The Kolbrek/Dunker book is an excellent source.
A really good landmark paper was written by Keele:
AES Papers -- Official website of D.B.Keele
I hope that it is ok to show a screenshot out of his paper:
"What's So Sacred About Exponential Horns?," Presented at the 51st Convention of the Audio Engineering Society, Preprint No. 1038 (F-3), (May 1975).
This is why he used a combination of both profiles CE horn. In fact looking from the throat it is an EC horn but I suppose that CE looks better ;-)
A really good landmark paper was written by Keele:
AES Papers -- Official website of D.B.Keele
I hope that it is ok to show a screenshot out of his paper:
"What's So Sacred About Exponential Horns?," Presented at the 51st Convention of the Audio Engineering Society, Preprint No. 1038 (F-3), (May 1975).
This is why he used a combination of both profiles CE horn. In fact looking from the throat it is an EC horn but I suppose that CE looks better ;-)
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Does it teach you how to make a high performance constant directivity waveguide?
Isn't what Don said being taken out of context by now?
In the statement....He said thats what he uses for nearly everything....because in application, its what usually matters mos. Thats not hard to understand....Where you want to consider the "F3" to be based off of is another topic...with horns you could choose differently based on the response vs how you may want to use filters etc...
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Does it teach you how to make a high performance constant directivity waveguide?
Should I ask Bjorn and Thomas that you get your own chapter in their next issue of the book and also delete some of the mediocre designs like jmlc?
Does it teach you how to make a high performance constant directivity waveguide?
This is a rather provocative question. Then I have a counter question
. Can you argue that constant directivity is a must for a high quality horn ? What other advantages does constant directivity provide other than the ability to apply electronic EQ correction to an acoustic power response ?! 
This is a rather provocative question. Then I have a counter question
It widens the HF while still keeping reflections low. Off axis transition is still smooth. Its actually more neutral than traditional horns from what I've seen possible.. Its a bigger listening window at the sacrifice of low end extension...
See what happens when ego is not involved...you can easily see pros and cons of both camps....Thats not directed at you Dmitrij btw =)
Both Approaches are worthy and neither has proven to be King as far as I'm concerned...It was argued that the more neutral off axis response, creates a more neutral room energy....at the of the degradation of transient response.....
The use of non constant directivity horns is proof enough that having a 100% neutral off axis isn't an absolute deterrent vs how undesirable a colorful off axis character is...
If we could have constant directivity along with loading, that would be the ultimate goal....If you guys could move past your differences, we could see what an attempt at that looked like. I think I said this before and it was said that it has already been done but from what I think I know, it wasn't done as well as you guys could do today........................................................................................................................................................
I think Dr. Geddes would say the approach of matching polar at XO fixes enough problems (in which cardioid answers directivity for the woofer)....I wonder what the cons of having the XO so high in the register (800-900hz?) is? Rarely do we so pros without cons.... Oh yeah...the lower excursion of the traditional horn situation.
Back n forth Back n forth...
I think I decided that higher directivity, period, is what I am personally after, which is why I figured why not try a 150hz horn....
Someone once said that I am creating giant headphones............Yes
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And, FWIW, Kolbrek/Dunker dedicate their book "To the memory of our friend Jean-Michel Le Cléac'h". Full page. Right before the Forward.
I like Keele's site. One of his papers that I think is especially applicable to the discussion of horn directivity is his paper #18 - 18. "The Effects of Interaural Crosstalk on Stereo Reproduction and Minimizing Interaural Crosstalk in Nearfield Monitoring by the Use of a Physical Barrier," Presented at the 81st Convention of the Audio Engineering Society, (Nov. 1986).
AES Papers -- Official website of D.B.Keele
The intro words at the page - "A study of the effects of interaural crosstalk on normal spaced-speaker stereo listening environments is presented. Interaural crosstalk detrimentally affects both imaging and frequency response. Imaging is affected by restriction of the sound stage to between the speakers and by the loss of realism and preciseness of the sonic images. Interaural crosstalk also creates very severe comb filtering in the frequency response of the direct sound field in which the listener's ears are placed. Furthermore, the amplitude and frequency characteristics of the response comb filtering are found to depend heavily on the positions of the panned images, and are at their worst for a centered image. The interaural crosstalk signal can be thought of as a high level early reflection coming from the direction of the opposite speaker, but whose timing and amplitude depend on the signal in the opposite channel. Current studio monitoring design techniques tend to accentuate the problems of interaural crosstalk. Preliminary psychoacoustic test results of a simple method to minimize the effects of interaural crosstalk in a nearfield stereo/binaural loudspeaker monitoring setup are described. The results show accurate horizontal imaging and localization over a 120° frontal angle for both intensity-difference and delay-difference stereo program material. The method depends on the use of a flat vertical boundary erected between two front-positioned, side-by-side nearfield monitor loudspeakers. The listener is situated facing the monitors with his/her ears on opposite sides of the boundary. Advantages include: independent control of amplitude, phase, and delay at each ear; solid frontal out-of-head imaging for side-to-side head shifts and head rotations; extremely good center image; creation of realistic lateral beyond-the-speaker acoustic images; minimization of crosstalk frequency-response comb-filtering effects; and excellent results with both stereo and binaural program material.
