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Old 3rd February 2019, 01:17 PM   #931
nc535 is offline nc535
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I appreciate that reply especially since its OT. I felt the same way about treatment but am limited by WAF so am trying to work with the room acoustics that I have, plus drapes, area rugs and padded furniture.

I suppose its also OT (apologies) but I'd like to show the attached on groundplane CBT directivity if for no other reason than to show off the power of Vituix.

These curves are from a 24 driver (2" piston), 36 degree CBT. Mirroring the drivers to approximate the ground plane response made a huge difference and directivity holds just about down to 100 Hz. The weighting/shading costs 3 db in SPL in excursion limited region and the 2" drivers are already a little bass shy. Trying to get this 3db back by essentially unshading below 100 Hz with first order PEQ causes vertical lobe to appear between 100 and 200 Hz. Perhaps this can be fixed with sharper roll off on the LF boost. Its awesome to be able to explore and optimize this before making any sawdust.
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Old 3rd February 2019, 03:46 PM   #932
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by nc535 View Post
Its awesome to be able to explore and optimize this before making any sawdust.
Maybe you are already aware that response data with 5 deg steps does not give very accurate vertical off-axis simulation with line arrays because frequency responses are not interpolated between measured/simulated angles. Delay/phase information is calculated by distance differences so that part in simulation is accurate, but program selects off-axis response from Drivers tab which is closest to angle between driver's axis and 3D line from center point of driver to mic/listening point.
We would need off-axis responses with 1 deg angle step to get the most accurate simulation VituixCAD could offer, but 360 off-axis responses (per plane) keeps program so busy that using becomes too inconvenient (though simulation result looks very nice). Minimum step in Diffraction tool is kept as 5 deg because simulated off-axis will not be accurate anyway.
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Old 3rd February 2019, 04:02 PM   #933
nc535 is offline nc535
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I wasn't aware of that. But how accurate is "not very"?

And how accurate does it need to be at this stage where I have already decided on a CBT and I have to make choices about height of the array, number and kind of drivers. Even not very accurate might be good enough and would be better than nothing provided its not misleading.

I think I will compare sim results for 15, 10, 5 degree steps and see if there is a trend
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Old 3rd February 2019, 04:25 PM   #934
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Originally Posted by nc535 View Post
I wasn't aware of that. But how accurate is "not very"?

And how accurate does it need to be at this stage where I have already decided on a CBT and I have to make choices about height of the array, number and kind of drivers. Even not very accurate might be good enough and would be better than nothing provided its not misleading.

I think I will compare sim results for 15, 10, 5 degree steps and see if there is a trend
Here are plots with 5,10, 15 degree steps set in diffraction tool. They are all qualitatively the same. If I look closely. I can see differences in the yellow green transition regions. I imagine with 1 degree steps, we could see fine detail in these regions. I wouldn't mind waiting a few minutes for Vituix to crank out that level of detail when I felt I needed it. But I'd probably also want a cancel button for when I forgot to see the step size back to a normal 5 degrees
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File Type: jpg CBT vertical vs driver directivity resolution.jpg (178.0 KB, 167 views)
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Old 3rd February 2019, 05:00 PM   #935
kimmosto is offline kimmosto  Finland
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Angle resolution of off-axis data and directivity difference between actual driver and ideal piston are the most obvious errors with simulated data. I could easily reduce minimum angle step of diffraction simulation down to 1 deg, but that would not reduce the other error a bit. This kind of simple simulation is inaccurate anyway, but hopefully gives some information about whole project before making any prototype for measurements.

With measured data we are able to reduce both errors (in addition to error in baffle diffraction simulation). Angle resolution could be 1 deg and off-axis data with actual driver - not just simple simulation with Bessel J1 function. No need to built whole array.
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Old 3rd February 2019, 05:21 PM   #936
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"some info about the whole project before making any prototype" is all I'm looking for! I've got it and I should move on. Still working driver evals and tradeoffs though. Nice 1.5" full range driver that needs help from a woofer vs 2" or 2.5" drivers that get well into subwoofer territory on their own but aren't as smooth on top

Interesting - you suggest measuring single driver with this 1 degree measurement step size and linking that data into the sim instead of diffraction export. That is a lot easier than building and putting the entire CBT on a turntable but its still a lot of measurements for a DIYer. hmmm
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Old 3rd February 2019, 05:59 PM   #937
kimmosto is offline kimmosto  Finland
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Originally Posted by nc535 View Post
you suggest measuring single driver with this 1 degree measurement step
I would measure with 5 deg step despite of some inaccuracy. 5 deg step allows merging of simulated LF directivity and measured HF directivity. That could be useful if directivity information of far field measurements is not logical and reliable enough at LF.

Motorized turntable would be helpful with 1 deg step If you decide to measure with 1 deg step, load response data after crossover and driver locations are done. And clear measurement data temporarily if you need to make big change to crossover. Otherwise program jams quite badly.
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Old 11th February 2019, 09:49 AM   #938
kimmosto is offline kimmosto  Finland
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Originally Posted by ergo View Post
Enclosure tool does not follow the main program Options -> Frequency range setting. Would it be possible to enable that?
This feature is now restored to Enclosure tool, rev. 2.0.13.2 (2019-02-11). Also diffraction response is restored to Align tab (earlier in Directivity tab). Full space response is shown in SPL graph (in brown) if Diffraction response is checked.
No export for full space response. That should be exported with Diffraction tool where off-axis responses (to full space) are available too.
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Old 15th February 2019, 01:35 AM   #939
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Don't want to derail this thread, did do some searching but came up empty. Let me know if there's a better place to post this.

The Vituix manual seems to indicate that the "ways" selection is the first step in speaker simulation, however when I open Vituix CAD, neither the 'Way" selection nor "Count & connect" input fields are present.

I have connected the generator to the driver with a single wire on the crossover schematic.

I have updated to the latest .NET version.

Any guidance on how to go about starting a simulation project would be greatly appreciated. Thanks!
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Old 15th February 2019, 05:10 AM   #940
kimmosto is offline kimmosto  Finland
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Originally Posted by rsbonini View Post
"ways" ... "Count & connect" input fields are present.
"Way" is now heritage abstract term describing driver or driver group with common filter in crossover. Version 1.1 had/has way enabling and selection, but with version 2.0 you need to make the same by adding driver names and loading measurement data to Drivers tab, adding separate components, wires and drivers to crossover schematic, and finally linking measurement data to each driver instance in crossover with combo box just below schematic image. More complex but limitless.

Please follow items in How to start working with VituixCAD. Refresh page to see the latest. Investigating demo projects is important to get idea what typical (passive) project contains, how response file naming works and response data linked to drivers in crossover.

Crossover manipulation is presented in video VituixCAD 2 free form network
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