Well, while kimmo says that DI graphs are all you need nowadays, everytime I see a sonogram I find it easier to see things.
1) In post #303, fluid suggested the TX system was more directive. But from the graphs, a significant difference is only beginning at around 8 kHz.
2) Between 2 - 5 kHz the TX system is radiating wider and with much more energy (-3 dB pattern considered) than the towers.
We would probably agree that the range between 2 - 8 kHz is more recognizable and effecting the perception of a system to a higher degree than the spectrum that lies beyond. At least I would be surprised, if the slightly lesser early reflections between 8 - 20 kHz of the TX system were more noticable than its significantly higher early reflections from the presence region up to brilliance spectrum, compared to the towers.
Lately, there was this discussion where Earl Geddes mentioned his hypothesis of a zero-sum game between spaciality and imaging. In post #301, Jim you where mentioning the better imaging performance of the TX system. I would, however, assume from the graphs that what you had heard was enhanced the spaciality of the TX system over the towers.
This is obviously a hypothesis from afar.
1) In post #303, fluid suggested the TX system was more directive. But from the graphs, a significant difference is only beginning at around 8 kHz.
2) Between 2 - 5 kHz the TX system is radiating wider and with much more energy (-3 dB pattern considered) than the towers.
We would probably agree that the range between 2 - 8 kHz is more recognizable and effecting the perception of a system to a higher degree than the spectrum that lies beyond. At least I would be surprised, if the slightly lesser early reflections between 8 - 20 kHz of the TX system were more noticable than its significantly higher early reflections from the presence region up to brilliance spectrum, compared to the towers.
Lately, there was this discussion where Earl Geddes mentioned his hypothesis of a zero-sum game between spaciality and imaging. In post #301, Jim you where mentioning the better imaging performance of the TX system. I would, however, assume from the graphs that what you had heard was enhanced the spaciality of the TX system over the towers.
This is obviously a hypothesis from afar.
Kimmo might not have much use for the sonogram view but I also didn't take it that a DI graph is all you need, mostly because that makes no sense.
It's always possible for different people to look at the same graph and assess it differently. Remember the context that there was a "slight" difference noticed between the two. The main difference between the two is the tweeter and woofers where there is enough of a change in size and cabinet to affect directivity. The small waveguide and larger tweeter diameter create a smoother but increasingly narrow response, above 8K is where the radiator size makes itself known but there is a difference from 5K. The 12" woofer is narrower than the 8" drivers. There is a difference in how quickly the pattern drops, the bevels smooth the response by spreading it out longer, there is more green. There are other areas where things flip, but overall the TX still presents as being narrower in directivity than the tower to me. GIF attached to make it easier to compare.
There is also the influence of the room and positioning which isn't included in those graphs. The positions weren't the same because of the trade off between bass and imaging with the towers.
Increased spaciousness from wider directivity almost always comes at the cost of specific image placement. Jim mentioned the placement being more precise so I would take that to mean less spacious. But this is another area where descriptions of sound can be misinterpreted.
I found a version of Blauert's Spatial Hearing which is probably worth reading on this topic for anyone who hasn't already.
https://www.researchgate.net/public...zation/link/61895e58d7d1af224bc6af23/download
It's always possible for different people to look at the same graph and assess it differently. Remember the context that there was a "slight" difference noticed between the two. The main difference between the two is the tweeter and woofers where there is enough of a change in size and cabinet to affect directivity. The small waveguide and larger tweeter diameter create a smoother but increasingly narrow response, above 8K is where the radiator size makes itself known but there is a difference from 5K. The 12" woofer is narrower than the 8" drivers. There is a difference in how quickly the pattern drops, the bevels smooth the response by spreading it out longer, there is more green. There are other areas where things flip, but overall the TX still presents as being narrower in directivity than the tower to me. GIF attached to make it easier to compare.
There is also the influence of the room and positioning which isn't included in those graphs. The positions weren't the same because of the trade off between bass and imaging with the towers.
Increased spaciousness from wider directivity almost always comes at the cost of specific image placement. Jim mentioned the placement being more precise so I would take that to mean less spacious. But this is another area where descriptions of sound can be misinterpreted.
