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Review of AR-303 by Julian Hirsch in June of 1995, He A/Bd the speaker against the AR-3a


Howard Ferstler

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We know better, now, no?

"Disingenuous" is the word I used, and "Promotional stunt." "Trick" and "Fooled" are now in play; it seems only Howard still ascribes probative significance to the LvR "entertainment" events.

[it's all that's left in his arsenal, alas. :lol: ]

Horn/waveguide enthusiasts everywhere certainly appreciate this hard-won concession on the part of Howard Ferstler.... ;)

""Disingenuous" is the word I used, and "Promotional stunt." "Trick" and "Fooled" are now in play; it seems only Howard still ascribes probative significance to the LvR "entertainment" events."

I don't think that is a fair characterization at all. While you and many others are focused exclusively on loudspeakers, I look at the much bigger picture, the problem of recording and reproducing high fidelity sound through the entire chain. What this reveals is not disingenuous, it means that much more must be done to achieve its best results than is implied in its advertising. And those results are only best within the limited context of the demonstration, they cannot be extrapolated to other situations.

The advertised implication was that in AR3 you had a loudspeaker that effectively created an acoustical analog of an electrical signal and that was all you needed to do, buy it, power it up, and voila you had perfect sound. Quite the opposite, you needed to very carefully engineer a test by making special recordings, avoiding nearyby reflective surfaces, equalizing to get the demontration to work. And then only in the context of the speaker and source sounding alike when in the same acoustic space. You could not get AR3 (or any other speaker) to create one acoustic space when playing in another. That being the case, even within those limitations others could not duplicate the feat and mere speculation that they could today if they tried is just that, speculation. I don't think they can. Certainly not for more than one or at most a very few at a time and I explained elsewhere why. I think an attempt using more "modern' loudspeakers would do more to reveal their shortcomings than their advances. In some important ways this art has gone backwards.

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The advertised implication was that in AR3 you had a loudspeaker that effectively created an acoustical analog of an electrical signal and that was all you needed to do, buy it, power it up, and voila you had perfect sound.

The LvR demos were not done for fun, rather, to sell product, and the advertised implication was that in AR3 you had a loudspeaker that would accurately render recordings of live performances and effectively transport them into your living room.... ;)

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As I have said many times, Bose sells in a couple of weeks what AR sold in its best years. Microsoft, Apple and Sony spend more on seasonal ad campaigns than any pure speaker company has ever sold in a year. "Hifi," and for that matter, "classical music," has always been a fringe thing. I love obscure artists and visionary scientists, but let's not confuse them with commerce.

Acoustically, the corner may be one's friend. Rhetorically, it should probably be avoided.

That's one reason why I asked David if his new employer seemed to have any interest in realistic simulations. Even if it's only being done by companies building theaters or theme park rides recreating non-music environments, it would still represent some kind of commercial effort.

I don't think that anyone on either side of this argument has maintained that that the mass market will necessarily flock to the best of anything, and the dueling listening panels that both sides like to hurl at each other were all people with supposedly more "educated ears" than John Q. Public. Whether people prefer putting vintage ARs or Allisons or brand-new JBL Pros in heir living rooms, these discussions have all been turf wars over a postage-stamp-sized plot. If we magically awakened this morning to discover that everyone here had reached a consensus on the best "ideal" speaker design, its chances of making anyone at Bose the least bit nervous would probably be nil.

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That's one reason why I asked David if his new employer seemed to have any interest in realistic simulations. Even if it's only being done by companies building theaters or theme park rides recreating non-music environments, it would still represent some kind of commercial effort.

Certainly not "concert hall realism" as we would know and love. I was hired because they felt that their audio was somehow lacking and detracting from the total experience. Our goals are the same as for all cinema sound: dialog inteligibility, dynamic effects (loud but clean), good music quality for emotional impact. We are somewhat saddled with extra difficulties because we add, at any given instant, wind machines and pneumatic actuation of seat motion, not a quiet environment!

People want good sound in the cinema but it is seldom about nuance, more frequently about banging you over the head with it. Still I deal with system frequency response, coverage patterns, room acoustics, clean output before clipping, bass output, inteligibility. Cinemas have made great strides in sound quality over the decades. It is an integral part of the experience and true high fidelity is one of the goals.

