying the same equations I'd used in my other idea, only I was applying it to a different aspect of the problem."

Actually, when Mark Davis was doing research for his dbx Soundfield One system, he analyzed the radiation patterns of a number of speakers, including the AR-9. In terms of radiation pattern behavior, it was not particularly different from a host of other forward-facing speakers. The speakers Toole mostly analyzed in his book were of that type, too, which is one of the criticisms I have of the book. He ignored models like the LST, Allison One, and dbx Soundfield One, and even the Bose 901 and Klipschorn. He also made remarks about the AR-3 (and by implication the AR-3a) that indicated a degree of contempt, in spite of what Villchur did with his demos. I will note that Toole has informed me that he has definitely had some experience with the LST and AR-3a, but those experiences were not discussed in the book. He basically dismissed much of what Mark Davis did and has not much use for the Klipschorn. Still, those are legendary speakers that deserved at least a footnote.

"In its current state, the prototypes I've built are not suitable to be marketable products. The difficulty of building a working simulator around DSP-1 and operating it satisfactorily are extraordinarily tedious even for me and I invented it. It's seems to me right now well beyond the skills of even advanced audiophiles. I'm working on that problem now. There will have to be much further R&D before this could be commercially exploited and then not in a manner familiar to the way products in this industry have been usually marketed. I've got some ideas about whom best to approach (not what you'd call audiophile type companies at all) but I'm not quite ready yet. Meanwhile another patent attorney wants me to apply for more patents. I don't think that's the best route this time having been burned once already."

Well, good luck to you. I am not sure that anybody can come up with solutions to the kind of problems you outlined, but I am sure that a number of speaker companies have developed models that can perform the job of providing a subjectively perfect copy of a given input. That may not work in terms of surround-sound envelopment and absolute concert-hall realism, but at least if you or somebody else does manage to come up with a processor that does the surround-sound trick there will be speakers out there that can exploit the effect to near subjective perfection. Villchur proved that was possible forty years ago.

Howard Ferstler

If flat acoustic power output was the ideal speaker, a constant directivity speaker used in sound reinforcement would be the ideal high fidelity loudspeaker because that is its design goal. It isn't ideal, I don't know of anyone who uses one that way. Consider that much of what you hear from a home sound system comes from reflections off the walls. If the frequency response of those reflections aren't flat, how can you expect the speaker to sound accurate no matter what else it does? I won't go into further details of my model, that is the crux of my "intellectual property" but it does take all of these factors into consideration in one equation. It doesn't matter if the source of sound is a musical instrument playing in a concert hall or a loudspeaker playing in a living room, it takes every variable into account and it is not an approximation. It accounts for every last echo. At least on paper.

"Maybe. However, given the customer living-space environments manufacturers have to deal with it is probably pointless for speaker manufacturers to get into a twist about what you are concerned with"

I am concerned about a sound system that produces sound from recordings that sound like real musical instruments played by real people. Considering the promises made and the prices charged for much of this gear, is that an unreasonable request? But the science just isn't there. Any person with normal hearing can tell immediately that he is listening to a recording and not a real musical performance from acoustic instruments no matter what the sound system is. To achieve that goal is beyond the current state of the art. The live versus recorded demonstrations were very carefully contrived with specially made recordings played under very carefully controlled conditions. I had the good luck to attend two of them. There were differences. What was remarkable was how similar they sounded in many ways, but not in all ways. Had AR3 been as successful at reproducing commercially made recordings, there would never have been any other speaker taken seriously and AR would still be making them. There would have been no point in going any further. How do you beat perfection? Countless tens of thousands of speaker models have appeared and vanished all claiming the same thing. No two of them sounded exactly alike, none of them sounded the same in one room as in another, and none of them sounded like real music almost all of the time. Gordon Holt lamented it. TAS lamented it. Most audiophiles refuse to admit it even to themselves though they are shopping for their next speaker only hours after they've gotten their last one unboxed.

"I was under the impression that they did basic research on the issue and essentially measured assorted halls in special ways, and then just applied the criteria discovered by those measurements to their processors. I assume you did some measuring yourself to prove that your concept not only works, but also is similar to what Yamaha did."

Yamaha's simulations are of no interest to me. I've never even tried one of them. The circuit is only of value to me in the user mode. Every recording requires its own customized transfer function according to the type of acoustics best suited to the music and variables inherent in the way the recording was made.

