Anything that needs to be well done needs an experienced hand.😉
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Few, i agree. If the drivers are minimum phase, equalisation only works over the angle of linearity. If the driver has an off axis problem, equalisation can make the result worse. That also applies for digital equalisation and that is the reason we choose a phase linear Linkwitz forth order and a low xover frequency in the Essex experiment. That way, the response was linear and low in strored energy over a wide range of angles.
If a driver were phase linear, the measurements would be the same regardless where you measured. However, in reality, you can measure at different distances from 1mm to 10cm or more, the response will change. The only reason why one cannot see changes further than that is because due to directivity of diffraction in the driver, the levels are low and does not show up in the normal manner unless you look at differences of 0.1db or so.
Hi,
Yes, it is absolutely true, however, you mentioned the crucial qualification: "at one point in space".
I personally have found any attempts to equalise narrow-band anomalies futile.
I nowadays only equalise broad response aberrations in the midrange/treble, only room modes can be tackled with some success using equalisation.
Ciao T
Yes, it is absolutely true, however, you mentioned the crucial qualification: "at one point in space".
I personally have found any attempts to equalise narrow-band anomalies futile.
I nowadays only equalise broad response aberrations in the midrange/treble, only room modes can be tackled with some success using equalisation.
Ciao T
At a listening distance of a meter or 2, I'd definitely say wide dispersion--a line array like Mr. Keele's CBT might be better as counter intuitive as that may seem. Just a theory. At 3 meters I'm truly not sure but I actually lean toward broad dispersion just b/c I've heard them and they definitely work. The spaciousness and imaging of the tight toe in narrow dispersion is sweet, but I've never heard a well engineered stereo pair of these set up in properly in a room.
Any way, if the directivity is matching at the crossover, I can't hear the hand off in any of the speakers that display this behavior. That has profound implications IMO, b/c I always thought it to be such a huge issue before--the hand off. It goes back to Mr. Haas I think and the integration of 30 milliseconds of sound. If there's a sudden, radically different amount of sound available to integrate, the ear can't ignore it especially if this is happening where the ear is sensitive even if the listening axis is good. No doubt the listening window is important, and the most important.
Look at this cone/dome 2 way's average over the front plane horizontally:
Then the same graph of one of those cheap Behringer B2031P 2 way with waveguided tweeter Directivity matched at the crossover:
I'd bet you can guess which one has an audible crossover. That's certainly not saying that the Behringer is perfect or anything wild.
Anyway, don't know how I got off on that tangent--worked 90 hrs in the last 7 days.
Oh yea, the wide vs. narrow pattern thing. I think as long as the pattern is matched at the crossover and you know how to set the system up with its strengths and weaknesses, you can't really go wrong. The degree that you work out the kinks is the degree of audible enjoyment you will receive and narrow is probably more difficult to get correct. Make sure your hand off is correct. I may have stated my views on this more clearly under the "psychacoustics" section of my blog.
I'm not sure if I added to the conversation or not,🙁
Dan
Any way, if the directivity is matching at the crossover, I can't hear the hand off in any of the speakers that display this behavior. That has profound implications IMO, b/c I always thought it to be such a huge issue before--the hand off. It goes back to Mr. Haas I think and the integration of 30 milliseconds of sound. If there's a sudden, radically different amount of sound available to integrate, the ear can't ignore it especially if this is happening where the ear is sensitive even if the listening axis is good. No doubt the listening window is important, and the most important.
Look at this cone/dome 2 way's average over the front plane horizontally:
Then the same graph of one of those cheap Behringer B2031P 2 way with waveguided tweeter Directivity matched at the crossover:
I'd bet you can guess which one has an audible crossover. That's certainly not saying that the Behringer is perfect or anything wild.
Anyway, don't know how I got off on that tangent--worked 90 hrs in the last 7 days.
Oh yea, the wide vs. narrow pattern thing. I think as long as the pattern is matched at the crossover and you know how to set the system up with its strengths and weaknesses, you can't really go wrong. The degree that you work out the kinks is the degree of audible enjoyment you will receive and narrow is probably more difficult to get correct. Make sure your hand off is correct. I may have stated my views on this more clearly under the "psychacoustics" section of my blog.I'm not sure if I added to the conversation or not,🙁
Dan
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Hi,
I think we are simply working with way too loose definitions.
Which is why the Pro's talk in terms of DI.