I found a version of Blauert's Spatial Hearing which is probably worth reading on this topic for anyone who hasn't already.
https://www.researchgate.net/public...zation/link/61895e58d7d1af224bc6af23/download
Attachments
It is just that we so often deceive ourselfs when we explain what we hear, that I thought maybe Jim was hearing something different than what he thinks he was. The directivity being lower for the towers in the lower frequencies, I must admit, I had not looked at. Maybe because the low frequency nulls in the TX system from integration of the sub, I thought, where an artifact from vCad. Only Jim can find out if what he decribed as a more precise placement could be an effect of the wider radiation from 2 - 8 kHz, hence related to spaciality, instead of imaging.
I may not be the right person to differentiate fine differences between spaciousness and image preciseness. Both are components of a believable illusion of three dimensional space. Until just now, I had not heard the theory that there is a tradeoff between spaciousness and image specificity. When I subjectively assess a speaker for image performance, for the most part I am simply assessing how believable the illusion is, without focusing on the cause.
Geddes’ theory, here:
https://www.diyaudio.com/community/...-beaten-by-behringer-what.177403/post-7110559
https://www.diyaudio.com/community/...-beaten-by-behringer-what.177403/post-7110559
I certainly don't want to analyse what other people think they heard 🙂
Your assessment might well be closer to Griesinger's assumption on what the word means
http://www.davidgriesinger.com/spatialization_and_loc.doc
"Of the many important aspects of the recording engineer's job two are specific to this medium: Localization, or placement of instruments and voices in the stereo field, and spaciousness. I will assume that spaciousness or spatial impression (sometimes also known as depth, richness, envelopment, or guts) is just as important in recorded sound as it is in concert halls. Creating interesting vocal placements and the illusion of spaciousness are two of the major duties of the recording engineer."
Many (perhaps from reading Floyd Toole or because of preferred musical style) enjoy lateral (side) wall reflections, this is linked with increasing spaciousness but one thing it almost always does is create a wider sound stage but a blurrier one. I tested this for myself at home by leaving or removing first reflection side absorber panels. There is an obvious difference just as there would be by increasing directivity of the source. For the music I like I am with Earl, leaving the side reflections in created a blurrier less precise image that I did not like as much as absorbing them. There was some music however where the choice was much harder and I could see why someone might choose to leave them in.
Your description earlier on of imaging improving when you moved the speakers in away from the walls, could have at least a coupe of effects happening, changing the direct to reverberant ratio and altering how any reflections are perceived due to distance. The Griesinger paper linked above is interesting reading (as are all of his other's).
Assuming that there is a tradeoff between image specificity and spaciousness, I would think that the correct ratio of each would depend on the particular piece of music being played, and the preferences of the listener. I could certainly believe that some genres of music would be better suited to more imaging, and other genres better suited to spaciousness. If this is all true, then I guess I am looking for the ratio that gives me the best illusion on whatever music I happen to be listening to at the moment. Very interesting that @Patrick Bateman is looking into the same question now...
However... I am not sure I agree that there is a tradeoff in all cases. I think a lot of speakers might benefit from better diffraction control and a smoother DI, in particular a smoother horizontal polar response. I think attention to these things can improve both spaciousness and image specificity. Perhaps at the extreme edge of performance, there is a tradeoff, but along the path toward perfection, I think both aspects can be improved.
I have thought about that a bit. Moving the towers out to create a bit more space around them did improve the illusion just a bit. When I moved the TX head units into the same position, the imaging might have improved, but if it did, it was very very slight. Why the difference? I don't know. The Griesinger website was quite interesting, thanks for the link.
j.
However... I am not sure I agree that there is a tradeoff in all cases. I think a lot of speakers might benefit from better diffraction control and a smoother DI, in particular a smoother horizontal polar response. I think attention to these things can improve both spaciousness and image specificity. Perhaps at the extreme edge of performance, there is a tradeoff, but along the path toward perfection, I think both aspects can be improved.
I have thought about that a bit. Moving the towers out to create a bit more space around them did improve the illusion just a bit. When I moved the TX head units into the same position, the imaging might have improved, but if it did, it was very very slight. Why the difference? I don't know. The Griesinger website was quite interesting, thanks for the link.
j.
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That is quite a difficult situation to imagine without using something like the Beolab 90 with active directivity control, or active reverberation controlling the amount and direction of delayed/reflected sound.
The specific trade off spoken of comes from using room treatment/position/amount of directivity. When you increase the amount of early reflected sound you decease the ability to specify the exact position of the image, but in doing so it spreads and broadens the image. This is not the only avenue for affecting imaging properties, the things you mention there in the speaker design itself certainly can have an effect, but nothing as pronounced as the grosser speaker/room options have.
