I have checked this and dips are less noticeable than peaks.
Very true, but only relevant with few reflections.
No I'm only eq ing the reverb not the direct sound.
Of cause these reflections come only from the speaker, so its an approximation.
Correct.
It's not an approximation. It simply doesn't show what you're trying to show.
From Toole "LOUDSPEAKERS AND ROOMS FOR SOUND REPRODUCTION":
"The acoustical sum of a sound and a delayed version of
the same sound produces two results. First, if measured, it
yields a frequency response that looks a bit like a comb,
with regularly spaced alternating (constructive interference)
peaks and (destructive interference) dips. Second, if
listened to, we can get any of several responses, including
coloration at worst and a pleasant sense of spaciousness at
best. In that sense, comb filtering is something akin to a
measurement artifact.
The worst situation is when the summation occurs in the
electrical signal path or within the loudspeaker itself. Then
the direct sound and all reflected versions of it contain the
same interference pattern. Another difficult situation is
one with only a single dominant reflection arriving from
close to the same direction as the direct sound. In a control-
room context, this could be a console reflection in an
otherwise dead room.
Fortunately such events are rare. Most reflections arrive
from directions different from the direct sound, and perceptions
vary considerably. Two ears and a brain have
advantages over a microphone and an analyzer. The fact
that the perceived spectrum is the result of a central (brain)
summation of the slightly different spectra at the two ears
attenuates the potential coloration from lateral reflections
significantly [34]. If there are many reflections, from
many directions, the coloration may disappear altogether
[35], a conclusion to which we can all attest through our
experiences listening in the elaborate comb filters called
concert halls."
Then do the test I suggested yesterday. You will be surprised how good spreading works with a signal that is EXACTLY the same as the direct signal.
Ok so my test may be wrong, but the last quoted paragraph is what I've been saying all along.
This is a trick used by many mixing engineers and its only 1 reflection.
The brain measures the difference in time of arrival at the ears to determine the location of the direct sound. This is what causes the shifting of the image.
Just that the soundfield in an acoustically small room is never diffuse. He is talking about concert halls NOT living rooms. All of this is also discussed in his book.
You've claimed that only uncorrelated reflections would cause spreading. This is simply wrong.
Why would something that is no longer associated with the direct sound cause any spreading???
This has to do with the high schroeder frequency of small rooms. see my remarks on that earlier.
We use the word spreading in two different meanings, this causes the confusion.
What I mean by spreading is that you can not pin point a sound source any more, it gets spread across the sound stage, it gets wider more diffuse in space.
Your test shows that time differences at the ears shift the location of the sound. But you can still pin point it.
You go to far.
The reflections must have a strong resemblance to the direct sound in order to be able to differentiate between direct sound and reflections. At some point when the resemblance is going to be less and less the hearing system thinks the reflections are coming from an other sound source. This causes the widening of the sound source.
Last edited:
No but it is all discussed in Toole's book. You seriously need to re-read it.
No. You have to play around with the concept a little bit more. There are distinct time and level thresholds. Here's one example: What is "Spaciousness"?
Your quote from Toole describes this. 1st paragraph.
And its not related to my usage and meaning of my definition of spreading.
In this example its the comb filtering that causes the "spaciousness"
Yes the mono flooder test was interesting, and it performed as described.
However later I did more tests with stereo flooders and then I was able to locate the speakers.
So it seems adding another speaker did ruin something. I suspect interaural crosstalk is the blame.
Yes that is reasonable, but in which time window ?
I think interaural distance (about 20cm) has a very special role here. It is about the same time for one wavelength to travel at the same frequency where perception changes from ITD to ILD. Can it be a coincidence ? I think not.
Also others should define which time window they are talking about when claiming about correlating vs non correlating sounds.
