Adason Please don't kill this thread, it's an important one for those of us who don't want to build an exact copy of Keele's CBT line array.
Bear was not questioning your earlier answer, he just wanted to know, same as me.
Sometimes I have to be told twice.
Adason, Would you prefer us to start a new thread? (no sarcasm intended, only respect)
Omholt. Who says a line array has to be straight?
Ron
Bear was not questioning your earlier answer, he just wanted to know, same as me.
Sometimes I have to be told twice.
Adason, Would you prefer us to start a new thread? (no sarcasm intended, only respect)
Omholt. Who says a line array has to be straight?
Ron
Adason, I was only asking about the SUBJECTIVE SOUNDSTAGE, in *your* opinion.
Fact is that the ear *tends* in most situations to identify the center of an array of HF drivers as the *source* of the HF sound. That would place the typical listener's identification of the soundstage as being "low" rather than "middle" or "high".
WRT to the question about the upper area being important to the listener, that would depend a great deal upon the listening environment.
In a room with very tall ceilings (like >20ft) probably the upper area of the curve would have nil effect as far as the listener's perceptions. But to make it clearer, if the ceiling was 10ft high, then reflections, delayed in time and WRT to frequency could very well have a significant effect on the *perception* of the listener.
hope this explains my interest...
_-_-
Fact is that the ear *tends* in most situations to identify the center of an array of HF drivers as the *source* of the HF sound. That would place the typical listener's identification of the soundstage as being "low" rather than "middle" or "high".
WRT to the question about the upper area being important to the listener, that would depend a great deal upon the listening environment.
In a room with very tall ceilings (like >20ft) probably the upper area of the curve would have nil effect as far as the listener's perceptions. But to make it clearer, if the ceiling was 10ft high, then reflections, delayed in time and WRT to frequency could very well have a significant effect on the *perception* of the listener.
hope this explains my interest...
_-_-
I've gone around and around on this one over the years and remain unconvinced that "Shading or Tapered Output" is a logical solution to the problem. I think that (what I believe you're advocating) is an inadaquate "bandage" approach, that fails to fully address the problem, or provide an elegant solution.
Best Regards,
TerryO
Line array shootout. AES (Audio Engineering Society) Convention paper. San Francisco 2010
http://www.xlrtechs.com/dbkeele.com...rmance Ranking of Loudspeaker Line Arrays.pdf
A little bit suspect as the testing was subjective. Lots of great graphs though.
Ron
http://www.xlrtechs.com/dbkeele.com...rmance Ranking of Loudspeaker Line Arrays.pdf
A little bit suspect as the testing was subjective. Lots of great graphs though.
Ron
Hi Mike,
I haven't heard them and I was a little unsure if I really understood what was going on. However, several people that I've known for "a long time" actually had and told me that the claims for the design seemed to be completely valid!
In fact, they claimed that the design actually sounded quite nice.
Best Regards,
Terry
I did the math myself; 25 of those 3 inchers is the equivalent cone surface area of a 16 inch woofer. 25 on each side means two 16 inch woofers in the room. The Xmax is the big difference and is very limited, but you can either add woofers below say 80HZ (with a 4 pole active crossover), or not turn it up so loud. I really like the sound of small woofers, as long as they go down to at least 30HZ acoustically at my chair. Those who want to show off how loud their system can go should definitely look elsewhere.
How any speaker interacts with room acoustics is in my opinion the weakest link in most systems. It makes sense to me that a floor to ceiling line array like Roger Russel's would deal with room acoustics better than perhaps any other speaker out there.
A bit depends on whose ceiling we're talking about and just how high said ceiling may be?
I think the Keele design's strong point is that it eliminates the problems that occur as the result of the *top* of the line array *terminating* in the air, without reaching another surface (the ceiling). A close read of his paper shows that close enough to a straight line array that does NOT reach the ceiling, or seated, that there is no major benefit to the Keele design.
This means that the Keele design can be shorter than a line array and can be used in rooms where there is a high ceiling or effectively no ceiling, and will sound the same (more or less) at any distance back from the speaker.
The distance back that one can go with a straight array is shown in Keele's graphs and diagrams WRT to height of listening position. In practice, and for most people, it may not make any difference. Certainly *if* the line array can go ceiling to floor the line array generally speaking does not suffer the problem that the Keele array addresses.
At least this is what I came away with.
Otoh, the Keele array in a room with a very moderate ceiling height, like 8' - 12' or maybe more, and depending to some extent upon the listening position and assuming a typical ceiling construction it seems to me that the reflections could be quite problematic.
Anyone who has heard the Keele arrays, I am curious about your subjective perception of the soundfield. Like where the apparent sound source was, low, medium, high. Did it sound like a small sound source (as with a typical small satellite speaker) or did it sound like a moderate size, or a tall or large sound source. I can imagine what my expectations might be based on experience and by looking at the design and how it works, but that really isn't the same as hearing it. Really curious about people's perceptions of it vs. their listening position and what the room was.