"...1 acoustic watt per 1000 square feet of floor area can be delivered when the auditorium is adjusted for optimum reverberation time.""

John Hilliard, 1936

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OK, I surrender.

It’s obvious that no one wants to even address the possibility of actually embarking on a rigorously-controlled, scientifically-valid experiment to test the original AR “max dispersion” premise. The 3a was far too flawed to be a credible representative of that design approach. The 11 was the best test candidate to test the theory. (We could also have used the 91, the 78LS or the 303.)

No one wants to do it, or even talk about it.

Instead, what we are left with are the usual arguments and suppositions from the usual people sniping about what people 45 years ago were or were not thinking (as if anyone here today can read EV’s mind from 1960!), whether or not persuasive demonstrations designed to increase a company’s visibility and sell some products is somehow a “disingenuous” activity for a for-profit company in a highly competitive industry to engage in, and the usual arguments—in the abstract—about whether or not the “market’s” move away from so-called “wide dispersion” to something else had anything at all to do with listener preferences or whether it was just a complete coincidence that the companies that marketed and presented their goods in a more advantageous fashion to the dealers, the reviewers, and the end customers just happened to be using cone midranges for reasons having very little to do with the “philosophy of” or “loyalty to” wide dispersion.

AR’s fall from market grace in the late-60’s thru late 70’s has been documented in great detail by me and others on these pages. Their fall had essentially nothing to do with “max dispersion” and everything to do with dealer policies, distribution strategy, advertising strategy, market identification, developing timely products, etc. The 1 ½” dome midrange’s dispersion at 2000 Hz vs. a 5” cone, per se, was not the reason.

All this conjecture gets us no where and advances the discussion very little, if at all. If no one will test an 11 vs. their favorite modern cd speaker, then I’ll give it a rest. To everyone’s great relief, I’m sure.

Steve F.

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The idea that reflections equal distortion is just one more audiophile absurdity. The only place where there aren't reflections is in an anechoic chamber and while that may be useful for making certain measurements, I can't imagine a worse place to listen to music.

Of course, reflections can very much cause spectral distortion, a linear distortion. Many studies have been done on the audibility of reflections. Toole has a chapter in his book with a great summary but note that these are not just studies by Toole and Olive but by Baron and Bech and others, none that I would brand as audiophiles prone to absurdity. Studies vary in what they were looking for. Some looked for thresholds of absolute detection, others look for the onset of image shift, still others look for modification of timbre, which is exactly what we frequently discuss.

That live music contains reflections is hardly comparable. Every instrument has a different distance relationship to the surfaces around it and the reflections add level and spatial richness. They are integral to the live sound as we know it. Still, I am sure that a single violin above a hard surface would have a signature that could be detected and would vary if the surface were moved (not doppler!), ditto for piano. In a loudspeaker reflections become a filter that every part of the signal must pass through. Even Howard grudgingly admitted that a single edge reflection was audible. He felt it unimportant, an opinion he is entitled to. On the other hand a rear boundary reflection is sanctioned by Allison as highly worth eradicating!

Read the work of Bech where he simulated a speaker in a room via many sources in an anechoic chamber. He could simulate the frequency response, level and angle of every typical reflection. He concluded that the side, rear and floor boundaries would be well audible, but the floor boundary would be the only one likely to distort human voice.

David

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OK, I surrender.

It’s obvious that no one wants to even address the possibility of actually embarking on a rigorously-controlled, scientifically-valid experiment to test the original AR “max dispersion” premise. The 3a was far too flawed to be a credible representative of that design approach. The 11 was the best test candidate to test the theory. (We could also have used the 91, the 78LS or the 303.)

No one wants to do it, or even talk about it.

I am not ignoring the suggestion; if I had any of those models here, I would measure them and post the data so we at least had a reference.