- Elias
This entire subject of loudspeaker directivity and and room reflections is so very complicated. If you look at my avatar you will see an earlier design that I did over 20 years ago. This was an enclosure with three vertically mounted waveguides and a down firing BR enclosure. My attempt was to produce all three waveguides with equal dispersion characteristics. I did that but that is only part of the problem. Having a very uniform frequency response is also a very large portion of what we are trying to do. Though this design was very good in the area of the waveguides the passive crossovers at that time were just not up to the standards of what both I and many others would be able to accept. I think that those who love horn loaded systems loved these and would today, but I was not satisfied. Today with active electronic crossovers and eq those problems could be overcome. But that does not take the room response out of the equation. We still have to consider that as a part of the greater picture. The limitation here was that I did not consider a directive waveguide in the lower frequencies as something that 99% of people could accept in a room. Any control of directivity in the lower ranges is just out of the question with any reasonably sized bass waveguide, think about even a 100 hz waveguide size, this is out of the question. So, even with controlled directivity down to a reasonable range the blend from there to the bass mid-bass region is going to have a discontinuity. If I was working behind the screen of a movie theater that would no longer be a problem, but in a room in a home we have different requirements. Smaller monitors systems can be created with direct radiator designs that are much better solving these problems. I agree that the off axis response is a major contributor to coherence and localization of the source. This is the area that I am currently working in. On axis frequency response is easy, it is the off axis control that is the challenge. Driver design alone is not the answer. The interaction of the driver, enclosure shape and width, crossover design and slope with time coherence, and placement in a room are a very complex paradigm to coordinate. This discussion is very useful, but there is not one answer to the question, all aspects of the reproduction have to work together along with the limitations of typical room acoustics.
Hi graff
I guess I would put it this way. Lets pretend that one had a way to actually capture a live stereo image (my goal) and one was watching a 4th of July parade.
A marching band goes by and you capture that event.
I guess I don’t care what other people working for speaker companies say about it but there is no way that adding anything additional to that capture can make it more real than the original capture, nothing your room ads can make the capture more like live than the original.
In recording music, often 2nd harmonic is added because subjectively it makes the sound “more full” but even that shouldn’t be confused with making it more like the original.
In the studies others have done, what they have not done was used speakers with enough directivity to eliminate / greatly reduce the room effects to a point being comparable to being outdoors. In addition, there are aspects of loudspeaker performance which also effect the ability to preserve an image which are NOT part of the room effects, it is not clear that any but a very few hifi speakers address these as well.
To be clear, I am not talking about a satisfying reproduction or one that sounds believable but preserving / reproducing the actual event, if the goal is to convince you that you are experiencing the original event, you can’t add room specific information to that and make it more like live.
Your right the company’s focus is commercial sound, unfortunately the impression they have of the hifi market is one which is not flattering, not based on science.
That being said, many of our loudspeakers were developed in my living room and are not released until they satisfy me as part of a stereo. An old friend and hifi critic / writer once said to me “there are speakers that sound good, there are speakers that play loudly but none do both”.
That seemed like an ideal target because many of the problems loudspeakers have get worse faster than the desirable part of what they produce. Also in commercial sound, fidelity is not something which is attainable using the popular approaches used now so that also made a ripe target.
While we don’t advertise much or pursue hifi, what our solutions do for stereo has attracted some interest as well. Doug Jones (the fellow who produced the LEDE listening tests, Heyser award recipient and Chair professor of the department of audio arts and acoustics at Columbia college) was so impressed by the stereo reproduction of the SH50’s that he retired from teaching and came to work for us.
Business Profiles and Company Information | ZoomInfo.com
When compared to the best of the best, our systems are often chosen over the others choices, for example, for the Omnimax theaters being retrofitted to Imax, a number of them use our loudspeakers;
Prosound Network: Danley Refits Chicago OMNIMAX
Most recently, sports stadiums have been using them as a much better sounding replacement for the line arrays that the market is so aware of. If you have heard a typical stadium sound system before and have headphones on your computer, try this video from a sound check for a demo from last year. This was done with three speakers powerful enough to fill a stadium yet sound great in a living room.
Penn State Demo.MOV - YouTube
These sound so much different than the norm that even the players occasionally comment on the sound;
Rodgers Likes New Danley Sound Labs System. "Nice to be back at Lambeau" - YouTube
Like all of our synergy horns, you can walk up to one, even stick your head in the horn mouth and you NEVER get any clue there is more than one driver. While reproducing a square wave or the input signals waveshape over a broad bandwidth or through crossover is not considered important even in hifi, most of our synergy horns can do that, they really act like, measure like one single impossibly wide band and powerful driver.. If interested here is some background which may explain my different approach..