Part 1: Preprint No. 2420-A (B-10)
Part 2: Preprint No. 2420-B (B-10)
~~~
The image stabilization I hear after applying the CD/horn combo I'm currently using, Radian951/XT1464, is much better than what I was using. So much so that it reminds be of listening to a pair of ESL-57's near/mid field. 2 channel image spread is well past the L&R speaker boundaries in the right recordings, and the image is rock solid. The directivity appears to mitigate the interaural crosstalk, without the use of physical panels. Intelligibility is improved.
I remember trying the flat vertical boundary approach in the 80's. It worked, but wasn't practical. Just an interesting experiment.
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Parametric Speaker Test - YouTube
Hows this for directivity....
I wonder what the specs are regarding max spl, distortion, bandwidth, etc
Hows this for directivity....
I wonder what the specs are regarding max spl, distortion, bandwidth, etc
The origin of the term "cutoff" refers to Webster's solutions for the exponential horn where the waves go "evanescent". The problem is that this solution is wrong and evanescent waves never occur in accurately analyzed horns. That makes the term "cutoff", defined this way, ill-defined as it describes something that never happens.
Thus, it is perfectly reasonable to define a new definition and I have no problem with the definition where Im = Re - it's as good as any other. The key here is that this definition is a parameter of only the horn, not the system. When you try and use a definition based on SPL then things fall apart, because this definition depends now on both the waveguide and the driver (as Marcel so correctly points out.) Only Re = Im is a workable definition.
Thus, it is perfectly reasonable to define a new definition and I have no problem with the definition where Im = Re - it's as good as any other. The key here is that this definition is a parameter of only the horn, not the system. When you try and use a definition based on SPL then things fall apart, because this definition depends now on both the waveguide and the driver (as Marcel so correctly points out.) Only Re = Im is a workable definition.
Why did EAW use the old B&C 2" (DE75, 750) drivers from about 1500 Hz with a shallow waveguide, from 800 Hz with a big diffraction horn, whereas Klipsch used the same driver from 500 Hz with the K402?
Apparently some people seriously think the Faital Pro HF108 will play equally well behind a 8 cm deep waveguide as it does behind a 38 cm deep horn... crossed at 600 Hz.
A few days ago I used 'frame of reference' in this context.
This, in itself has nothing to do with cutoff frequency, but everything with loading.
However, cutoff is a useful parameter to adjust hornloading, even with a modified classical horn profile.
Apparently some people seriously think the Faital Pro HF108 will play equally well behind a 8 cm deep waveguide as it does behind a 38 cm deep horn... crossed at 600 Hz.
A few days ago I used 'frame of reference' in this context.
This, in itself has nothing to do with cutoff frequency, but everything with loading.
However, cutoff is a useful parameter to adjust hornloading, even with a modified classical horn profile.
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Best of both worlds? I guess its already being done....whoops
B&C ME464 1.4" Constant Directivity Horn 80 x 60 4-Bolt
Tune it to 150hz and elliptical please
B&C ME464 1.4" Constant Directivity Horn 80 x 60 4-Bolt
Tune it to 150hz and elliptical please
Best of both worlds? I guess its already being done....whoops
B&C ME464 1.4" Constant Directivity Horn 80 x 60 4-Bolt
Tune it to 150hz and elliptical please
It's a nice horn.
But i strongly prefer the driver made for it (the dcx464) on straight-sided conical MEH's.
My thoughts regarding Synergy/mehs/unity horns....mind you I have no idea how to differentiate them....Is that the midrange SQ is better on a 15" mid woofer or large horn+large format CD
I base this theory on Sd involved. lack of loading, and Source size via port/holes that hide the mid woofers.
I base this theory on Sd involved. lack of loading, and Source size via port/holes that hide the mid woofers.
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