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Old 29th September 2011, 10:55 AM   #661
graaf is offline graaf  Poland
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Quote:
Originally Posted by Elias View Post
Upgrading the stereolithic projection. Removal of the pillow direct sound blocker. Low freqs are handled by crossed dipoles ! This way it is possuble to set the required level of direct sound attenuation by toeing the dipoles. The attenuation is possible through the whole audio band. High freqs handled by side firing box system.

Click the image to open in full size.

- Elias
but is the postulated high directivity <1 kHz realized in such a setup?
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Last edited by graaf; 29th September 2011 at 11:02 AM.
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Old 29th September 2011, 10:29 PM   #662
ScottG is offline ScottG  United States
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Originally Posted by graaf View Post
but is the postulated high directivity <1 kHz realized in such a setup?
Funny, I was more interested in how he was going to achieve the higher freq. pattern.
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Old 30th September 2011, 06:23 AM   #663
el`Ol is offline el`Ol  Germany
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If side-firing conventional domes are used one gets mainly direct sound up to about 5 kHz and someone who is as good in source localization as Elias will probably be able to localize them.
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Old 30th September 2011, 10:41 AM   #664
graaf is offline graaf  Poland
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partly stereolitic system and also inspired by Elias' design guide of high directivity <1 kHz
a bit of a flooder is in it too, could be the best of all worlds??
Attached Images
File Type: jpg Jordan-graaf-Elias reflector-delay setup ;-).jpg (84.6 KB, 750 views)
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Old 30th September 2011, 07:43 PM   #665
ScottG is offline ScottG  United States
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Originally Posted by el`Ol View Post
If side-firing conventional domes are used one gets mainly direct sound up to about 5 kHz and someone who is as good in source localization as Elias will probably be able to localize them.
That's the problem.

-up to 5 kHz it's much less directional, which is the opposite premise of having and frontal "blocker" like his sofa pillow. The dipoles aimed the way he has them in the figure do provide a null to the front, but getting a conventional tweeter to do that is something else.
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Old 3rd October 2011, 07:45 AM   #666
graaf is offline graaf  Poland
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Originally Posted by a_tewinkel View Post
Toole's opinion on early reflections is not really that simple. I quote from a studio designer on a Dutch forum who asked Floyd himself:

"Hi Bert.

People who say I dismiss room reflections as unimportant - and there are a few, it seems - simply have not read or understood my book. It is patently obvious that room treatment is necessary, if only to establish conditions suitable for comfortable conversation. This requires reverberation times under 0.5 second. This alone, also pretty much ensures that film dialog will be clearly understood.

The most debated issue relates to first lateral reflections. Some of those arguing vociferously in favor of eliminating them seem to have a conflict of interest, being providers of acoustical materials. Others have more reasoned arguments. I say up front that there can be no universally satisfactory answer because there is no universal scheme for recording stereo or multichannel signals. Only through controlled listening tests can we get useful insights, and these are in short supply. In the meantime opinions reign supreme, and there are many of them.

In the book I show results of several double-blind evaluations, some done by me, some done by others, showing that listeners tend not to be disturbed by lateral reflections, and many even prefer them. I also point out that the professional side of the industry almost universally feels the need to eliminate them. I suggest, respectfully, that humans have a remarkable ability to learn, to adapt, and that recording engineers spending their days adding, adjusting, and removing - at will - delayed sounds from mixes undoubtedly are more highly sensitized to these sounds than are lay listeners. This probably applies to any audio professional, acoustical consultant or enthusiast who focuses enough attention on this task. We learn to hear things and, once heard, they tend not to go away. I well remember that during the resonance detection experiments, we all became extremely skilled at hearing and identifying resonances. During the tests, and for some time afterward, we were hearing little resonances in everyday life that normally would have been totally unnoticed. From such things paranoia is born, and if we had taken this to an extreme, we would have damped our wine glasses.

For stereo listening I have found that it very much depends on the program. Music with lots of decorrelated sounds, classical for example, is sometimes enhanced by reflections, although coincident-mic recordings may benefit from a lack of reflections - letting the direct sounds be more dominant (the Blumlien stereo effects work best in an almost anechoic situation). Pan-potted recordings (the majority of pop) end up delivering essentially monophonic sounds from left and right loudspeakers, and these may well benefit from a bit of spatial enhancement. Otherwise we are left with what really annoys me about stereo: a relatively spatial set of phantom images created by both loudspeakers, and two "anchor" images created by the left and right loudspeakers playing solo. In some recordings we hear a whole string section emerging from a single loudspeaker. Not realistic, and not even pleasant. In the past, I have recommended that serious stereo listeners hang absorbent drapes along each side wall, pulling them out and pushing them back to suit what they are listening to. Our listening room at the National Research Council in Canada had this feature.

In the book, I put more emphasis on multichannel audio, where much of the important sound is delivered by the center loudspeaker, farthest from the side walls. In these situations I conclude that treatment of the side wall reflections is an option. There may be situations in which their effects are audible, but when all 5 or 7 channels are operating, it is improbable that natural room reflections have much of an effect. Other things being equal, the effects of the room are most audible when only a single loudspeaker is operating, and it becomes less so as other loudspeakers (channels) contribute additional uncorrelated sounds.

