You don't need the room, humans didn't develop hearing in a room (..and you can certainly hear low freq. and very low freq. outside).
-basically: you are over-thinking this.
But our hearing perception adapts to rooms. Check out Toole's book, chapter 7.6.1 Adaptation and Perceptual Streaming.
I don't know if evolutionary scientists traced down the source of where we adapted this ability but it didn't have to come from anatomically modern humans. Could have come from a small mammal hiding in caves trying to avoid T-Rex.
You didn't reference a specific paper but from what I've personally seen Greisinger talks about the perception of "envelopment". He started out with low frequencies in his two main channels but it didn't work. So he separated the low frequency sources from the mains (two subs) and placed them closer to the direct lateral plane -- away from the mains, closer to his sides.
The reason I'm saying this is just to clarify we aren't talking about stereo in the sense of imaging perception. I may not remember this correctly, but I think Greisinger said imaging perception at low frequencies is typically an artifact of visual dominance/capture, i.e. the reason you hear the bass on the left is because you see the bassist on the left.
Low frequency reproduction and perception of envelopment isn't really nailed down as far as I know. There's not enough research yet. Consequently, your nearfield dipole setup might be doing what should be done and we just don't know why yet. That's why I'm trying to think it through -- despite knowing there isn't going to be an answer yet.
I think what happens is that you say something personally rude and I sort of stop paying attention to the rest of what you have to say. Therefore, it's entirely possible I can miss your point. Except, that's not what happened in this instance. I've been clear to distinguish between the commercial product constraints and the DIY opportunities.
For anyone else who might be interested, that post contained a reference to useful information relative to the advantage of cardioid and sagittal/front room reflections.
https://www.diyaudio.com/forums/mul...tive-speaker-insipired-8c-13.html#post6614414
Adapting to small room sound is very poor at low freq.s (..the wavelengths are often larger than the room's dimensions, and there are multiple modal points distributed throughout the room). With these problems you have very little difference in intensity from one channel to the next in a stereo condition and virtually no difference from either channel vs. what the listener perceives from their right and left ears.
I didn't reference a paper because I've already read Griesinger's material, and going back through his website is annoying.
Still,
http://www.davidgriesinger.com/asa05.pdf
Yes Scott, it was asa05 (published 16 years ago...) I had it downloaded and I've read it many times, but details are hard to remember.
Conclusions;
Although widely held to be unnecessary or impossible, reproduction of envelopment at low frequencies in small rooms can be achieved, particularly with a multi-channel sound system. Successful results depend on:
1. having an input recording that includes at least two channels where the reverberation is independently recorded, and thus uncorrelated with the other channels.
2. The presence of independently driven room modes that overlap in such a way that the lateral pressure gradient of one mode combines with the pressure of another.
In the case of two channel stereo, the best results usually occur when an asymmetric lateral mode (driven by the difference signal between the loudspeakers) creates a pressure gradient at the listening position, and a medial mode (usually a front/back mode) supplies the pressure. Ideally both modal systems should be broad enough in frequency that there is a substantial frequency overlap, as well as a spatial overlap. Such spatial and frequency overlaps occur in rectangular rooms of various dimensions, but are rare in rooms that are close to square in dimension. Putting the front speakers along the long wall of a small room can be helpful, as can a somewhat asymmetric speaker layout. In many rooms it can be helpful to place low frequency drivers at the sides of the listening position rather than at the front of the room. Where high Q modes exist it is useful to damp the modes electronically by an inverse filter with precisely the same frequency and Q.
My living room setup fills the criteria quite well - speakers along the long wall in a quite large and asymmetric room. Distance between speakers is 3m, room width 8m. Below sweeps from L/R and you can see different mode maximums. I've had this setup for 8 years now, and listening to classical music has never earlier (with .1 sub and "normal" 2-way BR-speakers at same locations) been so satisfying!
Conclusions;
Although widely held to be unnecessary or impossible, reproduction of envelopment at low frequencies in small rooms can be achieved, particularly with a multi-channel sound system. Successful results depend on:
1. having an input recording that includes at least two channels where the reverberation is independently recorded, and thus uncorrelated with the other channels.
2. The presence of independently driven room modes that overlap in such a way that the lateral pressure gradient of one mode combines with the pressure of another.
