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#1
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Need advice for a small room
For me, stereo is about the imaging. I can't tell if my room is down
3db at 400hz, and frankly, I don't care as long as it sounds good. I don't even go in for room treatment of any sort. Every room, including a concert hall is going to have peaks and dips. I just live with that. Right now I have a pair of Apogee Divas in a room that is about 15.5'x25'. Maybe I just got lucky, but I can walk just about anywhere in the room and the image is locked in place. The only place this fails is if I stand within a foot directly in front of one of the speakers. I am planning to move and most of the rooms I am looking at tend to be on the order of 10-12'. Sometimes they are almost square. I was all hyped up on one product as a possibility for such a room until I found out it was more about getting correct response from the room then the kind of imaging I am after. So, are there any imaging nuts out there who are dealing successfully with small rooms? What are you doing? |
#2
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Need advice for a small room
On Thu, 26 Apr 2012 11:45:01 -0700, ScottW wrote
(in article ): On Apr 26, 6:23=A0am, Robert Peirce wrote: For me, stereo is about the imaging. =A0I can't tell if my room is down 3db at 400hz, and frankly, I don't care as long as it sounds good. I don't even go in for room treatment of any sort. =A0Every room, including a concert hall is going to have peaks and dips. =A0I just live with that. Right now I have a pair of Apogee Divas in a room that is about 15.5'x25'. =A0Maybe I just got lucky, but I can walk just about anywhere in the room and the image is locked in place. =A0The only place this fail= s is if I stand within a foot directly in front of one of the speakers. I am planning to move and most of the rooms I am looking at tend to be on the order of 10-12'. =A0Sometimes they are almost square. =A0I was all hyped up on one product as a possibility for such a room until I found out it was more about getting correct response from the room then the kind of imaging I am after. So, are there any imaging nuts out there who are dealing successfully with small rooms? =A0What are you doing? I find some of your comments contradictory to my experience. Imaging, IME, is somewhat inversely proportional to sweet spot size. Speakers that offer an image that doesn't change much around the room might be satisfactory for you, but have not offered to me that pinpoint image precision in the sweet spot which can be quite beyond realistic. Best imaging speakers I ever owned were Quad 63's with a sweet spot about the size of a cubic foot. As dipolars they need some space behind them and even then benefit from a rear wave diffuser (I fabricated a device similar to Soundlabs Sallie) for peak image clarity. But I don't think they (or any dipolar) will work well at all in a 12' room. For a small room I'd explore some decent bookshelfs with a sub. I heard some Spendor S3s in a small room at a dealer once with a Hsu sub that I thought really lacked nothing except the ability to drive a large room. Imaging was excellent and the separate sub allowed you to position and contour the bass to what the room could handle. Full range speakers forcing you to basically co-locate the bass drivers with the mid/hi freq sources creates an insurmountable problem and usually costs more as well. ScottW I agree that most speakers image properly only in a fairly small "sweet spot". That spot is usually the locus of the pick-up of the stereo pair of microphones used, and there is only one for each recording. One of the things about stereo recordings (and this is something that most audiophiles never think about) that differs from a live performance is that when you are there at a performance and move around from place to place, the stereo perspective moves with your ears. When listening to a recording, this does not happen because even though YOU move, your "surrogate ears" (the microphones) do not. They maintain the same perspective in the space where the recording was made and don't move with you. That's why the only place where the imaging is best is when you, the listener, are located in the acoustic focal point of the microphones. I could illustrate what I mean with a diagram, but I don't believe that graphics are supported on bulletin boards such as this one. Of course, what I just said presupposes a REAL stereo recording, not some multi-miked fiasco where there is a forrest of microphones all pan-potted into position and where the only "image" the recording has is of a bunch of musicians lined up in a straight line from the left side of the sound-stage to the right side. |
#3
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Need advice for a small room
There is imaging and there is imaging. I relate what I want to hear to
what I actually do hear at a live performance. From a reasonable distance, I can't exactly pick out that the bass is here and the drums are there. They sort of merge together. I think it is a function of the "included angle" of the performers from my listening position. It is one thing if you are on stage, maybe in the middle of the group. It is another thing if you are 50 or 100 feet back in the hall. I am trying to preserve the illusion of being back in the hall and I get that from my Apogee Divas. The fact that the apparent image doesn't shift much when I move about the room is a good thing. If I'm 100' from the stage and I move a few seats one way or the other I am not going to notice much difference and I am still going to have an image of the group in pretty much the same place. I am trying to translate that from a fairly large listening space, about 400 sq. ft., into something much smaller, about 140 sq. ft. I recognize that small monitors can give me pin-point imaging from the sweet spot, but that illusion is being much closer to the stage, perhaps on the stage. I am after the back in the hall illusion and I need something different for that. I just don't know what it is. |
#4
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Need advice for a small room
I can see I am running the risk of sounding like the guy from a few
weeks ago who denied the idea of a perfect amplifier in favor of his euphonic preferences. I don't deny the goal of perfect sound, which to me is live, unamplified, music in a real space. I have even heard sound reproduction that comes very close to that. My problem is every time I have encountered those conditions they existed for a relatively small space in the room. Move out of that space and the soundstage collapsed. My problem is I do not have a dedicated music room for one person. My space is multi-purpose. I have a small sofa, which I guess, is the prime listening spot. However, I also have a desk and chair a few feet behind the sofa which is where I spend a lot of my time. Sometimes I have a few friends over to listen to music, drink a little wine, wonder around the room and chat. One time I even rolled up the rug, moved the furniture and turned the space into a small ballroom for about 30 people. In all those cases I had the illusion of a live group at the front of the room. The sound wouldn't stand up to critical listening from the sweet spot, but it was very good sound for everybody and that is what I am after, except the space will be about 150' instead of 400'. For a while I was very enthusiastic about the Steinway-Lyngdorf system, as described recently in TAS. The idea of tuning a smaller, possibly odd-shaped, room sounded very good. Then I discovered they don't actually tune the room. The tune the sweet spot. I'm sure the sound in that spot is just wonderful, but what is it like a few feet away? Because of my experience with the Apogee planar speakers, I am now thinking something from Magnepan might work. They even have a speaker designed o mount on the wall, which makes a lot of sense for a very small room. However, I don't want to limit myself, but I don't want to go the sweet spot route either. Therefore, I am open to suggestions from people who have first-hand experience in this area, but under the circumstances, I cannot be interested in the comments of people who just want to tell me how wrong I am and what I should really be doing to get perfect sound forever. |
#5
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Need advice for a small room
Robert Peirce wrote:
Therefore, I am open to suggestions from people who have first-hand experience in this area, but under the circumstances, I cannot be interested in the comments of people who just want to tell me how wrong I am and what I should really be doing to get perfect sound forever. I have a suggestion to make: Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd Toole. Beware of anyone who tells you of easy solutions to this problem, but being well-informed won't hurt. Andrew. http://www.amazon.com/Sound-Reproduc...dp/0240520092/ |
#6
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Need advice for a small room
In article ,
Andrew Haley wrote: I have a suggestion to make: Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd Toole. Beware of anyone who tells you of easy solutions to this problem, but being well-informed won't hurt. Andrew. http://www.amazon.com/Sound-Reproduc...cs-Loudspeaker s/dp/0240520092/ No doubt, but I lack the luxury of using some of the ideas spelled out here. My current listening room was purpose built and has worked well. Now I am in a situation where I will have to make do with what I can find and I will be limited with what I can do with the space. The room dimensions are unknown at this point, but they will be fairly small. I will be forced to have only two (or four with separate woofers) fairly small speakers near the front of the room and limited room treatment beyond furniture and rugs. Yet I want to be able to hear a decent soundstage from just about anywhere in the room. Given those constraints, actual experience in solving this problem is likely to prove more helpful. Regardless of room constructions and shape, there are speakers that work well if you are in a single position but not so well if you are not, and speakers that possibly aren't the best for a fixed location but provide good sound throughout the space. I'm not going to find that out from a book. I could learn something by going around and listening, which is what I did twenty years ago, but that has become almost impossibly difficult today. From experience, I am skeptical of most mini-monitors, yet I remember the Spica speaker from years ago throwing a broad stable sound stage. On the other extreme, large panel speakers like I have now can do the job but they won't fit in a very small room. I am reasonably confident others have the same goals I do and have solved, or at least made inroads into, this problem. |
#7
Posted to rec.audio.high-end
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Need advice for a small room
Robert Peirce wrote:
In article , Andrew Haley wrote: I have a suggestion to make: Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms by Floyd Toole. Beware of anyone who tells you of easy solutions to this problem, but being well-informed won't hurt. http://www.amazon.com/Sound-Reproduc...dp/0240520092/ The room dimensions are unknown at this point, but they will be fairly small. I will be forced to have only two (or four with separate woofers) fairly small speakers near the front of the room and limited room treatment beyond furniture and rugs. Yet I want to be able to hear a decent soundstage from just about anywhere in the room. Given those constraints, actual experience in solving this problem is likely to prove more helpful. Do you really think that actual experience from a few here will be more helpful than Toole's book, which addresses this issue, and is based on the largest body of research in this area? You may get information about someone's room, but with no guarantee that it applies to yours. Regardless of room constructions and shape, there are speakers that work well if you are in a single position but not so well if you are not, and speakers that possibly aren't the best for a fixed location but provide good sound throughout the space. This is to do with the directivity of a loudspeaker and the way that it interacts with a room. Many loudspeakers that have an excellent frequency response on axis are very ragged off-axis. The most desirable trait, from your point of view, is that the directivity of your loudspeakers should be constant, or at least only gradually changing, over most of the frequency range. Loudspeakers with higher off-axis radiation will help. But -- and this is only my subjective experience, based on a few examples -- some rooms will never sound very good, no matter what you do. I'm not going to find that out from a book. But, strangely, you will find it out from Usenet! Andrew. |
#8
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Need advice for a small room
On Sat, 28 Apr 2012 15:23:55 -0700, Robert Peirce wrote
(in article ): From experience, I am skeptical of most mini-monitors, yet I remember the Spica speaker from years ago throwing a broad stable sound stage. On the other extreme, large panel speakers like I have now can do the job but they won't fit in a very small room. I am reasonably confident others have the same goals I do and have solved, or at least made inroads into, this problem. Interesting comment. I have found that small monitors on good, sturdy stands image better than most large speakers (the "infinitely small" sound-source theory) when fed true stereophonic material (no, multi-miked, multi-track recordings made with a forest of microphones with each instrument pan-potted into place across the soundstage, or divided into three mono groups, right, center, and left, don't qualify as stereo.) and I think the best imaging speakers I ever heard were a pair of Rogers' LS3 "BBC monitors" that a friend of mine once owned. They had no bass to speak of, but that's another story. Big bipolar panel speakers throw a huge soundstage but they don't do image specificity very well, in my experience. I have a pair of Martin-Logan electrostatics now, and due to their curved surface, they act like a line source at higher midrange and treble frequencies and they image pretty darn well too, having some of the characteristics of the large panels (like Maggies or Apogees) and some of the characteristics of small monitors. They're not as good as those BBC monitors though. Of course, the imaging must be on the recording for any speaker to reproduce it realistically. You'll not get any imaging (especially image height and front-to-back depth) from any rock/pop recording where the sound is totally a product of the studio, or most jazz recordings where close-up miking and three-channel mono are the order of the day. |
#9
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Need advice for a small room
In article ,
Andrew Haley wrote: Robert Peirce wrote: In article , Andrew Haley wrote: Regardless of room constructions and shape, there are speakers that work well if you are in a single position but not so well if you are not, and speakers that possibly aren't the best for a fixed location but provide good sound throughout the space. This is to do with the directivity of a loudspeaker and the way that it interacts with a room. Many loudspeakers that have an excellent frequency response on axis are very ragged off-axis. The most desirable trait, from your point of view, is that the directivity of your loudspeakers should be constant, or at least only gradually changing, over most of the frequency range. Thanks. I couldn't exactly describe the desired characteristics of the speaker but I think that is pretty close. The panel speakers I have probably aren't terribly directional, especially since half the sound is bouncing of the front wall. The mini-monitors I have described as working well only at a point are probably highly directional. So, where does one find information on small, non-directional speakers that can get down to, say, 25-30Hz, probably with the addition of woofers? |
#10
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Need advice for a small room
In article ,
Audio Empire wrote: Big bipolar panel speakers throw a huge soundstage but they don't do image specificity very well, in my experience. Yes. That is what I am after. The image (Apogee Diva) isn't as specific but it is very stable from many points in the room. On the mini-monitors I have run into the image is great at one point but the soundstage collapses if you get too far away from that point. I like to listen from multiple locations in my current room and am willing to trade-off really great sound at one point and nowhere else for very good sound everywhere. I am prepared to hear there are exceptions. For example, I have been told the Steinway Lyngdorf S-series actually does this very well; I had started to come to the conclusion it wouldn't. There are probably many other small speakers of which I am unaware that also can serve my purposes. The key is very good sound everywhere at the expense of close to perfect sound at one spot. |
#11
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Need advice for a small room
On Mon, 30 Apr 2012 15:58:37 -0700, Robert Peirce wrote
