Allison on Soundfields

[Zilch]

One interesting thing about the Villchur concerts was that a really wide-dispersing speaker was not required. Decent, yes, but not ultra wide. Why? Because the concerts were done in rooms that were not as small as typical home-listening rooms, and so wide-dispersion might actually have worked against the spectral and imaging realism Villchur was after.

On the other hand, in a typical home listening room, with typical recordings (those that involve acoustic instruments where the recording engineer was doing his best to simulate a real-world concert-hall soundstage), a super-wide dispersing speaker can impart a sense of both width and depth to the presentation that more directional speakers cannot. This is not always the case, however, since some recordings (even some very good ones) lend themselves to playback with more directional speakers. I reviewed the full spectrum of this approach in my many recording reviews published both in books and magazines.

It's certainly getting tortured again, Howard. You're now suggesting that narrow-dispersion does it better, and that AR3a and Allison designs might not perform so well in LVR demos after all? If so, a rewrite of your Toole review is clearly in order.

I know you laud the GedLee approach, and I would not be surprised in the least if they do what you say when it comes do delivering a coherent and precise direct-field signal with minimal sidewall reflection artifacts above the lower midrange.

Please, Howard, read it again; it's obvious you do not understand this.

That is a subjective opinion, of course, but all I have to go on is my perception of live music, and while directional and focussed speakers of the kind you appear to admire do an exemplary job of behaving like oversized headphones, they do not do as well as good wide-dispersing speakers at simulating a live-music sense of space. Of course, this would only be important to somebody who likes the sound of live, acoustic-instrument music. In a past post you speculated that nobody likes that sort of thing any more.

You're making stuff up again to substantiate your personal perspective. My thesis is that there are better ways to get there than those devised 40+ years ago, independent of whether anybody gives a whit for any particular application or not....

[Zilch]

Zilch seems to think that sound reflected off of room walls is going to be seriously colored, which is why he and Geddes want to reduce any sounds headed in that direction. However, I simply do not believe that the reflected sounds will be all that compromised. They may tilt downward if there is absorbing materials on the walls (drapes, say) and they may be scattered erratically at higher frequencies if the walls are lined with hard items that reflect erratically (book, knick knacks, pictures, etc.). However, the spectral balance of those reflections is not going to be all that different from the initial signal hitting the wall. It is the quality of the initial signal that is going to be the problem in most rooms, which is why Roy wanted the off-axis response to be as wide-dispersing and smooth as the on-axis signal. That keeps the cumulative spectral effect over that first 30 ms as coherent as possible.

You're getting closer now.

1) Look again at the off-axis response of AR3a as measured by Allison 40 years ago, which I have confirmed is still the case today. What does the first reflection likely look like compared to the on-axis response, knowing the off-axis angle, or range of angles, from which it is most likely generated?

2) Even with his own speakers, Allison conceded that the off-axis response differed. He also continued to argue, as he earlier did at AR, that the reverberant field smooths it all out, as I quoted from Allison data you posted. Allisons obviously did a better job than ARs, but "issues" clearly remained evident.

[soundminded]

80 ms seems to be the IACC dividing line for ASW enhancement; this must somehow all fit together.

I don't think it's semantics, as we discussed earlier. I can see how late reflections might sum into generating a diffuse, integrating, reverberant field such as what is dominant in large spaces like concert halls beyond the first few rows, which Howard assumes also prevails in small rooms. I argue that Allison & Berkovitz clearly demonstrated that it does NOT exist in typical home listening spaces, and thus, it's the combination of the direct source and early reflections that best describes the spectral balance we hear above a relatively low transition frequency, and those are far more accurately characterized by the on- and off-axis anechoic measurements than by the "total energy" response as measured in a reverberant chamber. We can then argue whether wide dispersion is advantageous or even necessary to achieving the desired objective, and that's not so clear as Howard presumes, either.

See Toole p. 342, bottom. I think he makes a credible case for a combination of derivatives of anechoic response measurements as definitive, as shown in Fig. 18.5. We don't need in-room measurements to predict how a speaker will sound in typical listening spaces, once their own characteristics are known and understood in a normative sense, and Howard's total energy/reverberant field theory provides a decidedly erroneous answer.