As part of my patent application, I tried to get coverage for a new method of acoustic measurement consistent with my model. The patent office said that was a different art and would require a second application. It was beyond what I could afford. That approach is unique. No measurements exist that would meet my criteria, the instrument for measuring them has never been built yet. In fact, until I figured out a way to measure what I needed, I felt I'd hit a dead end. I must admit that in my first prototype, I guestimated and quite frankly lucked out. Results were much better than I hoped for. That's when I decided to apply for a patent. I've followed the art of various measuring methods for concert halls on and off. I'm glad to see Leo Beranek isn't blowing his ear drums out with blanks fired from starter's pistols anymore. There are still vestiges of that part of my application that were left in the patent, notably one or two sketches. Given that there is no text to explain them, they must seem incomprehensible. BTW, Beranek uses a dodecahedral speakr array as a source. Not omnidirectional at all frequencies but fairly good. At least he has some measure of control now.

"Obviously, good surround sound requires good speakers to do the job, but even here we have different opinions,"

Can you configure a sound system that generates a subjectively isotropic sound field, one with no apparent source? Not if you use any speakers I've ever seen. But that is exactly what is required to reproduce a reverberant sound field of a good concert hall or other venue. There is no evident source to the reverberation, it's just there. Rather odd, don't you think considering that it is created by reflections each arriving from a specific direction. I had to design my own speakers for this part of the problem. It was not a matter of sound quality in the conventional sense. They had to generate sound fields with a particular energy distribution in space. One of the differences in my approach is that unlike other designers, I do not fight the listening room, I do not try to cancel it out. IMO that is a hopeless goal. Nobody lives in an anechoic chamber. Instead, I exploit the listening room. The success of my ideas depends entirely on it.

"I am pretty sure that even Mr. Soundminded, with all of his 35 years of work on the issue, is not going to be able to come up with a system design that will work to that kind of perfection in typical home-listening rooms."

"There are more things in heaven and earth, Horatio,

Than are dreamt of in your philosophy."

WILLIAM SHAKESPEARE / Hamlet Act 1. Scene V abt. 1601

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I am concerned about a sound system that produces sound from recordings that sound like real musical instruments played by real people. Considering the promises made and the prices charged for much of this gear, is that an unreasonable request? But the science just isn't there. Any person with normal hearing can tell immediately that he is listening to a recording and not a real musical performance from acoustic instruments no matter what the sound system is. To achieve that goal is beyond the current state of the art. The live versus recorded demonstrations were very carefully contrived with specially made recordings played under very carefully controlled conditions. I had the good luck to attend two of them. There were differences. What was remarkable was how similar they sounded in many ways, but not in all ways. Had AR3 been as successful at reproducing commercially made recordings, there would never have been any other speaker taken seriously and AR would still be making them. There would have been no point in going any further. How do you beat perfection? Countless tens of thousands of speaker models have appeared and vanished all claiming the same thing. No two of them sounded exactly alike, none of them sounded the same in one room as in another, and none of them sounded like real music almost all of the time. Gordon Holt lamented it. TAS lamented it. Most audiophiles refuse to admit it even to themselves though they are shopping for their next speaker only hours after they've gotten their last one unboxed.

As someone whose only role in the audio process is to spend money and listen to things bought, I have no illusion that any audio gear I own, or have ever owned, accomplishes this goal with anything remotely approaching "perfection." During my 40+ years of adult life I have been fortunate enough to have heard several hundred live music performances, about evenly divided (my guess) between orchestras in concert halls and various other performers in small theaters, nightclubs, open-air stadiums, rain-soaked festivals, etc. I'm fortunate enough to have some recordings that were released of performances I actually attended, and have never once heard a playback system that could come anywhere near to making me believe I might be back there again. For me, audio is a mnemonic aid that helps me imagine myself back, and what I require from my audio system is that it not emit obvious faults that might hinder my ability to do that, such as screeching treble, booming bass or virtual instruments that seem to move around the room when I do. AR speakers do this "best" for me; other speakers do it "best" for other people. This is about as subjective a standard as any I can conceive of, and IMO the fact that there is even a debate about what type of speaker (acoustic suspension, ported, dome, horn, east coast, west coast, etc.) is "best" is a burning red flag that measurements notwithstanding, there isn't anyone with ears whose concept of what sound or instrument readings represent "good" is any less subjective than mine.