In the case of two channel stereo, the best results usually occur when an asymmetric lateral mode (driven by the difference signal between the loudspeakers) creates a pressure gradient at the listening position, and a medial mode (usually a front/back mode) supplies the pressure. Ideally both modal systems should be broad enough in frequency that there is a substantial frequency overlap, as well as a spatial overlap. Such spatial and frequency overlaps occur in rectangular rooms of various dimensions, but are rare in rooms that are close to square in dimension. Putting the front speakers along the long wall of a small room can be helpful, as can a somewhat asymmetric speaker layout. In many rooms it can be helpful to place low frequency drivers at the sides of the listening position rather than at the front of the room. Where high Q modes exist it is useful to damp the modes electronically by an inverse filter with precisely the same frequency and Q.
My living room setup fills the criteria quite well - speakers along the long wall in a quite large and asymmetric room. Distance between speakers is 3m, room width 8m. Below sweeps from L/R and you can see different mode maximums. I've had this setup for 8 years now, and listening to classical music has never earlier (with .1 sub and "normal" 2-way BR-speakers at same locations) been so satisfying!
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I don't see where I said anything rude to you, it was certainly not my intention. I have put in quite a bit of effort in a number of threads to try and help you to see where you have misunderstood something. I don't like to see quotes from some of the greatest minds in audio, repeated with an incorrect interpretation. Much damage has been done that way albeit with good intentions.
Since not only Griesinger has studied the object, I suggest reading chapter 5 of "Computational Auditory Scene Analysis: Principles, Algorithms, and Applications" by Brown and Wang. Furthermore, the study by Hill and Hawksford shows the last word on low frequency source localization hasn't been said yet. But this sure is all off-topic, just like the discussion on merits of various source types.
Of course. Thank you for trying to help me. I returned the favor by letting you know why I gloss over a lot of your efforts. Do you have a Patreon where I can support your mission to damage control the internets?
Tapio Lokki's lab in Finland has been studying music concert halls and small rooms. Here's some of Lokki's very recent work.
https://www.aalto.fi/en/news/can-yo...all-this-music-is-being-played-in-test-to-see
Lokki is doing things in concert halls today that will help everyone in home audio. One thing he did was record instruments in anechoic chambers to replay them with individual speakers in concert halls to study how the halls work. But then he takes that and is able to reproduce those halls in multi-channel systems and headphones. The combination of those two things is going to help a great deal with the small room problems we're talking about here.
Despite the fact we don't know some things that would be nice to know it's nice to know people are working on it.
You can see in the article I linked how concert hall perception changes with listening volume. Lokki also did research that found concert hall dynamics influenced emotional reaction. So maybe there are good reasons to stick low frequency sources in the near field. On the other hand, it may reinforce arguments in favor of high SPL monopole rather than sources that cause destructive interference.
I do think the arguments in favor of placing small 8 inch drivers in the back of 2 main channels look pretty grim if you can avoid it. You'll most likely want nearfield or multisub which means you need to be able to move them independently of the mains. On the other hand, there seems to be good arguments in favor of keeping the front portion of the D&D 8C. Possibly upgrading the cardioid portion to active rather than passive and the waveguide to compression driver. Not for Dutch and Dutch because they need to serve consumer demand, but for DIYers who build their own stuff.
I'm impressed by the Fins so now I'm curious what the Germans and some others are up to.
Rather than trade snide comments I would ask you read carefully anything you choose to respond to whether written by me or anyone else.
Hill and Hawksford's paper (2013) concludes:
5 CONCLUSIONS & FUTURE WORK
Upon close inspection of sound propagation within closed spaces alongside binaural localization cues (as described in Rayleigh’s duplex theorem), the issue of low-frequency localization has been clarified. This research highlights that the difference between the arrival of the direct sound and first reflection to a listener is the primary determinant of localization time. In addition, the average absorption of a space affects localization time, whereby high absorption coefficients (above 0.7) give multiple additional milliseconds of localization time.
Listening tests conducted in relation to this work have been informal in nature, but nonetheless reflect the objective findings of this paper and previous papers.
5 CONCLUSIONS & FUTURE WORK
Upon close inspection of sound propagation within closed spaces alongside binaural localization cues (as described in Rayleigh’s duplex theorem), the issue of low-frequency localization has been clarified. This research highlights that the difference between the arrival of the direct sound and first reflection to a listener is the primary determinant of localization time. In addition, the average absorption of a space affects localization time, whereby high absorption coefficients (above 0.7) give multiple additional milliseconds of localization time.
Listening tests conducted in relation to this work have been informal in nature, but nonetheless reflect the objective findings of this paper and previous papers.
Exactly. And this, however the statement is in line with Geddes’ findings about the 50ms delay in perceiving a tone, is about the localization mechanism. So it is perfectly possible that localization in our brain happens swift whereas active awareness takes longer. That again would be in line with our evolutionary history.