_-_-
I think the Keele design's strong point is that it eliminates the problems that occur as the result of the *top* of the line array *terminating* in the air, without reaching another surface (the ceiling). A close read of his paper shows that close enough to a straight line array that does NOT reach the ceiling, or seated, that there is no major benefit to the Keele design.
This means that the Keele design can be shorter than a line array and can be used in rooms where there is a high ceiling or effectively no ceiling, and will sound the same (more or less) at any distance back from the speaker.
The distance back that one can go with a straight array is shown in Keele's graphs and diagrams WRT to height of listening position. In practice, and for most people, it may not make any difference. Certainly *if* the line array can go ceiling to floor the line array generally speaking does not suffer the problem that the Keele array addresses.
At least this is what I came away with.
Otoh, the Keele array in a room with a very moderate ceiling height, like 8' - 12' or maybe more, and depending to some extent upon the listening position and assuming a typical ceiling construction it seems to me that the reflections could be quite problematic.
Anyone who has heard the Keele arrays, I am curious about your subjective perception of the soundfield. Like where the apparent sound source was, low, medium, high. Did it sound like a small sound source (as with a typical small satellite speaker) or did it sound like a moderate size, or a tall or large sound source. I can imagine what my expectations might be based on experience and by looking at the design and how it works, but that really isn't the same as hearing it. Really curious about people's perceptions of it vs. their listening position and what the room was.
_-_-
I have not tried the shading on my arrays either .. but I like them a lot. My ceiling is 9' high and the tweeters cover the entire 36 degree curve.
http://www.diyaudio.com/forums/multi-way/239278-building-some-cbt-clones.html
http://www.diyaudio.com/forums/multi-way/239278-building-some-cbt-clones.html
Right now I have the speakers about 15 feet apart and I think that is too far. The imaging of the system is excellent . so having the speakers so far apart makes things unrealistically large.
I also notice with these that when I leave the room, there is noticeably less sound that comes out into the hallway than with other speakers I have had in the same room. Pretty tight horizontal dispersion.
I also notice with these that when I leave the room, there is noticeably less sound that comes out into the hallway than with other speakers I have had in the same room. Pretty tight horizontal dispersion.
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I must not be asking things right or explaining myself properly.
My question is related to the perception of the soundstage compared to other types and sizes of speakers. For example many people complain that a large line array causes them to hear "voices like they are ten feet tall", compared with mini monitors that can cause the opposite reaction...
I'm wondering with the array being curved if the perception is that of a single small speaker on axis or a tall speaker (for example)?
Forget about how it looks, what does it do when you close your eyes and listen?
My question is related to the perception of the soundstage compared to other types and sizes of speakers. For example many people complain that a large line array causes them to hear "voices like they are ten feet tall", compared with mini monitors that can cause the opposite reaction...
I'm wondering with the array being curved if the perception is that of a single small speaker on axis or a tall speaker (for example)?
Forget about how it looks, what does it do when you close your eyes and listen?
In the AES paper with all the nice graphs, I didn't see any mention of what kind of room the various line arrays were tested in. To my way of thinking, the whole point of using a line array is about making a speaker that works better with listening room acoustics. If a line array goes floor to ceiling you get a certain acoustic interaction. If it only goes part way to the ceiling, you get a substantially different acoustic situation.
On the issue of sound images seeming bigger than life or bigger than real, consider how the recordings are made. The lead singer or whatever, has a mono mic right up against their mouth... what would you expect a perfect reproduction system to do with that? That's pretty different than if they had used a stereo head mic at a distance from the lead singer, which one could argue is a more accurate recording technique.
So now you've got two things you're trying to optimize for; room acoustics and making a mono mic'd sound in the middle sound the right size... If you shrink the lead singer down to the right size, do you not shrink everything else too?
I had to wonder if the AES paper wasn't written as a sales pitch for the truncated curved speaker. It may have missed the point of how a speaker works with actual typical listening room acoustics. If you've got a particularly high ceiling, then maybe line arrays aren't the best speaker for the job. Maybe the Linkwitz approach would be more pleasing (minimal room mode stimulation rather than maximum).
A point source might measure best in an anechoic chamber, but may cause worse case acoustic reflection issues in a typical real world listening room. When there are lots of reflections caused by drivers that are all physically displaced from one another, the comb filter cancellations at any listening positions get filled in my the signals from other drivers, that have their cancellations at different frequencies. You end up with a small amount of ripple in the frequency response rather than large cancellations. Most of the rooms I've measured speakers in have been highly reactive, creating peaks and dips on the order of 10dB+. Bass gets "boomy" and the rest is colored randomly. These rooms do lots of damage by the time the sound gets to the listener. That's what I consider perhaps the main problem with a reproduction system.
On the issue of sound images seeming bigger than life or bigger than real, consider how the recordings are made. The lead singer or whatever, has a mono mic right up against their mouth... what would you expect a perfect reproduction system to do with that? That's pretty different than if they had used a stereo head mic at a distance from the lead singer, which one could argue is a more accurate recording technique.
