VituixCAD v2

[tktran]

Can you show examples what names did not work? What measurement system or naming policy forced you to rename manually instead of following one of six supported file naming styles right away?

[Reet]

I've been thinking this too. It doubles the data but won't increase performance without doubling memory consumption because files should be read from project file at least every time when Delay is changed. That action must use very original data with ppo file type.

A 3-way project loaded uses about 50MB of RAM, I'm not worried about memory usage.


Thanks for your considerations of minor file loading and saving items.

[theSven]

Sorry about that, I have been trying to be proactive to catch these when they happen. There is a spam service the forum uses and it can get cranky sometimes. Apologies kimmosto

[kimmosto]

2.0.101.5 (2023-04-20)

General

• Separate file extension filters returned to Save frequency response and Save impedance response dialogs to allow selection of certain type from a list without typing.
• Frequency response exports with constant frequency step starting at 0 Hz exported as Easera .etx instead of .fri (originally added for FourAudio). Sample rate setting is taken from Options and FFT length (time samples) from Impulse response window.
• 0 Hz point of extrapolated frequency response set to 0 Pa, 0 deg for Impulse response and ETC calculation.

Diffraction

• Added warning to export about limited angle range if axis distance is shorter than longest baffle distance.

Convert IR to FR

• Added file extension filter including supported file types (pir, mls*, crp, txt and wav) to Select impulse response dialog. Separate filters are still available to avoid selection of wrong files or mix of different types.
• Accidental overwriting of input files with output files due to same directory and file extension prevented. User should change output directory or file extension to export.
• FFT session (.vxf) is possible to open with command line argument.

Merger

• Accidental overwriting of input files (in HF list) with output files due to same directory and file extension prevented. User can add 'VXM ' prefix to output files or cancel export for changing output directory or file extension.

[kimmosto]

Fck! One typo fix and . That feature must be removed.

[kimmosto]

I preferred the old "_mrg" suffix, even if the files are in a different directory. Potentially a file suffix entry box similar to the calculator tool could help here.

_mrg suffix was removed because suffix is not possible with 5/6 file naming styles. Only naming style which accepts suffix is 'Generic 2D'. For example I'm forced to use CLIO 3D balloon naming (hor is phi=0, ver is phi=9000) due to Outline turning table controlled by CLIO 12 QC with auto save feature. But we could consider prefix such as "MRG " + rootname + ... which is possible with all file naming styles.

driver response loader. In the main driver response selection, the open dialog always replaces the entire selection, rather than adding a file to the list. This makes the "clear" button redundant,

Clear button returns default flat omni response so it's not entirely redundant. For example Active TF block has clear button to remove transfer function, but still leave the block without shorting it. Or file targets for Optimizer. So Clear button is generally kinda cleaning unnecessary filenames from vxp file.
Driver's frequency response list has some weight of history down to 0.1 version with support of LspCAD "extended" format. All responses must be located in the same directory because directory name and filenames are separate fields in UI and .vxp file. In 0.1-1.1 versions directory field could have single response file including all off-axis directions. Adding files to list would enable loading from different directories which would lead to conflict and error (without validity check and ignoring). All this could be fixed with new version which includes directory name to every filename, but that wouldn't be backwards compatible in that feature - just like any version down to 2.0.0 at the moment.

convert IR to FR open file dialog doesn't include all supported file types as a single selection, so .PIR, .WAV, .MLS files require manual dropdown selection

We can try at least some limited single file extension filter in the next revision. User should select just one type because different IR file formats could have different default settings such as Skip samples. That is set once right after loading (not for each file) to keep possible user adjustments. Another risk with mixed input formats is that output files can easily overwrite input files. Risk of overwriting source IR is very high especially with txt and wav IRs because both are also standard output types. That risk exists at the moment though extension filter is separated. Only way to avoid losing original IR file is to check are input and output filenames equal and skip (if user does not export to different directory). I'll add verification to the next revision.

An alternative solution to avoid all file/folder structure issues would be to integrate everything to a single project file.

I've been thinking this too. It doubles the data but won't increase performance without doubling memory consumption because files should be read from project file at least every time when Delay is changed. That action must use very original data with ppo file type.

[Reet]

What? I can at least consider returning detailed file extension filter lists to save file dialogs, remove setting of initial/default directory from open file dialogs, clear initial filename from open and save file dialogs etc. though some of those changes would change it worse imo.