Few more things. So, stereo low bass might be more like sensation than perception/localization. That suits me well, and perhaps Griesinger too. Science tries to find exact answers, but this is on thin ice still.
A large room is reguired with wide distance between speakers, or close to ears bass units. Placing two subs near chair/sofa is not easy to do at home, unless one has a dedicated listenig room (in a palace or old scool or factory building... Two full range speakers like D&D8c might be just enough... Desktop nearfield system might be pretty good too, like what Griesinger has
A large room is reguired with wide distance between speakers, or close to ears bass units. Placing two subs near chair/sofa is not easy to do at home, unless one has a dedicated listenig room (in a palace or old scool or factory building... Two full range speakers like D&D8c might be just enough... Desktop nearfield system might be pretty good too, like what Griesinger has
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It doesn't make sense to me that the ear/brain localization mechanism for subwoofers keys off how long it takes to perceive a low freq tone.
Tones are steady state without much if any transient character...
...iow, with very little time domain information.
Music, bass transients, are quite different....with considerable time domain info.
I cannot localize steady sub tones (below 80-100 Hz), but can easily localize a sub's contribution to a kick drum whack, even when the sub is steeply low passed at 100Hz.
A weird question went to me at reading you guys in this very informative thread
Could we make something looking like a beginning of cardioid behavior on playing with the front wave of a driver ?
By surounding the front bafle with an open foam frame or wool felt ?
By using the front cache with its frame made something open on all its sides with something like a variovent (a sort of resistive sides front cache instead of classic rounded angles of the cabinet) ?
Could we make something looking like a beginning of cardioid behavior on playing with the front wave of a driver ?
By surounding the front bafle with an open foam frame or wool felt ?
By using the front cache with its frame made something open on all its sides with something like a variovent (a sort of resistive sides front cache instead of classic rounded angles of the cabinet) ?
It's been a while since I last logged onto my favorite forum. Today I came across this topic. I feel honored that people from this community where I've learned so much are now inspired by the 8c!
Some interesting subjects have been discussed here. However, it seems the same scientific facts and papers that are being discussed that were discussed years ago. There doesn't seem to be a lot of new factual information on cardioids. Unfortunately, in that sense, I don't have a lot to contribute either, just my own biased subjective experiences over the years.
With its waveguide and cardioid midrange, the 8c has constant directivity down to 100 Hz. If the 8c is placed relatively close to the front-wall (60 cm or less between the back of the cabinet and the boundary), below 100 Hz you'll get a hemispherical radiation pattern. That actually has a pretty good directivity match with the cardioid midrange. The benefit of this is that the 8c has more or less constant directivity even in rooms with a very low Schroeder frequency. This results in easy room integration in rooms of various sizes.
Much has been said about the 8c's rising distortion in the low mids and bass. In theory, it doesn't look very nice. In practice though, the 8c's sound clean and uncompressed, even at relatively high levels. It has a very effortless, relaxed quality to it. How is this possible?! It's a well-known fact that low-order harmonic distortion does not strongly correlate with sound quality. To a large extent, it's masked by other tones present in the music, and by the ear's own inherent distortion. Sure, whenever I see people online sharing distortion measurements of the 8c and commenting on them negatively, I kind of wish the numbers were better. But then I remind myself that it's the result of listening tests and a conscious engineering decision: Dutch & Dutch has a strong focus on science and objective data, but ultimately objective data are a means to a subjective end. Before there were any measurements to be found online, nobody ever complained about the 8c's not playing loud enough. Rather the contrary! Food for thought.
Before the 8c, we made a full-range cardioid sound reinforcement system, which consisted of a 2-way monitor consisting of a 15" passive cardioid midrange and 1" exit compression driver on a waveguide, combined with an active cardioid subwoofer with an 18" driver in the front and a 15" driver in the back. Based on non-controlled listening tests, I'd say the free-field (outside, no reflections) sound quality of a good cardioid subwoofer is more or less the same as a bass-reflex monopole - I don't recognize the sound quality issues described in this thread. I also never heard any of the softness that I've come to recognize (and sort of appreciate) from dipoles.
Around that same time, we also made a full-range cardioid hifi-speaker prototype. The bass section consisted of six 9" Scan-Speak 23W woofers per side. Just like other full-range cardioids I've heard through the years, this speaker sounded really good! However, we didn't do any controlled listening tests. I really wish we had properly compared them to a monopole and multi-sub system, but objective listening tests are just so much work to do well. Therefore, my subjective impressions are as biased as anybody else's.