To give you an idea, if we took an ideal pulsating sphere and placed it into infinite baffle, the DI observed on either side of the baffle would be 6dB.
This means the sound radiated into a 360 degree angle would be 6dB less than that radiated by an "un-baffled" ideal pulsating sphere having the same frequency response on the axis to the listener into a 360 degree angle.
Hence, an idealised soffit mounted system exhibits a DI of 6dB, yet it has 180 degrees vertical and horizontal coverage, which most people would class as "wide" dispersion.
Let us instead consider a system that is a true cardiodid with also 6dB DI. It is unlikely that we can achieve much better than 20dB rearward cancellation (at least I cannot) and even 10dB rear attenuation over a broad range (like most MEG "K" Models) is challenging.
Now 10dB rear attenuation only would mean we have to have some attenuation at 90 degrees (maybe around 3dB) to get our overall DI of 6dB.
So even with such a cardiodid we do not have anything like major "beaming" or such, we have only a mild attenuation towards the sides and a strong attenuation towards the rear. More crucially, if we maintained this 6dB DI from (say) 20Hz to 20KHz we are in effect saying that all reflections in the room would have precisely the same tonality as the direct sound, unless our reflective surfaces introduce frequency response deviations, as the sound radiated varies only in intensity, not in frequency response.
So, what is the difference between the Cardiodid and an idealised full Omni?
The Cardidid will exhibit a ratio between direct sound and room reflected sound that is 6dB greater than the Omni, or you may say (if you view omni's as "a bad thing" like I do) 6dB less unwanted reverb (to me this extra room reverb is unwanted, but others may differ and may prefer such reverb, let them buy B*se 9O1's).
Of course, by moving closer to the speaker, in case of an omni, we also increase the level of direct sound over reflected sound. And with an omni or near omni in the close-in field of the speaker, we will not experience significant tonality shifts with small movements of our heads, which would be the case with highly directional speakers.
This now for example makes it very clear to me why when I was using single-driver (8" Dual Cone Drivers which where quite beamy) in studio's as monitors I always had to place them well back from the console, never on the meter bridge, to be usable...
So we can formulate by inductive analysis a simple Axiom:
To obtain a given ratio between direct and reflected sound we require a greater DI the greater the distance between listener and speaker is and the shorter the distance from the speaker to room surfaces is, while preserving an even tonality across the intended listening area.
From this it would seem Joachims approach for near-field monitors is entirely sensible and valid and equally, my approach to far-field monitors makes a lot of sense. It also seems to link in with the existing body of work, from Toole to Geddes and others AND (more important to me, who does not recognise any "authorities" on the strength of publications and making much noise) it squares very well with quite a few decades of experience of yours truely.
So we are back to "horses for courses" and "different strokes for different blokes", which is kind of where all this discussion on Directivity started, but we have learned a crucial piece of information that helps us to better choose which Horse we put on which course. Not that we really break new ground, but I think things make a little more sense (to me at least).
Ciao T
I think we are simply working with way too loose definitions.
Which is why the Pro's talk in terms of DI.
To give you an idea, if we took an ideal pulsating sphere and placed it into infinite baffle, the DI observed on either side of the baffle would be 6dB.
This means the sound radiated into a 360 degree angle would be 6dB less than that radiated by an "un-baffled" ideal pulsating sphere having the same frequency response on the axis to the listener into a 360 degree angle.
Hence, an idealised soffit mounted system exhibits a DI of 6dB, yet it has 180 degrees vertical and horizontal coverage, which most people would class as "wide" dispersion.
Let us instead consider a system that is a true cardiodid with also 6dB DI. It is unlikely that we can achieve much better than 20dB rearward cancellation (at least I cannot) and even 10dB rear attenuation over a broad range (like most MEG "K" Models) is challenging.
Now 10dB rear attenuation only would mean we have to have some attenuation at 90 degrees (maybe around 3dB) to get our overall DI of 6dB.
So even with such a cardiodid we do not have anything like major "beaming" or such, we have only a mild attenuation towards the sides and a strong attenuation towards the rear. More crucially, if we maintained this 6dB DI from (say) 20Hz to 20KHz we are in effect saying that all reflections in the room would have precisely the same tonality as the direct sound, unless our reflective surfaces introduce frequency response deviations, as the sound radiated varies only in intensity, not in frequency response.
So, what is the difference between the Cardiodid and an idealised full Omni?