Allison tells us the East Coast design objective: "to simulate live acoustic concert sound as closely as possible." To the extent that was achieved, it was more as an artifact than a direct result of the principles employed to accomplish it....

"QUOTE (speaker dave @ May 12 2009, 12:32 PM)

Maybe its just semantics, but I think reverberation refers to everything following the direct sound. You might split that into early reflections and later reverberation, but it seems an artificial distinction with no real definable dividing line."

What if there is no direct sound? Many musical instruments radiate little if any sound directly at the audience either because of the way they are constructed or the way they are played. Good examples are tubas, clarinets, oboes, french horns, and depending on where you are listening from and whether or not the top is propped open, closed, or removed, a piano. That is why I prefer to call the sound heard coming from the direction of the instrument, the anisotropic field.

Zilch;

"80 ms seems to be the IACC dividing line for ASW enhancement; this must somehow all fit together.

I don't think it's semantics, as we discussed earlier."

Unless there is some physical or psychoacoustic significance to 80 ms as a break point for which there is data, I don't get it.

"and thus, it's the combination of the direct source and early reflections that best describes the spectral balance we hear above a relatively low transition frequency, and those are far more accurately characterized by the on- and off-axis anechoic measurements than by the "total energy" response as measured in a reverberant chamber."

I think both those ideas are wrong. They fail to take into account the acoustics of the listening room which are different for every different room and every different speaker placement in the same room. I think it was around 1982 that I heard Peter Snell say that it wasn't what came out of the speakers that mattered but what reached the listener's ears. I'd come to the same conclusion 8 years earlier. Typically a speaker showroom is large and dead, an average apartment living room small and live. Saying there is some magic transition frequency below which it doesn't matter if the speaker is omnidirectional while the sound above can be highly directional is a fudge. In a highly reverberant room, omnidirectional bass sound does not fall off nearly as quickly with distance as it does for a point source, the tweeter. There are also more intense cancellations and reinforcements (standing waves) at different locations. Even on axis, in a real room the spectral balance of a speaker with a beaming tweeter will change with distance far more drastically than one that is less directional. That is due to lack of contribution of HF reflections to the total field to balance LF reflections.

[Zilch]

"80 ms seems to be the IACC dividing line for ASW enhancement; this must somehow all fit together.

I don't think it's semantics, as we discussed earlier."

Unless there is some physical or psychoacoustic significance to 80 ms as a break point for which there is data, I don't get it.

Well, somebody gets it; it was you who found the two definitions about that breakpoint, as I recall.

It'd be good if you got the book, so you're on the same page with Speaker Dave, Howard, and myself in this....

[Zilch]

Nope. I am just suggesting that the somewhat narrow dispersion of the AR-3, compared to the 3a, LST, and those Allison models, was apparently not a problem with the concerts, which were done in larger spaces than a typical home-listening area. What did matter was smooth output, and the AR-3 obviously did the job, in spite of direct-field artifacts that give you hives.

Somebody has measured AR-3s? COOL! Link us, please.

Obviously, the 40-year old approach worked well enough for Villchur to face it off against live performers. Has any outfit you have worked with or have lauded done as well?

JBL has virtually defined live performances worldwide for over 50 years, now.

Perhaps you should submit your challenge to Bose for their Wave Radio.

Only if one believes that the Villchur live-vs-recorded concerts were only attended by naive individuals with poor hearing. You seem to think that a pair of ears only hears one signal coming from the speaker and also one or two coming from reflecting surfaces. That is it: two or three signals, tops, and no more to speak of. Well, some people like things simple that way.

Help me, now, the LVR demos were done in typical listening rooms, right?

I am going to assume you have read my review of the book in the Library section.

It'd be good if you learned how to consolidate your posts when writing them, Howard.

It's beginning to look like you're a post whore, which would not be inconsistent with your otherwise apparent intent here....

[soundminded]

""80 ms seems to be the IACC dividing line for ASW enhancement; this must somehow all fit together.

I don't think it's semantics, as we discussed earlier."

Unless there is some physical or psychoacoustic significance to 80 ms as a break point for which there is data, I don't get it"

Well, somebody gets it; it was you who found the two definitions about that breakpoint, as I recall.

