Guest David H Posted October 27, 2011 Share Posted October 27, 2011 I have been working with Conical/Tractrix hybrids, due to the interest in constant directivity horns. What I have come up with is a 60/40 Conical mix. I was a bit surprised at how different it sounds compared to pure Tractrix, however that may just be due to the lower Fc of the Tractrix. I am curently waiting for the polar mapping results, however the Contrac-T paired with the B&C DE-10 had smooth response to 18K. Quote Link to comment Share on other sites More sharing options...
Guest David H Posted October 27, 2011 Share Posted October 27, 2011 Contrac-T in ALK/Martinelli KHorn grill frame. Quote Link to comment Share on other sites More sharing options...
Guest David H Posted October 27, 2011 Share Posted October 27, 2011 Initial testing. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted October 27, 2011 Share Posted October 27, 2011 Hey..........very cool idea. Workmanship looks great as usual too. How did you decide on 60/40%? You have your standard conical to compare polars, right? Quote Link to comment Share on other sites More sharing options...
Guest David H Posted October 27, 2011 Share Posted October 27, 2011 You have your standard conical to compare polars, right? I do not. I am sure I can find some available though. How did you decide on 60/40%? T.L.A.R. engineering. That looks about right. Built and listened to several, 50/50, 70/30, and the 60/40. Dave Quote Link to comment Share on other sites More sharing options...
justinsweber Posted October 28, 2011 Share Posted October 28, 2011 We need to see your horns with a Khorns at RMAF or your drifts. As always, workmanship to the 1st order! Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted October 28, 2011 Share Posted October 28, 2011 Interesting project! I am trying to understand your description. Does 60/40% mean the initial 60% of the horn length is a conical expansion and the last 40% is tractrix?. Is there any special geometry at the horn's throat (for instance: oblate spheroid or Quadratic throat)? Quote Link to comment Share on other sites More sharing options...
Guest David H Posted October 28, 2011 Share Posted October 28, 2011 We need to see your horns with a Khorns at RMAF or your drifts. As always, workmanship to the 1st order! Thanks Justin.Dave Quote Link to comment Share on other sites More sharing options...
Guest David H Posted October 28, 2011 Share Posted October 28, 2011 I am trying to understand your description. Does 60/40% mean the initial 60% of the horn length is a conical expansion and the last 40% is tractrix?. Precisely Is there any special geometry at the horn's throat (for instance: oblate spheroid or Quadratic throat)? No, the throat is pure Conical, with a Tractrix mouth which should reduce edge diffraction. I was under the impression the quadratic throat was to reduce distortion in a rectangular cross section Conical designs. Dave Quote Link to comment Share on other sites More sharing options...
Guest David H Posted October 29, 2011 Share Posted October 29, 2011 Here is a simplified visual representation of the Contrac-T. The section in red is Conical, the white is Tractrix. Quote Link to comment Share on other sites More sharing options...
Pete H Posted October 29, 2011 Share Posted October 29, 2011 Great looking job as usual. Do you ever sleep Dave? Someday I hope I can comment on the technical aspects of your designs but for now I just have to appreciate the detail you put into all of it. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted October 29, 2011 Share Posted October 29, 2011 I am trying to understand your description. Does 60/40% mean the initial 60% of the horn length is a conical expansion and the last 40% is tractrix?. Precisely Is there any special geometry at the horn's throat (for instance: oblate spheroid or Quadratic throat)? No, the throat is pure Conical, with a Tractrix mouth which should reduce edge diffraction. I was under the impression the quadratic throat was to reduce distortion in a rectangular cross section Conical designs. Dave The geometry at the throat is an interesting issue, and I certainly do not have a good understanding of it. Oblate Spheroid (Geddes) and the Quadratic Throat (Hughes / Peavey) is an attempt to aid the transition of the wavefront from "flat" to "spherical". In fact Geddes argues strongly that it is this transition that can create additional reflections which are deleterious. The OS geometry will asymptote to a conical geometry. The advanatge to either of them (OS or QT - they are similar) is that the profile does not present any major discontinuities between the throat and the driver and the throat and the "middle portion". If you are interested in trying them (don't we all love "volunteering" the guy with the CNC machine ....) the math is straight forward and there are spreadsheets available. You have already done the hard part, the mating of the conical to the tractrix mouth. Quote Link to comment Share on other sites More sharing options...
Guest David H Posted October 30, 2011 Share Posted October 30, 2011 If you are interested in trying them (don't we all love "volunteering" the guy with the CNC machine ....) the math is straight forward and there are preadsheets available. You have alsready done the hard part, the mating of the conical to the tractrix mouth.I can do that. I will check into it.Dave Quote Link to comment Share on other sites More sharing options...
Guest David H Posted November 1, 2011 Share Posted November 1, 2011 OS-Contrac-T The OS throat efects the cutoff, and depth of the horn, makes Fc prediction difficult. Here is a visual of the OS throat, you can see the flair at the throat expands similar to tractrix, them becomes very consistant mid way through the horn, them once again flairs at the mouth. Quote Link to comment Share on other sites More sharing options...
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