The Cardidid will exhibit a ratio between direct sound and room reflected sound that is 6dB greater than the Omni, or you may say (if you view omni's as "a bad thing" like I do) 6dB less unwanted reverb (to me this extra room reverb is unwanted, but others may differ and may prefer such reverb, let them buy B*se 9O1's).
Of course, by moving closer to the speaker, in case of an omni, we also increase the level of direct sound over reflected sound. And with an omni or near omni in the close-in field of the speaker, we will not experience significant tonality shifts with small movements of our heads, which would be the case with highly directional speakers.
This now for example makes it very clear to me why when I was using single-driver (8" Dual Cone Drivers which where quite beamy) in studio's as monitors I always had to place them well back from the console, never on the meter bridge, to be usable...
So we can formulate by inductive analysis a simple Axiom:
To obtain a given ratio between direct and reflected sound we require a greater DI the greater the distance between listener and speaker is and the shorter the distance from the speaker to room surfaces is, while preserving an even tonality across the intended listening area.
From this it would seem Joachims approach for near-field monitors is entirely sensible and valid and equally, my approach to far-field monitors makes a lot of sense. It also seems to link in with the existing body of work, from Toole to Geddes and others AND (more important to me, who does not recognise any "authorities" on the strength of publications and making much noise) it squares very well with quite a few decades of experience of yours truely.
So we are back to "horses for courses" and "different strokes for different blokes", which is kind of where all this discussion on Directivity started, but we have learned a crucial piece of information that helps us to better choose which Horse we put on which course. Not that we really break new ground, but I think things make a little more sense (to me at least).
Ciao T
<snip>
Then the same graph of one of those cheap Behringer B2031P 2 way with waveguided tweeter Directivity matched at the crossover:
I'd bet you can guess which one has an audible crossover. That's certainly not saying that the Behringer is perfect or anything wild.
Anyway, don't know how I got off on that tangent--worked 90 hrs in the last 7 days.
I'm not sure if I added to the conversation or not,🙁
Dan
Hello,
That tangent is how I found this thread.
I have been the user of a pair of B2031P’s for the last couple of weeks. I took the headphones off my head, searched and found this thread and have been listening near field. The improvement in sound stage is beyond my expectations.
Yes you are on target; perhaps the ZDL will offer improvement over the $300 Behringers?
DT
All just for fun!
Thank you for that explanation Thorsten. Most clear. If Thorsten"The Man" had any ring to it, I'd hand it over to you.
Yea DT, those things made me feel like DIY was too expensive. ha ha They are really pretty darn good. Better than I've built and they just cost peanuts. That's not to say I'll never step back in the ring, but I've learned a lot from them and other studio monitors. Thorsten just put it very clearly. Add in the understanding of diffraction, SBIR, and modes, and we really have something.
Dan
Yea DT, those things made me feel like DIY was too expensive. ha ha They are really pretty darn good. Better than I've built and they just cost peanuts. That's not to say I'll never step back in the ring, but I've learned a lot from them and other studio monitors. Thorsten just put it very clearly. Add in the understanding of diffraction, SBIR, and modes, and we really have something.
Dan
Hello,
When this ZDL thing jells there is the other room in my house where the large screen lives. The vision of a plan is to integrate JBL 2123 10 inch mids with 075 bullet tweeters, stuff you may have seen at a large venue. Seated farther away even a “narrow beam” will allow a nice sweet spot. The trick is to is to match beam widths, XO slopes and phase to adjust the beam up of beam down to wrap around my head.
DT
All just for fun!
When this ZDL thing jells there is the other room in my house where the large screen lives. The vision of a plan is to integrate JBL 2123 10 inch mids with 075 bullet tweeters, stuff you may have seen at a large venue. Seated farther away even a “narrow beam” will allow a nice sweet spot. The trick is to is to match beam widths, XO slopes and phase to adjust the beam up of beam down to wrap around my head.
DT
All just for fun!
Tonal balance is the one most impotant parameter and as we have found out here putting a speaker at different distances from the listener requires differents DI´s. Still the physical sensation if you compare a wide dispersion ZDL in the nearfield to a waveguide design in the farfield is not the same even if the energy response at the listening position is the same. That has to do with the ear treating sounds comming from various distances
differently. The Haas effect playes a role and i could swear that there are other effects involved that are not researched in depth. I like the effect of a ZDL in the nearfield and others may not. This has to do with taste but also with experience. I listen a lot in the nearfield since decades so i got used to it. The brain seems to be able to adapt over time and then it is hard to adapt to another setup.
differently. The Haas effect playes a role and i could swear that there are other effects involved that are not researched in depth. I like the effect of a ZDL in the nearfield and others may not. This has to do with taste but also with experience. I listen a lot in the nearfield since decades so i got used to it. The brain seems to be able to adapt over time and then it is hard to adapt to another setup.