(in article ): In article , Andrew Haley wrote: Robert Peirce wrote: In article , Andrew Haley wrote: Regardless of room constructions and shape, there are speakers that work well if you are in a single position but not so well if you are not, and speakers that possibly aren't the best for a fixed location but provide good sound throughout the space. This is to do with the directivity of a loudspeaker and the way that it interacts with a room. Many loudspeakers that have an excellent frequency response on axis are very ragged off-axis. The most desirable trait, from your point of view, is that the directivity of your loudspeakers should be constant, or at least only gradually changing, over most of the frequency range. Thanks. I couldn't exactly describe the desired characteristics of the speaker but I think that is pretty close. The panel speakers I have probably aren't terribly directional, especially since half the sound is bouncing of the front wall. The mini-monitors I have described as working well only at a point are probably highly directional. So, where does one find information on small, non-directional speakers that can get down to, say, 25-30Hz, probably with the addition of woofers? With the addition of proper subwoofers, ANY small speakers will "get down" to 25-30 Hz. The thing about small speakers is that price-wise, they're all over the map. You can go for a pair of Magico Q1's (approx. 14" X 14" X 9" - two way) for twenty-five THOUSAND dollars a pair, to a pair of Usher "Tiny Dancer" 2-way for about $2,700 a pair down to the similar (and also excellent) Monitor Audio BX1s at less than $500/pair. Hint: The British are really good at making this type of speaker and most British speaker brands have these small stand-mounted speakers as part of their product lineup. I have heard the Magicos, and they are magic, but I've also heard the BX1s and they too are amazing for 1/50 the price with an on-axis frequency response of 55 to 30KHz +/- 3 dB! But whatever you decide on don't forget to budget for some decent stands. |
#12
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Need advice for a small room
In article ,
Audio Empire wrote: with an on-axis frequency response of 55 to 30KHz +/- 3 dB! That's the problem. Apparently, what I am looking for is a speaker that has an off-axis response very similar to its on-axis response. That seems to explain a soundstage that stays focused from various points in the room, unless I completely mis-read what Haley was saying. |
#13
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Need advice for a small room
Robert Peirce wrote:
In article , Audio Empire wrote: with an on-axis frequency response of 55 to 30KHz +/- 3 dB! That's the problem. Apparently, what I am looking for is a speaker that has an off-axis response very similar to its on-axis response. In practice that's extremely hard to do: the best you can hope for is something that's reasonably well-behaved. Even that won't guarantee you a good soundstage everywhere in the room, because stereo isn't really adequate for that. A separate subwoofer is good advice, though, because the ideal speaker placement for lower bass may not be the same place as that for the rest if the spectrum. Andrew. |
#14
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Need advice for a small room
On 5/1/12 9:12 AM, in article , "Robert
Peirce" wrote: In article , Audio Empire wrote: with an on-axis frequency response of 55 to 30KHz +/- 3 dB! That's the problem. Apparently, what I am looking for is a speaker that has an off-axis response very similar to its on-axis response. That seems to explain a soundstage that stays focused from various points in the room, unless I completely mis-read what Haley was saying. How about this: http://linkwitzlab.com/Pluto/intro.htm and the upgrade: http://linkwitzlab.com/Pluto/Pluto-2.1.htm |
#15
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Need advice for a small room
In article ,
John Stone wrote: How about this: http://linkwitzlab.com/Pluto/intro.htm and the upgrade: http://linkwitzlab.com/Pluto/Pluto-2.1.htm Can't say. I bookmarked both URLs for later review. |
#16
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Need advice for a small room
On Tue, 1 May 2012 08:38:24 -0700, John Stone wrote
(in article ): On 5/1/12 9:12 AM, in article , "Robert Peirce" wrote: In article , Audio Empire wrote: with an on-axis frequency response of 55 to 30KHz +/- 3 dB! That's the problem. Apparently, what I am looking for is a speaker that has an off-axis response very similar to its on-axis response. That seems to explain a soundstage that stays focused from various points in the room, unless I completely mis-read what Haley was saying. How about this: http://linkwitzlab.com/Pluto/intro.htm and the upgrade: http://linkwitzlab.com/Pluto/Pluto-2.1.htm I can't say. I have heard the Orion at the "Burning Amp" DIY audio show and they were very good, but I don't know how wide their soundstage is , or how stable their imaging is off-axis. |
#17
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Need advice for a small room
On Tue, 1 May 2012 07:12:53 -0700, Robert Peirce wrote
(in article ): In article , Audio Empire wrote: with an on-axis frequency response of 55 to 30KHz +/- 3 dB! That's the problem. Apparently, what I am looking for is a speaker that has an off-axis response very similar to its on-axis response. That seems to explain a soundstage that stays focused from various points in the room, unless I completely mis-read what Haley was saying. Well, since 30 KHz is well beyond the best human hearing, I suspect that these speakers will still have good response to AT LEAST 15 KHz off-axis. That's why I mentioned them. You'll just have to make a short list and go listen.... |
#18
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Need advice for a small room
"Robert Peirce" wrote in message
... I am prepared to hear there are exceptions. For example, I have been told the Steinway Lyngdorf S-series actually does this very well; I had started to come to the conclusion it wouldn't. There are probably many other small speakers of which I am unaware that also can serve my purposes. The key is very good sound everywhere at the expense of close to perfect sound at one spot. If and when I ever have to move to a smaller apartment, I would relish the chance to experiment with multiple small computer speakers suspended from the ceiling. I would be able to aim them any which way I want, reflect some sound from front and side walls, establish a center channel with wide dispersion, and have multiple surround speakers anywhere I want. The number of these speakers would make up for any lack of power put out by each one, and a subwoofer would take care of bass duties. All this while remaining relatively invisible and needing no Wife Acceptance Factor. Gary Eickmeier |
#19
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Need advice for a small room
"Andrew Haley" wrote in message
... Robert Peirce wrote: That's the problem. Apparently, what I am looking for is a speaker that has an off-axis response very similar to its on-axis response. In practice that's extremely hard to do: the best you can hope for is something that's reasonably well-behaved. Even that won't guarantee you a good soundstage everywhere in the room, because stereo isn't really adequate for that. A separate subwoofer is good advice, though, because the ideal speaker placement for lower bass may not be the same place as that for the rest if the spectrum. Not hard to do. It's called an omni. But omni is not necessarily the ideal radiation pattern. What you want is time/intensity trading in both the direct and early reflected domains. This plus a certain speaker positioning scheme that is very easy to do and very beneficial no matter what speakers you have. Just think of your walls as mirrors, and position the two stereo speakers 1/4 of the room width in from side walls and out from front wall. If you make a drawing of this, you can see that the two actual and six reflected (virtual) speakers are positioned in an even lattice equidistant from each other, for a solid, even, deep, wide soundstage that can "project" any program material like a 3-dimensional canvas on which you paint the recorded sound. Notice also that we position speakers for imaging, not frequency response. For that, we can EQ and use subwoofers placed in the corners of the room. Take a look at my earlier response below, the last post in the current thread. I said it would be fun to take a bunch of small speakers, like computer desk speakers or home theater sattelites and hang them from the ceiling and position and aim them to create this magical sound field that has all of the characteristics of depth, imaging, time/intensity trading so you can walk all around and get even imaging everywhere. It would be done with techniques similar to Mark Davis's experiment in creating the Soundfield One speaker. Add a center channel and surround speakers placed ideally for your small room, and voila - a sonic Holodeck. Gary Eickmeier |