This is one of those topics where semantics can easily be a barrier.
This is the explanation why I and some other dipole fans love their speakers. Positioned on the long wall of the room, dipoles give good localization with direct sound, and give lots of late reflections for spaciousness. But for this to happen, they do need a rather large and moderately reflective room - not often possible. For nearfield and monitoring, as well as home theater, coaxial monopoles are best IMO.
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yes, very true. Add to the fact that that imaging and spaciousness are not easily quantified.
I enjoy a wide variety of music, especially when in my car or when casually listening while doing other things. However, when I do critical listening, it is a certain kind of experience I am seeking, and my musical choices become far more limited. I am sure this colors my assessment of the relative importance of image specificity and spaciousness.
So true. The research of Griesinger gives an indication, as does the research of Blauert. More than that i do not know of studies i can provide links for or copy of.
I think Dr. Geddes is doing a horn vs infinite baffle comparison. Does anyone have a graph of the GD of a horn? I kinda assume horns break time/phase but have the benefit of not lighting up the walls.
I think you are correct in your suspicion and advice. Things are so complex that there is no way to get a clear answer. I did have fun listening to both so there is that.
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I figured I could write some more about the experience if that helps any but I think fluid is spot on.
While listening to either system, I moved my body/head to the right and left of my center position. The Towers had a shift in space/power while the Textremes did not. This was in stereo and did not matter what track. So the sound of the towers was complex enough that a small shift in position changed my perception of space.
When listening to my music, I was allowing my focus to jump around. The great bass on both kept on grabbing my attention in a good way.
Just before we switched out the towers for the textreme, we listened to the first 30 seconds or so of a track. So that I did not focus on something new, I locked onto the spaciousness of just one instrument and made a mental note of where I thought it started and ended in the room using hifijim's tv stand as a visual reference. Hifijim had a sweet track with a bass trombone if I recall. So this was really all I had to A/B in a more critical way and it was from memory. Still not the most ideal but this is how I approached it.
hifijim gave me no opinions until I said what I thought. He put me in a tight spot because I did not want to tell him I liked his old system more than his new one.
Narrow vs wide directivity, a good waveguide if not all waveguides are minimum phase devices so the phase follows the frequency response. Exponential horns have a defined cutoff frequency where the frequency response drops off rapidly and consequently so does the phase. This is why they should generally be used an octave above cutoff.
Always good to hear more descriptions, tends to help to find common ground amongst everyone's individual terms.
Headshake> did you hear this shift in some frequency range? These two speakers are so different in a number of ways it will be hard to pin down the cause, but I am curious if any of the differences you heard have to do with the mid/tweet CTC specifically, since I have my own wide CTC speaker in development. But if it is some other factor accounting for the difference, that would be informative too.
First, as I told hifijim in person: he should be proud of both. The towers immediately told me the sound power was nice- i could not separate the highs from the mids like I can if this is off. Any nitpick I have is extreme.
If I moved my head there was a screen door or jail bars shift of timbre just on the tweeter and only with certain sounds.
In hifijim's data you can see at 3-4khz there is a dip on-axis but the power is more even off-axis. Now imagine a frequency trying to have a phase shift moving forwards or backward. The inversion causes a cancellation on axis and can make the on-axis sound different than the room sound. This is my guess anyways.
The inversion of power shows up in my basic 2d sims so my guess is the baffle is kicking back at some frequencies as it transitions from 4pi to 2pi.
Well, there goes that assumption of mine. I guess I have been looking at simple sims too much and not enough real data. My other observation is a horn cancels itself at some frequencies and can never be extremely flat. I still think this is true.
This is from the jbl 306p. Those dips are what I am talking about.
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That is diffraction
Probably need to rethink that one as well, the frequency response dips there in the measurements and for the main one at 1.6KHz that is due to the crossover. Time and frequency are linked you cannot look at one without seeing the other, you can trade resolution of one to the other and some things are easier to see in one domain or the other because of this. The waterfall dips line up with the FR dips marked in yellow, green is a dome waveguide interaction that disappears off axis. A waveguide can be made to be very flat on axis and linear off axis, but mostly there is some on axis wiggle left which disappears off axis. Without having simulated the waveguide with an ideal source, it is hard to know what comes from the waveguide or from the driver itself. A dome tweeter on it's own depending on the baffle will tend to do the opposite, flat on axis and wiggly off axis due to diffraction.
I'd love to read a comment by @gedlee on this. Why?
