I use mostly directivity control to minimize early reflections and increase the delay to the onset of reverberation. The stuff that Kates talks about, which supports the polar patterns that I use, is about the tradeoff effects for enhanced reagion of the "sweet-spot". Not irrelavent, its a nice additional benifit, but not my primary concern.
...and it does not work for me. I wish it would but obviously I'm too sensitive to certain localization cues.
I use your highly acclaimed speakers with a damped front wall and toe-in. I'd think this is very similar to your room but there might be a certain acoustic quality that's missing which brings us to the question, "When do we finally see measurments from your room"?
I use your highly acclaimed speakers with a When do we finally see measurments from your room"?
If I go to AKFest I might have to make a stop at Dr. Geddes' house with my mic, laptop and Holm.
Just kidding! Well sort of as measuring with you I might learn something too.
I am seeing light!! There IS light at the end of the tunnel! I have someone doing all the finishing for me now, I stopped going to China, I can actually see where I might be able to take the tie to do thiose measurements.
Honestly, I am as intereed as you are. I did do room measurements many years ago, but not since I have had Holm. So I don;t have anything very good, and I couldn't find those anyways. I looked.
My room has not changed in almost a decade. I am not one of those who "tweeks". I use my room for what it was deisgned for movies and music - which I do just about every single day. Thats how I reward myself for a hard day - a few hours in the theater. I am not about to drag in the measurement gear!!
It funny, I am on my fifth projector in that time. Each one is better than the last and costs less (they only have about a two year life span) . Second HT Receiver (needed HDMI for Blueray), but I haven't changed the speakers except a small crossover change about three years back.
Honestly, I am as intereed as you are. I did do room measurements many years ago, but not since I have had Holm. So I don;t have anything very good, and I couldn't find those anyways. I looked.
My room has not changed in almost a decade. I am not one of those who "tweeks". I use my room for what it was deisgned for movies and music - which I do just about every single day. Thats how I reward myself for a hard day - a few hours in the theater. I am not about to drag in the measurement gear!!
It funny, I am on my fifth projector in that time. Each one is better than the last and costs less (they only have about a two year life span
) . Second HT Receiver (needed HDMI for Blueray), but I haven't changed the speakers except a small crossover change about three years back.
Originally from the BAS, I think this article sums up the 'you are there' vs 'they are here' aspects of dispersion
http://www.thecarversite.com/yetanotherforum/default.aspx?g=posts&m=17121#post17121
http://www.thecarversite.com/yetanotherforum/default.aspx?g=posts&m=17121#post17121
Thanks, I guess it sums up even much more than that
But help me out, "who" is the author ?
Thanks, I guess it sums up even much more than that
But help me out, "who" is the author ?
It was an article in the BAS speaker
Article By Alvin Foster
From BAS Volume 22, Number 2 May 1999
Its a decent paper, well ahead of its time.
A few noteworthy statements:
Agreed, but difficult to impossible in most small rooms, but yet, it should still be the goal.
I don't think that everyone here would agree with this statement, although I do, but for a different reason. If one matches the directivities of the upper and lower transducers, there will still be a power response dip at the crossover because of the lobes (non-coincident WAVEGUIDES assumed). Dips are not as audible as the sawtooth being mentioned, but I suspect that they are still audible.
Here is a comment that I don't agree with but no explaination is given so its hard to argue against. The comment about a smaller "reverb" field is not actually true, the reverb field depends on the power response and room absorption not on the directivity. It is VERY true that the reverb field will take many more ms to establsih with a narrow directivity speaker and this, I claim, is a very good thing.
This comment often gets my anger up. It simply discounts anything but "concert hall" reproduction as relavent. This is a major failing oif a great many researchers. The vast majority of my customers, and most listeners in general, are not after this kind of effect. Its the old paradigm of the assumed "audiophile", but its not true any longer. For some perhaps, but I, and many others are not among them.
Quite true - I have been saying this for a very long time now myself.
Hence, short of a few objections, its mostly a very insightful discussion. Worthy of being posted here.
A few noteworthy statements:
Agreed, but difficult to impossible in most small rooms, but yet, it should still be the goal.
I don't think that everyone here would agree with this statement, although I do, but for a different reason. If one matches the directivities of the upper and lower transducers, there will still be a power response dip at the crossover because of the lobes (non-coincident WAVEGUIDES assumed). Dips are not as audible as the sawtooth being mentioned, but I suspect that they are still audible.
Here is a comment that I don't agree with but no explaination is given so its hard to argue against. The comment about a smaller "reverb" field is not actually true, the reverb field depends on the power response and room absorption not on the directivity. It is VERY true that the reverb field will take many more ms to establsih with a narrow directivity speaker and this, I claim, is a very good thing.