#20
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Need advice for a small room
Gary Eickmeier wrote:
"Andrew Haley" wrote in message ... Robert Peirce wrote: That's the problem. Apparently, what I am looking for is a speaker that has an off-axis response very similar to its on-axis response. In practice that's extremely hard to do: the best you can hope for is something that's reasonably well-behaved. Even that won't guarantee you a good soundstage everywhere in the room, because stereo isn't really adequate for that. A separate subwoofer is good advice, though, because the ideal speaker placement for lower bass may not be the same place as that for the rest if the spectrum. Not hard to do. It's called an omni. But omni is not necessarily the ideal radiation pattern. What you want is time/intensity trading in both the direct and early reflected domains. This plus a certain speaker positioning scheme that is very easy to do and very beneficial no matter what speakers you have. Just think of your walls as mirrors, and position the two stereo speakers 1/4 of the room width in from side walls and out from front wall. If you make a drawing of this, you can see that the two actual and six reflected (virtual) speakers are positioned in an even lattice equidistant from each other, for a solid, even, deep, wide soundstage that can "project" any program material like a 3-dimensional canvas on which you paint the recorded sound. Notice also that we position speakers for imaging, not frequency response. For that, we can EQ and use subwoofers placed in the corners of the room. Well, hold on. Placing the speakers at exactly 1/4 of the room width is going to maximally excite the second mode. Notching that out isn't going to be so easy, especially if you want to be able to listen in more than one position. Placing subwoofers in the corners is efficient, but it also maximally excites *all* of the room modes. I repeat to the OP: don't believe any simple solutions. I recommend CARA http://www.cara.de which alows people to do some simulations. Andrew. |
#21
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Need advice for a small room
"Andrew Haley" wrote in message
... Well, hold on. Placing the speakers at exactly 1/4 of the room width is going to maximally excite the second mode. Notching that out isn't going to be so easy, especially if you want to be able to listen in more than one position. Placing subwoofers in the corners is efficient, but it also maximally excites *all* of the room modes. I repeat to the OP: don't believe any simple solutions. I recommend CARA http://www.cara.de which alows people to do some simulations. Andrew. I can only suggest to you that if the room is large enough for realistic reproduction, and if the radiation pattern is not pure omni, or mostly direct, but rather has a D/R ratio with negative directivity, then most of these classical engineering "rules" go out the window. There will be no serious comb filtering, no room mode problem, no notches or bad peaks. The reason is that if the direct field is not as strong as most are used to, then it will not add and subtract in equal proportions to the early reflected sound. This is the sea change that permits us to position speakers for imaging, not for frequency response. The CARA series looks interesting, but I'm not so sure it isn't just another look at frequency response only, like most of them out there. It is loaded with pink noise signals and - horrors - sine waves! What the devil use are sine waves in room acoustics studies? In my old age curmudgeon phase, I am thinking more and more that the best test records are well-recorded music and effects that have things happening all around. Test signals are just a starting point, and you should adjust levels and EQ by ear more than meters. Gary Eickmeier |
#22
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Need advice for a small room
Gary Eickmeier wrote:
"Andrew Haley" wrote in message ... Well, hold on. Placing the speakers at exactly 1/4 of the room width is going to maximally excite the second mode. Notching that out isn't going to be so easy, especially if you want to be able to listen in more than one position. Placing subwoofers in the corners is efficient, but it also maximally excites *all* of the room modes. I repeat to the OP: don't believe any simple solutions. I recommend CARA http://www.cara.de which alows people to do some simulations. I can only suggest to you that if the room is large enough for realistic reproduction, and if the radiation pattern is not pure omni, or mostly direct, but rather has a D/R ratio with negative directivity, then most of these classical engineering "rules" go out the window. There will be no serious comb filtering, no room mode problem, no notches or bad peaks. C'mon Gary, you must know this is nonsense. Below the transition frequency, speakers are mostly ominidirectional anyway, and you can't get away from room modes. We cannae change the laws of physics, captain! The reason is that if the direct field is not as strong as most are used to, then it will not add and subtract in equal proportions to the early reflected sound. This is the sea change that permits us to position speakers for imaging, not for frequency response. The CARA series looks interesting, but I'm not so sure it isn't just another look at frequency response only, like most of them out there. Certainly not. It is loaded with pink noise signals and - horrors - sine waves! I have no idea what you are talking about. Andrew. |
#23
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Need advice for a small room
On Wed, 9 May 2012 06:07:59 -0700, Gary Eickmeier wrote
(in article ): "Andrew Haley" wrote in message ... Well, hold on. Placing the speakers at exactly 1/4 of the room width is going to maximally excite the second mode. Notching that out isn't going to be so easy, especially if you want to be able to listen in more than one position. Placing subwoofers in the corners is efficient, but it also maximally excites *all* of the room modes. I repeat to the OP: don't believe any simple solutions. I recommend CARA http://www.cara.de which alows people to do some simulations. Andrew. I can only suggest to you that if the room is large enough for realistic reproduction, and if the radiation pattern is not pure omni, or mostly direct, but rather has a D/R ratio with negative directivity, then most of these classical engineering "rules" go out the window. There will be no serious comb filtering, no room mode problem, no notches or bad peaks. The reason is that if the direct field is not as strong as most are used to, then it will not add and subtract in equal proportions to the early reflected sound. This is the sea change that permits us to position speakers for imaging, not for frequency response. The CARA series looks interesting, but I'm not so sure it isn't just another look at frequency response only, like most of them out there. It is loaded with pink noise signals and - horrors - sine waves! What the devil use are sine waves in room acoustics studies? In my old age curmudgeon phase, I am thinking more and more that the best test records are well-recorded music and effects that have things happening all around. Test signals are just a starting point, and you should adjust levels and EQ by ear more than meters. Gary Eickmeier My current rig, which consists of a pair of Martin-Logan Vantages and a pair of Aethena self-powered subwoofers in the corners was improved a hundredfold by using my amp's built-in DSP-based computer EQ system. This works by following the amp's VF display instructions on where to place an included microphone for each test. Not only did it EQ my speakers to be flat in frequency response at my listening position, but it also, finally, got the crossover right between the main speakers and the subs. I had been trying to do this by ear for the better part of a year without much joy. After the EQ program had done its stuff, I never again felt the need to touch the sub-woofer's controls! I'm very happy with the sound of my system, frequency-response wise at this time. I even find that the system images better than it did before it was EQ'd and I put that down to the smoothing of the frequency response in the room. |
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Need advice for a small room
On Apr 26, 9:23=A0am, Robert Peirce wrote:
For me, stereo is about the imaging. =A0I can't tell if my room is down 3db at 400hz, and frankly, I don't care as long as it sounds good. I don't even go in for room treatment of any sort. =A0Every room, including a concert hall is going to have peaks and dips. =A0I just live with that. Right now I have a pair of Apogee Divas in a room that is about 15.5'x25'. =A0Maybe I just got lucky, but I can walk just about anywhere in the room and the image is locked in place. =A0The only place this fail= s is if I stand within a foot directly in front of one of the speakers. I am planning to move and most of the rooms I am looking at tend to be on the order of 10-12'. =A0Sometimes they are almost square. =A0I was all hyped up on one product as a possibility for such a room until I found out it was more about getting correct response from the room then the kind of imaging I am after. So, are there any imaging nuts out there who are dealing successfully with small rooms? =A0What are you doing? Yikes: Coming in late, I get to see what has already been discussed to-date. Cutting to the chase, I would refer you to advice published in the early 1960s from no less than Acoustic Reseach on speaker placement. Given that they specialized in acoustic-suspension 'bookshelf' speakers of conventional/conservative (today) design, this will not apply in detail to your speakers, but it will do so in general. Take the longest wall in your room. Place one speaker (A) about two woofer-diameters in from one corner. Place the other (B) about midway between the first speaker and the other wall. Experiment with the placement of speaker B until you have the what you perceive as the best placement. Start with both speakers as close to the wall as possible, moving only speaker B until you are happy. Then A out from the wall (or not) and so forth. In/out from the wall affects bass primarily. Distance from the walls and each other affects soundstage primarily. Asymmetrical placement reduces/eliminates standing waves and cancellation waves as well as multiple sorts of room effects. This will give you the widest "sweet spot" available - closest to what you (apparently) perceive in your present location. Repeat the process on the shorter wall. AR suggested at the time that if there was a listening audience and if the listening room was used for other purposes than music, the long- wall placement would quite regularly 'win' as it gave the greatest audience spread. If for a single listener in a dedicated room, the short-wall would win as the sweet spot could be made quite small. And the natural progression to that concept is headphones. OPINION (typical rant removed): I find the concept of a tiny sweet spot as antithetical to the listening experience and about the furthest thing from duplicating a live setting as is possible (except for headphones). If I *must* keep my ears within a 12"/31cm cube in order to realize the best possible performance from my speakers - that is simply nuts. Peter Wieck Melrose Park, PA AR3a Maggie MG-III Revox Piccolo ARM5 AR14 AR Athena Dynaco A25 |
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Need advice for a small room
On May 10, 11:55=A0am, ScottW wrote:
On May 10, 6:10=A0am, Peter Wieck wrote: On Apr 26, 9:23=A0am, Robert Peirce wrote: =A0 I felt the same way...until my Quads created an oh so small, but oh so sweet...spot. ScottW I would never dispute the sweetness of the spot - but I would dispute the adequacies of the speakers and/or the forced placement in the room if that spot were the only truly sweet option. Point being that headphones will accomplish that ideal at a fraction of the cost, time or trouble. Peter Wieck Melrose Park, PA |
#26
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Need advice for a small room
On Thu, 10 May 2012 06:10:57 -0700, Peter Wieck wrote
(in article ): OPINION (typical rant removed): I find the concept of a tiny sweet spot as antithetical to the listening experience and about the furthest thing from duplicating a live setting as is possible (except for headphones). If I *must* keep my ears within a 12"/31cm cube in order to realize the best possible performance from my speakers - that is simply nuts. Peter Wieck Melrose Park, PA AR3a Maggie MG-III Revox Piccolo ARM5 AR14 AR Athena Dynaco A25 While I agree with you in theory, the reality is that the "sweet spot" concept is part of the baggage that stereo recording methodology carries with it. I've mentioned this before, but it doesn't hurt to reiterate: When you are at a live, unamplified concert, and you move around with respect the stage (or other locus of performance) your ears go with you and your perspective changes with location. When listening to a recording, and you move around the room, your surrogate ears, the microphones, and ultimately, (in the case of multi-miked, multi-channel recordings) the final mix has one set perspective because the "mikes" DON'T move. That being the case, there is only ONE set place where the perspective is correct, IOW, there is only one place in front of the speakers (right to left) where the listener is on the same axis as the surrogate ears. Naturally, this is the place where the imaging and soundstage snap into sharp focus. If you aren't in that spot, you still hear a sound-field, but the focus will be gone. An analogy would be a 3-D visual image. As you move the right-eye image and the left-eye image closer together and further apart, there is only one relative position where these two images coalesce in your mind as a single 3-D image (assuming, of course, you are wearing the glasses) with depth as well as height and width. That's because your surrogate eyes are a pair of lenses on a camera that are a set distance apart. That means that when viewing those images they must give the illusion of being the same distance apart to your brain, or you won't see the stereo effect - with or without the glasses. |
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Need advice for a small room
On Thu, 10 May 2012 11:53:52 -0700, Peter Wieck wrote
(in article ): On May 10, 11:55=A0am, ScottW wrote: On May 10, 6:10=A0am, Peter Wieck wrote: On Apr 26, 9:23=A0am, Robert Peirce wrote: =A0 I felt the same way...until my Quads created an oh so small, but oh so sweet...spot. ScottW I would never dispute the sweetness of the spot - but I would dispute the adequacies of the speakers and/or the forced placement in the room if that spot were the only truly sweet option. Point being that headphones will accomplish that ideal at a fraction of the cost, time or trouble. Peter Wieck Melrose Park, PA Not really. Unless we are talking about binaural recordings, 'phones don't really do stereo very well. The images are usually inside one's head (I mean spatially, not as in "sound is made in the brain rather than the ears) when a stereo recording is played. But good binaural can be extremely realistic sounding (until one moves one's head and the image moves it). |
#28
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Need advice for a small room
"Audio Empire" wrote in message
... While I agree with you in theory, the reality is that the "sweet spot" concept is part of the baggage that stereo recording methodology carries with it. I've mentioned this before, but it doesn't hurt to reiterate: When you are at a live, unamplified concert, and you move around with respect the stage (or other locus of performance) your ears go with you and your perspective changes with location. When listening to a recording, and you move around the room, your surrogate ears, the microphones, and ultimately, (in the case of multi-miked, multi-channel recordings) the final mix has one set perspective because the "mikes" DON'T move. That being the case, there is only ONE set place where the perspective is correct, IOW, there is only one place in front of the speakers (right to left) where the listener is on the same axis as the surrogate ears. Naturally, this is the place where the imaging and soundstage snap into sharp focus. If you aren't in that spot, you still hear a sound-field, but the focus will be gone. An analogy would be a 3-D visual image. As you move the right-eye image and the left-eye image closer together and further apart, there is only one relative position where these two images coalesce in your mind as a single 3-D image (assuming, of course, you are wearing the glasses) with depth as well as height and width. That's because your surrogate eyes are a pair of lenses on a camera that are a set distance apart. That means that when viewing those images they must give the illusion of being the same distance apart to your brain, or you won't see the stereo effect - with or without the