WMcD Posted December 30, 2007 Share Posted December 30, 2007 Attached is an article about some aspects of CD horns. One of the authors is John T. Post. Sorry about the quality of the image. This is off microfilm at the public library. Gil A Theoretical_and_Experimental_Investigation_-_CD_Horns.pdf Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted December 30, 2007 Share Posted December 30, 2007 doc post is one of the guys that helped to explain tractrix to paul in a language he could understand. i remember him sending me this paper and it kinda helped verify to me why i wanted to either get rid of or mimized the effect of the diff slot. if you have a chance, read his paper on the tractrix investigation he did. in Christ, because of God's grace, roy Quote Link to comment Share on other sites More sharing options...
WMcD Posted December 30, 2007 Author Share Posted December 30, 2007 If anyone is interested, I posted the article which Roy mentions. It is in Technical Questions on Oct 29, 06. There use to be numbers on posts which allowed for posting of shortcuts. I don't see them now. But you can search for ARTICLE TRACTRIX and it pops up. Gil Quote Link to comment Share on other sites More sharing options...
DizRotus Posted December 30, 2007 Share Posted December 30, 2007 Short cut Article re Tractrix Horn http://forums.klipsch.com/forums/t/44621.aspx?PageIndex=1 Quote Link to comment Share on other sites More sharing options...
WMcD Posted December 30, 2007 Author Share Posted December 30, 2007 Hey Diz, can you tell me how you did that. Gil Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted December 30, 2007 Share Posted December 30, 2007 maron posted this: ROY....Mike Klementovich sent me 165 pages of a study by John T Post and Elmer L Hixson....A Modeling and Measurment Study of Acoustic Horns. (May 1994) from the Electroacoustic Reasearch Labratory..Dept. of Electrical and Computer Engineering..University of Texas at Austin.....Its heavy in math & formulas..Right up your alley.....Have you read it? I can send it your way if interested. this is the tractrix paper that i was referring to. in this paper he compares the exponential and tractrix expansion and some other stuff. in Christ, because of God's grace, roy Quote Link to comment Share on other sites More sharing options...
WMcD Posted December 30, 2007 Author Share Posted December 30, 2007 Okay, some overlap which could become confusing. We're now talking about two publications about tractrix. Diz Rotus, earlier tonight, put up a link to the Audio article by Delgato Geist Hunter. Something which I posted. Roy references the Dr. Post thesis (100 plus pages) which I also posted, and to which Roy responded back in those days. Gil Quote Link to comment Share on other sites More sharing options...
DizRotus Posted December 31, 2007 Share Posted December 31, 2007 Gil, It's explained in a PM. Thanks for posting another interesting article. Quote Link to comment Share on other sites More sharing options...
DrWho Posted December 31, 2007 Share Posted December 31, 2007 Dang Gil, you're an article machine! Thanks for posting. [Y] One thing that came to mind when reading this article is that not all CD horns need to use diffraction slots [] - and now I can understand a few more reasons why Roy/Klipsch tries to avoid slotted horns. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted December 31, 2007 Share Posted December 31, 2007 Diffraction slotted horns (CD) are not all bad... You just have to know how to EQ them properly. Thats a real pain... But you have to EQ the 402/69 because of its limitations too. Thats why my Smith Horns sound better... Even though the Smiths diffract vertically ....I,m surprised the Jubs didnt morph in that direction. It would be an interesting audition. I may get the oppertunity to do this combination soon... Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted December 31, 2007 Share Posted December 31, 2007 Diffraction slotted horns (CD) are not all bad... You just have to know how to EQ them properly. Thats a real pain... But you have to EQ the 402/69 because of its limitations too. Thats why my Smith Horns sound better... Even though the Smiths diffract vertically ....I,m surprised the Jubs didnt morph in that direction. It would be an interesting audition. I may get the oppertunity to do this combination soon... i respectfully disagree. in diffraction slot horns that attempt to have constant coverage, we are not talking about the constant coverage and the typcial fall off in spl that is asscociated with that. all horns with constant coverage slotted or not have that effect. i, as well as doc post's paper, am talking about discountinuities in the area expansion. any discontinuity causes a distruption in the bubble trying to expand. and as the paper shows, the acoustic impedance along with the electrical varies accordingly. this causes the loading on the diaphragm to vary and thus can stress the diaphragm leading to distortions (imagine a series of resonances). there is a way to have constant coverage without discontinuities or if you have to have a slot (discontinuity) at least a way to lessen the severity of the symptoms. i would be interested in your audition and would also be interested in what horns you compared. in Christ, because of God's grace, roy Quote Link to comment Share on other sites More sharing options...