Of course the degree to which reflections are activated depends on the directional properties of loudspeakers, and the extent to which the loudspeakers are well behaved in their far off-axis responses (side wall reflections can be 50 degrees and more off axis). It has become clear over the years that, with hard side walls, the more uniform the off axis frequency response, the higher the rating of the loudspeaker. So, one has to wonder whether at least some of the dissatisfaction with reflective side walls has to do the misbehaving loudspeakers. Sadly, most manufacturers don't provide us with sufficient data to judge. And that is another, and I would argue much more worthy topic, to argue about.

Best wishes,

Floyd"
an insightful opinion that is worth reposting in this thread too

underline mine - check it out Elias! it seems that Dr Toole has problem with hearing phantoms as well
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Old 3rd October 2011, 08:07 AM   #667
el`Ol is offline el`Ol  Germany
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My Carlssons with a directivity pattern most people in this forum would call weird have the ability to disappear even if playing mono and I think it is exactly that "weird" directivity pattern is responsible for that. I think you'll never have believable phantom images with speakers that don't disappear in mono operation.
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Old 3rd October 2011, 08:31 AM   #668
graaf is offline graaf  Poland
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ay-men!
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Old 3rd October 2011, 12:27 PM   #669
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Default 3 experiences

In despite of my deficient hearing, my improper room and as a result my approximative speakers, I've done some acoustical funny tests.

"The" driver is an indonesian made 12" with a mega wizzer. It's filmsy coil and 39 g mms claim 15000 Hz. Its other great quality is it's price (33 euros for both).

As the goal of this game is only comparative, the configuration "naked driver" + digital equalisation will be enough. Of course, without EQ, it's a nightmare. They are also extremely directive in the HF.


Experience 1 :

Swinging drivers, 1 m high, equilateral triangle 4.5 meters. Drivers vertical, either full in my face, either toed in just in front of me.
Surprisingly good in tune (I'm not a FR fan normally), but the pattern is two sources + sometimes something in the middle. No envelopment, ambient, perspective, depth, whatever...
The test of the passing train is reduced to a brutal switch left to right. Test on pink noise, as always with this config : HF dichotomy.
For this reason, a strong toe out works better

Some will say that with such a primitive setting this failure is not a surprise. But wait for these primitive when disposed differently.


Experience 2 :

Same drivers, same EQ, this time simply put on the floor, as close as possible from the back boundary, 4.5 m from each other, 6 meters from the listener.
Since a while I wanted to verify this, to make sure that graaf or tinitus were not too sick.

Result : it's shocking when considering that it's the same drivers than 1 minute ago. All the claims of these gentlemen are real, with the drivers set up like a flower pot (but decoupled from the floor with thick rubber).
Not only the soundstage occupies all the wall (9 meters here) but there is eventually a strong center presence, it's ok for girl and guitar as for giant choruses or symphony. The trains circulate progressively. I insist it's not a mess up.
The Hf is not perceptually reduced (- 2 dB roll off at measure), and that's puzzling because the part over 2500 Hz stays in a 10 cone @ 0 dB. Even with one only running, the source is unlocalizable. Subs are not mandatory except for organ.

For me, adept of multi ways-multi amped systems, this is a double bottom kick : the flooder and the FR. Just the envelopment and perspective are not very good, all this is a kind of 2D image. But for 33 euros...

joined plots : > steady state of the flooder from 6 meters
> CDS with short gate (ok, it's 1/1 smoothed and has a lazy decay, but could be much worse)
> ETC with sub on (mistake), no floor bounce, the 9.33 ms peak is the side wall.



Experience 3 :

Same drivers, but now almost stuck by the magnet, back to back. You will all recognize a side firing, but it's also a linear quadrupole. The big novelty is that this time the drivers are only at 1 meter in front of the listener in the horizontal plane. But in the vertical plane they are 3 meters high, and still far from the ceiling. The test starts after a slightly adaptation of the EQ.

Result : baffling ! The flooder config was not localizable, but at least, the sound came from a logical direction : in front, where the drivers are.

Here, the sound still comes from the front, normal height, but the speakers are at 6 meters from this. So much that I had to call the wife to make it sure that I was not going mad. These speakers are only localizable when watching them or standing up and walking around. Extremely tricky ! It's really in the acoustical illusion domain.

The restitution style is globally close from the flooder but complementary : more envelopment, but missing the beautiful center presence.

A good idea could be a combination of both : flooder + glider(!), trivial, one for the center, one for the sides (envelopment), all this with some wood around the drivers and a DSP able to control their respective EQ and delay.

Attached Images
File Type: png 1230flooder 1.png (21.8 KB, 725 views)
File Type: png CSD flooder.png (43.9 KB, 710 views)
File Type: png flood+sub ETC.png (17.1 KB, 702 views)

Last edited by Radugazon; 3rd October 2011 at 12:47 PM.
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Old 3rd October 2011, 12:59 PM   #670
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Bernard, what you describe is the whoa effect that one has when listening to a symphony orchestra for the first time. Strong early reflections, louder than the direct sound.
Aim the drivers in 2) so they hit the first reflection point at the ceiling - you'll hear sounds coming from there.

Could you post or email the IR of setup 2?
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