glasses. No. Not analogous. There need not be a single "sweet spot" nor a single perspective that was viewed by some single stereo microphone. The example in my Mars paper - which I think I sent you - was of an imaginary recording made with one microphone per instrument, then played back on speakers that have similar radiation patterns to the instrument they are reproducing, and are placed in positions that are geometrically similar to the original. Such an ideal system creates a sound field that is spatially a duplicate of the original. You can move around in it just like live. The realism of it depends on the size of the room being similar to the original, or what the original would be good in. And most notably, neither the recording nor the reproduction have anything to do with the number of ears on your head or the spacing between them or any single position of any microphone during the recording. Stereo is not a head-related system like binaural, nothing to do with the human hearing mechanism, but rather the creation of sound fields in rooms. It is confusing when we begin to simplify the system down to fewer channels, especially if it gets all the way down to two channels, because then we begin to think that the two speakers are reproducing EAR SIGNALS, which they are not. The only aspect of playback that relates to the human hearing mechanism is the summing localization that is employed to create the phantom imaging between speakers. Discrete surround sound with the center channel gets us some of the way away from that confusion, but the nature of the system remains the same, and the confusion will always be with us. But even with a simplified-down system there needn't be a single sweet spot or single perspective on the instruments, if you employ a proper radiation pattern, speaker positioning, and a good room. Gary Eickmeier |
#29
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Need advice for a small room
On Fri, 11 May 2012 06:02:09 -0700, Gary Eickmeier wrote
(in article ): "Audio Empire" wrote in message ... While I agree with you in theory, the reality is that the "sweet spot" concept is part of the baggage that stereo recording methodology carries with it. I've mentioned this before, but it doesn't hurt to reiterate: When you are at a live, unamplified concert, and you move around with respect the stage (or other locus of performance) your ears go with you and your perspective changes with location. When listening to a recording, and you move around the room, your surrogate ears, the microphones, and ultimately, (in the case of multi-miked, multi-channel recordings) the final mix has one set perspective because the "mikes" DON'T move. That being the case, there is only ONE set place where the perspective is correct, IOW, there is only one place in front of the speakers (right to left) where the listener is on the same axis as the surrogate ears. Naturally, this is the place where the imaging and soundstage snap into sharp focus. If you aren't in that spot, you still hear a sound-field, but the focus will be gone. An analogy would be a 3-D visual image. As you move the right-eye image and the left-eye image closer together and further apart, there is only one relative position where these two images coalesce in your mind as a single 3-D image (assuming, of course, you are wearing the glasses) with depth as well as height and width. That's because your surrogate eyes are a pair of lenses on a camera that are a set distance apart. That means that when viewing those images they must give the illusion of being the same distance apart to your brain, or you won't see the stereo effect - with or without the glasses. No. Not analogous. There need not be a single "sweet spot" nor a single perspective that was viewed by some single stereo microphone. The example in my Mars paper - which I think I sent you - was of an imaginary recording made with one microphone per instrument, then played back on speakers that have similar radiation patterns to the instrument they are reproducing, and are placed in positions that are geometrically similar to the original. Such an ideal system creates a sound field that is spatially a duplicate of the original. You can move around in it just like live. The realism of it depends on the size of the room being similar to the original, or what the original would be good in. And most notably, neither the recording nor the reproduction have anything to do with the number of ears on your head or the spacing between them or any single position of any microphone during the recording. Stereo is not a head-related system like binaural, nothing to do with the human hearing mechanism, but rather the creation of sound fields in rooms. It is confusing when we begin to simplify the system down to fewer channels, especially if it gets all the way down to two channels, because then we begin to think that the two speakers are reproducing EAR SIGNALS, which they are not. The only aspect of playback that relates to the human hearing mechanism is the summing localization that is employed to create the phantom imaging between speakers. Discrete surround sound with the center channel gets us some of the way away from that confusion, but the nature of the system remains the same, and the confusion will always be with us. But even with a simplified-down system there needn't be a single sweet spot or single perspective on the instruments, if you employ a proper radiation pattern, speaker positioning, and a good room. While much of what you say is true, with two channels, there is only a very narrow range of listening positions where the aural images are in focus. This has to be. Microphones aren't ears and they don't even ACT like ears and in fact we don't want them to act like ears, because if they did, we would have binaural recordings, not stereo recordings. But they do build-up a snapshot of the performance from a fixed perspective. It doesn't matter whether this perspective is the result of some co-incident microphone technique such as M-S or ORTF, or whether it's the result of widely-spaced omnis, or whether it's a studio-mixed sound-field made up from the outputs of dozens of microphones recorded to dozens of separate channels all mixed down to two. The result, on the listener's end is the same. A fixed perspective that does not move when the listener moves. You are right again when you say that the only way around this is to have a microphone and channel per instrument and a speaker on the listening end per instrument all arranged exactly where the original instrument was arranged during the recording process. This would give the playback a similar image specificity to a real performance. Bell Labs noted this in their 1933 stereophonic experiments. They started with one channel per instrument (not recorded, of course, merely piped-in by hard-wire from another, remote location) and kept reducing the number of channels (on both ends) until but two remained. They noted that it was entirely practical to convey the stereophonic effect with merely two channels, but they also added the caveat that with two channels, the optimum stereo effect was achieved only at the point in front of the speakers where the sound-fields from the two channels intersect. |
#30
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Need advice for a small room
On Fri, 11 May 2012 16:11:51 -0700, ScottW wrote
(in article ): On May 11, 6:02am, "Gary Eickmeier" wrote: "Audio Empire" wrote in message ... Snip You can move around in it just like live. The realism of it depends on the size of the room being similar to the original, or what the original would be good in. And most notably, neither the recording nor the reproduction have anything to do with the number of ears on your head or the spacing between them or any single position of any microphone during the recording. All very nice theory, but reality is most of us are dealing with stereo recordings. One reason I think the Quads image so well is there lack of wide dispersion and therefore reduced reflection interference. Best imaging systems are in either highly damped (non-reflective rooms), near field setups, or controlled dispersion IMO. Frequency response doesn't have a lot of correlation with imaging to me. ScottW I can't speak for the Quads as I've never lived with a pair, but I can tell you that the reason why the Martin-Logans image so well is because of their curved screens, I once had a pair of Innersound flat panel electrostatics in my listening room for about three months and they drove me mad. The flat panel ES element required that the LISTENER (notice the lack of a plural, here) do an elaborate set-up involving holding a small flashlight in one's mouth and pointing ones' head dead-ahead. Then one moved the panels until one could see the flashlight reflection, equally, in the center of both panels. Then one had to sit as if one's head was in a vise or the imaging would collapse and the highs would go away. If you sat perfectly still, OTOH, they did sound marvelous. With the M-Ls, the curvature of the screen, meant that starting in the upper midrange, the section of the curve facing the listener acts as a line source. So wherever you sit, as long as you are on axis with both curved surfaces, you get a decent image. Indeed, the sweet spot is very wide with these speakers and can comfortably accommodate several listeners at once. |
