Coytee Posted February 4, 2011 Share Posted February 4, 2011 As simple of question that seems to be....let me put it in more detail. We hold a compression driver in our hand. If we put that compression driver to some wires & play it...SOMETHING will come out of it. Now, if you will pardon me using perhaps a bad anlogy.... let's now look at a garden hose. With the garden hose, we have no nozzel on the end. (the nozzel might represent the horn lens for this analogy) Think of just the end of the garden hose with the threaded end piece. With the hose end, we turn the water on and what happens... the water comes out in a stream. This stream is essentially the same shape as the end of the hose end. About 1" diamater and circular. If we take a finger or something and simply put it into the path of the water, tension will help pull the water to the side and in a sense, we can redirect the water outwards a little bit. Let go of the tension and the water will go back to the narrow beam. If we instead, put sort of a 'cone' (down to say a 1/4" outlet) this cone will "collect" the wider distribution of water and redirect it down to the nozzel size we have now put in front of it. This will raise the pressure and reduce the volume I know, but the main point here is it is taking a wider dispersion and controlling it to a more narrow dispersion. Now to horns. When the sound emits from a driver, does the sound come out like the water in the hose and the horn lens then "pulls" the sound out to the pattern of the horn or, does the driver spray the sound out in (for example) 180 degrees and the 90 degree horn gathers the width of the sound and narrows the spray down to the pattern of the horn? I can't imagine that if you have a 90x90 horn lens that the driver will magically have a 90x90 output. Perhaps they do? Quote Link to comment Share on other sites More sharing options...
Ironsave Posted February 4, 2011 Share Posted February 4, 2011 Wow, That question is a can of worms. You realize you will have people at each other's necks debating this one; don't you? [] I always understood it to collect, than "redirect" the driver's output..... (And "projects it outward based on the horn type; rectangular or 90X90; or round; etc).... A 90X90 Tractrix horn has a larger listening area than my H Is. I am no expert; and I am sure others will be along with more correct and detailed info! [] Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 4, 2011 Author Share Posted February 4, 2011 You realize you will have people at each other's necks debating this one; don't you? I never do things like that. It is however, a genuine question that I sometimes wonder about....as I'm out walking my 5 dogs on leashes [&] [&][Z]---[&] [&] [&] Quote Link to comment Share on other sites More sharing options...
Ironsave Posted February 4, 2011 Share Posted February 4, 2011 I am always up for a better explaination to something...... Quote Link to comment Share on other sites More sharing options...
Max2 Posted February 4, 2011 Share Posted February 4, 2011 Someone a lot smarter than me can answer this, but here is my shot at it.... doesnt sound disperse as it is emitted? Somewhat in all directions? Direct sound will obviously be louder in a stright path, but it seems to me the horn collects sounds and disperses it better like putting your hands around your mouth and yell as opposed to not using your hands. I would think that there is a very major increase in DB when the horn in attached to the driver as compared to without it. Quote Link to comment Share on other sites More sharing options...
russ69 Posted February 4, 2011 Share Posted February 4, 2011 Horn or compression horn? Quote Link to comment Share on other sites More sharing options...
Ski Bum Posted February 4, 2011 Share Posted February 4, 2011 Your water analogy doesn't hold water. (Sorry, couldn't help myself.) Music is an AC signal, not a continuously flowing signal like water. Imagine the volume of water in your hose, and the attached nozzle/horn, jiggling back and forth. Small fluctuations in water pressure from the hose are reflected in the jiggling water at the nouth of the horn, which couple to the air over the entire opening of the horn, rather than just from the small hose orifice, thus moving more air. The horn acts as an impedance coupler between the water vibrating back and forth (driver movement), and the lower impedance air, the medium through which the sound is transmitted. The horn acts to exapand the effective radiating area of the driver by better coupling it to the air, with the air (or water in your analogy) within the horn acting in piston like motion between the driver at the throat and the room air at the mouth. The direction of motion at the mouth is focused specifically by the particular horn shape. I don't think that horns act like hose nozzles. There's a lot more to it than I know, which is very little (tractrix vs exponential, square mouth vs. rectangular mouth vs ellipsoid mouth, etc). Perhaps others will chime in. Quote Link to comment Share on other sites More sharing options...