It'd be good if you got the book, so you're on the same page with Speaker Dave, Howard, and myself in this....

You have me mixed up with someone else. My analysis doesn't even look at it in remotely that way. In my analysis, the echoes are part of a continuum which start immediately after the direct wave or if there is no direct wave then instead of the direct wave and don't end until they are inaudible. No break points, no distinctions although I think the variables of the components arriving at different times and from different directions have different psychoacoustic effects. Perhaps they have been studied such as which ones help the brain estimate distance to the source and which ones help it estimate the size of the room.

I'm still waiting for data on typical home listening rooms showing detailed acoustic energy transfer functions so that I know the relative role of the direct and reverberent fields, what the RT as a function of frequency looks like and absolute RTs. Based on data I've recently received on a conference room project I've been working on (5/8" sheetrock on metal studs, low pile broadloom carpet on concrete, 9' ceilings using Armstrong Second Look acoustic tiles and rooms ranging from about 300 sf to around 1100 sf, RT at mid frequencies ranges from about 0.3 to about 0.7 seconds. Got any data for your own living room Zilch?

[Zilch]

How has JBL done this defining of live performances you mention? The fact is that those "live" performances of theirs probably involved electronic support for rock concerts. That is not a good way for a company to define its status as a high-fidelity sound reproduction organization. You owe JBL an apology, Zilch.

Not hardly, Howard. This is JBL Pro - at your theater, your church, your schools, city hall, the airport, the mall, your auditoriums, your concert halls, your park, your sports fields, swimming pools, colliseums, theme parks, arenas, the neighborhood bar, nightclub, restaurant, and of course, your personal favorite disco:

http://www.jblpro.com/

And then, here is JBL bringing that pro sound home:

http://www.jbl.com/

"Pro Sound Comes Home" here:

http://www.jbl.com/home/products/default.a...&Region=USA

I'm still waiting for data on typical home listening rooms showing detailed acoustic energy transfer functions so that I know the relative role of the direct and reverberent fields, what the RT as a function of frequency looks like and absolute RTs.

Get the book, Soundminded. "More data ... less wank."

[i forget who said that.... ]

[soundminded]

Not hardly, Howard. This is JBL Pro - at your theater, your church, your schools, city hall, the airport, the mall, your auditoriums, your concert halls, your park, your sports fields, swimming pools, colliseums, theme parks, arenas, the neighborhood bar, nightclub, restaurant, and of course, your personal favorite disco:

http://www.jblpro.com/

And then, here is JBL bringing that pro sound home:

http://www.jbl.com/

"Pro Sound Comes Home" here:

http://www.jbl.com/home/products/default.a...&Region=USA

That stinks. If you want to hear music and all you are going to get is what comes out of an electrical machine, you might as well stay home and listen to a recording or a broadcast for all you will hear. It is clear you and I live in entirely different worlds when it comes to what a high fidelity sound system is supposed to do. Sadly, your view is probably very common, mine rather rare these days. People who think music is a direct communication between people using acoustical instruments they make sounds with by blowing their own breath into, striking with their hands and arms, or bowing or plucking with their fingers, hands, and arms, or by singing with the power of their own voice alone and that musical instruments are crafted to make specific beautiful sounds, we are a dying breed. When the last of us is gone and music is reduced to the sounds a machine can make, technology will have completely triumphed and real music will be dead. What a poorer world it will be for that.

[Zilch]

Two hundred thirty thousand? The lunatics have certainly taken over the asylum.

Two hundred forty thousand one hundred seven right now, actually, Howard.

While I do appreciate your support, you're gonna wear out your left-click button viewing it 1000+ times a day over there like this. It's just unnecessary, really....

[soundminded]

Two hundred forty thousand one hundred seven right now, actually, Howard.

While I do appreciate your support, you're gonna wear out your left-click button viewing it 1000+ times a day over there like this. It's just unnecessary, really....

Howard, don't sound so surprised. There's one born every minute. PT Barnum's advice was right on target, never give one an even break.

How many of those things did you say you shipped out so far Zilch?