1) In my layman's understanding, that I had picked up from numerous threads, the frequency range >1k was always stressed as more important to perception. Does this also hold true for early reflections?
2) In the frequency band between 2 - 8k, the TX system radiates wider. From my experience, wider radiation results in a bigger image, that is less prone to shifts with head movements. I have listened to super wide radiating speakers (Elac Carina 247), and whilst they feature a very dark stereo phantom center, moving your head left or right does not change much. Whilst the image of CD speakers is much more constrained in my experience.
3) If 1 was true, this could be indicative for the effect of directivity.
1) In my layman's understanding, that I had picked up from numerous threads, the frequency range >1k was always stressed as more important to perception. Does this also hold true for early reflections?
2) In the frequency band between 2 - 8k, the TX system radiates wider. From my experience, wider radiation results in a bigger image, that is less prone to shifts with head movements. I have listened to super wide radiating speakers (Elac Carina 247), and whilst they feature a very dark stereo phantom center, moving your head left or right does not change much. Whilst the image of CD speakers is much more constrained in my experience.
3) If 1 was true, this could be indicative for the effect of directivity.
To my knowledge the left-right discrimination of our hearing is between ~200 and ~8000 Hz with maximum at ~1600Hz, the TX has a slight dip between ~1 and ~2 kHz but it is smooth, also off axis. The Tower not so, a somewhat abrupt change also off axis.. Just my thoughts and thanks to this thread very much more a focus area for me for my measurements next week. (Note at higher frequencies strong anomalities in radiation pattern can result in noticing a direction.)
I appreciate all the discussion. I always learn something.
It may not have been clear from my earlier post: When Headshake and I compared these two systems, they were located in the exact same place. I thought that would be the most fair way to compare them. However, I have experimented with other locations for the Towers, and if they are moved about 12 inches closer to the listening position, their imaging/spaciousness/3D performance improves a little. To me it seems that it becomes about equal to the TX system at that point. If I only listened to simple acoustic music i.e. "little girl with a guitar", or opera, I would put them in this position. But in this position, I thought kick drum, electric bass, double bass etc became ever so slightly less clear. If I was going to listen to these long-term, I am not sure which position I would end up using.
For now they are in my upstairs library, waiting for a preamp.
Sometime in the next couple of weeks I hope to listen to Headshake's latest experiment. Based on this, I will decide whether my next project will involve a waveguide tweeter, or whether it will be a de minimus baffled tweeter, something like a small spherical baffle suspended aboe the midrange box.
j.
It may not have been clear from my earlier post: When Headshake and I compared these two systems, they were located in the exact same place. I thought that would be the most fair way to compare them. However, I have experimented with other locations for the Towers, and if they are moved about 12 inches closer to the listening position, their imaging/spaciousness/3D performance improves a little. To me it seems that it becomes about equal to the TX system at that point. If I only listened to simple acoustic music i.e. "little girl with a guitar", or opera, I would put them in this position. But in this position, I thought kick drum, electric bass, double bass etc became ever so slightly less clear. If I was going to listen to these long-term, I am not sure which position I would end up using.
For now they are in my upstairs library, waiting for a preamp.
Sometime in the next couple of weeks I hope to listen to Headshake's latest experiment. Based on this, I will decide whether my next project will involve a waveguide tweeter, or whether it will be a de minimus baffled tweeter, something like a small spherical baffle suspended aboe the midrange box.
j.
Sounds fun, I'll be awaiting your observations! Some years ago I did an experiment where I designed a small 2-way using the Vifa NE19VTT tweeter. One speaker had a waveguide and the other didn't. Everything else identical so I could switch back and forth between the two. My first session I had to bring the waveguide up in level one dB or so to get the speakers to sound similarly "loud". What was really interesting as I spent the next 2 hours comparing was how my initial perception changed. At first the bare tweeter sounded more spacious and the waveguide smaller or muted. But as I kept switching back and forth I found the waveguide had a calmness and focus about it that was appealing. More switching back and forth and the waveguide no longer sounded smaller, but correct, and the bare tweeter had become very "splashy". I did more sessions, and always tried to "reset" my brain so any preferences I'd developed could be reset (not easy, but at least I made the attempt). I never could go back to liking the bare tweeter, it always sounded splashy and just had too much energy thrown around. Now I hear when I listen to many other hifi designs. That sold me on the waveguide, but it still very enlightening that my initial impressions in that first hour of listening were so different than what I expected going into the test, and changed so much as I listened.