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Old Yesterday, 02:35 AM   #1761
nc535 is offline nc535
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Join Date: Apr 2011
Quote:
Originally Posted by David McBean View Post
Hi Jack,

Doesn't pressing the F9 function key or clicking the 'Export Data' command button give you what you want?

Kind regards,

David
Hi David:
I'm supposedly a smart guy but sometimes I have blinders on. This time I was in the Transmission Line Loudspeaker Wizard power screen and I wasn't aware of the F9 option or the export button on the memory & width screen. Thought I was on my one because the result was just in the wizard. But I was planning to ask you next. And was right to be cautious because I get different IR result using the F9 export. Thanks for the tip.
Jack
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Old Yesterday, 06:36 AM   #1762
kimmosto is offline kimmosto  Finland
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Location: Kuopio
Quote:
Originally Posted by celef View Post
kimmosto, i can not find the post now but i think you said that the edge (baffle simulation software) is not very accurate, especially not when simulating offaxis
On-axis and off-axis within typical listening window are very good as far as I understand. So typical cases for axial simulation and full space to half space conversion work without problems with The Edge.

It's obvious that program is not designed for off-axis simulation because off-axis angle is not user parameter and you cannot simulate shadow sector 90-180 deg. Of course one could hope valid result also with short Mic distance and long X or Y, but the result is not okay. It has full baffle step of 6 dB also close to 90 deg which is not correct. Response to 90 deg should be quite flat with some curves. The same issue exists with some other diffraction simulators such as Bagby's and Laub's Excel sheets. I'm not aware what diffraction model each program uses. Probably 'Bews & Hawsford' is the most popular. That model gives full baffle step to all angles and support ends to 90 deg off-axis.

The Edge, circular baffle dia=340mm, circular driver dia=25mm:
Click the image to open in full size.

VCAD Diffraction uses Distributed Edge Dipole (DED) Model by Urban, Heil, Pignon, Combet and Bauman - with few empirical additions and possible faults DED supports also high off-axis angles and shadow sector 90-180 deg. It's simplified and not accurate either, but a step closer to universal approach. Also decades easier and faster to use with off-axis angle parameters.

DED by VCAD: red=0deg, orange=88deg with non-ideal edge, blue=88deg with ideal edge, yellow=180deg
Click the image to open in full size.
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Old Yesterday, 02:21 PM   #1763
celef is offline celef
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Join Date: Nov 2012
thank you very much for your reply!

then the edge looks accurate enough for me, i am most interested in the shape of the frequency ripple offaxis and not so much about correct level

thanks again!
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Old Yesterday, 03:15 PM   #1764
kimmosto is offline kimmosto  Finland
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^Note that also ripple amplitude is too high to off-axis with simulators which are insensitive to off-axis angle. Main problems in off-axis simulation with Edge are horrible user interface, slowness and level normalization by Mic distance which drops response level quite much. E.g. I had to use VCAD Calculator to normalize previous 0 deg and 88 deg curves at 5 Hz to show them in the same graph. But please continue with Edge if self punishment is essential
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Old Today, 05:29 AM   #1765
David McBean is offline David McBean  Australia
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Quote:
Originally Posted by nc535 View Post
I'm supposedly a smart guy but sometimes I have blinders on.
:-).
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