[kkantor]

That stinks. If you want to hear music and all you are going to get is what comes out of an electrical machine, you might as well stay home and listen to a recording or a broadcast for all you will hear. It is clear you and I live in entirely different worlds when it comes to what a high fidelity sound system is supposed to do. Sadly, your view is probably very common, mine rather rare these days. People who think music is a direct communication between people using acoustical instruments they make sounds with by blowing their own breath into, striking with their hands and arms, or bowing or plucking with their fingers, hands, and arms, or by singing with the power of their own voice alone and that musical instruments are crafted to make specific beautiful sounds, we are a dying breed. When the last of us is gone and music is reduced to the sounds a machine can make, technology will have completely triumphed and real music will be dead. What a poorer world it will be for that.

This sure sounds like what people said about that darn pianoforte. Or what the church elders proclaimed when harmony displaced plainchant. Musical instruments have always been machines. If a composer can write for a wooden box with catgut and ivory, or a strange melange of welded brass tubes with bored steel valves and polished silver orifices, why can't a composer write for a box with wires and magnets in it?

Lord protect us from the lower classes obtaining instruments of sound! Heaven forbid the mechanical reproduction of, uh, a spinet in sitting room, without tickets or dinner jackets!! Why these people could have sex with Ravel in the background. Scandalous! Socialism!

-k

[kkantor]

Hey Zilch,

I'm not sure what you mean with the reference to 80ms. That time is often used to define a border between early sound and late sound for music in concert halls (50ms is typically used for speech). Concert hall reflections prior to 80 ms are desired to give increased clarity, reflections later degrade clarity. Ditto reflections prior to 50ms for speech. Lecture halls, in spite of lowish Rt targets overall, are designed with hard ceilings to increase reflections prior to 50 ms. This increases the received level in the audience without decreasing inteligibility.

Of course with music reproduction, we get fussier about our reflections and don't want them to modify the reproduced timbre at all.

I just looked at Ken's paper on the MGC-1 again and he uses 20ms as an appropriate delay because lesser delays were felt to give reflections that distorted tonal balance. Why greater delays wouldn't be even better, I'm not sure. (Ken are you out there?)

Maybe its just semantics, but I think reverberation refers to everything following the direct sound. You might split that into early reflections and later reverberation, but it seems an artificial distinction with no real definable dividing line.

Regarding neither you or Soundminded making the cut; we love you both just the same.

David

You are taxing my memory.... I think 20ms, more or less, was enough to get beyond the fusion/coloration time, but not so long as to provide an obvious discete echo. Also... it was achievable with the technology of the day....

-k

[Zilch]

How many of those things did you say you shipped out so far Zilch?

I've not shipped out any E'Waves, as we haven't done a group buy of components, but there are 45 systems thus far "Officially" registered of those hundreds that have likely been built.

KISS me, Soundminded....

[soundminded]

This sure sounds like what people said about that darn pianoforte. Or what the church elders proclaimed when harmony displaced plainchant. Musical instruments have always been machines. If a composer can write for a wooden box with catgut and ivory, or a strange melange of welded brass tubes with bored steel valves and polished silver orifices, why can't a composer write for a box with wires and magnets in it?

Lord protect us from the lower classes obtaining instruments of sound! Heaven forbid the mechanical reproduction of, uh, a spinet in sitting room, without tickets or dinner jackets!! Why these people could have sex with Ravel in the background. Scandalous! Socialism!

-k

If that was all there was left to listen to, I'd set fire to my AR9s in a ceremony lamenting the death of music. It will be only one step more from there before computers are writing what is purported to be music for an audience of automotons. When I saw photos and film of throngs of spaced out hippies on LSD exposing themselves to deafening raucus cacophonies that left them as deaf as they were mindless, I thought we'd almost arrived there already. Apparently there's been a reprieve of a couple of decades but the siege against anything thoughtful and beautiful by the banal, the mediocre, the crass is waged as fiercely as ever. When what comes out of a loudspeaker is all there is to hear, music will be for all practical intents and purposes dead and burried. Now I see why you spent your evenings at the Paradise Club instead of at Boston Symphony Hall listening to actual music. How sad to have wasted such a rare and precious opportunity for enriching your life. How contemporary to embrace the sterility of a machine and spurn direct contact with humanity. Why bother arguing about loudspeakers and audio equipment when the equipment itself is the standard by which it is judged? That is the most irrational argument you've ever made.

