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Old 9th December 2019, 10:38 AM   #1701
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by AllenB View Post
Why are angles interpolated?
Frequency responses to simulated directions are interpolated from measured responses (because measured directions are not necessarily exactly equal to simulated directions). Did I get it right?
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Old 9th December 2019, 10:49 AM   #1702
AllenB is offline AllenB  Australia
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I'm just trying to understand what is happening. What if there was no interpolation at all. Is it necessary? What does it do?
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Old 9th December 2019, 11:53 AM   #1703
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by AllenB View Post
I'm just trying to understand what is happening. What if there was no interpolation at all. Is it necessary? What does it do?
VituixCAD versions from 0.1 to 2.0.20.0 (2019-08-20) did not have frequency response interpolation. Program just selected the closest measured angle, and compensated measured magnitude and phase with mechanical geometry ~ difference between simulated flying distance and length of design axis. That approach is okay especially with circular radiators if angle step while off-axis measurement sequence is small enough e.g. 5 degrees to avoid large jumps in response shape when position of virtual mic travels in the simulation or location of driver in crossover is adjusted or design axis is moved or nominal listening distance is changed.
Sparse angle steps e.g. 30 degrees while off-axis measurement sequence cause quite big jumps in response shape, and result between measured directions is not necessarily very logical and accurate.

The most dramatic flaw of missing interpolation is behavior with rectangular radiators. Rectangular radiator is not possible to tilt vertically or rotate horizontally in the simulation without quite high error and stepped jumps in response shape if measurement data includes horizontal and vertical planes only. Of course we could measure rectangular radiator in it's final & fixed tilted/rotated position, but that would be as inflexible because does not offer rotation of simulated planes/orbits or change of design axis or listening distance etc.
Free simulation of rectangular radiators require either balloon data all around the speaker or response interpolation between measured planes/orbits. The last one is selected to VituixCAD.

The most inflexible approach would be measuring everything at predecided listening point. That is accurate for sure, but requires large anechoic. Possibilities to adjust construction in the simulation are gone also with adjustable constructions so designer cannot optimize construction at the same time with crossover.
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Old 9th December 2019, 11:58 AM   #1704
AllenB is offline AllenB  Australia
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I'm sorry for all the questions, I just want to turn it off and if I cant, then I want the knowledge to control the result. If I can't then I will have to use other methods.

Will measured data every 5 degrees mean there will be no interpolation? or will there be some, diagonal angles calculated for power?

Last edited by AllenB; 9th December 2019 at 12:10 PM.
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Old 9th December 2019, 12:50 PM   #1705
kimmosto is offline kimmosto  Finland
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Interpolation is automatically "off" if location of all drivers in the crossover is X,Y,Z=0,0,0 mm and T=0 deg and R=0 deg and angle step while off-axis measurements equals to angle step setting in Options window.

Power response is calculated normally in horizontal and vertical planes only. That changes along with axis rotation; Planes deg parameter in Drivers tab.
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Old 9th December 2019, 06:23 PM   #1706
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by AllenB View Post
I just want to turn it off
I'd like know actual reason for this.
Optional selection of the closest measured angle would be easy to add, but I'm not very eager to restore old flaws and add more switches and instructions if measurement data producing acceptable interpolation result is possible to arrange. Magnitude interpolation is not a problem, but phase could be if timing of responses to be interpolated are "from different worlds".
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Old 9th December 2019, 06:40 PM   #1707
geotone is offline geotone  Europe
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I'd be interested in a possibility to select angles.
I am working on a prismatic speaker where the sides are angled 18 degrees (up and down). I planned to measure in 3 or 6 degree intervals, and then enter the position and angle of each driver accordingly. I am not sure if the interpolation to 5 degrees makes much of a difference to the result or if it's just my engineer's OCD here.

Anyway, time to send another huge thanks to Kimmo for continuously well thought through and generous work.

/G
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Old 10th December 2019, 12:56 AM   #1708
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by kimmosto View Post
Interpolation is automatically "off" if location of all drivers in the crossover is X,Y,Z=0,0,0 mm
Ok, this must be zero if measurements cover the delays and don't require VC to do the physical rearranging. No problem.
Quote:
and T=0 deg
Two reasons I would change this. One is when I want to see phase better so I delay both drivers to control wrapping. Other is when I plan to delay in software.
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Old 10th December 2019, 12:58 AM   #1709
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by kimmosto View Post
I'd like know actual reason for this.
Angle windowing. I'd like to set the size of a slice and the energy in each slice, but not have numbers bleed over into the next slice (or over many slices).
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Old 10th December 2019, 04:40 AM   #1710
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by AllenB View Post
I'd like to set the size of a slice and the energy in each slice
Why? Is something wrong with interpolation calculation? Or is measurement data incompatible with the program? It yes, why it is incompatible and can you do something about it in the future?

No need to answer if driver's XYZRT=00000 is adequate trick at the moment.

Quote:
Originally Posted by AllenB View Post
Two reasons I would change this. One is when I want to see phase better so I delay both drivers to control wrapping. Other is when I plan to delay in software.
T deg parameter of driver in XO is vertical rotation (tilt) around it's center point. That does not change delay by distance from driver to mic.
Global timing to e.g. improve readability of phase responses is set with Delay [us] parameter in Drivers tab.
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