Live Sound: In Profile: Tom Danley, Exploring The Possibilities Of Audio Technology - Pro Sound Web
Don’t take my word for what I suggested about stereo imaging, do the experiments I described and see and remember unlike most of the sources you quote, we don’t even sell hifi speakers.
Best
Tom Danley
I guess I would put it this way. Lets pretend that one had a way to actually capture a live stereo image (my goal) and one was watching a 4th of July parade.
A marching band goes by and you capture that event.
I guess I don’t care what other people working for speaker companies say about it but there is no way that adding anything additional to that capture can make it more real than the original capture, nothing your room ads can make the capture more like live than the original.
In recording music, often 2nd harmonic is added because subjectively it makes the sound “more full” but even that shouldn’t be confused with making it more like the original.
In the studies others have done, what they have not done was used speakers with enough directivity to eliminate / greatly reduce the room effects to a point being comparable to being outdoors. In addition, there are aspects of loudspeaker performance which also effect the ability to preserve an image which are NOT part of the room effects, it is not clear that any but a very few hifi speakers address these as well.
To be clear, I am not talking about a satisfying reproduction or one that sounds believable but preserving / reproducing the actual event, if the goal is to convince you that you are experiencing the original event, you can’t add room specific information to that and make it more like live.
Your right the company’s focus is commercial sound, unfortunately the impression they have of the hifi market is one which is not flattering, not based on science.
That being said, many of our loudspeakers were developed in my living room and are not released until they satisfy me as part of a stereo. An old friend and hifi critic / writer once said to me “there are speakers that sound good, there are speakers that play loudly but none do both”.
That seemed like an ideal target because many of the problems loudspeakers have get worse faster than the desirable part of what they produce. Also in commercial sound, fidelity is not something which is attainable using the popular approaches used now so that also made a ripe target.
While we don’t advertise much or pursue hifi, what our solutions do for stereo has attracted some interest as well. Doug Jones (the fellow who produced the LEDE listening tests, Heyser award recipient and Chair professor of the department of audio arts and acoustics at Columbia college) was so impressed by the stereo reproduction of the SH50’s that he retired from teaching and came to work for us.
Business Profiles and Company Information | ZoomInfo.com
When compared to the best of the best, our systems are often chosen over the others choices, for example, for the Omnimax theaters being retrofitted to Imax, a number of them use our loudspeakers;
Prosound Network: Danley Refits Chicago OMNIMAX
Most recently, sports stadiums have been using them as a much better sounding replacement for the line arrays that the market is so aware of. If you have heard a typical stadium sound system before and have headphones on your computer, try this video from a sound check for a demo from last year. This was done with three speakers powerful enough to fill a stadium yet sound great in a living room.
Penn State Demo.MOV - YouTube
These sound so much different than the norm that even the players occasionally comment on the sound;
Rodgers Likes New Danley Sound Labs System. "Nice to be back at Lambeau" - YouTube
Like all of our synergy horns, you can walk up to one, even stick your head in the horn mouth and you NEVER get any clue there is more than one driver. While reproducing a square wave or the input signals waveshape over a broad bandwidth or through crossover is not considered important even in hifi, most of our synergy horns can do that, they really act like, measure like one single impossibly wide band and powerful driver.. If interested here is some background which may explain my different approach..
Live Sound: In Profile: Tom Danley, Exploring The Possibilities Of Audio Technology - Pro Sound Web
Don’t take my word for what I suggested about stereo imaging, do the experiments I described and see and remember unlike most of the sources you quote, we don’t even sell hifi speakers.
Best
Tom Danley
but crosstalk is essentially just hearing the speaker with both ears - does a presence of another speaker and corelated signals in both speakers change anything in that matters?
yes, I agree - this (~0.6 ms) seems to be the sampling interval of this kind of data by our hearing
Mavo,
I agree that what we are reproducing in the center channel can have a lot to do with the sound and the blending or comb filtering from that center channel. If we are reproducing a vocal track that can be quit different than a music track. Having a mono vocal track coming from multiple locations can lose the ability to localize the positioning, should the voice be center or left or right panned?
