138 replies to this topic

[speaker dave]

I wasn't questioning the reference, just referring to it being mentioned in post #145 instead of, say, #4 or #5.

Sorry Gene, I was letting my frustration get the better of me.

David

[Zilch]

Alison and Berkovitz disproved this decades ago.

Allison and Berkovitz disproved their own theories, as I have profusely demonstrated in these pages, and you refuse to appreciate that fact because it goes to the very core of your outmoded belief system as to how loudspeakers and rooms work.

If this is the case then the successful LVR sessions Villchur did with the AR-3 make no sense at all.

Drivel. They were contrived promotional hype, not science, and the last best evidence of the inanity of your argument, fully deserving of the short shrift accorded them by Toole, which is where all of this began.

I can better Villchur and Allison in accomplishing their wide dispersion objectives using constant directivity in a mere 30 seconds, as I have suggested several times before here.

Actually, I was hoping that Carl would pick up on it, and build something to measure. Neither was I successful in tempting you to step out to your workshop and dirty it up with sawdust. Bah!

This thread might have been 140 posts shorter if people had described real-world test results instead of just hurling dueling theorists at each other...

Wishful thinking. That ain't what the blather is about....

[genek]

Sixth, I am not sorry you re-opened this thread at all. It introduces the issue to newcomers who may have joined up since the last series of observations.

You really think anybody's still reading this topic besides the four principal posters? The only reason I'm still here is to see which of you is going to make the post that shuts it down.

[genek]

Well, there is always the chance that by staying here you will learn something.

That was actually happening for the first 20-30 posts in the thread. Then it went into reruns.

[Zilch]

I suggest you get busy and write....

zzzzzzz

[kkantor]

You really think anybody's still reading this topic besides the four principal posters? The only reason I'm still here is to see which of you is going to make the post that shuts it down.

Yeah, and who's interested in all those old speakers, too! It's really stupid to discuss old stuff, or defend boring ideas. Or take a photo of a mountain or cook spaghetti, join a political party, procreate, or any of that meaningless, repetitious trivia. Obviously, the people here are losers, who do nothing in the real world.

But, you know what's not stupid? Hanging around, waiting for a chance to shut it down triumphantly. That's really cool. That's what winners do!

-k

BTW- the first 20 or 30 posts in this thread were reruns, too. In 1965.

[kkantor]

.

[genek]

Yeah, and who's interested in all those old speakers, too! It's really stupid to discuss old stuff, or defend boring ideas. Or take a photo of a mountain or cook spaghetti, join a political party, procreate, or any of that meaningless, repetitious trivia. Obviously, the people here are losers, who do nothing in the real world.

But, you know what's not stupid? Hanging around, waiting for a chance to shut it down triumphantly. That's really cool. That's what winners do!

I don't have any thoughts about who here is a "loser" in the real world. If I did,I wouldn't air them here.

There's nothing particularly triumphant about a thread becoming abusive enough to warrant a shutdown, and if there was, moderating CSP would be a waste of time. There's only been one that's gotten that far out of hand so far. The triumph, if there is any, is in keeping the discussions focused on the old speakers and ideas (or mountains, spaghetti or other trivia if necessary) instead of sniping at each other so there doesn't have to be another.

[Zilch]

Generally speaking, I find there to be a relatively high level of discourse here in The Kitchen; everyone's insults are skillfully crafted.

I, for one, put considerable effort into each derisive having at least a modicum of entertainment value, and not being repetitive.

[I don't always succeed in that, tho.... ]

[soundminded]

Reverberant field simulations.

This is somewhat relevant to our Geddes discussion but more directly relevant to this older thread so I've attached it here.

I'm doing some work on simulating a loudspeaker in a reverberant field. As has been discussed on a number of threads the measurement of a speaker in a live room is a combination of its direct response, its total radiated power, the varying absorption of the room and the distance from source to listener. I need this for work and also because I'm thinking of writing and AES paper on the history and falacy of X curve cinema equalization.