[Zilch]

If that was all there was left to listen to, I'd set fire to my AR9s in a ceremony lamenting the death of music.

Yeah, Soundminded doeth not rock; I think we get that.

Zilch, this is large-area PA-grade work. And sound-support systems are not configured for fidelity (although the speakers should at least be decent) as much as they are configured for powerful directional outputs for those sitting in the back rows.

And max dispersion in the front ones.

"PA" once again exposes your "old school" perspective. Get a clue, man, fidelity is paramount in sound reinforcement today, far more sophisticated than is common in home listening spaces such as your own, even, and several highly skilled professions are dedicated to the science of accomplishing it. There is much to be learned here....

[Zilch]

The most I can about your comment and the one that led up to it is that it tells me a great deal about your taste in both speakers and music. What I cannot figure out is given those tastes why on earth are you participating on this web site?

Let's not pretend that everyone here is exclusively, or even primarily, an acoustic music in the concert hall simulation enthusiast such as you apparently suppose, or that understanding how it might actually be achieved is devoid of merit.

Howard, don't sound so surprised. There's one born every minute. PT Barnum's advice was right on target, never give one an even break.

UT, oh:

http://www.classicspeakerpages.net/IP.Boar...?showtopic=5465

[soundminded]

Yeah, Soundminded doeth not rock; I think we get that.

And max dispersion in the front ones.

"PA" once again exposes your "old school" perspective. Get a clue, man, fidelity is paramount in sound reinforcement today, far more sophisticated than is common in home listening spaces such as your own, even, and several highly skilled professions are dedicated to the science of accomplishing it. There is much to be learned here....

The real reason you, Ken Kantor, and others of your mentality prefer to think about reproducing the sound of electronic musical instruments is because when it comes to reproducing the sound of the most valuable music we have as it should be heard...you can't get it right. For all the papers written, the lab equipment bought and used, the prototypes and models created, the measurements made, the schemes and theories dreamt up....the problem has beaten you...all of you. You not only don't have a right answer, you don't even know which way to turn to look for one. After over a hundred years, probably over a billion dollars spent, countless hundreds of thousands of mandays expended, the best you can do still sounds to anyone with normal hearing in both ears like sound coming out of boxes, a machine. This effort, a poor second best that's been made based on results obtained may be good enough for a lot of people, even most people, especially for those who have never heard what the real thing is like...but not for me. I don't concede one inch to your obvious surrender to mediocrity in any of the fields related to what you do including the music and performances themselves.

Maybe you shouldn't go listen to a Symphony Orchestra at Davies Hall or some place like it. The shock of the experience of hearing live unamplified music that's beautiful to listen to might kill you

[Zilch]

I can't speak for Ken, but it's unmitigated insult for you to presume, much less even suggest, that we are incapable of enjoying a performance by the SF Symphony at Davies Hall, California Shakespeare in Orinda with the coyotes howling in the backdrop hills as if on cue, an avant-garde play presented at Berkeley Rep, Pilobolus Dance Theater at Zellerbach Hall (accompanied by BOSE, BTW), an emerging jazz combo at a local club (JBL), or just an after-dinner stroll on the waterfront with someone we love, to watch the sun set behind the Golden Gate Bridge, any less than more pedestrian facsimiles of these in our own homes. We are not the imperceptive knuckle-dragging dolts you imagine us to be, even though we may occasionally also enjoy snapping a note or two on a Strat in drive mode. Get over it; you'll not elevate yourself by standing on our backs here. We fart in your general direction....

[kkantor]

I don't concede one inch....

It's a good thing, too! From what I've heard, you don't have an inch to concede.

-k

"Classical Music... Because 168 Fans Can't Be Wrong!"