The benefits of cardioid down to the modal range are too great to ignore. I've done many one-on-one comparisons and a cardioid simply sounds less colored, more open. It's easy to explain based on theory (neutral reflections plus less boundary interference). But when it comes to the bass, there are so many factors besides directivity that affect the sound. Speaker location plays an important role with respect to which modes are excited; distortions; what about room EQ? Are we listening at only one location, or does spatial variance play a role as well? And obviously, how well do results in one room translate to another? I'd love to be involved with proper scientific research on this topic, I feel it's long overdue. Who knows someday somebody will approach us to do a master's thesis on this subject with us.
Over the years my impression has remained that in the modal range the sound quality is remarkably well explained by steady-state frequency response alone. I'm a big proponent of using EQ to fix issues in the bass. Particularly if there's only one main listening position, simple room EQ leads to incredible improvements in most rooms. I also have a lot of experience with multi-sub + EQ, as per Todd Welti of Harman. It really works as advertised. The biggest advantage over just EQ is the reduced spatial variance. A cardioid has the interesting property that it couples to both the pressure and velocity parts of the mode. This probably is of benefit in most situations. Based on the theory I'd say a multi-sub system has less spatial variance than a full-range cardioid up to the second-order mode in any room dimension, but above that, I'd put my money on the cardioid.
Let's move on to the 8c's bass: it sounds really good. It actually surprised me how good it sounded, the first time I heard it. The boundary-coupling subjectively results in a very punchy, and fast bass. My theory is that it is because boundary coupling results in a phase-coherent first wave-front. However, I have no reason to assume you won't get similarly good results with a cardioid satellite speaker and separate subwoofers placed in different room locations, the corners perhaps. This is a relatively easy thing to compare, I'll probably do a proper blind comparison one of these days.
To Dave123: It's not easy to get the cardioid to work really well. There are a few DIY people and companies who have tried, but nobody seems to get results better than a wide-band rejection of approximately 10 dB relative to the front. That's what I got as well in my first few designs. I've since figured out a repeatable method to achieve between 15 and 20 dB. Inside I still feel like the DIY nerd I was ten years ago, and therefore I feel this urge to share all my 'secrets'. But my partners would be very angry with me if I did.
Some general pointers (some of which have been raised by others as well): the depth of the enclosure matters a lot; the kind of material has an influence (rockwool, fiberglass, polyester wool all work well); it generally helps to have the slots relatively close to the front baffle.
Here you'll find a photo of the inside of the 8c's cabinet: 6moons: audioreviews Dutch & Dutch 8c
The Olympus' cardioid works better than most I've seen, but only after I replaced the perforated back-panel with a solid panel: 2-way: Waveguide + Cardioid-like
If you feel the 8c doesn't play loud enough, I can highly recommend the 12" mid format with multi-sub!
Some interesting subjects have been discussed here. However, it seems the same scientific facts and papers that are being discussed that were discussed years ago. There doesn't seem to be a lot of new factual information on cardioids. Unfortunately, in that sense, I don't have a lot to contribute either, just my own biased subjective experiences over the years.
With its waveguide and cardioid midrange, the 8c has constant directivity down to 100 Hz. If the 8c is placed relatively close to the front-wall (60 cm or less between the back of the cabinet and the boundary), below 100 Hz you'll get a hemispherical radiation pattern. That actually has a pretty good directivity match with the cardioid midrange. The benefit of this is that the 8c has more or less constant directivity even in rooms with a very low Schroeder frequency. This results in easy room integration in rooms of various sizes.
Much has been said about the 8c's rising distortion in the low mids and bass. In theory, it doesn't look very nice. In practice though, the 8c's sound clean and uncompressed, even at relatively high levels. It has a very effortless, relaxed quality to it. How is this possible?! It's a well-known fact that low-order harmonic distortion does not strongly correlate with sound quality. To a large extent, it's masked by other tones present in the music, and by the ear's own inherent distortion. Sure, whenever I see people online sharing distortion measurements of the 8c and commenting on them negatively, I kind of wish the numbers were better. But then I remind myself that it's the result of listening tests and a conscious engineering decision: Dutch & Dutch has a strong focus on science and objective data, but ultimately objective data are a means to a subjective end. Before there were any measurements to be found online, nobody ever complained about the 8c's not playing loud enough. Rather the contrary! Food for thought.
Before the 8c, we made a full-range cardioid sound reinforcement system, which consisted of a 2-way monitor consisting of a 15" passive cardioid midrange and 1" exit compression driver on a waveguide, combined with an active cardioid subwoofer with an 18" driver in the front and a 15" driver in the back. Based on non-controlled listening tests, I'd say the free-field (outside, no reflections) sound quality of a good cardioid subwoofer is more or less the same as a bass-reflex monopole - I don't recognize the sound quality issues described in this thread. I also never heard any of the softness that I've come to recognize (and sort of appreciate) from dipoles.