The dilemma in the larger sense would be how to evaluate the subjective performance. Yes, I could listen, but to what purpose? Anything definitive would require controlled conditions and a statistical approach using many listeners, because, contrary to common wisdom expressed by others here, while our ears may be the final arbiters of our personal preference at any point in time, they are notoriously unreliable. Who here has access to such resources? :unsure:

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The dilemma in the larger sense would be how to evaluate the subjective performance. Yes, I could listen, but to what purpose? Anything definitive would require controlled conditions and a statistical approach using many listeners because, contrary to common wisdom expressed by others here, while our ears may be the final arbiters of our personal preference at any point in time, they are notoriously unreliable. Who here has access to such resources? :unsure:

I tend to agree. I can believe that an AR11 is a 3a with most of its earlier era shortcomings improved, although I don't have direct experience on that. But in the end, if we are comparing a good 3-way speaker with 12", 5" and 1" components vs. an equally good 12", 1.5", 3/4" AR11, how dramatic of a difference would you expect?

I know it is presupposing the outcome, but wouldn't that be a pretty subtle difference?

I will tell you of an experiment that I tried once on the same subject. Anyone can repeat it. While listening to a pair of speakers in a conventional listening room (at Snell) I had a helper stand behind with two large pieces of fiberglass, about 2' x 3' x 4inches thick. He could lower them down to the sides of my head (say an arms width apart) such that they would effectively block/absorb the bulk of side wall reflections. They would in no way block the direct sound.

The effect was very audible. Although I didn't hear distinct wall reflections when the absorbers were away, there was a discernable change in effect when they were present, the stereo image became more something confined to the speakers and the space in-betweeen and things were a little less natural.

There you go, Howard. A gift.

David

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You love to fall back on this as if satisfying an audience in a well conducted LVR demo is proof that speaker perfection had been achieved and further technical improvements are empty advances. Of course we keep reminding you of the many successful LVR demonstrations over the decades from 1916 on yet apparently none of those count, only the single one you want to give credence to. Not exactly an unbiased view.

I think Steve's question was about AR design philosophy and speaker dispersion. First note that as an industry insider I'll tell you that engineering and marketing are always entertwined. What the engineers can achieve the marketers will want to tout as monumental advances. After acoustic suspension EV developed the dome mid and tweeter and since they measured quite well this became part of AR marketing and mantra. They were able to show measurements of drivers that had ideal performance under a particular condition: when measured individually on large smooth baffles they looked great. In fact they might have measured better that way than any other manufacturers drivers at the time, its hard to say since others didn't rise to the challenge (well there were some ADC models that copied the ad approach).

To AR's credit, when they did the AES papers, they showed the whole system and we can see that there were technical problems with driver blending, edge reflections (both internal reflections and defraction related), tweeter sensitivity and woofer response in 4pi.

My question is can we assume that since AR achieved wide dispersion, and advertised wide dispersion, do we really know that they believed it was an essential parameter?

Regarding power response, my feeling is that they found it secondary to individual driver frequency response. Clearly the drivers and networks were optimized to be totally direct-field-flat. That these individual curves were so clearly optimized implies it was their primary objective. The power response would follow on based on driver directivity and individual driver sensitivities. The first dome tweeter was inherently heavy and would never match the sensitivity of the woofer or mid. As such power response would have to roll off. You can show a power curve and compare it to a concert hall RT curve and say "Its okay, Beranek approves", but comparing radiated power response and concert hall curves is tenuous science. Wouldn't the recording have been made in the concert hall with reduced treble reverberation? Why would we want to roll it off again when playing through the speaker? Also, no one ever points out that the power curve they compare to a concert hall is measured with mid and tweeter levels at max, a position that AR advises against.

I tried to calculate the directivity index curve of the AR3a a few months ago. You should be able to subtract the frequency response curve from the power response curve, as published in the various papers, and get the measure of directivity. I scanned and digitized curves and did the subtraction but the results made no sense. I would guess that the curves weren't accurate enough or came from somewhat different samples. It was apparent, though, that directivity was fairly constant while frequency response and power response both rolled off at HF. In the end the power response of an AR3a is similar to any other speaker, but it is achieved by falling frequency response rather than by rising directivity. This leads to its known, relatively dull balance, but is probably better than achieving flat power response and sounding way too bright.

David

Excellent post David thanks for hanging in there!

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I tend to agree. I can believe that an AR11 is a 3a with most of its earlier era shortcomings improved, although I don't have direct experience on that. But in the end, if we are comparing a good 3-way speaker with 12", 5" and 1" components vs. an equally good 12", 1.5", 3/4" AR11, how dramatic of a difference would you expect?

