OK, I understand what your saying and I don't agree with your interpretation.
The difference is about six dB, and with the toe in, the direct on axis sound will have to travel, in most rooms at LEAST twice as far to the opposite ear. That seems to fit well with Geddes' theory.
The on axis "non-linearity" you speak of must be the dip centered at @ 5kHz and it's going to be well down by the time it gets to the listener's ear. I don't see the psychoacoustic problem.
Here's the graph I'm looking at. It appears the same as the one he posted on the Gedlee site
http://www.ai-audio.com/products_esp12.html
FrankWW said:
That graph is too small to see the overlaying 15 or '30' degree response. Look at the first post in the thread and click on the manufactures link, then click on the manufactures link on his page referring to 'horns versus waveguides'
From what I gather the manufacture says they sell a 'constant directivity device' ( a horn they label a waveguide) but then says it has to be listened to at least 30 degrees off axis.
Why is this? Because it is not constant directivity!
You are grasping at straws. :bs:
An externally hosted image should be here but it was not working when we last tested it.
FrankWW said:
Well, no, we have merely redefined constant directivity so as to excise the anomalous center thid of the design dispersion window here....
Gedlee himself suggests that the vertical is of little consequence, so why is axi-symmetric inviolable, and, if so, why not the elliptical he posits would not exhibit this issue?
Yes, thank you too.ZilchLab said:
I've read a lot of your posts on Audioheritage with interest too.
Well, yes. I see now the criticism is that the device does not work perfectly at every angle. No claim is made for perfection. The measurements are published and the anomaly is noted by the designer here and elsewhere. At this size of OS waveguide that's the axial cancellation you get. It still remains a CD waveguide and I stick by my claim there's lots of :bs: here:
The amount of toe-in Earl recommends is indeed unorthodox, and not everyone is comfortable with scientific explanations unaccompanied by subjective commentary from third parties.
For those who would like to see some ears-on assessment of how such drastic toe-in works with speakers that follow his general guidelines, here we go.
I build speakers of similar configuration, though without some of the features Earl's have. Here are some subjective comments on the imaging and sweet spot width using Earl's recommended 45 degrees of toe-in, the first five from online audio show commentary; the sixth from an audio club meeting; and the seventh from a print magazine:
"...the speakers threw a huge soundstage..." - Jason Victor Serinus, Stereophile online, RMAF 2006 report
"After the sound, the first thing that captured my attention was the 45-degree toe-in. Duke explained that the Stormbringer has a 90-degree radiation pattern and the extreme toeing creates a soundfield where the axes crisscross in front of the listening area. That creates a wider than normal "sweet spot" and avoids the early reflection off the near sidewall. I can attest to the wide sweet spot. I wandered around the room and even listened from the adjoining room in their suite. The off-center listening rivalled the quality of my beloved Apogees." - Don Shaulis, Stereo Times, CES 2007 coverage
"Another newish speaker company is AudioKinesis... HUGE sweet spot." - "Grover", Audio Asylum post, January 11, 2007
"When set up with considerable toe-in such that the speakers' paths crossed in front of the listener, an extremely wide sweet spot resulted, such that a reasonable soundstage was heard from pretty much anywhere in the room." - Larry Borden, Stereo Times, RMAF 2007 coverage
"...presented a wonderful soundstage that felt as if I was there. " - Thomas Portney, online commentary on Stereophile's RMAF 2007 coverage
"As mentioned in my caption, they sound very very good off-axis (with a generous toe in)" - "low.pfile", Audio Circle post, February 11, 2008
"...superb imaging and a concert-hall-natural reverberant field... very much like the live experience." - Robert E. Greene, The Absolute Sound, June/July 2008, page 36 [For the record, I do not advertise in The Absolute Sound.]
Finally, let me offer my commentary on Earl's Summa in this area: The Summa does off-axis soundstaging even better than mine do, and utterly disappears as the apparent sound source. You really do get the impression that the music is completely independent of these two large objects in the room, and you get this from throughout the listening area.
Duke
For those who would like to see some ears-on assessment of how such drastic toe-in works with speakers that follow his general guidelines, here we go.