So now you've got two things you're trying to optimize for; room acoustics and making a mono mic'd sound in the middle sound the right size... If you shrink the lead singer down to the right size, do you not shrink everything else too?
I had to wonder if the AES paper wasn't written as a sales pitch for the truncated curved speaker. It may have missed the point of how a speaker works with actual typical listening room acoustics. If you've got a particularly high ceiling, then maybe line arrays aren't the best speaker for the job. Maybe the Linkwitz approach would be more pleasing (minimal room mode stimulation rather than maximum).
A point source might measure best in an anechoic chamber, but may cause worse case acoustic reflection issues in a typical real world listening room. When there are lots of reflections caused by drivers that are all physically displaced from one another, the comb filter cancellations at any listening positions get filled in my the signals from other drivers, that have their cancellations at different frequencies. You end up with a small amount of ripple in the frequency response rather than large cancellations. Most of the rooms I've measured speakers in have been highly reactive, creating peaks and dips on the order of 10dB+. Bass gets "boomy" and the rest is colored randomly. These rooms do lots of damage by the time the sound gets to the listener. That's what I consider perhaps the main problem with a reproduction system.
Moving them closer will not alter that much if at all.
Not sure I would want that to change. Get farther back and away and the soundstage will appear subjectively a bit smaller. When you get effectively closer in, definitely within the 45degree triangle for the listening position this speaker and any speaker will cast a much bigger soundstage - generally speaking.
Bob Richards,
Part of the problem is that in "normal" size listening rooms, *every* speaker is some range of compromise. The question is always which compromises are you willing to accept and which compromises are unacceptable for *your room* (and ears).
A close look at the graphs that Keele posted shows that at some heights and distances the response at the ear is "fine" with a straight array. Further back in distance/height is where the Keele array appears to make corrections.
However, somewhere up the array, like half way or so, the delay between the nominally direct firing speakers and halfway up starts to get significant. I presume it averages out to some extent, but there has to be a response variation between sitting low and standing up I would expect.
As far as the size of the image vs. speakers, there are issues with this which is why I am inquiring about how the Keele/CBT or similar non-CBT curved arrays fare in this regard.
I have my views, opinions and experiences in this regards, but I am hoping to get unbiased reports before dropping in what I think.
Here's a pix of an array built in ~1976.
A Peerless 5 1/4" driver - tweeter set up not shown.
Not sure I would want that to change. Get farther back and away and the soundstage will appear subjectively a bit smaller. When you get effectively closer in, definitely within the 45degree triangle for the listening position this speaker and any speaker will cast a much bigger soundstage - generally speaking.
Bob Richards,
Part of the problem is that in "normal" size listening rooms, *every* speaker is some range of compromise. The question is always which compromises are you willing to accept and which compromises are unacceptable for *your room* (and ears).
A close look at the graphs that Keele posted shows that at some heights and distances the response at the ear is "fine" with a straight array. Further back in distance/height is where the Keele array appears to make corrections.
However, somewhere up the array, like half way or so, the delay between the nominally direct firing speakers and halfway up starts to get significant. I presume it averages out to some extent, but there has to be a response variation between sitting low and standing up I would expect.
As far as the size of the image vs. speakers, there are issues with this which is why I am inquiring about how the Keele/CBT or similar non-CBT curved arrays fare in this regard.
I have my views, opinions and experiences in this regards, but I am hoping to get unbiased reports before dropping in what I think.
Here's a pix of an array built in ~1976.
A Peerless 5 1/4" driver - tweeter set up not shown.
Attachments
I've heard Keele's array twice, in different rooms in different states. I would say it sounds bigger than it looks, but not the over-blown giant sound of most line arrays. The CBTs are quite small, actually. They are tall, but slim of footprint. They sound bigger than they look, but not too big. The image seems to come out of the middle of the space between them, left right, top, bottom.
One remarkable thing is that you can walk far down the hall into another room to get a cup of coffee* and the sound changes very little. I suppose that means good power response and polars.
*test not done with tea
I just read something that puzzled me, Fuji is coming out with a new instant film camera. The article said that Polaroid had licensed the technology from them!! I always thought they had patented it?
Anyhow, yeah.
They sounded totally awesome! Incredible. Effortless. Capable of playing VERY loud without ever sounding loud. The effect was like having your listening chair on rails, when you cranked the volume higher it was like moving down the aisle in the audience toward the stage. Especially with live 2 mic tapes.
Used EQ on the bottom - at the time a self built parametric equalizer. Ran it with a Phase Linear 700 (for headroom ya know?).
Anyhow, yeah.
They sounded totally awesome! Incredible. Effortless. Capable of playing VERY loud without ever sounding loud. The effect was like having your listening chair on rails, when you cranked the volume higher it was like moving down the aisle in the audience toward the stage. Especially with live 2 mic tapes.
Used EQ on the bottom - at the time a self built parametric equalizer. Ran it with a Phase Linear 700 (for headroom ya know?).
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