The bottom line: no matter what the experts put into new tech and new products, I will listen and I will either like the sound or not, and all the measurements in the world verifying the "accuracy" of the reproduction will make little difference, because anytime I get to choose between my idealized fantasies and reality, reality usually loses.

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I didn't bother to read it, but here it is "Soundminded's" patent:

http://www.google.com/patents?id=gw4yAAAAE...stic+Simulation

I will point out there there are no "referenced by" listings with regard to later patents.

In contrast my patent here is referenced by IBM, Microsoft, and Harmon International, just to name a few:

http://www.google.com/patents?id=IAkKAAAAEBAJ&dq=6341166

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If flat acoustic power output was the ideal speaker, a constant directivity speaker used in sound reinforcement would be the ideal high fidelity loudspeaker because that is its design goal. It isn't ideal, I don't know of anyone who uses one that way.
Uhmmm, Geddes, maybe?

http://www.gedlee.com/downloads/Cum%20laude.pdf

OH, and me, of course and thousands of others.... :D

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As someone whose only role in the audio process is to spend money and listen to things bought, I have no illusion that any audio gear I own, or have ever owned, accomplishes this goal with anything remotely approaching "perfection." During my 40+ years of adult life I have been fortunate enough to have heard several hundred live music performances, about evenly divided (my guess) between orchestras in concert halls and various other performers in small theaters, nightclubs, open-air stadiums, rain-soaked festivals, etc. I'm fortunate enough to have some recordings that were released of performances I actually attended, and have never once heard a playback system that could come anywhere near to making me believe I might be back there again. For me, audio is a mnemonic aid that helps me imagine myself back, and what I require from my audio system is that it not emit obvious faults that might hinder my ability to do that, such as screeching treble, booming bass or virtual instruments that seem to move around the room when I do. AR speakers do this "best" for me; other speakers do it "best" for other people. This is about as subjective a standard as any I can conceive of, and IMO the fact that there is even a debate about what type of speaker (acoustic suspension, ported, dome, horn, east coast, west coast, etc.) is "best" is a burning red flag that measurements notwithstanding, there isn't anyone with ears whose concept of what sound or instrument readings represent "good" is any less subjective than mine.

The bottom line: no matter what the experts put into new tech and new products, I will listen and I will either like the sound or not, and all the measurements in the world verifying the "accuracy" of the reproduction will make little difference, because anytime I get to choose between my idealized fantasies and reality, reality usually loses.

"During my 40+ years of adult life I have been fortunate enough to have heard several hundred live music performances, about evenly divided (my guess) between orchestras in concert halls and various other performers in small theaters, nightclubs, open-air stadiums, rain-soaked festivals, etc. I'm fortunate enough to have some recordings that were released of performances I actually attended, and have never once heard a playback system that could come anywhere near to making me believe I might be back there again. For me, audio is a mnemonic aid that helps me imagine myself back,"

This is IMO the universal experience of all people with normal hearing who listen to live music. I can't say how many performances I've heard, I have no idea. I've heard probably well over a hundred performances, perhaps several hundred by symphony orchestras (including outdoor performance which IMO are the worst but I've never been to the LA bowl) in many venues including practice rooms, empty concert halls (at dress rehearsals), and all manner of other live performances. If I counted the times I've heard live music in my own home and in others including practicing, its got to be over 5 or 10 thousand and because there were always musicians in my family, it started as soon as I was born. We also have many students come here who get lessons in violin, viola, and piano. Also shortly after I was born, by a strange set of circumstances, I was exposed frequently to places having a very high level of reverberation. As a result, I've been a reverb freak all of my life. I still can't walk under a concrete highway overpass without shouting and listening to the echoes of my own voice. As a result, I've come to understand the overwhelming importance of acoustics of venue in not only the way listeners perceive sound but in how music is written and performed according to the acoustics. For example, conductors will adjust the tempo of playing according to the RT. Too fast and notes are blurred. Too slow and there is a discontinuity between notes especially after a rest. This is why the world's finest symphony orchestras invariably sound best when performing in their home city in the hall whose acoustics they are most familiar with. It's also why you won't frequently hear music written for a pipe organ with 32nd or even 16th notes.

Given the time and effort that has been devoted to improving the technology of recording and reproducing music, and I think many along the way were sincere in their efforts at improving the state of the art, the wide gap that still exists between live and recorded sound should certainly make anyone who is thoughtful about it realize that there are serious flaws in the basic understanding and conceptual approach to the problem. Trying to perfect equipment and systems based on flawed paradigms is a pointless effort. A square wheel, even one honed to a millionth of an inch won't roll. It was my good luck to not only have had a lifelong interest in both live and recorded music but the intellectual tools the result that an excellent engineering education confers without having been dragged down the same mental rut those who studied the problem before me had gotten tunneled into. I had to think it through from scratch and my anwers are different from theirs.