I build speakers of similar configuration, though without some of the features Earl's have. Here are some subjective comments on the imaging and sweet spot width using Earl's recommended 45 degrees of toe-in, the first five from online audio show commentary; the sixth from an audio club meeting; and the seventh from a print magazine:
"...the speakers threw a huge soundstage..." - Jason Victor Serinus, Stereophile online, RMAF 2006 report
"After the sound, the first thing that captured my attention was the 45-degree toe-in. Duke explained that the Stormbringer has a 90-degree radiation pattern and the extreme toeing creates a soundfield where the axes crisscross in front of the listening area. That creates a wider than normal "sweet spot" and avoids the early reflection off the near sidewall. I can attest to the wide sweet spot. I wandered around the room and even listened from the adjoining room in their suite. The off-center listening rivalled the quality of my beloved Apogees." - Don Shaulis, Stereo Times, CES 2007 coverage
"Another newish speaker company is AudioKinesis... HUGE sweet spot." - "Grover", Audio Asylum post, January 11, 2007
"When set up with considerable toe-in such that the speakers' paths crossed in front of the listener, an extremely wide sweet spot resulted, such that a reasonable soundstage was heard from pretty much anywhere in the room." - Larry Borden, Stereo Times, RMAF 2007 coverage
"...presented a wonderful soundstage that felt as if I was there. " - Thomas Portney, online commentary on Stereophile's RMAF 2007 coverage
"As mentioned in my caption, they sound very very good off-axis (with a generous toe in)" - "low.pfile", Audio Circle post, February 11, 2008
"...superb imaging and a concert-hall-natural reverberant field... very much like the live experience." - Robert E. Greene, The Absolute Sound, June/July 2008, page 36 [For the record, I do not advertise in The Absolute Sound.]
Finally, let me offer my commentary on Earl's Summa in this area: The Summa does off-axis soundstaging even better than mine do, and utterly disappears as the apparent sound source. You really do get the impression that the music is completely independent of these two large objects in the room, and you get this from throughout the listening area.
Duke
FrankWW said:
LOL, there are lots of them here. I thing gedlee has a handful of 'em too. Here he compares a cheap driver and horn eq'd by him that appears to be doing what it's designed to do to his much more expensive horn and driver eq'd to his liking . You'd think him being a scientist and all he would of used the same drivers with and without eq in each horn.
" The design goal of the CD horn is to provide the same SPL at all frequencies within the designed coverage angles.
The term "Constant Directivity" is a trademark of ElectroVoice but has become somewhat of a catchall phrase to describe constant-beamwidth horns. In 1975, Electro-Voice introduced a single-cell horn that consisted of three-stages. The design incorporates a hybridized hyperbolic/exponential throat section coupled to a conical, vertically flared, radial bell section. Flanges that correct for midrange beaming caused by edge diffraction are comprised of a second, wider conical, vertically flared, radial bell-section. As with classic radial horn designs, the sidewalls are straight, but in two flange sections. Having constant beamwidth in both the vertical and horizontal directions, and an unprecedented high directivity index, these horns became the model for virtually all-new horn designs for the next decade. Additionally, they horn loaded the driver well, and as a result sounded very good.
audiokinesis said:
Hi Duke, how is your 0 to 30 response compared to 30 and out with the Selenium driver eq'd like gedlee eq'd them?
Do you think there is measurable difference between the Selenium driver the B&C gedlee uses and what you use?
Why did you not use the gedlee horn? Do you use his foam attenuator too?
Don't you drastically change the radiation between your horn and bass by using a bipole bass?
This seems to be the opposite of the gedlee approach. Do you have plot of that?
I like these horns - the 18 Sound ellipticals - XT120 and XT1086
Here is plots at 0,15,30,45,60,75,90 deg - no eq, BMS driver
"The peak at 18 kHz is in the driver and is not a horn resonance."
Horizontal
Vertical
Don't cost much, sound great and no nasty holes or peaks in the response - they also can be listened to on axis!
Here is plots at 0,15,30,45,60,75,90 deg - no eq, BMS driver
"The peak at 18 kHz is in the driver and is not a horn resonance."
Horizontal
Vertical
Don't cost much, sound great and no nasty holes or peaks in the response - they also can be listened to on axis!
Well I have not heard any of the speakers built by the various thread Pontiffs here - but I have heard Duke's speakers.
They are wonderful. Really World Class. Duke is always the hit of the show wherever he goes. That counts for a lot.
And it's not just me and all the quotes in Duke's post above - many other people whom I know and trust think his speakers sound great and image like few others. He does seem to know what he's doing.
Warning: You do have to take what Duke says about other speakers with a grain of salt. You see, Duke is so nice and polite that he would hardy speak ill of a rig unless it fell over, burst into flames and burnt a hole in the floor. And maybe not even then. 😉
They are wonderful. Really World Class. Duke is always the hit of the show wherever he goes. That counts for a lot.
And it's not just me and all the quotes in Duke's post above - many other people whom I know and trust think his speakers sound great and image like few others. He does seem to know what he's doing.
Warning: You do have to take what Duke says about other speakers with a grain of salt. You see, Duke is so nice and polite that he would hardy speak ill of a rig unless it fell over, burst into flames and burnt a hole in the floor. And maybe not even then. 😉
Duke
Thanks for the input.