djk Posted February 4, 2011 Share Posted February 4, 2011 The diaphragm in the horn moves air, not water. The air then goes everywhere, and the horn aims the sound wavelengths. The size of the horn and the speed of sound determine how low the horn can aim things. Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 4, 2011 Author Share Posted February 4, 2011 The diaphragm in the horn moves air, not water. Well, if my wife had her way, my diaphragms would be moving water... AFTER it's application to the flame she'd love to ignite [] Now, seriously.... think about talking to your 6 year old. The air then goes everywhere, and the horn aims the sound wavelengths (and I am talking about our beloved compression horns) For general purposes, it would then be fair to say that the sound emits out of the mouth of the driver (with no horn attached) at 'essentially' a 360 degree dispersion since I know some waves will curl around the back. So under this logic then, the horn lens itself limits or focuses the sound waves from wide to narrow, rather than dispersing them from narrow to wide? My question really is as simple as that.... maybe I need fewer dogs. [] Quote Link to comment Share on other sites More sharing options...
BigCliff Posted February 4, 2011 Share Posted February 4, 2011 Try reading this and see it it explains: http://en.wikipedia.org/wiki/Compression_driver and then this: http://en.wikipedia.org/wiki/Horn_loudspeaker Quote Link to comment Share on other sites More sharing options...
Islander Posted February 4, 2011 Share Posted February 4, 2011 Ski Bum is right. The driver doesn't push the air, it jiggles it. The speakers don't push the air away from them. Think of an electric shaver. When it's turned on, it buzzes and shakes in your hand, but it doesn't try to move in any particular direction. Also, although air and water are both fluids, air is compressible, unlike water (for practical purposes), so it behaves differently. The horn's function is to enable the small diaphagm of the driver to get a better "grip" on the large amount of air in the room, in order to vibrate it in an ear-pleasing fashion. The shape of the horn will control the pattern of the vibrations. Coytee said: "So under this logic then, the horn lens itself limits or focuses the sound waves from wide to narrow, rather than dispersing them from narrow to wide?" It's the natural tendency for a sound to spread in all directions from its source, so, as you first thought, the horn limits or focusses the sound waves from wide to narrow. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted February 4, 2011 Share Posted February 4, 2011 "So under this logic then, the horn lens itself limits or focuses the sound waves from wide to narrow, rather than dispersing them from narrow to wide?"It's the natural tendency for a sound to spread in all directions from its source, so, as you first thought, the horn limits or focusses the sound waves from wide to narrow. The sound wave from a compression driver is a flat waveform. As it travels down the horn it is transformed into a spherical wave. If the wavelength is shorter than the mouth of the horn it will continue out of the horn at approximately the same angle as the horn exit angle. If the wavelength is longer than the mouth it will diffract around the horn, losing directional control. Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 4, 2011 Share Posted February 4, 2011 Horns can both spread out the sound (diffraction slot) and/or "squish it down" (I like to say "focus"). However, the behavior is very dependant on the size of the wavelength and the size/type of the horn and the size/type of the driver. The behaviour also changes depending on how close to the horn you are. Ultimately though, the behavior is based on the idea that you have a bunch of little radiators and the directivity is a result of relative phase and amplitude between all the little radiators from a single point in space. Areas where you have little to no output are the result of phase cancellation. Quote Link to comment Share on other sites More sharing options...
Islander Posted February 4, 2011 Share Posted February 4, 2011 The sound wave from a compression driver is a flat waveform. As it travels down the horn it is transformed into a spherical wave. If the wavelength is shorter than the mouth of the horn it will continue out of the horn at approximately the same angle as the horn exit angle. If the wavelength is longer than the mouth it will diffract around the horn, losing directional control. Ah, so that's why the 402 can do a better job off-axis than the 510. Thanks for clarifying that, Don! Quote Link to comment Share on other sites More sharing options...
Guest " " Posted February 4, 2011 Share Posted February 4, 2011 pressure decreases as distance from the diaphragm increases. displacement increases as distance from the diaphragm increases. at the flair rate of course. Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 4, 2011 Author Share Posted February 4, 2011 Horns can both spread out the sound (diffraction slot) and/or "squish it down" (I like to say "focus"). However, the behavior is very dependant on the size of the wavelength and the size/type of the horn and the size/type of the driver. The behaviour also changes depending on how close to the horn you are. Ultimately though, the behavior is based on the idea that you have a bunch of little radiators and the directivity is a result of relative phase and amplitude between all the little radiators from a single point in space. Areas where you have little to no output are the result of phase cancellation. I'd hate to be your 6 year old however, you hit my level when you said "squish it down" [] Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 5, 2011 Share Posted February 5, 2011 Just be glad I didn't post any of the wave equation integrals [] Quote Link to comment Share on other sites More sharing options...
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