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21st February 2011, 08:07 AM  #1701 
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Join Date: Jun 2007

Thanks Jeremy :).
Kind regards, David
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21st February 2011, 08:44 AM  #1702  
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Join Date: Jun 2007

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A possible starting point: Hornresp Tutorial Kind regards, David
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21st February 2011, 08:59 AM  #1703  
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Join Date: Oct 2005

Hello Helmuth,
You asked: Quote:
My answer will differ somewhat of David's one (sorry David). You can simulate a 1" or a 2" horn without knowing the Thiele and Small parameters, introducing Eg = 0 (in place of the normal value Eg = 2,83). Doing this the driver will be considered as a "constant velocity source". This feature is very interesting when designing new horns without knowing the Thiele and Small parameters. For sure the results will be better than with a real driver, specially in the HF (because moving mass = 0) Best regards from Paris, France JeanMichel Le Cléac'h 

22nd February 2011, 06:37 AM  #1704 
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Join Date: Jun 2007

Hi JeanMichel,
Many thanks. I had completely forgotten about the driver diaphragm constant velocity option, included in Hornresp at your suggestion :). Kind regards, David
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22nd February 2011, 07:16 PM  #1705  
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Location: Winterswijk

Quote:
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23rd February 2011, 06:47 AM  #1706 
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Join Date: May 2007

Hello David and JeanMichel,
In the JMLC_horn_v2 spreadsheet I get the impression that the sides of a square horn(4petals) are radius*2 of the round(at the same length in the horn). Voight recommends the same in his patent. Ie this is a area difference of a factor ca 1,27 relative round. Seems like the area is the same whatever shape in Hornresp. Have I gotten it all wrong? Anyway, pros and cons of the two ways of doing it? 
23rd February 2011, 07:59 AM  #1707  
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Join Date: Jun 2007

Quote:
The approach taken in Hornresp for square / rectangular horns is very simple. Assuming the plane crosssectional area at axial length X is given by AREA, then Width at X = AREA / (Height at X). It is quite some time since I last looked at JeanMichel's spreadsheet, but I seem to recall that it takes into account the area of the curved wavefront when determining the required rectangular crosssection at a given axial length. JeanMichel's approach would be more correct theoretically. I'm not sure how much of practical difference it makes though. He may care to comment further. Kind regards, David
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23rd February 2011, 08:03 AM  #1708 
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Join Date: Oct 2005

Hello Revintage,
This question is a bit off topic here. Anyway I hope David will not feel offended if I reply here. If you use a number of petals of 4, both the mouth and the throat are square. A square possess an area 1.2372 times larger than the inscribed circle. As square drivers are pretty rare, if you want to use a circular driver you'll have to use an adpatator from round to circle between the driver and the horn. I once wrote an Excel spreadsheet to calulate adptatators of the desired frequency from circle to retcangular. Infortunately it is in French, see here attached the excel spreadsheet in txt format). Best regards from Paris, France JeanMichel Le Cléac'h 
23rd February 2011, 08:44 AM  #1709 
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Join Date: May 2007

Hello David and JeanMichel,
I am aware that the 4 petal horn is square from start to end. I am sure you menat 1,2734? Still the thing making me wonder is that the "4petal" from the spreadsheet does not equal a square LeCleach in Hornresp. The question came up as I thought of using a cone driver to a midbasshorn that should be square all the way. Just for fun this is from Voigts patent 1927: "In the case of a square horn, the tangent to the corners is longer than that to the middle of the sides and a compromise is unavoidable. I prefer to make the section correspond to the tractrix. The shortest tangent is then correct, but the area is 4/Pi=1,27 times that of the corresponding tractrix. If the area is made equal to the corresponding tractrix, the tangent at the sides will be short, a defect which is partly compensated for by the excess length of the tangent to the corners." About the OT I too did a round to square spreadsheet a few years ago intended for tractrix. Must check to see if mine where made good enough... 
23rd February 2011, 09:06 AM  #1710 
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Join Date: Jun 2007

Hi Lars,
I think JeanMichel actually meant to say 1,2732 (4 / Pi accurate to 4 decimal places), but managed to transpose the 7 and 3 :). Kind regards, David
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www.hornresp.net Last edited by David McBean; 23rd February 2011 at 09:08 AM. 
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