All
The axial hole will be diminished by an elliptical waveguide because the edge diffraction can now no longer be in phase on axis at any frequency. If the mouth is round then it can. There is nothing magical about round except for a few points:
1) the woofer is round
2) making an elliptical mold is extremely difficult
3) the compression drivers throat is round.
Elliptical is certainly possible to fix the hole, but the hole is not really a problem so whats the point of fixing it?
There is another reveiw of my waveguide speakers and the toe-in setup at http://www.diyaudio.com/forums/showthread.php?s=&threadid=122318&perpage=25&pagenumber=5 post 108
The reason that I posted a comparison of a cheap driver horn combination to one that is considerably more expensive was to prove a point. The claim was made that the JBL horn was "recent technology that was a waveguide with improved performance". I looked at it and could see that it was none of these things. So I offered to measure one. As I said the horn was actually made some 6 years ago and it was not any different than the diffraction honrs of 10 - 20 years ago. The waveguide that I compared it too is expensive NOT because there is anything complex about it, but only because each one has to be hand made and this gets expensive. If I could sell thousands of them I could probably do it for nearly the same price as the JBL - although the foam plug (being made from oil) material costs are quite high.
As a cheap alternative the Selenium/JBL combo is an extremely good deal. As an example of a high quality waveguide design for Hi-Fi, it fails in this regard. I guess you get what you pay for.
Thanks for the input.
All
The axial hole will be diminished by an elliptical waveguide because the edge diffraction can now no longer be in phase on axis at any frequency. If the mouth is round then it can. There is nothing magical about round except for a few points:
1) the woofer is round
2) making an elliptical mold is extremely difficult
3) the compression drivers throat is round.
Elliptical is certainly possible to fix the hole, but the hole is not really a problem so whats the point of fixing it?
There is another reveiw of my waveguide speakers and the toe-in setup at http://www.diyaudio.com/forums/showthread.php?s=&threadid=122318&perpage=25&pagenumber=5 post 108
The reason that I posted a comparison of a cheap driver horn combination to one that is considerably more expensive was to prove a point. The claim was made that the JBL horn was "recent technology that was a waveguide with improved performance". I looked at it and could see that it was none of these things. So I offered to measure one. As I said the horn was actually made some 6 years ago and it was not any different than the diffraction honrs of 10 - 20 years ago. The waveguide that I compared it too is expensive NOT because there is anything complex about it, but only because each one has to be hand made and this gets expensive. If I could sell thousands of them I could probably do it for nearly the same price as the JBL - although the foam plug (being made from oil) material costs are quite high.
As a cheap alternative the Selenium/JBL combo is an extremely good deal. As an example of a high quality waveguide design for Hi-Fi, it fails in this regard. I guess you get what you pay for.
I have worked extensively with the JBL asymmetric defined directivity horns RobH linked above.audiokinesis said:
The effect of having a stable image somewhat independent of position is disconcerting at first, but ultimately, pleasantly engaging. I like it. It facilitates social listening.
However, it is also "trompe l'oreille," and for critical listening, the fact remains that there is only one true "sweet spot," in the vertical plane equidistant from the sources....
Yup.Magnetar said:
From your measurements, they fall off rapidly outside the design dispersion window in the horizontal.
If there's a "diffraction device" in them, as earlier alleged here, I don't see one. Have I been cheated..? 😛
ZilchLab said:
However, it is also "trompe l'oreille," and for critical listening, the fact remains that there is only one true "sweet spot," equidistant from the sources....
A bit semantic really. The idea is to make the sweet spot not so precisely critical.
I once listened to a pair of Wilson loudspeakers. In the sweet spot they were pretty good, obviously a result of a very high precision EQ in the crossover. But within inches the image and sound quality totally collapsed. I did not find this appealing at all. I don't want my head in a vise when I listen. Sometimes I sit, sometimes I lay down, I may sit off to the side to rest against the arm of the sofa. Yes, my listening position is a sofa which seats three and every seat has a virtually identical sound stage. This IS NOT a bad thing!
"This IS NOT a bad thing!"
I agree it's nice having a larger sweet spot. I can't stand having my head in a vise either. I like to be able to move around as well and have it large enough to cover more than one seating position.
Rob🙂
I agree it's nice having a larger sweet spot. I can't stand having my head in a vise either. I like to be able to move around as well and have it large enough to cover more than one seating position.
Rob🙂
I had a similar experience with Wilson Duettas. They were so "dialed in" by the gourmet audio dealer in his listening room, they were wonderful.
Alas, the image and soundstage collapsed within inches of head movement....
Alas, the image and soundstage collapsed within inches of head movement....
Forgot about a request earlier for impulse responses. I have those and I will post them. I'd be interested in a CSD of them, but I don't have any software that will do that. If I provide the impulse responses as a text file can someone generate and post the CSD?
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