P.S. I just recall that I have not remembered to add an alternative directory structure recommendation to user manual. Maybe because my preference for directory naming is still to follow measurement and processing workflow:
1) Far field measurements of drivers to Far/Drivername directory. Results of Convert IR to FR tool, autosave files of CLIO and FFT session projects to the same directory.
2) Near field measurements of LF drivers, ports and M drivers to Near/Drivername directory. Results of Convert IR to FR tool to the same directory with IR files.
3) Impedance response measurements of all drivers to Impedance directory.
4) Baffle loss simulation to Diffraction or Near/Drivername directory. Diffraction project file to project's main directory.
5) Merging to Merger/Drivername directory. Merger project file to project's main directory.
6) Simulation of crossover. Project vxp to project's main directory.

Part of the nitpicky stuff is an expected folder organizational structure. Perhaps the "new project" button could create project file as well as sub-folders for project files if they don't already exist, to dissuade someone from making up their own system. I think you will find that if left to their own decisions, many users will attempt to locate all woofer files, near, far, merge, impedance, diffraction, within a single "woofer/drivername" folder, with file name suffix to identify the specific file within the folder. This user will become frustrated with the merger tool that forces a new directory to avoid overwriting, and many people won't read the help until they encounter a problem (if at all). Personally, I preferred the old "_mrg" suffix, even if the files are in a different directory. Potentially a file suffix entry box similar to the calculator tool could help here.

Nitpicking item 2 is the driver response loader. In other locations of the software where a list of files is loaded, calculator or merge tool, the open file dialog adds files to the list. In the main driver response selection, the open dialog always replaces the entire selection, rather than adding a file to the list. This makes the "clear" button redundant, since the list is always cleared on open, and prevents the ability to simply add a missed file, you have to select the entire list of files again.

Nitpick 3, convert IR to FR open file dialog doesn't include all supported file types as a single selection, so .PIR, .WAV, .MLS files require manual dropdown selection.

An alternative solution to avoid all file/folder structure issues would be to integrate everything to a single project file. I understand there is a fair bit of work in this solution. My though would be such that the loaded frequency response and impedance files are effectively imported to a single project large file. There would be needed change to diffraction and merge tool to provide a driver selection menu to allow for multiple diffraction and merge settings within a single project, but it ultimately would make the whole process a bit simpler on the user for project organization.

An alternative to the above would be a single project file, and individual driver files that contain the driver responses, impedance, diffraction and merge response files and settings.

Anyway, this is all minor details of personal preference, nothing critical and all is workable with the software as it is today.

[kimmosto]

2) Near field measurements of LF drivers, ports and M drivers to Near/Drivername directory. Results of Convert IR to FR tool to the same directory with IR files.

Oops. That went wrong. Should be
2) All near field measurements of LF drivers, ports and M drivers to Near directory. Results of Convert IR to FR tool to the same directory.

[JonMarsh]

Exactly!!

[kimmosto]

I could nitpick about the file loading and saving

What? I can at least consider returning detailed file extension filter lists to save file dialogs, remove setting of initial/default directory from open file dialogs, clear initial filename from open and save file dialogs etc. though some of those changes would change it worse imo.

P.S. I just recall that I have not remembered to add an alternative directory structure recommendation to user manual. Maybe because my preference for directory naming is still to follow measurement and processing workflow:
1) Far field measurements of drivers to Far/Drivername directory. Results of Convert IR to FR tool, autosave files of CLIO and FFT session projects to the same directory.
2) Near field measurements of LF drivers, ports and M drivers to Near/Drivername directory. Results of Convert IR to FR tool to the same directory with IR files.
3) Impedance response measurements of all drivers to Impedance directory.
4) Baffle loss simulation to Diffraction or Near/Drivername directory. Diffraction project file to project's main directory.
5) Merging to Merger/Drivername directory. Merger project file to project's main directory.
6) Simulation of crossover. Project vxp to project's main directory.

[kimmosto]

it won’t take my fileNAME, so I gave up and used a hack- I just renamed everything to hor_0.frd, hor/ver_+/-10… 170.frd

Can you show examples what names did not work? What measurement system or naming policy forced you to rename manually instead of following one of six supported file naming styles right away?

[kimmosto]

What I'm trying to say is; can I rely on the simulation?

Reliability depends on reliability and applicability of your measurement data. Crossover simulation does not add any other simulation to whole equation except assumption that SPL drops 6.02 dB when distance from rotation center to virtual mic doubles. The last one is quite close to fact at far field with single point source.

[kimmosto]

So I have assumed that the software uses some modelling internally to build up some sort of generic driver from the curves, and kind of deduces the phase out of the curves.
Is that right?