The simulation is an excel spread sheet for room acoustics that adds up all the surfaces of the room with defined abosrption for each surface. This gives reverb. time and room constant vs. frequency. I've added a source with flat direct field or anechoic response and a 1/3rd octave defined directivity index. I then calculate the response at various distances as you move away from the speaker, culminating with the response at a distance in a purely reverberant field. This is always a combination of the direct sound, falling off with distance, and the reverberant field that is (fairly) constant around the room.

The hypothetical speaker has rising directivity and a power response hole at crossover. Although its response is flat on axis (defined as 100dB for all frequencies at 1m) as you move away the high frequency "deadness" of the room and the radiated power of the speaker start to impact the measured response.

Of course we can still debate whether the reverberant field curves are what we hear.

David

"Of course we can still debate whether the reverberant field curves are what we hear. "

The question itself demonstrates a profound lack of understanding of the nature of acoustic fields.

The correct answer is that we hear both. The direct field is exactly what you would hear were the source and listener in the same relative position in an anechoic chamber.

The precise nature of the reverberant field depends on a large number of variables and cannot be computed using Sabine's equation even enhanced for variable frequencies and modified for room size. It is far too imprecise, too generalized and lacks many variables. An infinite number of different fields will give exactly the same solution to Sabine's equation. Nor can the "ray analysis" method be used as it is far too crude. In what would seem like an unrelated area of mathematical modeling called computational flow dynamics (CFD) which combines analysis of both the fluid dynamic and thermodynamic performance of air conditioning systems, the aspect of interest is the fluid dynamic part of the model since acoustic fields are fluidic fields. In this much simplified version of the problem, it was the general consensus of end users in the summer of 2008 that the best available model incorporated in the most expensive software was not at all accurate in predicting the nature of the fluidic field when compared against real world mesurements. Therefore the conclusion is that as of now, the solution to the much more complex acoustic field equations is beyond the current state of the art. I expect that one day this will change but not yet. The instrument for measurement of the more complex acoustic field in the real world has never been built nor disclosed, nor has the method of using it. In my patent application, this was said by the patent office to be a "different art" from simulation of those fields and therefore would require a separate patent application.

[kkantor]

" 'Of course we can still debate whether the reverberant field curves are what we hear.'

The question itself demonstrates a profound lack of understanding of the nature of acoustic fields."


Gene K take note:

This isn't hostility or sniping. It's comedy, plain and simple. High comedy at that!


As usual, the kitchen is my favorite room. (Have you seen my waistline since 1980?) I hope the mental health inspectors get bribed.

-k

[soundminded]

" 'Of course we can still debate whether the reverberant field curves are what we hear.'

The question itself demonstrates a profound lack of understanding of the nature of acoustic fields."


Gene K take note:

This isn't hostility or sniping. It's comedy, plain and simple. High comedy at that!


As usual, the kitchen is my favorite room. (Have you seen my waistline since 1980?) I hope the mental health inspectors get bribed.

-k

"This isn't hostility or sniping. It's comedy, plain and simple. High comedy at that!"

Ya think so? I see it as more like tragedy.

Over a hundred years of research and experimentation by countless tens of thousands of engineers, scientists, professors, musicians, and just plain old tinkerers. Who knows, maybe millions of mandays expended and this is what it all comes down to;

"Of course we can still debate whether the reverberant field curves are what we hear."

BTW, while I think of it, is this thing any good?

http://www.parts-exp...iewRand=1576527

Would it work as well as say a Bose Acoustimass subwoofer for a small HT system in a kid's bedroom? It's certainly cheap enough. Not much of a risk buying one or two of them to experiment with. Just thought you might know Ken.

[speaker dave]

Ya think so? I see it as more like tragedy.