[soundminded]

I can't speak for Ken, but it's unmitigated insult for you to presume, much less even suggest, that we are incapable of enjoying a performance by the SF Symphony at Davies Hall, California Shakespeare in Orinda with the coyotes howling in the backdrop hills as if on cue, an avant-garde play presented at Berkeley Rep, Pilobolus Dance Theater at Zellerbach Hall (accompanied by BOSE, BTW), an emerging jazz combo at a local club (JBL), or just an after-dinner stroll on the waterfront with someone we love, to watch the sun set behind the Golden Gate Bridge, any less than more pedestrian facsimiles of these in our own homes. We are not the imperceptive knuckle-dragging dolts you imagine us to be, even though we may occasionally also enjoy snapping a note or two on a Strat in drive mode. Get over it; you'll not elevate yourself by standing on our backs here. We fart in your general direction....

"it's unmitigated insult for you to presume, much less even suggest, that we are incapable of enjoying a performance by the SF Symphony at Davies Hall"

I was just concerned for your safety. I was afraid you might hurt yourself. But if you risk it anyway, try to find a concert hall near a hospital with a good trauma center.

[soundminded]

It's a good thing, too! From what I've heard, you don't have an inch to concede.

-k

"Classical Music... Because 168 Fans Can't Be Wrong!"

" From what I've heard, you don't have an inch to concede."

From your own accounts of your experiences of blasting your eardrums out at the Paradise Club, it's remarkable you can still hear anything at all.

[Zilch]

You are taxing my memory.... I think 20ms, more or less, was enough to get beyond the fusion/coloration time, but not so long as to provide an obvious discete echo. Also... it was achievable with the technology of the day....

That's the issue I'm attempting to resolve. If the near-wall first reflection has the same spectral content as the direct, is down 2 dB and delayed 2.7 ms (see Toole Fig. 8.5), what does that do in terms of coloration?

And alternatively, if the first reflection is contralateral instead, -6.3 dB and delayed 12.3 ms, with the same content, what does THAT do to the perceived spectral balance? Clearly, it has the low IACC desired for ASW enhancement, no, as in the Geddes alignment? Can I crank that one's SPL up to 0 dB without consequence?

See Toole Fig. 9.3 and also here:

http://www.jblpro.com/catalog/support/getf...1&doctype=3

[kkantor]

" From what I've heard, you don't have an inch to concede."

From your own accounts of your experiences of blasting your eardrums out at the Paradise Club, it's remarkable you can still hear anything at all.

Yes, no doubt better to go deaf enjoying wonderful, passionate rock than to have to listen to a full spectrum of boring, anachronistic drivel that has failed the test of time and the marketplace. Besides, just as a great conductor can "hear" an orchestra from reading a score, I can "hear" almost perfect musical fidelity from watching an oscilloscope.

-k

"I live for your love, (every day), every minute. I live for your love,"

Natalie Cole

[soundminded]

Yes, no doubt better to go deaf enjoying wonderful, passionate rock than to have to listen to a full spectrum of boring, anachronistic drivel that has failed the test of time and the marketplace. Besides, just as a great conductor can "hear" an orchestra from just reading a score, I can "hear" almost perfect musical fidelity from watching an oscilloscope.

-k

"I live for your love, (every day), every minute. I live for your love,"

Natalie Cole

It might not have failed in the marketplace...had engineers who undertook the challenge of reproducing the sound of it done their jobs with sufficient insight to have made it sound the way it does to the relatively few who are fortunate enough to have access to hear it live. But sadly they failed so miserably that the best results they got were a pale caricature of the real thing. From their smug satisfaction with their handiwork standing on their piles of technical papers, mountains of measurements, and peerig from around the masses of test equipment they bought and acres of products they produced, you'd never guess that it all sounds like the people who conceived it were all half deaf...until you turned it on and actually listened to it. And then there would be no doubt remaining.

My offer to you stands. In two weeks I'll be attending a reunion of my old alma mater Stevens Institute. One of the alums from my class is on the board of directors at Stevens and teaches Electrical Engineering at MIT. I'll try to enlist his help on your behalf as well if you think it will help.

[Zilch]

It might not have failed in the marketplace...had engineers who undertook the challenge of reproducing the sound of it done their jobs with sufficient insight to have made it sound the way it does to the relatively few who are fortunate enough to have access to hear it live. But sadly they failed so miserably that the best results they got were a pale caricature of the real thing.

And to think you could have saved it merely by dorking with Bose 901s for 35 years.

How sad....