No. Loaded impedance response of the driver contains phase of complex impedance so it's relative to voltage at driver terminals. Loaded acoustical frequency response measurement contains phase of acoustical signal relative to voltage at driver terminals. When driver is installed to crossover network, magnitude and phase of impedance response measurement affect to voltage and it's phase at driver terminals. When simulated complex voltage at driver terminals is multiplied by measured acoustical frequency response, the result is acoustical response with crossover.
So any modeling is not needed to calculate acoustical response with crossover. Just frequency and impedance response measurements with phase, and other components and connection of crossover network.

[Toe In]

Hi, this is a theoretical issue I have been pondering a bit. I have used this program for simulations now for a while, and it seems to model reality quite well. In the crossover section, the behavior of the system is defined only by the frd and zma curves of the drivers. No TS-parameters seems to be needed. This is a bit of a mystery. For example, in a gives frequency, the SPL is perhaps 90dB and the z is 5 ohms. But there is no information in the zma curve about phase. What part is resistive and what is reactive?

So I have assumed that the software uses some modelling internally to build up some sort of generic driver from the curves, and kind of deduces the phase out of the curves.
Is that right?
What I'm trying to say is; can I rely on the simulation? Will it do the best from the information even without the TS-parameters?

OK, I'm not too good at math, so don't go too deep . Unless if you want to.

BTW, I like the visual appearance of the GUI, that's important if you have to sit a long time doing simulations.

Regards.

[kimmosto]

I always have errors loading those pesky 70 polar measurements!

What the heck is this? Never heard about pesky 70...

[tktran]

, I could nitpick about the file loading and saving, but just minor details at this point.

Do you have problems with file parsing as I do?

no matter what I do and change settings in the Options with the Plane keywords, I always have errors loading those pesky 70 polar measurements!

it won’t take my fileNAME, so I gave up and used a hack- I just renamed everything to hor_0.frd, hor/ver_+/-10… 170.frd

[kimmosto]

I struggle to find a software tool to design TLs and horns with a friendly user interface. Hornresp appears to be the most popular, but the UI is quite awful and confusing to those who aren't familiar with the internal math behind the numerical input. I wonder if there is any plan to expand the enclosure tool within VituixCAD to include horns and transmission lines?

My brain resources and available time are not adequate for programming TL and horn calculation. But I can add calculation and UI to VCAD if someone is willing to make or send me a source code in C# or other human readable such as Java, Pascal, Basic, ANSI C, C++ etc. Not matlab etc. higher level which cannot be converted to C# without some proprietary library.

[kimmosto]

2.0.101.4 (2023-04-15)

Impulse response

• Value of window function shown as 0-100% with mouse cursor. Also in dB if right Y axis is visible and curve is not selected.

Convert IR to FR

• Value of window function shown as 0-100% with mouse cursor. Also in dB if right Y axis is visible and curve is not selected.

[Reet]

I'm curious what is on the roadmap for future development in VituixCAD. Current features and workflow is very good and stable, I could nitpick about the file loading and saving, but just minor details at this point.

I struggle to find a software tool to design TLs and horns with a friendly user interface. Hornresp appears to be the most popular, but the UI is quite awful and confusing to those who aren't familiar with the internal math behind the numerical input. I wonder if there is any plan to expand the enclosure tool within VituixCAD to include horns and transmission lines?

[kimmosto]

2.0.101.3 (2023-04-14)

• Value adjustment can be accelerated by pressing Ctrl-key while mouse wheeling. Acceleration is typically 5-10x. Does not work over XO schematic because Ctrl+mouse wheel is reserved for zooming.

Main

• About box is able to detect .NET 4.8.1 or later

Power dissipation

• Changed to top-level window.
• Basic unit of current changed from mA to A.
• Initial crest factor of pink noise changed from 13 to 12 dB. Tooltip fixed.

[kimmosto]

1. How does one approximate facets on the baffle with the Diffraction tool?
2. Do you have any plans/possibilities to extend the Diffraction modeller into 3D space?

1. I would set R = W or D of facet. Someone compared rounding and facet by looking measurements if I recall... Listening gives final result = facets should not be used with small direct radiators.
2. That would not change much if/when diffraction tool is used according recommendation i.e. for creating on-axis baffle loss response for near field response of LF cones/ports. Reflection simulation will be deleted to maintain simplicity and performance if I decide add 2nd order diffraction from rear edges. It will not replace Akabak etc. no matter much I improve so motivation (and time) to develop further is not very high.