I do have direct experience, but only listening, not measuring. In 1976 the audible differences between a brand-new pair of AR-3a and a brand-new pair of AR-10pi that were sitting next to each other on the same shelf in the same dealer room was brightness (the 10pi had more). Once the HF and MR controls were adjusted to level that difference off, they were indistinguishable from each other, both from a seated position and moving about the listening space.

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I tend to agree. I can believe that an AR11 is a 3a with most of its earlier era shortcomings improved, although I don't have direct experience on that. But in the end, if we are comparing a good 3-way speaker with 12", 5" and 1" components vs. an equally good 12", 1.5", 3/4" AR11, how dramatic of a difference would you expect?

I know it is presupposing the outcome, but wouldn't that be a pretty subtle difference?

David

A "subtle" difference?

We've spent the last two years here in the Kitchen debating that wide-dispersion vs. cd or narrow was anything BUT subtle. Some people here think that the entire industry turned on that exact point--that listeners were so definitive in their preference for cd or narrow (or to put it conversely, their dislike of 'max dispersion'), that it was that precise subject that had determined AR and Allison's demise and others' gains.

Now we think the entire subject has been reduced to 'a pretty subtle difference'? Then what's the debate?

I guess there is none, after all.

Steve F.

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A "subtle" difference?

We've spent the last two years here in the Kitchen debating that wide-dispersion vs. cd or narrow was anything BUT subtle. Some people here think that the entire industry turned on that exact point--that listeners were so definitive in their preference for cd or narrow (or to put it conversely, their dislike of 'max dispersion'), that it was that precise subject that had determined AR and Allison's demise and others' gains.

Now we think the entire subject has been reduced to 'a pretty subtle difference'? Then what's the debate?

I guess there is none, after all.

Steve F.

Not exactly, my side of the arguement has always been that the direct and early soundfield take precedence and that dispersion or power response were secondary. If the comparison we are talking about is two speakers with the same direct sound characteristics and a power response differing by the size or dispersion of the mid and tweet, then my argument has always been that they would sound the same or very nearly so.

The big argument has been whether we can toss out the direct sound and aberations such as cabinet reflections or poor driver stitching and rely on power response alone to define the goodness of a system.

David

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Not exactly, my side of the arguement has always been that the direct and early soundfield take precedence and that dispersion or power response were secondary. If the comparison we are talking about is two speakers with the same direct sound characteristics and a power response differing by the size or dispersion of the mid and tweet, then my argument has always been that they would sound the same or very nearly so.

The big argument has been whether we can toss out the direct sound and aberations such as cabinet reflections or poor driver stitching and rely on power response alone to define the goodness of a system.

David

And my contention has been all along that the 11 or 91 or 78LS or 303 would be a great test subject, because all had excellent on-axis FR behavior, and none of the cab reflection etc. issues of the 3a/5. The 11, 91, 78LS and 303 had both excellent 1 m FR response AND wide disp.

By listening to them and comparing them to narrower disp models, we'd isolate the "wide dispersion" aspect of their behavior as the variable.

Then we could eval the variable.

That's the correct way to conduct an experiment.

Steve F.

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But, both soundminded and I have wondered at length just how much live-music hall time you have logged that would give you an idea of what speakers are able to do in good rooms. You claim to know how speakers are supposed to sound (based upon measurments you and others make, and of course based upon what you have read from Toole), but nobody has been able to squeeze any info out of you regarding your own experience at live, acoustic-instrument performances, or your own experiences doing level-matched A/B comparisons of variety of good (and maybe not so good) speakers in good listening rooms. No comments, no evidence, and certainly no photographs.

And you'd be hard pressed to find any statements as to how anything sounds to me, because I know that counts for next to nothing to anyone else. Maddening, I appreciate, to those for whom subjectivist blather is the sum and substance of insight. What I DO offer, however, is that literally hundreds of identifiable others have now built loudspeakers according to my humble prescription with apparent pleasurable result; count on me not apologizing for that anytime soon.

I'll have to check the Allisons I have in the dungeon here, but I believe them to incorporate Allison tweeters, which will be interesting to measure, now that you have assured me that they will not have deteriorated over time, and should perform very much in accordance with their original specification. :)

What a great list address you posted. I have saved it for future use.

I thought you had RETIRED! :lol:

Nobody has mentioned that the AR-303 could probably do the job just as well as the AR-11.