The ongoing research into Auditory Scene Analysis (ASA) tries to understand the world "beyond" the Haas effect. Experiments with real music content (NOT pink noise) and multiple repetitions/reflections suggest two things, which I believe to be relevant to your ZDL:
1. If you "keep the reflections coming", even very late reflections will integrate into the primal tone and contribute to a clear and sharp image. The echo treshold will only work, if the time gap between successive reflections becames too large.
2. The tonal content of these reflections needs to be as similar to the primal signal as possible to be well integrated. Otherwise it will become a disturbing component in the scene analysis.
From the above I see two design strategies that somehow are swimming against the main stream:
Accept all reflections, as long as the loudspeaker design and the room properties allow them to have an undisturbed tonal character.
If you want (for whatever reasons) to attenuate radiation into certain parts of the room or reflections from certain parts of the room, this should to be done frequency neutral. At least in the band, which is responsible for the definition of image size and integrity. Otherwise you will get reflections, which are more harmful than the "original".
Two links for a first compressed look into ASA:
The chapter "Ultimate Reverse Engineering" in your link from post #75.
Audio Scene Analysis
A look into the book by A.S.Bregman
Rudolf
Some more thoughts. If the tweeter response is flat, the it probably would have more directivity, wouldn't it? Plasma tweeter above 10KHz maybe?😀
Hello,
When i sit down in my chair to listen to Jimi Hendrix play Voodoo Child i am a willing participant. I want to go to that place away from the pain of my day. When the album side is over my head is clear, that is when the solution to the puzzle of the day comes easy (sometimes).
So how many point sources does it take to create the illusion of Jimi being there and how many distractions does it take to ruin it?
The consultant in me wants to “value engineer” the gold plating.
Joachim keep up the good work.
DT
All just for fun!
When i sit down in my chair to listen to Jimi Hendrix play Voodoo Child i am a willing participant. I want to go to that place away from the pain of my day. When the album side is over my head is clear, that is when the solution to the puzzle of the day comes easy (sometimes).
So how many point sources does it take to create the illusion of Jimi being there and how many distractions does it take to ruin it?
The consultant in me wants to “value engineer” the gold plating.
Joachim keep up the good work.
DT
All just for fun!
I will give my best and i think the result could be better then the sum of the parts so sure, here is some "value engineering" going on. Fortunately the drivers i found that have the right properties for my experiment are not that expensive and i whoud be hard pressed to find some that work better. I just do not know if i can come away with only one midrange.
Rudolf, thanks for the links. So that research is called "Audio Scene Analysis" and it seems to be a new discipline. I have followed what Linkwitz is doing of cause and there is some research at the University of Würzburg where they use the Manger transduces that i am aware off.
Rudolf, thanks for the links. So that research is called "Audio Scene Analysis" and it seems to be a new discipline. I have followed what Linkwitz is doing of cause and there is some research at the University of Würzburg where they use the Manger transduces that i am aware off.
I have now put the Scan wideband into an experimental plastic ball. To my surprise that driver is more directional then i thought. A low order crossover somewhere around 3kHz whould be a compromise and i hope the tweeter will help out somewhat off axis. Again the on axis response is very linear with a smooth rising trend. The ball is a bit too small, maybe 1 liter, so there is considerable sensitivity loss under a certain frequency. The sphere i plan to use is bigger at 3 liters and i hope to get more sensitivity that way in the deeper region. Maybe a 4 way solution is the way to go but i will try to get the best out of a 3 way system first.
Attachments
Thank you sir.
Your 0,45,90, and 180 degrees:
Looks like Scan is delivering the goods. Bravo to both and that's a nice little FRer.
Dan
An externally hosted image should be here but it was not working when we last tested it.
Your 0,45,90, and 180 degrees:
Looks like Scan is delivering the goods. Bravo to both and that's a nice little FRer.
Dan
Hi Joachim, what kind of sensitivity and what kind of max SPL are you considering at what distance? I use 2.5 liters even for a 3". It seems for a 4" 3 liters is going to provide too much loading.
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