I understand what Tom is trying to do with his Paraline loudspeakers, but to me this is just another implementation of a PA application, not something I would want to listen to music on in my home. I just don't buy some of the arguments that he makes, that he is actually achieving that quality of musical reproduction in the frequency response that I would require. Yes I do appreciate the use of this system in the PA arena and the blending of devices, but I do not find that the implementation is perfect in any way. Tom, this is your design and I am glad that you are happy with what you have done, I just question some of your premises with what your goal is and the actual final results. More power to you and I really do hope that you are very successful with what you are doing. Your design is not the only implementation that attempts to achieve these results, it is one of many different manufacturers approaches to this difficult application of coherent PA sound.
I agree that what we are reproducing in the center channel can have a lot to do with the sound and the blending or comb filtering from that center channel. If we are reproducing a vocal track that can be quit different than a music track. Having a mono vocal track coming from multiple locations can lose the ability to localize the positioning, should the voice be center or left or right panned?
I understand what Tom is trying to do with his Paraline loudspeakers, but to me this is just another implementation of a PA application, not something I would want to listen to music on in my home. I just don't buy some of the arguments that he makes, that he is actually achieving that quality of musical reproduction in the frequency response that I would require. Yes I do appreciate the use of this system in the PA arena and the blending of devices, but I do not find that the implementation is perfect in any way. Tom, this is your design and I am glad that you are happy with what you have done, I just question some of your premises with what your goal is and the actual final results. More power to you and I really do hope that you are very successful with what you are doing. Your design is not the only implementation that attempts to achieve these results, it is one of many different manufacturers approaches to this difficult application of coherent PA sound.
Hi Kindhornman
I am not sure you have the picture straight, the Paraline is a patented lens design that allows one to make a line source and can be configured to make a plane wave, diverging or converging pattern in one plane.
The Synergy horns I have talked about are different beast, they are a constant directivity point source loudspeaker which radiate as if they had a single wide band driver and no crossover.
While the Paraline is harder to understand, how the Synergy horns work is easy.
You are probably aware that when you place two or more subwoofers very close together, they add coherently into one new source. Any identical sources combine coherently when they are less than about ¼ wavelength apart but they radiate independently and produce an interference pattern (pattern of lobes and nulls) when greater than about ½ wl.
The idea here is that while the horns have multiple drivers, they are always less than a quarter wavelength apart where they interact with each other or at crossover with a range above or below. By preserving that coherent addition, the speaker have no lobes and nulls at crossover and show no change in the radiation pattern through crossover, the radiation angle is set only by the horn walls which have a fixed angle.
The acoustic transformation horns are known for has a “high pass” filter effect based on the rate the passage way expands. A 30Hz horn can expand no faster than doubling it’s area about every 2 feet while a 300Hz horn can expand no faster than doubling every 2.4 inches etc.
Conical horns have the advantage that they have near constant directivity down to the pattern loss frequency described by Don Keele in his paper “what’s so sacred about exponential horns” BUT they also have poor low frequency loading. The idea for these came about when I realized why that was, it was that the rate of expansion is very fast near the apex and so is not a low frequency horn, on the other hand as you move away from the apex, the expansion rate slows and so if you tap in to the horn forward of the hf driver at the apex, you can find a place where the expansion rate is suitable for mid range or even low frequency loading.
The drivers all couple into one horn, they feel the radiation pressure of each other and the range they couple to at crossover. Normal crossovers above first order exhibit an “all pass” phase response, they have a phase rotation which is equal to the order times 90 degrees and so when you examine group delay, you find h elow frequency crossover output emerges after the high frequency.
It is said that you can’t hear that delay but by using adaptive slopes and the physical offset in the drivers, one can derive a crossover which does not have the normal phase shift and in some cases, there is no phase shift through crossover. In that condition, the system radiates like it has a single driver in the horn as well as a single driver in Time and while not as good in Time as a Manger transducer (the best driver time wise I have ever measured), it can still reproduce a square wave or other waveshape over more than a decade wide bandwidth even with a passive crossover.