#31
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Need advice for a small room
Audio Empire wrote:
While much of what you say is true, with two channels, there is only a very narrow range of listening positions where the aural images are in focus. This has to be. Microphones aren't ears and they don't even ACT like ears and in fact we don't want them to act like ears, because if they did, we would have binaural recordings, not stereo recordings. But they do build-up a snapshot of the performance from a fixed perspective. It doesn't matter whether this perspective is the result of some co-incident microphone technique such as M-S or ORTF, or whether it's the result of widely-spaced omnis, or whether it's a studio-mixed sound-field made up from the outputs of dozens of microphones recorded to dozens of separate channels all mixed down to two. The result, on the listener's end is the same. A fixed perspective that does not move when the listener moves. Well, I hope you can see that this "fixed perspective" is a property of the reproduction and not a basic property of the system. In fact, if you have a multi-miked recording (which is NOT in incorrect technique in any sense) then there IS no "perspective" from which the recording was made. If you had the multitrack master, if it was recorded that way, then you could actually pipe each mike thru a channel of its own out to a speaker positioned where it was and you would have my example. You are right again when you say that the only way around this is to have a microphone and channel per instrument and a speaker on the listening end per instrument all arranged exactly where the original instrument was arranged during the recording process. This would give the playback a similar image specificity to a real performance. Bell Labs noted this in their 1933 stereophonic experiments. They started with one channel per instrument (not recorded, of course, merely piped-in by hard-wire from another, remote location) and kept reducing the number of channels (on both ends) until but two remained. They noted that it was entirely practical to convey the stereophonic effect with merely two channels, but they also added the caveat that with two channels, the optimum stereo effect was achieved only at the point in front of the speakers where the sound-fields from the two channels intersect. Yes, again, playback only situation, not systemic. And I thought they ended up with a three channel system. The movie people are always one step ahead of the pure audio people. You can see that at least with DD 5.1 surround sound, you can be anywhere in the audience and perceive the center channel dialog as coming from the center of the screen. Stereo theory is constantly confused with binaural theory due to the widespread use of the two channel system. We've got to shake that off and start from scratch. I really like your example of the Innersound electrostatics driving you mad. I had the same reaction to the Acoustats. The classical theorists would think this an ideal situation, if the two channels were "ear signals" meant to be piped to your ears. All that would be missing would be crosstalk cancellation to get all the way to binaural and total confusion. I hope that your listening experience with the curved panel electrostatics also includes a more natural, realistic sound field generated in your room. Some listeners (Siegfried Linkwitz among others) realize that the reflected sound can be a part of the realistic construction of the stereo image, and in fact should be the same frequency response as the direct sound, not an accidental byproduct of whatever sound comes off the back of a box speaker. The whole theory of stereo is usually taken wrong because of these multiple errors and misconceptions, and there doesn't seem to be a path out of it, because of a lot of folklore and a lack of a single theory on exactly what it is that we are doing with auditory perspective systems. Two channel stereo is the main culprit, and multichannel is a partial solution, thanks to the film people. But can't we short-circuit all the cut and try fumbling and examine the macro situation and state it once and for all? Gary Eickmeier |
#32
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Need advice for a small room
On Sat, 12 May 2012 18:23:01 -0700, Gary Eickmeier wrote
(in article ): Audio Empire wrote: While much of what you say is true, with two channels, there is only a very narrow range of listening positions where the aural images are in focus. This has to be. Microphones aren't ears and they don't even ACT like ears and in fact we don't want them to act like ears, because if they did, we would have binaural recordings, not stereo recordings. But they do build-up a snapshot of the performance from a fixed perspective. It doesn't matter whether this perspective is the result of some co-incident microphone technique such as M-S or ORTF, or whether it's the result of widely-spaced omnis, or whether it's a studio-mixed sound-field made up from the outputs of dozens of microphones recorded to dozens of separate channels all mixed down to two. The result, on the listener's end is the same. A fixed perspective that does not move when the listener moves. Well, I hope you can see that this "fixed perspective" is a property of the reproduction and not a basic property of the system. In fact, if you have a multi-miked recording (which is NOT in incorrect technique in any sense) I suppose that depends upon what you are trying to record. If you are recording a rock-n-roll band, it's fine (since most rock-n-roll performances can't exist outside of the studio, anyway). It is even "the correct way" if you are recording a jazz group using the "traditional" 3-channel mono technique (where the ensemble in broken up into three groups and the groups are pan-potted right, left, and center). However, it would be a misnomer to call any multi-miked, muti-track recording "stereo". It simply isn't ; it is merely multi-channel monaural sound. And if you think that it is not an incorrect technique to multi-mike a symphony orchestra, then we are going to have to agree to disagree, because in my estimation, that procedure is EVERY KIND OF WRONG! then there IS no "perspective" from which the recording was made. I still disagree. The "perspective" is the one chosen by the mix engineer when he assigns instruments or groups of instruments to their left-to-right positions by pan-potting them into place. For instance if he is mixing a jazz quartet where the dominant instrumentalist is a sax, and he pan pots it equally between left and right, then it will appear in the phantom center channel. He might then pan the drum kit to the left, the bass to the right, along with the piano. That's the "perspective" that the mix engineer (and, ostensibly, the producer), wants. If you had the multitrack master, if it was recorded that way, then you could actually pipe each mike thru a channel of its own out to a speaker positioned where it was and you would have my example. Certainly you would. And as long as the speaker occupied the same relative space on the playback side that the original instrument occupied in the record space, then you would have a fair representation of the original DIRECT sound field (but none of the venue's ambience). You are right again when you say that the only way around this is to have a microphone and channel per instrument and a speaker on the listening end per instrument all arranged exactly where the original instrument was arranged during the recording process. This would give the playback a similar image specificity to a real performance. Bell Labs noted this in their 1933 stereophonic experiments. They started with one channel per instrument (not recorded, of course, merely piped-in by hard-wire from another, remote location) and kept reducing the number of channels (on both ends) until but two remained. They noted that it was entirely practical to convey the stereophonic effect with merely two channels, but they also added