This comment often gets my anger up. It simply discounts anything but "concert hall" reproduction as relavent. This is a major failing oif a great many researchers. The vast majority of my customers, and most listeners in general, are not after this kind of effect. Its the old paradigm of the assumed "audiophile", but its not true any longer. For some perhaps, but I, and many others are not among them.
Quite true - I have been saying this for a very long time now myself.
Hence, short of a few objections, its mostly a very insightful discussion. Worthy of being posted here.
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The sound field in small rooms is highly directional. Is there even any significant (diffuse) reverberation field?
Why does it need to be mutually exlusive? The optimal reproduction chain should be capable of delivering both experiences.
I agree. Had to roll my eyes a bit at that one.
You can have pinpoint imaging with some recorded material and a large, diffuse field with others. My system can do it, and so can others I've heard. It does not have to be either/or, as Markus said. Granted, there are many speakers which can do neither, but I hope we are ignoring those.Another thing (a detail) that has come up in some recent threads and posted papers is that the center channel is used in the cinema because it's needed for people sitting far off axis. Well, kinda, sorta. The reason the center channel is used in the cinema is because - it was always there.
Where was the speaker before multi-channel? Right in the center of the screen - were the actor's mouths are. Keeping that center channel when we moved to 4 channels not only pegged the dialog in the center, it provided mono compatibility. Just as not every film was made in color, not every film was made in stereo for a long time. Having that center channel ensured mono compatibility.
Ditto the optical sound track. Even after it was split into two tracks, it could still be read on a mono sound head. And a mono track would still be mono on a stereo sound head, you didn't even have to flip a switch. Great! Depending on your setup a LCR+S soundtrack could be easily reproduced as 1, 2, 3 or 4 channels. Very flexible and backward compatible.
The off axis performance of the center channel is just a happy fringe benefit of mono compatibility.
Difuse is a continuum. There is some diufusivity in a small room its not completely directional unless the room is very dead, but then its just a "bad room". I suspect that the reverb in my room is fairly difuse. Its a hard thing to measure.
I don't discount the possibility of both experinces as much as the "concert hall" people discount any need for imaging.
To get that "concert hall" experince, I'd rather go to a concert hall. I can no longer tollerate live rock performances because the mixing is so bad. (Alison Kraaus excluded as I have said before.) People like Linda Ronstadt don't tour much anymore. But I can go to a concert hall and weekedn that I want (and sometimes do.)
My front wall is well damped like yours. I don't think there's a significant amount of reflections coming back. That way the sound field stays highly directional. Discrete early reflections, more but dimished reflections from the back.
Fully agree.
Regarding imaging precision, I frequently will close my eyes at a classical concert to see how sharp the image is with the "video" turned off. I find it generally pretty good. All the instrumental groups can be picked out by general area and more directional instruments (trumpets, trombones) can be very precisely placed. With the benefit of sight we don't need any more imaging precision. Without sight, at home, then sharp imaging is a nice thing to have. It is the precision vs. envelopment compromise that becomes more difficult.
I wouldn't agree that Allison has proven anything regarding the importance of sound power in the home listening room, as I have stated many times before. The recent tests that various forum members have done surprised me in that they show we are all sitting somehwat inside the critical distance. Some markedly so. (Meaning that our in-room curves will be biased toward the direct field, even before we factor in directional hearing and our ability to focus on the early sound.)
A home listening room is as diffuse as any other room, above the Schroeder frequency. Since scale modeling of rooms and concert halls is frequently done, why would anyone think differently?
Finally, the reverberent field is related to directivity in that you will turn down a system as high directivity makes it louder on the listening axis. Turning down the system reduces the reverberent level.
David S.
I wouldn't agree that Allison has proven anything regarding the importance of sound power in the home listening room, as I have stated many times before. The recent tests that various forum members have done surprised me in that they show we are all sitting somehwat inside the critical distance. Some markedly so. (Meaning that our in-room curves will be biased toward the direct field, even before we factor in directional hearing and our ability to focus on the early sound.)
A home listening room is as diffuse as any other room, above the Schroeder frequency. Since scale modeling of rooms and concert halls is frequently done, why would anyone think differently?
Finally, the reverberent field is related to directivity in that you will turn down a system as high directivity makes it louder on the listening axis. Turning down the system reduces the reverberent level.
David S.
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Yep, me too. It depends on the hall, of course, but even in very live spaces precision is still possible. I have a good example involving a flute, a parasol and the Maui High School auditorium, but won't bore you with that long story.
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