In hifi terms, one thing you would notice if/when you actually hear one is that you can walk up to one and even put your head in the horn mouth and NEVER have any clue there is more than one driver or more than one frequency range. The whole point is to radiate a simple portion of a spherical wavefront.
In large sound systems that is very audible, the conventional approach radiates an interference pattern which is very noticeable if the wind blows, with a single point source, the wind has close to no audible effect. With the modern arrays that we replace or any speaker that radiates an interference pattern, they also sound different as you change the listening distance, they sound / measure differently everywhere while a simple point source only gets quieter with distance.
By having a high degree of directivity, one can aim at the farthest seat and when the mounting height is right, one has very little change in SPL vs distance. It is not uncommon to have only a +- 1 or 2 dB variation in loudness over an entire stadium or other venues like a Church. They also radiate much less sound outside the intended pattern compared to an array and that makes a large difference in a room.
The stadium speakers we sell at work are very large versions of the Synergy horn but they have the same function, to get all the drivers to add into a single source and it is the way they perform that has caused them to be used in many large venues, replacing the systems you are more familiar with. Until you hear the difference a single arrival makes all this is arm waving however.
One of the ways we refined these was using generation loss recordings, the closer to “perfect” the speaker (or what ever is being tested) is, the more generations one can record and play back music through one before it sounds bad.
We tested both our speakers as well as many of our competitors just to get a handle on where we were. Probably the closest you can get to hearing the difference is putting headphones on and listening to a couple video’s.
This was the first outdoor demo of the stadium sized speakers;
The Jericho Horn plays The Hunter | Facebook
Danley Sound Labs - YouTube
Some of these in a Church
First Baptist Goodletsville w/Danley JH90 cabinets Main floor on Vimeo
A stadium demo using three loudspeakers, a job slated for next year.
Penn State Demo.MOV - YouTube
I even found a video of some small ones in Europe in a home hifi system
Danley SH100B, Lavry DA10, MC2 Audio MC1250 - YouTube
Unfortunately, while it is my love, i have not been able to get the folks at the company to be interested in hifi yet, the reputation of voodoo makes them scared and the booming business in stadium scale hifi makes it a low priority.
Best,
Tom
Oh, if you catch the Bears /Packers game tomorrow, they have our speakers at Lambau field.
I am not sure you have the picture straight, the Paraline is a patented lens design that allows one to make a line source and can be configured to make a plane wave, diverging or converging pattern in one plane.
The Synergy horns I have talked about are different beast, they are a constant directivity point source loudspeaker which radiate as if they had a single wide band driver and no crossover.
While the Paraline is harder to understand, how the Synergy horns work is easy.
You are probably aware that when you place two or more subwoofers very close together, they add coherently into one new source. Any identical sources combine coherently when they are less than about ¼ wavelength apart but they radiate independently and produce an interference pattern (pattern of lobes and nulls) when greater than about ½ wl.
The idea here is that while the horns have multiple drivers, they are always less than a quarter wavelength apart where they interact with each other or at crossover with a range above or below. By preserving that coherent addition, the speaker have no lobes and nulls at crossover and show no change in the radiation pattern through crossover, the radiation angle is set only by the horn walls which have a fixed angle.
The acoustic transformation horns are known for has a “high pass” filter effect based on the rate the passage way expands. A 30Hz horn can expand no faster than doubling it’s area about every 2 feet while a 300Hz horn can expand no faster than doubling every 2.4 inches etc.
Conical horns have the advantage that they have near constant directivity down to the pattern loss frequency described by Don Keele in his paper “what’s so sacred about exponential horns” BUT they also have poor low frequency loading. The idea for these came about when I realized why that was, it was that the rate of expansion is very fast near the apex and so is not a low frequency horn, on the other hand as you move away from the apex, the expansion rate slows and so if you tap in to the horn forward of the hf driver at the apex, you can find a place where the expansion rate is suitable for mid range or even low frequency loading.
