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How to Make a New Wave Biradial Horn
How to Make a New Wave Biradial Horn
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Old 9th February 2018, 03:52 PM   #131
gedlee is offline gedlee  United States
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Let me offer my perspective on this discussion.

Back in 1919 I published an AES paper using the term "waveguide" for the first time referencing an acoustic horn-like device. (For reasons that I have elaborated on at my website.) In this paper I showed how one could design a device that had the desired directivity with a minimum of internal reflections and diffraction. Following that paper, I entered into a contract with JBL, through my friend John Eargle, to develop such devices. However, shortly after that a change in status whereby my employer at the time - Ford - became contractually tied to JBL, and my association with JBL was deemed to be a conflict of interest and the contract was terminated.

My approach to this problem was also shown to be optimal by a PhD thesis in AUS that showed numerically that my curvature was in fact the ideal one to achieving a constant directivity device with minimal internal reflections.

Hence, clearly, the problem that JBL was trying to solve in their "waveguides" had already been solved, but for some reason they chose not to use it (it's not hard to see why they would want to do that.) What they came up with may work well - I have never seen accurate data on them - but I would place a bet that it does not work any better than, and probably worse, than my own approach.

Does this mean that the changes were done for "cosmetics"? Hard to say, but it does appear that they wanted something unique, rather than using something that had already been proven.
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Old 9th February 2018, 04:55 PM   #132
silverprout is offline silverprout  France
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Originally Posted by gedlee View Post
Back in 1919 I published an AES paper.
1979 ?
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Old 9th February 2018, 09:55 PM   #133
gedlee is offline gedlee  United States
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OOPS! 1991!!
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Old 10th February 2018, 07:09 AM   #134
silverprout is offline silverprout  France
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Originally Posted by Ro808 View Post
"instead of considering that that cabinet is all around you." > I don't understand what you exactly mean by this. Multiple subs perhaps?Assuming a 2-way hornloaded or BR system, isn't it the size of the cabinet you are willing to accept or can accommodate that, to a certain extent, defines the size of a suitable horn?
I guess, the previous posts are quite illustrative in this regard.
But if you think you could make (big) radial horns work with small cabs or get 100dB sensitivity with decent bandwith from a 15" in 25L, I am more than happy to learn how.

IMHO the multisub configuration is not a concept or a degin rule, when you are considering the room as a internals of a baffle you simply fight against the enclosure issues with better accuracy by defocusing ond the emissive device and expand your POV to its perfect integration to the environement without paying too much credit to "what you want or what you feel".
My room is the real designer of my multisub setup, it decides where i put the emissive devices and what are their technical requirements, i've chosen nothing at all.
I'm building a Geddes inspired desing apdapted to a small bedroom for a near field very low listening level purpose.
The goal is to keep the sensivity as high as possible around the multisub crossover frequency and an Eminence Delta15A2 can reach more than 97dB at 100Hz (25L-1.10Q)
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Old 10th February 2018, 03:11 PM   #135
gedlee is offline gedlee  United States
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Originally Posted by silverprout View Post
IMHO the multisub configuration is not a concept or a degin rule, when you are considering the room as a internals of a baffle you simply fight against the enclosure issues with better accuracy by defocusing ond the emissive device and expand your POV to its perfect integration to the environement without paying too much credit to "what you want or what you feel".
Wow, that's a mouthful of a sentence, but for the life of me I can't figure out what it means.
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My room is the real designer of my multisub setup, it decides where i put the emissive devices and what are their technical requirements, i've chosen nothing at all.
In a inverted sense, that's what everyone does right? We fit the system to the room, not the other way around.
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I'm building a Geddes inspired desing apdapted to a small bedroom for a near field very low listening level purpose.
"Inspired" in what way?
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Old 10th February 2018, 04:14 PM   #136
silverprout is offline silverprout  France
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Originally Posted by gedlee View Post
Wow, that's a mouthful of a sentence, but for the life of me I can't figure out what it means.
For me it means that the concept of two hifi loudspeakers able to cover the widest possible frequency range and radiating exclusively in front of the listener is an outdated concept.

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Originally Posted by gedlee View Post
In a inverted sense, that's what everyone does right? We fit the system to the room, not the other way around.
The emissive devices fits the room like we try shoes, i have 5 very different kind of subwoofers (Closed, BR, OB, with loudspeakers drivers of 20cm to 46cm) and i map and test each position on each frequency range with each loads in order to see the effects on the CSD.

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"Inspired" in what way?
A B&C DE250 in a OSWG crossed at 1200Hz with a 12' and a multisub configuration under 100Hz.
Finally replaced the OSWG by a exponential horn 60x80 in order to reduce the reflexions and made a very personal subwofer configutation because of the room topology.

Edit : And shrinked a lot the front loudspeakers AND made an infidelity to B&C
Click the image to open in full size.
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Old 10th February 2018, 04:20 PM   #137
gedlee is offline gedlee  United States
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For me it means that the concept of two hifi loudspeakers able to cover the widest possible frequency range and radiating exclusively in front of the listener is an outdated concept.
That's an odd statement. Outdated because its only two channels? That's what stereo is. I wasn't aware that two channel was going away anytime soon. It's still the dominate source material.
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Old 10th February 2018, 05:03 PM   #138
silverprout is offline silverprout  France
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That's an odd statement. Outdated because its only two channels? That's what stereo is. I wasn't aware that two channel was going away anytime soon. It's still the dominate source material.
I'm talking for a stereo setup and i'm perhaps too generalising but i only know very few people that have large rooms dedicated to audio and in barely all small rooms that i've seen, the bad (only aestetical) placement of the front loudspeakers was causing large uncomfortable spikes and nulls in the FR under 150Hz.
I've also very, very often heared that the small rooms can only and exculsively accomodate of very small loudspeakers and so ..the hifi seems to die of extreme loudspeaker shrinkage.
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Old 10th February 2018, 07:04 PM   #139
gedlee is offline gedlee  United States
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To me what you say is not the case. Small rooms can utilize large speakers very well, it's just that manufacturers would have you believe that their small speakers work best, because that's what the customer wants to hear. SO they buy ever smaller speakers and get ever poorer playback quality. It's simply the market trend, ala Bose. It's wrong, but that doesn't seem to matter to people.
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Old 10th February 2018, 07:47 PM   #140
marco_gea is offline marco_gea  Italy
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Originally Posted by gedlee View Post
To me what you say is not the case. Small rooms can utilize large speakers very well, it's just that manufacturers would have you believe that their small speakers work best, because that's what the customer wants to hear. SO they buy ever smaller speakers and get ever poorer playback quality. It's simply the market trend, ala Bose. It's wrong, but that doesn't seem to matter to people.
SO true!
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