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horn beaming

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Keen View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keen Quote  Post ReplyReply Direct Link To This Post Posted: 11 March 2013 at 8:23am
Is lower mid approx <1K?
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thepersonunknown View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thepersonunknown Quote  Post ReplyReply Direct Link To This Post Posted: 11 March 2013 at 9:23am
Originally posted by Steve_B Steve_B wrote:

It depends what you mean by beaming. The generally accepted definition usually refers to a horn whose directivity increases as the frequency rises. If you mean why don’t horns radiate omni-directionally it is because the walls of the horn constrain the sound to a smaller angle. This is usually a desirable thing but it is possible to design a horn that radiated omni-directionally if required.

So why do horns confine the radiation pattern? Because they have solid walls that stop sound waves passing through (yes I know there will be a little transmission).  The sound waves therefore have to radiate at an angle dictated by the horn shape.

At low frequencies the horn loses control over the radiation pattern. This is due to diffraction. The mouth of the horn can be considered an opening through which sound passes. Where the opening is small compared to the wavelength the radiated sound is spherical. The following diagram illustrates what happens.

When the horn becomes large relative to the wavelengths most of the sound just keeps going at the angle of the horn.

Exponential horns and others with curved walls have a radiation pattern that narrows as the frequency increases. The best way to explain this without the use of maths is to start from what we said above; that the sound is constrained by the walls of the horn. If you flip that the other way round then if the sound can’t feel the horn wall it has no control over the radiation pattern. If you now imagine the sound wave as a bubble whose diameter expands until it is equal to one wavelength of the frequency. If the dimension across the horn is greater than that dimension the bubble loses contact with the wall. Lower frequencies see more of the horn and radiate at the angle set near the mouth whereas higher frequencies only see the section close to the throat where the wall angle is less.

At very high frequencies, where the throat dimension is comparable with the wavelengths involved, the horn becomes largely irrelevant.



that bit is what i didnt understand, but thanks, clear as cristal now.
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snowflake View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 11 March 2013 at 10:42pm
http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20(1975-05%20AES%20Preprint)%20-%20Whats%20So%20Sacred%20Exp%20Horns.pdf
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Lee In Montreal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lee In Montreal Quote  Post ReplyReply Direct Link To This Post Posted: 11 March 2013 at 10:57pm
Originally posted by thepersonunknown thepersonunknown wrote:

which horns dont beam, and how can this be done?


CD horns don't beam and have an extended range. Those can be small and big.





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thepersonunknown View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thepersonunknown Quote  Post ReplyReply Direct Link To This Post Posted: 12 March 2013 at 6:52am
Yea I was thinking more for midrange
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Lee In Montreal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lee In Montreal Quote  Post ReplyReply Direct Link To This Post Posted: 12 March 2013 at 6:48pm
White papers about beaming and CD horns

http://www.storebox1.info/v826?product_name=EV%20PABible%2007%20Add06%20Constant%20Directivity%20White%20Horn%20Paper%201980%20pdf&installer_file_name=EV%20PABible%2007%20Add06%20Constant%20Directivity%20White%20Horn%20Paper%201980%20pdf&reffer=http%3A%2F%2Fwww.electrovoice.com%2Fsitefiles%2Fdownloads%2FEV_PABible-07-Add06-Constant_Directivity_White_Horn_Paper-1980.pdf

If you are only interested in midrange horns with good dispersion, then look for Smith-designs with those distribution fins. There are many around. Check JBL 2397 and similar designs.


Edited by Lee In Montreal - 12 March 2013 at 6:49pm
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thepersonunknown View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thepersonunknown Quote  Post ReplyReply Direct Link To This Post Posted: 12 March 2013 at 9:04pm
cool. nice one
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thepersonunknown View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thepersonunknown Quote  Post ReplyReply Direct Link To This Post Posted: 14 March 2013 at 12:53am
watch out for the above link in eliots post. when i tried to download it there was some plugin which tried to install itself on my system and wouldnt take no for an answer. i refused to not be installed and as it was installing it i couldnt even access the task bar. i actualy stopped it by cutting the power cos i didnt realy trust it and am very sus of anything which forces itself on my system. sorry for the vague warninge, but im not sure what it was and could have been harmless and only happened because of something to do with my system, but be warned.

@eliot: it was something about notebooks (some plugin called notebook such and such) any idea what it might have been about? did you have something similar happen on your system?

its probably just me being paranoid, but at the moment my laptop is my only system as last week my processor fuked out on my desktop, and untill i get round to finishing of my new system im being extra careful with my laptop. (i have the stupid problem of not having a tall tower and the motherboard im using is one of the big ones with the extra slots at the bottom). a coiple of days ago i actualy had the new system all up and running and reformated with the motherboard, power supply, dvd and hard drive all just lose, sitting on the ground Tongue.

you might imagine i am a very self taught diyer with IT stuff. (not at all pro)LOL
They keep telling me life is short, but its the longest thing ive ever done!!!
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