DrWho Posted December 31, 2007 Share Posted December 31, 2007 EQ won't fix distortion... Btw, that JBL 2360 is a real ear bleeder. Quote Link to comment Share on other sites More sharing options...
DrWho Posted December 31, 2007 Share Posted December 31, 2007 flat power response. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted December 31, 2007 Share Posted December 31, 2007 Dr Who....I know you cant EQ out distortion !! Roy yes that discontinuity is annoying I can hear it In CD horns...But the Smith Horn has the widest biggest diffraction slot ever designed.... But I,m still scratching my head on why it still sounds so smooth... I know where there is a Pro Jube for the borrowing (briefley) and might get the chance to use it (briefley) The reason i have,nt jumped on it is getting the time (after midnight) to stuff it in the anechoic chamber at C.I.D. (I want to run some polor plots) I,m not holding my breath. Quote Link to comment Share on other sites More sharing options...
WMcD Posted December 31, 2007 Author Share Posted December 31, 2007 I think Roy is teasing us a bit here by hinting there are a few ways of making a CD without a discontinuity. My guess is as follows. Both start with the bell of the horn having somewhat straight sides. - - - Part 1. The K-5 used an exponential expansion at the throat using the little vanes. This made for exponential expansion near the throat but only in the horizontal direction. Let me say you wind up with a rectangular slot feeding the bell of the K-5. The original K-5 had a bell which is sort of like a radial sectoral. However, as originally shown in the patent on the K-5, the exponential area in the bell was maintained by larger vanes. This made it look more like a multicellular. However, the walls were somewhat flat and therefore more like a squared off cone or trapezoidal or pyramidal. I'm guessing, but suspect that sometime or other, the vanes in the bell section of the K-5 were removed by accident or experimentation. I suspect they were found as unnecessary. But then you wind up with an exponential horn at the throat feeding the conical section. And this is the basis of Keele's prototypes. Here it is worth stepping back. The exit angle of the K-5 was to be 90 x 40 degrees (iirc). PWK had written that this matches the solid angle of a corner (in which the K-Horn bass horn sits). With matching acoustic power sources, the outputs would match. I entertain some fuzzy logic to try to get into PWK's head. The bass horn was an exponential feeding the cone of the corner. Then he used the same idea for the K-5 (or X-3 treble) scaled down for the treble. The bell of the K-5 is a warped corner. I think that is more evident in the X-3 photos. It is interesting to look at Don Keele's math for matching an exponential to a conical. There is the Gamma reflection coefficient analysis per transmission line theory. If you do a bit of backwards math, something simple comes out. The optimum mouth size, small-throat-horn-to-bell, is where the rate of change of the exponential is the same as the conical bell. - - - - - Part 2. Let's assume we want a trapezoidal horn at the side walls. They'd be flat. The area expansion is not exponential and therefore not a good load to the driver. What to do? What to do could be vanes, per Part 1. However, we could use a spindle / bullet at the center axis to make up the space/area and return it to an exponential. There are bullet tweeters like this which use circular walls. Now, one place I've seen this is the Paladium midrange. It has a spindle / bullet insert, if I read the pictures correctly. = = = = That is what I think. Gil Quote Link to comment Share on other sites More sharing options...
DrWho Posted December 31, 2007 Share Posted December 31, 2007 Roy yes that discontinuity is annoying I can hear it In CD horns...Do you mean slotted horns? []Btw, the polars for the K402 have already been run...the directivity is rather impressive actually. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted December 31, 2007 Share Posted December 31, 2007 Yes the directivity is impressive....But I always run my own findings to verify claims. Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted December 31, 2007 Share Posted December 31, 2007 flat power response. very good grasshopper! in Christ, because of God's grace, roy Quote Link to comment Share on other sites More sharing options...
ZAKO Posted December 31, 2007 Share Posted December 31, 2007 "Killing two direct radiaters with one horn" having two woofers. to be precise. Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted December 31, 2007 Share Posted December 31, 2007 Yes the directivity is impressive....But I always run my own findings to verify claims. if they could, everyone should verify what the speaker is doing. in Christ, because of God's grace, roy Quote Link to comment Share on other sites More sharing options...
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