Over a hundred years of research and experimentation by countless tens of thousands of engineers, scientists, professors, musicians, and just plain old tinkerers. Who knows, maybe millions of mandays expended and this is what it all comes down to;

"Of course we can still debate whether the reverberant field curves are what we hear."

Being one of those tens of thousands held in such contempt, I'm too dumb to even figure out if I'm being insulted or not. I guess I'll just let it pass.

David

[kkantor]

Ya think so? I see it as more like tragedy.

Over a hundred years of research and experimentation by countless tens of thousands of engineers, scientists, professors, musicians, and just plain old tinkerers. Who knows, maybe millions of mandays expended and this is what it all comes down to;

"Does God Exist?"

"Is There Free Will?"

"Nature or Nurture?"

"Particles, Waves or Strings?"

"Is There A First Cause?"

"What Shall I Sacrifice To The Greater Good?"

"Is My Computer Sad?"

"How Do I Set My Equalizer?"

Sheesh, can't humanity figure >anything< out???

-k

So, completely seriously: I hope nobody here ever knows which AR models I love and which I hate. I worry about conflicts of interest, and regret, if I start to opine about products. This is especially true for products I had/have a direct involvement with. I would also worry about the site itself if it became any kind of commercial sounding board. Thus, I don't even put my work email on my posts anymore.

[soundminded]

Being one of those tens of thousands held in such contempt, I'm too dumb to even figure out if I'm being insulted or not. I guess I'll just let it pass.

David

Ooops! Did I say "tragedy?" I meant "travisty."

And it's too late for an edit. My bad!

[Zilch]

[It'd be better if you spelled it correctly.... ]

[Carlspeak]

FYI, here's a link to a site with NRC measurements of a number of modern speakers FWTW.

http://www.soundstag...p...6&Itemid=18

[soundminded]

These curves were all run at 2 meters, with the microphone at one vertical location: usually either between the tweeter and woofer or between the tweeter and midrange, or on the tweeter axis. Because of this variability between measurements, and knowing that moving the microphone up or down a tad from the measurement points chosen with each speaker would give substantially different results, plus the bias towards first-arrival energy, they really do not tell us much about how the speakers would behave in real rooms. The listening window measurement +/- 15 degrees, tells us that what matters most to them is the direct field performance and not the way the speaker inputs power to the listening area. They do give us an idea of the rather simplistic measurement approach of the NRC.

Howard Ferstler

"They do give us an idea of the rather simplistic measurement approach of the NRC."

I guess that's why Canada's manned space mission to the moon never got off the ground

[Zilch]

These curves were all run at 2 meters, with the microphone at one vertical location: usually either between the tweeter and woofer or between the tweeter and midrange, or on the tweeter axis. Because of this variability between measurements, and knowing that moving the microphone up or down a tad from the measurement points chosen with each speaker would give substantially different results, plus the bias towards first-arrival energy, they really do not tell us much about how the speakers would behave in real rooms.

Still having the same difficulties with reading comprehension, are ya, Howard?

Listening window - Averages five frequency response measurements and plots them as a single frequency response. The five frequency response measurements that are averaged for the Listening Window are: on-axis, 15 degrees left and right off-axis, 15 degrees up and down off-axis.

Purpose: Gives increased perspective of on-axis loudspeaker response in listening position. Takes into account subtle variations of on- and off-axis response on both the horizontal and vertical plans.

What it tells you: Averaging multiple measurements is important because subtle frequency response changes occur in small increments on- and off-axis, both laterally and vertically. This measurement is especially useful because it allows for small variations in the listening position and ear height and can be a more useful determinant of real-world listening than the standard on-axis measurement. Like any frequency response one should take note of the bandwidth (the upper and lower frequencies the speaker extends to), as well as the smoothness of the response across all frequencies. Dips in response mean a speaker is "less-loud" at that point, while peaks mean it is "louder" (i.e., more sound energy). Depending on the frequency it may result in a more distant or forward quality.