I don't know about AR-11, but looking at the polars, AR-303 doesn't get it, directivity-wise, in the top octave.... :unsure:

http://www.stereophile.com/standloudspeake...5ar/index4.html

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And you'd be hard pressed to find any statements as to how anything sounds to me, because I know that counts for next to nothing to anyone else. Maddening, I appreciate, to those for whom subjectivist blather is the sum and substance of insight. What I DO offer, however, is that literally hundreds of identifiable others have now built loudspeakers according to my humble prescription with apparent pleasurable result; I'll not be apologizing for that anytime soon.

It should be possible for you to say whether you can hear a difference between the same recording played on two speakers or between a live sound and a recorded sound and describe those differences without having to reveal anything about your personal likes or dislikes. I will freely admit to having no taste for heavy metal or rap, but if someone played me some Black Sabbath or Run DMC on different audio systems I would still be able to describe how the sound of music I didn't like differed when being played on different systems. I doubt that anyone likes the sound of frequency sweeps well enough to put one on for recreational listening, but that doesn't render one's perceptions of their sound invalid as data, does it?

I'll have to check the Allisons I have in the dungeon here, but I believe them to incorporate Allison tweeters, which will be interesting to measure, now that you have assured me that they will not have deteriorated over time, and should perform very much in accordance with their original specification. :unsure:

Does anybody know offhand how much involvement Allison had with the design of the smaller Allison models, especially the ones in the last attempt that was made to revive the brand? Did he actually have a hand in them, or did others just put things together using some of his component designs?

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(they had been subcontracted to build the woofers after years of Allison doing it himself and had shares in company stock)

A mistake that more than a few US companies seem to have made over the years: you should never pay your vendors and subcontractors (domestic or overseas) with shares in your company.

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Taste dictates, and I can understand, and even tolerate, those who prefer speaker sound that is different from what I prefer (assuming that both results are at least smooth and low in distortion harmonics). What I cannot understand are people like Zilch who say that any approach that he, Toole, Geddes, etc. do not prefer are, ipso facto, the wrong approach, period. That Zilch does it without offering up any first-person examples of his own listening experiences is even less understood.

It is YOU who are here telling everybody that we have it wrong, and that wide-dispersion as designed by Allison and practiced in your perfect listening room(s) is the be-all and end-all of quality reproduction. FACT is, incorporating contemporary knowledge of how loudspeakers and rooms interact, we can do it as well, if not better, without having to mitigate the adverse impacts of your approach, and in large measure, independent of the room.... :unsure:

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Whoa, whoa, whoa! I indicated that only at a very close (arm's length) distance were reflections audible even with a yardstick placed at different close distances and angles along side the tweeter/midrange combo. At any distance past 8 feet those reflections were more than inconsequential: they were inaudible, period, even with pink noise. With musical source material the impact was less than zero.

I guess I was thinking of my duplicate to your experiment. I could hear it at arms length and at my listening position, and even in the farthest corner of the room only slightly diminished. Maybe my Snell tweeters have wider dispersion?

The rear boundary reflection Allison worked to combat (which also would involve reflections from nearby side walls and the floor) was in a different category altogether. That kind of reflection would come back to the woofer driver itself and cancel out sound in some section of the midbass. How deep the cancellation might be would involve whether the multiple wall boundaries were all the same distances from the woofer center or at staggered distances. (Staggering would broaden the cancellation dip and reduce its depth.) A dip of that kind impacts both the direct-field and power response, because it is reducing the ability of the woofer to input power to the room, and the breadth of its spectral balance is large enough to be heard. (Allison outlined this in two different JAES papers that came later than his and Berkovitz's paper on soundfields.) The cancellation artifacts you are concerned with are narrow enough to be inconsequential, in my opinion, and in most real-world cases the cabinet moldings involved are themselves at staggered distances. They certainly were with the AR-3 and 3a.

Howard Ferstler

You need to check with Allison to see if your understanding is the same as he intended. My interpretation was that the power response was simply the area weighted energy sum in the hemisphere around the woofer. You seem to be saying that the radiation is perterbed because the woofer sees rear wall reflection.

