Deang Posted July 14, 2003 Share Posted July 14, 2003 When sound leaves the surface of a tweeter, does it spread across the baffle, 'fall' off the edge -- then travel to wall behind the speaker? Or is it like they show you in the pictures -- usually coming off of the driver at 45 degree angles into the listening room. These questions relate specifically to diffraction and dispersion. If a driver doesn't have off-axis dispersion typically better than 45 degrees or so -- how can diffraction be an issue? Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted July 14, 2003 Share Posted July 14, 2003 In the simplest sence, the smaller the size of the driver in relation to the length of the sound wave, the closer to the to the "water" analogy you were using. A large driver producing high frequency sound where the length of the soundwave is substantially smaller than the diameter of the driver will "beam" the sound like the picture you refer to. This is why tweeters are made as small as possible - so the high frequencis will not be "beamed" in a narrow window in front of the speaker and fall off rapidly to the sides. Actually, it is a very complicated issue, and when you're talking about horns, it gets even more complicated. I believe the "rule of thumb" is that when the driver is smaller than 1/4 the wavelenth, then the driver radiates (basically) 360 degrees. So, an 8 inch driver would be, effectively, omnipoloar at frequencies below about 410 Hz, and start beaming in a tighter and tighter focus as the frequency increases. A 1/2 inch tweeter begins beaming above 6.5kHz or so. Quote Link to comment Share on other sites More sharing options...
Soundthought Posted July 14, 2003 Share Posted July 14, 2003 Sound is a wave of colliding particles whereas water is a medium by which the wave is carried. I always use the old "pebble in a still pond" analogy. Examining how wave interacting occurs in a calm pool of water can give a better visial cue of how sound waves interact in the open air. Granted, a wave is a wave, but the higher one goes in frequency of a waveform, the more involved are it's interactions with any medium. The nature of how complex sound waves leave the surface of a cone/horn is very difficult to break down. Many things occur at that point, but rest assured the most important are the first, sencond and third order reflections and how the enclosure/driver design are engineered to accomodate those issues in any given listening environment. I think..... Quote Link to comment Share on other sites More sharing options...
Manuel Delaflor Posted July 15, 2003 Share Posted July 15, 2003 Dean is your question if sound waves behave more or less the same on air than on water? The answer would be yes, and I'm interested also in the difraction question. I hope someone will develop a room with thousands of mics in order to "map" the precise behaviour of sound waves in a graphical way. Damn, I would love to run this and other experiments... Quote Link to comment Share on other sites More sharing options...
Guest BobG Posted July 15, 2003 Share Posted July 15, 2003 Manuel, do a web search for the research of Dr. Floyd Toole. He is an employee of Harman International and a very sharp guy. Has done lots of research on room interaction etc. Dean, we used to do wave tank experiments in HS physics. If you take a very shallow tank of water (1/2" deep) and light it from below you can generate waves in the water and then place objects in the tank. You can see how waves interact with the objects in the patterns created in the light. Gives a reasonable analogy for diffraction and dispersion. You probably cannot tell what I mean from this rambling reply but might find something if you do a google. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted July 15, 2003 Share Posted July 15, 2003 Hi Bob. Long time no see. How are you? Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted July 15, 2003 Share Posted July 15, 2003 DeanG, these don't specifically answer your question, but the animations are pretty cool... http://www.kettering.edu/~drussell/demos.html Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 15, 2003 Share Posted July 15, 2003 Dean, That depends if the sound is coming out of RF series speakers or Heritage ! The former can really sound like water Craig Quote Link to comment Share on other sites More sharing options...
Deang Posted July 15, 2003 Author Share Posted July 15, 2003 I'm glad you are finally coming around. Yes, The RF-7 is extremely accurate, and does an admirable job of reproducing the sound of running water when called upon to do so. The best Heritage can do with the sound of running water and rainfall is to spit out the sound of frying bacon. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 16, 2003 Share Posted July 16, 2003 Yea but they do it with the utmost perfection ! Man you need to reconsider your RF cronies are dropping like fly's over to the sound of frying bacon Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted July 16, 2003 Share Posted July 16, 2003 ---------------- On 7/15/2003 10:46:01 PM DeanG wrote: I'm glad you are finally coming around. Yes, The RF-7 is extremely accurate, and does an admirable job of reproducing the sound of running water when called upon to do so. The best Heritage can do with the sound of running water and rainfall is to spit out the sound of frying bacon. ---------------- Dean, Is that really true? As I read your post, it doesn't read like your kidding about the difference in RK and Heritage. Haven't done personal comparison, but this is one of those amazing things that whatever magic heritage does, music is more pleasing than something more accurate. Seems like I read something in a thread about this months ago where someone articulated a resonable explanation for how this was so. Dee Quote Link to comment Share on other sites More sharing options...
ChrisK Posted July 16, 2003 Share Posted July 16, 2003 Dean, Why don't you try posing your question on Audio Asylum? Go to the "High Efficiency Speakers" forum and give it a try. There are some very knowlegable horn speaker guys that regularly participate in the discussions. BTW, I'm going by Dr. Bruce Edgar's shop later this week to retrieve a record he borrowed from me. I'll show him your post and let you know what he says. Regards, Chris Quote Link to comment Share on other sites More sharing options...
Deang Posted July 16, 2003 Author Share Posted July 16, 2003 Actually Dee, I think the Heritage guys would say that Heritage is pretty "accurate", and I think I would have to agree for the most part. I don't think anyone here has Reference and Heritage except Audioreality, so mabe he can chime in here if he sees this. What I heard, and what I'm am specifically thinking of is the scenes in Martrix where Neo is on his way to see Morpheous for the first time. There are several scenes shot in a rainstorm. When I watched this for the first time on the Cornwalls, I thought the rain sounded like frying bacon. John Warren mentioned about a month ago that the sound of crowd applause sound likes frying bacon. I thought it was funny that he used 'frying bacon' to describe the sound -- because it was what came to my mind during the Martrix scenes. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 16, 2003 Share Posted July 16, 2003 Well I have RF's and Heritage. I have no clue how I'm going to hear matrix thru my Heritage I guess I could try it with Heresy's that would be easy enough. I can tell you first hand I have many recordings with applauses and none of them sound like frying bacon to my ears they sound like applauses ! Craig Quote Link to comment Share on other sites More sharing options...
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