Around that same time, we also made a full-range cardioid hifi-speaker prototype. The bass section consisted of six 9" Scan-Speak 23W woofers per side. Just like other full-range cardioids I've heard through the years, this speaker sounded really good! However, we didn't do any controlled listening tests. I really wish we had properly compared them to a monopole and multi-sub system, but objective listening tests are just so much work to do well. Therefore, my subjective impressions are as biased as anybody else's.
The benefits of cardioid down to the modal range are too great to ignore. I've done many one-on-one comparisons and a cardioid simply sounds less colored, more open. It's easy to explain based on theory (neutral reflections plus less boundary interference). But when it comes to the bass, there are so many factors besides directivity that affect the sound. Speaker location plays an important role with respect to which modes are excited; distortions; what about room EQ? Are we listening at only one location, or does spatial variance play a role as well? And obviously, how well do results in one room translate to another? I'd love to be involved with proper scientific research on this topic, I feel it's long overdue. Who knows someday somebody will approach us to do a master's thesis on this subject with us.
Over the years my impression has remained that in the modal range the sound quality is remarkably well explained by steady-state frequency response alone. I'm a big proponent of using EQ to fix issues in the bass. Particularly if there's only one main listening position, simple room EQ leads to incredible improvements in most rooms. I also have a lot of experience with multi-sub + EQ, as per Todd Welti of Harman. It really works as advertised. The biggest advantage over just EQ is the reduced spatial variance. A cardioid has the interesting property that it couples to both the pressure and velocity parts of the mode. This probably is of benefit in most situations. Based on the theory I'd say a multi-sub system has less spatial variance than a full-range cardioid up to the second-order mode in any room dimension, but above that, I'd put my money on the cardioid.
Let's move on to the 8c's bass: it sounds really good. It actually surprised me how good it sounded, the first time I heard it. The boundary-coupling subjectively results in a very punchy, and fast bass. My theory is that it is because boundary coupling results in a phase-coherent first wave-front. However, I have no reason to assume you won't get similarly good results with a cardioid satellite speaker and separate subwoofers placed in different room locations, the corners perhaps. This is a relatively easy thing to compare, I'll probably do a proper blind comparison one of these days.
To Dave123: It's not easy to get the cardioid to work really well. There are a few DIY people and companies who have tried, but nobody seems to get results better than a wide-band rejection of approximately 10 dB relative to the front. That's what I got as well in my first few designs. I've since figured out a repeatable method to achieve between 15 and 20 dB. Inside I still feel like the DIY nerd I was ten years ago, and therefore I feel this urge to share all my 'secrets'. But my partners would be very angry with me if I did.
Some general pointers (some of which have been raised by others as well): the depth of the enclosure matters a lot; the kind of material has an influence (rockwool, fiberglass, polyester wool all work well); it generally helps to have the slots relatively close to the front baffle.
Here you'll find a photo of the inside of the 8c's cabinet: 6moons: audioreviews Dutch & Dutch 8c
The Olympus' cardioid works better than most I've seen, but only after I replaced the perforated back-panel with a solid panel: 2-way: Waveguide + Cardioid-like
If you feel the 8c doesn't play loud enough, I can highly recommend the 12" mid format with multi-sub!
..well about that distortion:
1. as spl increases, higher order products will also go up, a few pages back (pg 15) on this: look to the 5th order result at 96db.
2. It's really impossible to say it isn't audible under the same condition unless you have near identical systems - one with low non-linear effects and one without. At higher spl my guess is that it would be audible relative to a near-identical system that had much lower non-linear distortion.
3. "eh" , it's a design choice: chasing after certain objective results often entails some compromise, and it's not like there is any design that doesn't have some objective compromise. As long as it's favorably marketable (enjoyed by end-users), it doesn't matter much.
1. as spl increases, higher order products will also go up, a few pages back (pg 15) on this: look to the 5th order result at 96db.
2. It's really impossible to say it isn't audible under the same condition unless you have near identical systems - one with low non-linear effects and one without. At higher spl my guess is that it would be audible relative to a near-identical system that had much lower non-linear distortion.
3. "eh"
, it's a design choice: chasing after certain objective results often entails some compromise, and it's not like there is any design that doesn't have some objective compromise. As long as it's favorably marketable (enjoyed by end-users), it doesn't matter much.
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YUP! The critical stuff that still requires some trial and error relative to any given driver.
-well, at least if you are doing this "passively".
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