the caveat that with two channels, the optimum stereo effect was achieved only at the point in front of the speakers where the sound-fields from the two channels intersect. Yes, again, playback only situation, not systemic. And I thought they ended up with a three channel system. Read and Welch ('From Tinfoil to Stereo' C. 1967 Howard Sams & Co., Inc.) say that the Bell Labs stereo experiements settled on two channels. The movie people are always one step ahead of the pure audio people. You can see that at least with DD 5.1 surround sound, you can be anywhere in the audience and perceive the center channel dialog as coming from the center of the screen. They use three discrete channels in front , so I suspect they would get a strong dialog channel in the center. Stereo theory is constantly confused with binaural theory due to the widespread use of the two channel system. We've got to shake that off and start from scratch. I really like your example of the Innersound electrostatics driving you mad. I had the same reaction to the Acoustats. The classical theorists would think this an ideal situation, I can't imagine why. I would think that the ideal would be a broad, stable stereo image with wide dispersion that would give listeners a decent stereo image no matter where in the sound field they sat. if the two channels were "ear signals" meant to be piped to your ears. All that would be missing would be crosstalk cancellation to get all the way to binaural and total confusion. Binaural only works with headphones. Even then it's not perfect. The binaural miking setup cannot differentiate sounds coming from the dead front from sounds coming from the dead rear of the "head". I hope that your listening experience with the curved panel electrostatics also includes a more natural, realistic sound field generated in your room. Some listeners (Siegfried Linkwitz among others) realize that the reflected sound can be a part of the realistic construction of the stereo image, and in fact should be the same frequency response as the direct sound, not an accidental byproduct of whatever sound comes off the back of a box speaker. Well, as with most domestic situations, it is what it is. The whole theory of stereo is usually taken wrong because of these multiple errors and misconceptions, and there doesn't seem to be a path out of it, because of a lot of folklore and a lack of a single theory on exactly what it is that we are doing with auditory perspective systems. Two channel stereo is the main culprit, and multichannel is a partial solution, thanks to the film people. But can't we short-circuit all the cut and try fumbling and examine the macro situation and state it once and for all? I don't think so. The live sound field is incredibly complex. Each instrument's sound takes it's own path(s) from the instrument to the ear. It is also mixed in the air with the other instruments accompanying it and it is followed by primary and secondary reflections off of every surface, hard or soft, in the room. How can one ever decide how many channels is enough to convey all the right cues for every conceivable mix of instruments in every conceivable type of venue? I think that just getting two-channel stereo right is difficult enough (witnessed by the fact that it is so seldom done correctly) and that's a worthy goal, in and of itself. |
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Need advice for a small room
"Audio Empire" wrote in message
... I suppose that depends upon what you are trying to record. If you are recording a rock-n-roll band, it's fine (since most rock-n-roll performances can't exist outside of the studio, anyway). It is even "the correct way" if you are recording a jazz group using the "traditional" 3-channel mono technique (where the ensemble in broken up into three groups and the groups are pan-potted right, left, and center). However, it would be a misnomer to call any multi-miked, muti-track recording "stereo". It simply isn't ; it is merely multi-channel monaural sound. And if you think that it is not an incorrect technique to multi-mike a symphony orchestra, then we are going to have to agree to disagree, because in my estimation, that procedure is EVERY KIND OF WRONG! I can only offer you the Telarc and Mercury three spaced omni technique which won popular acclaim for a long period of time. So much so that Stan Lip****z found it important to rail against it in his famous article "Stereo Microphone Techniques: Are the Purists Wrong?". http://www.aes.org/e-lib/browse.cfm?elib=11494 I claim in my papers that the spaced omni technique is the more correct, for reasons pointed out in my stereo theory (Image Model Theory, IMT) http://www.aes.org/e-lib/browse.cfm?elib=5825 Basically, the three omnis are sampling the sound field at 3 locations in the concert hall, rather than at one central location as with Stanley's coincident technique and your ideas. There is no single "perspective" from which you are supposed to witness the sound; if done properly, you should be able to move around in your playback room and perceive the sound from various perspectives, just as live. Note also that the three microphones are picking up not just direct sound, but the room ambience from the left and right sides and from the center. To play these recordings properly, you do NOT want that ambience to come from the direct field of your three front speakers, but from a wide set of incident angles, modeled after the real thing, and supplemented by surround speakers on delay. Hence, the importance of the radiation pattern of the front speakers and a correct mix of direct and reflected emanating from the speakers, with equi-omni frequency response and room positioning that also models the playback situation after the live event.. I still disagree. The "perspective" is the one chosen by the mix engineer when he assigns instruments or groups of instruments to their left-to-right positions by pan-potting them into place. For instance if he is mixing a jazz quartet where the dominant instrumentalist is a sax, and he pan pots it equally between left and right, then it will appear in the phantom center channel. He might then pan the drum kit to the left, the bass to the right, along with the piano. That's the "perspective" that the mix engineer (and, ostensibly, the producer), wants. That is the layout of the instruments that the engineer wants, but you may be able to move around in your listening room and perceive them from various perspectives. Doesn't work like a visual 3D image or a binaural audio recording. My IMT sees the reproduction as a model of the real thing, that you can move around in, rather than a sort of "window" or portal to another acoustic space, through which you must sit and listen from a single perspective. If you had the multitrack master, if it was recorded that way, then you could actually pipe each mike thru a channel of its own out to a speaker positioned where it was and you would have my example. Certainly you would. And as long as the speaker occupied the same relative space on the playback side that the original instrument occupied in the record space, then you would have a fair representation of the original DIRECT sound field (but none of the venue's ambience). Why? Where did it go? I don't think so. The live sound field is incredibly complex. Each instrument's sound takes it's own path(s) from the instrument to the ear. It is also mixed in the air with the other instruments accompanying it and it is followed by primary and secondary reflections off of every surface, hard or soft, in the room. How can one ever decide how many channels is enough to convey all the right cues for every conceivable mix of instruments in every conceivable type of venue? I think that just getting two-channel stereo right is difficult enough (witnessed by the fact that it is so seldom done correctly) and that's a worthy goal, in and of itself. You are unnecessarily confusing yourself. All of that "complexity" is being recorded by the microphones and can be reproduced fairly well - well enough for musical enjoyment - in a loudspeaker playback situation. We cannot get all the way there because of the nature of the system (the "central recording problem" of having to run the sound through two different acoustic spaces), so we must understand what is happening and the limitations of the system and what we can hear. All of this does pertain to the OP's initial question, so I don't feel like we are hijacking the thread too bad, but I would like to take it to a new thread with a new tack from my usual line, if you would like to follow me there. What can we hear? Gary Eickmeier |
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