[tktran]

Kimmo,

even though they seem insignificant I think it’s very helpful to guide Best Practice principles.

btw,
1. How does one approximate facets on the baffle with the Diffraction tool?
2. Do you have any plans/possibilities to extend the Diffraction modeller into 3D space?

[kimmosto]

Insignificant updates continue...

2.0.101.2 (2023-04-11)

Main

• Tools menu and Tools section in user manual reorganized according recommended design procedure in 'Checklist for designing a loudspeaker' of user manual.
  Enclosure and Diffraction tool (before measurements), and Convert IR to FR and Merger tool (after measurements). Calculator, Auxiliary calculator and SPL Trace last because they are not normally needed.

[Reet]

I don't recall where I got this file, but I was going through my documents and found this, for another source of information for "how far is far field".

[kimmosto]

2.0.101.1 (2023-04-03)

Convert IR to FR

• Added support for WAV and TXT impulse response files exported from Audio Precision.

[kimmosto]

Some reading about TLS https://en.wikipedia.org/wiki/Transp...nd_development

[kimmosto]

I should check the change log every Sunday, on principle...

I think it's not necessary VituixCAD was using TLS 1.0 security protocol for downloads up to revision 2.0.100.0 (2023-03-10). That protocol was deprecated already few years ago. My service provider made some update to servers so downloads were prevented. Both newer TLS safety protocols (1.1 and 1.2) were enabled in VCAD 2.0.100.1 (2023-03-12) so downloads should work as long as TLS 1.2 is supported in web server. Some day in far future TLS 1.3 will be minimum requirement so I have to upgrade .NET Framework requirement from 4.5.2 to 4.8 to continue because 4.5.2 supports (natively) up to TLS 1.2.

[JonMarsh]

Well, interesting- since doing a manual update earlier this week, (the first update in over a month, as I was not getting any prompts during that time, this morning I got a prompt for installing an update, in the usual manner.

I had made a mental note to myself that if auto-update prompts weren't working, I should check the change log every Sunday, on principle...

[JonMarsh]

That should be interesting to see!

[tktran]

Some more information on "how far is far enough" from Audio Precision:

https://drive.google.com/file/d/1ICLgcjqGtyvNaSva4jPQ8Z3vYwFN9_Ex/view?usp=share_link

Interesting. So for my 40cm (H) x 20cm (W) x 30cm (D), then M = 50cm (by pythagorean theorem).

Tomrrow I measure full polars at 1.5m. Then we merge 0-180 degree measurements taken at 1.5m, 1.0m, 0.80 m, 0.60m, 0.40m with the nearfield, and compare results!

[kimmosto]

Unapproved message waits for moderation. Why that feature is still active?

[kimmosto]

Are there any problems of measuring at 50cm, or 2 ft etc, and adjusting the timing offset?

This is very case dependent. I had to make instructions shorter than few hundred pages which would be required to speculate (all) different speaker concepts and measurement conditions. Line arrays, long (or wide) planars, horns, deep waveguides etc. could require different approach. Simplified theoretical limit for far field is 6a i.e. 3 x diameter of "radiating surface". 1000 mm is nice rounded value which enables 4.5 ms time window in almost any living room, and supports cones up to ca. 15" or baffle width or height or longest dimension up to 33 cm - depending on how radius of radiating surface is interpreted. But 1000 mm is not carved to stone. I have measured 18" at 1 m. Some tractrix horns at 1.2-1.5m due to very different wavefront and possible frequency dependent far field point and acoustic center quite far from rotation center which is different compared to other ways with direct radiators.
Using near field measurement, diffraction simulation and merging allows violating simple far field rules. For example Audio Precision's AN assumes that radiating surface includes all diffractions (~full baffle loss) in the measurement data. That is not strictly required in VCAD measurement instructions because it's impossible to achieve with large constructions by measuring indoors at home.
Life is full of compromises, and user makes final decisions.

[kimmosto]

2.0.101.0 (2023-04-01)

• Added EASERA .etx file format option to impedance response exports. f, Ohm Re and Ohm Im columns. Constant frequency step directly for complex FFT. Sample rate 44100 Hz. 8193 data lines (16k FFT).

Convert IR to FR

• Added WAV 32-bit IEEE mono impulse response file format option to Export command. Smoothing not yet supported.
  dBSPL in Pascal so scaling of +94dB is needed if reader does not assume that values are in Pascal.