The drivers all couple into one horn, they feel the radiation pressure of each other and the range they couple to at crossover. Normal crossovers above first order exhibit an “all pass” phase response, they have a phase rotation which is equal to the order times 90 degrees and so when you examine group delay, you find h elow frequency crossover output emerges after the high frequency.
It is said that you can’t hear that delay but by using adaptive slopes and the physical offset in the drivers, one can derive a crossover which does not have the normal phase shift and in some cases, there is no phase shift through crossover. In that condition, the system radiates like it has a single driver in the horn as well as a single driver in Time and while not as good in Time as a Manger transducer (the best driver time wise I have ever measured), it can still reproduce a square wave or other waveshape over more than a decade wide bandwidth even with a passive crossover.
In hifi terms, one thing you would notice if/when you actually hear one is that you can walk up to one and even put your head in the horn mouth and NEVER have any clue there is more than one driver or more than one frequency range. The whole point is to radiate a simple portion of a spherical wavefront.
In large sound systems that is very audible, the conventional approach radiates an interference pattern which is very noticeable if the wind blows, with a single point source, the wind has close to no audible effect. With the modern arrays that we replace or any speaker that radiates an interference pattern, they also sound different as you change the listening distance, they sound / measure differently everywhere while a simple point source only gets quieter with distance.
By having a high degree of directivity, one can aim at the farthest seat and when the mounting height is right, one has very little change in SPL vs distance. It is not uncommon to have only a +- 1 or 2 dB variation in loudness over an entire stadium or other venues like a Church. They also radiate much less sound outside the intended pattern compared to an array and that makes a large difference in a room.
The stadium speakers we sell at work are very large versions of the Synergy horn but they have the same function, to get all the drivers to add into a single source and it is the way they perform that has caused them to be used in many large venues, replacing the systems you are more familiar with. Until you hear the difference a single arrival makes all this is arm waving however.
One of the ways we refined these was using generation loss recordings, the closer to “perfect” the speaker (or what ever is being tested) is, the more generations one can record and play back music through one before it sounds bad.
We tested both our speakers as well as many of our competitors just to get a handle on where we were. Probably the closest you can get to hearing the difference is putting headphones on and listening to a couple video’s.
This was the first outdoor demo of the stadium sized speakers;
The Jericho Horn plays The Hunter | Facebook
Danley Sound Labs - YouTube
Some of these in a Church
First Baptist Goodletsville w/Danley JH90 cabinets Main floor on Vimeo
A stadium demo using three loudspeakers, a job slated for next year.
Penn State Demo.MOV - YouTube
I even found a video of some small ones in Europe in a home hifi system
Danley SH100B, Lavry DA10, MC2 Audio MC1250 - YouTube
Unfortunately, while it is my love, i have not been able to get the folks at the company to be interested in hifi yet, the reputation of voodoo makes them scared and the booming business in stadium scale hifi makes it a low priority.
Best,
Tom
Oh, if you catch the Bears /Packers game tomorrow, they have our speakers at Lambau field.
Tom,
I guess it is that I think of the Paraline as being a part of your Synergy horns, a complete system together let's say. I couldn't imagine using the Paraline without the front horn flare. I completely understand what you are saying about how the source coming from one point is working, I have been making horn lenses for longer than I would want to admit. But having a bass or mid working through the slit loading you are using must be causing a substantial loading on the driver and I have done enough of that to understand what that does to the frequency response curve. It will create a high Q device, no way around that. This really isn't the forum for us to discuss engineering design I wouldn't think. Like I think I said once before I think we would have some fairly interesting conversations over a beer in a one on one conversation.
Steven
I guess it is that I think of the Paraline as being a part of your Synergy horns, a complete system together let's say. I couldn't imagine using the Paraline without the front horn flare. I completely understand what you are saying about how the source coming from one point is working, I have been making horn lenses for longer than I would want to admit. But having a bass or mid working through the slit loading you are using must be causing a substantial loading on the driver and I have done enough of that to understand what that does to the frequency response curve. It will create a high Q device, no way around that. This really isn't the forum for us to discuss engineering design I wouldn't think. Like I think I said once before I think we would have some fairly interesting conversations over a beer in a one on one conversation.
Steven
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