Once the fascination and novelty of being able to engineer sound fields (and this is what the problem is all about, not amplifiers, speakers, cd players, wires) wore off to some degree, I turned my attention to why this kind of approach can work. This led me to investigae how sound is perceived, another critical area of understanding where real knowledge is badly lacking. Besides being important for setting design criteria for the minimum performance necessary to create a specific illusion, the question of whether or not these differently engineered sound fields are better or just different from others, and if they are better, why they are better needed answering. That is a much tougher question, one I've spent a lot more time thinking about and drawing tentative conclusion about.

BTW, if anyone does bother to read my patent in its strange required blend of techno-legalese jargon, I'll be the first to admit it wasn't well written and if I had to do it over again, it would be worded rather differently, not that it would have mattered being a consolation.

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Wow, pretty impressive theoretical discussion but I pretty much agree with Genek. Here's the personal test I always used: Does the speaker sound good? Check yes or no. If NO, say thanks and leave. If YES, pay money and drive home with speakers. :)

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As for the flat axial frequency response that Toole justifies as important, with a given speaker one is only going to get that at one small vertical head location. Move the head up or down a small distance and that direct-field flatness goes away. (Even Dunlavy specified a set head height when listening to his speakers.) Frankly, I find it mysterious that Toole could take such full-system measurements and then come to conclusions about the direct-field response of such speakers. Away from a specific and preferred vertical measuring point that direct-field measurement goes to pot, which is why Villchur and Allison favored driver curves as a way to determine if a speaker could put flat power into a listening room.

True for most all conventional multi-ways, but two-way using constant-directivity waveguides maintain uniform power response in the vertical, as well, and carefully designed, the vertical nulls can be placed to reinforce the vertical dispersion limits so as to minimize floor and ceiling reflections. See Wayne Parham's discussion of the particular effectiveness of axi-asymmetric constant-directivity waveguides in accomplishing this objective on his Pi-Speakers website forum and in AudioKarma's EconoWave thread.

Here are the AR3a system response curves as presented by Allison, 1970:

Fig 9. is the on-axis system curve with molding, level controls at maximum. Some representative curves at other angles appear in Figs. 10 and 11.

post-102716-1237422400.jpg

post-102716-1237422446.jpg

post-102716-1237422491.jpg

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First, we need to also realize that Allison also printed out an overlap series for those curves, and then did a power curve that showed that the average output for all of them, at all angles, was remarkably flat.

What figure number, please? The average of 16 AR3as at 22 locations of the microphone in 8 living rooms is certainly not flat; it's rolled off 10 dB between 5 kHz and 10 kHz. The objective was to replicate concert hall response and ambient soundfield; they didn't give a whit about imaging, as was subsequently revealed in the Allison Stereophile interview.

It is nice to know that constant-directivity horns can do what you say. However, they still need to be aimed, and that works against them operating optimally in a lot of home listening rooms.

Nope. That's what constant directivity is about. Pick your dispersion pattern, and the power response is uniform within that. Aim it at the side walls, if you prefer, and wash the room in reflections, but that's not the optimum deployment. Geddes teaches how to generate a 6-foot wide "sweet spot" with controlled directivity, in fact....

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Uhmmm, Geddes, maybe?

http://www.gedlee.com/downloads/Cum%20laude.pdf

OH, and me, of course and thousands of others.... :)

"GedLee LLC is proud to offer what is arguably the best loudspeaker in the world."

Ho hum, another "best loudspeaker in the world." Get to the back of the line. It goes downstairs, outside, around the corner, and ends just before you get to Pluto.

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Ho hum, another "best loudspeaker in the world." Get to the back of the line. It goes downstairs, outside, around the corner, and ends just before you get to Pluto.

Well, THAT's certainly a worthy contribution to the discussion. :)

You gave it a thorough read, obviously.

And you were last interviewed when?

http://www.audioxpress.com/magsdirx/voxcoi...a/mowry1008.pdf

And you have how many papers that have been published by the AES?

http://www.google.com/search?q=Geddes+site:aes.org

[He DOES have a few patents, too.... ;) ]

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