[Reet]

Some more information on "how far is far enough" from Audio Precision:

https://drive.google.com/file/d/1ICLgcjqGtyvNaSva4jPQ8Z3vYwFN9_Ex/view?usp=share_link

So how do time selective techniques work in practice? Consider the measurement setup depicted in Figure 4. A measurement microphone is positioned on-axis in front of a loudspeaker in a semi-reverberant room. To be in the far field of the loudspeaker, the distance d is chosen such that it is more than 3 times M, the largest significant dimension of the loudspeaker. The path length of the direct sound from the loudspeaker to the microphone is d, and the path length of the first reflection from the nearest reflecting surface (the floor in this case) is 2d_R. Based on this geometry, the time difference, T, between the direct sound arrival at the microphone and the first reflection is T = (2d_R - d) / c, where c is the speed of sound.

[tktran]

This is a midwoofer with response down to below 50Hz, yes.

However, to get a reflection free (anechoic) response down to 50Hz; we need a gate time of 20ms
The math is T = 1/f where f is the frequency in Hz and T is the period in seconds.

So if you want to measure to 50Hz, you need a window of 1/50 = 0.02 secs = 20ms.

There's a tool included in VituixCAD2:

Auxiliary -> Time window that you can use to calculate this-

eg. to measure down to 50Hz, at a distance of 1.5m; that means the speaker and microphone have to be off the ground by more than 4.15m:







To measure at 2m, the speaker has to be off the ground at least 4.4m



If you're NOT using VituixCAD2 you can try it for yourself online:

https://mehlau.net/audio/floorbounce/


I do have the ability to measure at 5m above the ground, but I'm too lazy- to set up and pack up is even more bothersome than the basketball court!

I prefer to do it indoors in my lab and merge the farfield with the nearfield, as per Kimmo's instructions:
page 14 of:

VituixCAD_Measurement_REW.pdf (kimmosaunisto.net)

[Nil L]

Is this a tweeter? Not indicative. Do you have a driver in the enclosure that plays below 50Hz? If you could measure such a driver from a distance of 1m, 1.5m, 2m, it would be interesting.

[tktran]

Far field measurements first



Edit: Scale and colours changed for clarity

[tktran]

LIVE!

stay tuned…

[Reet]

And what will measurements look like with a speaker that plays at least up to 50 hertz? I think 2*speaker diameter won't work. 1.5 m, and preferably 2 m will be required.

use nearfield for low freq measurements…For far field measurements, baffle width is limiting factor on mic distance, not speaker diameter.

[Nil L]

Very interesting!!

I will try a similar experiment this weekend, outdoors, at 2m height.

Wow, I was thinking of asking you to do this. So phones are not needed.

[tktran]

Very interesting!!

I will try a similar experiment this weekend, outdoors, at 2m height.

[Nil L]

For the responses here, overall bass balance was not greatly affected until at 22cm distance.

All the same, 33 cm. Since 5 out of 8 measurements fit one into one. And 33 cm is 2 * speaker diameter.
And these are measurements of a speaker that plays up to 100 hertz. And what will measurements look like with a speaker that plays at least up to 50 hertz? I think 2*speaker diameter won't work. 1.5 m, and preferably 2 m will be required.

[Reet]

Looking back on the above measurements, the closer mic distance has greater influence of near reflections from whatever table the speaker is sitting on, and the increased window length really provided very little difference to overall measurement resolution. 1m distance reduces impact from early reflections, so I’ll stick with that.

[Reet]

I should mention as well, that each response at each distance had the window length set to about the same location on the first reflection. For each measurement, the following right window length was used:

3cm - 1000ms
11cm - 5ms
22cm - 5ms
33cm - 4.8ms
44cm - 4.6ms
55cm - 4.35ms
66cm - 4.1ms
77cm - 3.87ms
88cm - 3.7ms
99cm - 3.5ms

[Reet]

Today's adventure. Compared measurements of a bookshelf speaker at various distances. Tweeter is disconnected so only woofer is measured. Speaker is 17.5cm wide, so 2x baffle width is 35m, 3x would be 52.5cm. Here I measured in some small arbitrary increment of 11cm, all the way out to 99cm.
This is just the far field response. Normalized amplitude at the bump at 1300Hz so they are all represented at about the same 4pi amplitude.



I then merged the whole set with nearfield + diffraction response at 300Hz.


For the responses here, overall bass balance was not greatly affected until at 22cm distance, however there is difference in the response >500Hz all the way up to 1kHz, likely early reflections from my very non-ideal office space used for this test.