I believe Roy would tell you that the mechanical impedance of a woofer is such that they are barely aware of the outside room, that standing waves and back wall reflections don't change woofer velocity in a substantial way. One proof of this is that the impedance curve is seldom impacted by room reflections or standing waves (yes, I've seen the odd 1/2 dB ripple). Secondly, a lot of engineers use ground plane measurements where they can find a large open parking lot to place the speaker on and then set the microphone on the surface at a distance. Think of it as measuring a speaker with a mic above a hard surface but no other walls. The spacing of the mic above the ground will cause a distinct reflection and a dip/peak sequence. As we move the mic towards the ground the dip frequency goes up and when we lay the mic on the ground it is generally high enough that we get a perfect reflection free measurement (with 6dB extra gain from the in phase ground bounce).

Now if you moved a second mic to be directly above the speaker this would be equivalent to the Allison case of a woofer with a wall directly behind it. The dip would very much be in evidence at that mic position. Yet the mic on the ground would not have and power suckout due to constrained cone motion. I and others have measured systems many times with that technique and the mic on the ground does not see the Allison dip.

The dip in the radiated power stems from enough of the points on the sphere seeing cancelation for it to become a substantial part of the average.

As for dips being narrow enought o be inconsequential, look again at the measurments of Olson of a driver on a rectangular box and tell me if they look inconsequential.

David

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PS: Allison does not know you and does not even know about you. However, if he did and he realized that you had a pair of his speakers he would probably break out in hives.

There WERE others, some with upward-firing woofers, all on their way to the landfill, but they were not in as good condition as these.

[by your view, they went to "A Better Place...." :unsure:

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Villchur came in to help for a while (he was very wealthy and planned on injecting capital), but he was out of touch with current listener tastes and so agreements could not be reached about marketing and other issues, and Villchur jumped ship after a short while.

Howard Ferstler

That warrants some explanation!

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It works at the woofer, period.

Howard Ferstler

And that is exactly what I am disputing. It is a matter of reflection from the rear wall and it varies with observation angle. In fact it disappears when you move to the side and approach the wall.

Another way to model this is with a pair of point sources spaced by twice the usual woofer to back wall distance. As you know the acoustical case is similar to an optical case of a woofer in front of a mirror. You see the front (real) woofer and the virtual reflection behind. Move into free space and use two woofers and exactly the same performance will be seen. You have just created a 2 element line source. In the end fire direction there will be frequencies of addition and frequencies of cancellation. That is the Allison effect. For the broadside case (equadistant from the two sources or at the wall surface in the case of a single woofer and its reflection) there is no path time difference and cancelation never happens.

Another way of stating this is that if we have a system with two woofers on a baffle, we see flat response when we are on the usual axis perpendicular to the two woofers. We do not see a cancelation dip due to their spacing.

Exactly the same thing.

David

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Of course, reflections can very much cause spectral distortion, a linear distortion. Many studies have been done on the audibility of reflections. Toole has a chapter in his book with a great summary but note that these are not just studies by Toole and Olive but by Baron and Bech and others, none that I would brand as audiophiles prone to absurdity. Studies vary in what they were looking for. Some looked for thresholds of absolute detection, others look for the onset of image shift, still others look for modification of timbre, which is exactly what we frequently discuss.

That live music contains reflections is hardly comparable. Every instrument has a different distance relationship to the surfaces around it and the reflections add level and spatial richness. They are integral to the live sound as we know it. Still, I am sure that a single violin above a hard surface would have a signature that could be detected and would vary if the surface were moved (not doppler!), ditto for piano. In a loudspeaker reflections become a filter that every part of the signal must pass through. Even Howard grudgingly admitted that a single edge reflection was audible. He felt it unimportant, an opinion he is entitled to. On the other hand a rear boundary reflection is sanctioned by Allison as highly worth eradicating!

Read the work of Bech where he simulated a speaker in a room via many sources in an anechoic chamber. He could simulate the frequency response, level and angle of every typical reflection. He concluded that the side, rear and floor boundaries would be well audible, but the floor boundary would be the only one likely to distort human voice.

David

"Of course, reflections can very much cause spectral distortion, a linear distortion."

:unsure: Yes they do. Every time. unavoidable in real rooms, even with Zilchophonic speakerphones. A worthy challenge for an engineer I'd say. Or an inventor. O someone who is both.

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