VituixCAD

There may be some drivers that are designed like this, but certainly not nearly all cone drivers. It really depends on what a driver is designed for. For instance, a bass driver does not need to have flat response higher than a few hundred Hz.
Maybe a subwoofer driver doesn't care about the response to a few hundred hertz but a normal woofer or mid-bass driver does.

The woofer I gave as an example is a 12" woofer and in the "show effect of voice coil impedance" mode is shown to be 3dB down at 300Hz and 6dB down at 1Khz. The real driver response is nothing like this and is pretty much flat up to 1Khz on axis on an infinite baffle. As the driver may be crossed over realistically as high as about 250-300Hz, that's a large error.

Whether explicitly designed for or not, directivity counterbalancing impedance rise tends to happen naturally as a small driver which starts beaming at a high frequency tends to have a small, low inductance voice coil that doesn't start attenuating until a high frequency, while a larger driver which starts beaming at a lower frequency tends to have a much larger voice coil inductance that starts attenuating at a lower frequency.

In a sense we don't even think about or notice this natural balance occurring until you directly compare two drivers which are the same apart from one having a shorting ring - the one with the abnormally low inductance for it's size then has an upwards slope in its on axis response due to the lack of this natural attenuation through inductance.

So I'd say this is very common in cone drivers.

Now you're talking about actual drivers in practice. Not ideal piston with current driven motor.
Yes, I'm talking about actual drivers in practice - that's what's of interest to me of course. :)

Although keep in mind that an ideal piston is actually even more directional at high frequencies than real drivers that have cone breakup and decoupling effects whose active area can shrink at high frequencies, whether by design or lucky accident.

So the effect of directivity counteracting voice coil inductance would be even more pronounced on an ideal piston used up to high frequencies.
Enclosure tool tries to play both of those, but user is responsible to select which SPL curve is shown and exported. For example I never look SPL curve with impedance effects because it's not very practical approach and useful for purpose of enclosure simulation (which is driver selection and box dimensioning). Basic simulators are not able to simulate HF response so that range is quite useless no matter is there some Z effects or not.

Exactly, so as I suggested earlier I can't see the purpose of that mode or why it's enabled by default. I certainly wouldn't use it.

Incidentally I had a look at WinISD and it also has a mode that tries to include voice coil impedance (although again, why ? The manufacturer already designed the driver for constant voltage operation) however the effect of switching it on is much more subtle than the effect in Vituixcad.

So I'm not sure how they're calculating that...
 
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Incidentally I had a look at WinISD and it also has a mode that tries to include voice coil impedance (...) however the effect of switching it on is much more subtle than the effect in Vituixcad.

'Simulate voice coil inductance' checkbox was added to new WinISD version. It was forced on in earlier versions so you had to zero Le to get flat HF.

You will get equal result by entering equal parameters to both programs. WinISD does not have basic impedance model with Z1k and Z10k so you need to manipulate parameters in Vituix to compare; enter Le and set Z1k and Z10k to zero. That usually gives the worst result with too steep low pass slope at HF though it might look more subtle at LF.
I've never tested more advanced Z parameters (semi-inductance KLe, fLe) with WinISD. Extended Z model is the most accurate for simulating impedance response with Vituix Enclosure.
 
What a truly awsome effort.However I am quite unable to do anything with it !! I have used CAD from autocad to ltspice for over 20 years and rarely have to consult a manual to get going.Doing ANYTHING with this has got me beat.Perhaps a step by step user start guide If someone would write one would be helpfull.Looking at some of the math that has been implimented gives me great confidence of the potential and comprehensivness of this software.NB I do have the help file from the site.(but alas still wont sink in).Since I am corpus mentus with the theory involved the problen I have is one might say is driving the software.Still I shall persist with it.(It seems to good to let it pass)
 
Perhaps a step by step user start guide If someone would write one would be helpful.
Such a guide exists. It tells you in detail even how you are expected to measure, what you are expected to measure, how you are expected to store the measurement files, the settings you are supposed to make in VituixCAD, etc. I am surprised you haven't found it yet.

And no, I'm not referring to the help document, which is more of a user manual for the UI.
 
No Linux,Apache ect are open source with thousands/millions of contriutors globally.I was just making the point that for One man to do this is impressive!!!.Also to make it freely available. (Not casting ANY asertions on freeware)
While on this topic, it's best to be clear that VituixCAD is not open source. Its licence permits free download and use in binary form.
 
Problem seems is that I was trying to work `theoretically` rather fron actual measurements.

Recommended procedure is to use measurement data because it's decade(s) more accurate and faster than trying to create reliable/accurate simulated acoustical response data. Common user does not have access to parameters needed for decent acoustical simulation of any kind of radiator so that would be unpractical i.e. quite useless approach.
But VituixCAD does not force you to measure. Response data can be produced with Enclosure tool, Diffraction tool, SPL Trace or any external simulator which is able to export frequency or impulse responses (though it's probably inaccurate and valid only for preliminary studies).
See post #1283.
 
I have some questions related to positioning the microphone for far-field measurements (or which "convention" is implemented in Vituix). I guess the answers should be in the manual (downloaded from the Vituix CAD website), but I could not find it, so please bear with me... or just tell me the page number of the manual so I can look it up.

For a multiway loudspeaker, what is the convention adopted in Vituix regarding the height of the microphone (for far-field measurements)?

For example, how do I place the microphone for on-axis measurements of the drivers in a three way loudspeaker with the three drivers stacked on top of each other?
  • Do I set the microphone at the level of the center of the tweeter for the tweeter measurement, at the midrange level for the midrange measurements, and at the woofer level for the woofer?
  • Or do I set the microphone at some level that is "centered between the three drivers"?
  • Something else?

Also, when it comes to off-axis measurements (both vertical and horizontal), what is the Vituix convention regarding the direction of the angles (positive vs. negative anglues)? I remember we had this discussion before, but I can't find it anymore, and it seems this did not make it into the manual.
 
I have some questions related to positioning the microphone for far-field measurements (or which "convention" is implemented in Vituix). I guess the answers should be in the manual (downloaded from the Vituix CAD website), but I could not find it, so please bear with me... or just tell me the page number of the manual so I can look it up.

For a multiway loudspeaker, what is the convention adopted in Vituix regarding the height of the microphone (for far-field measurements)?

For example, how do I place the microphone for on-axis measurements of the drivers in a three way loudspeaker with the three drivers stacked on top of each other?
  • Do I set the microphone at the level of the center of the tweeter for the tweeter measurement, at the midrange level for the midrange measurements, and at the woofer level for the woofer?
  • Or do I set the microphone at some level that is "centered between the three drivers"?
  • Something else?

Also, when it comes to off-axis measurements (both vertical and horizontal), what is the Vituix convention regarding the direction of the angles (positive vs. negative anglues)? I remember we had this discussion before, but I can't find it anymore, and it seems this did not make it into the manual.


Hi Mbrennwa,


I see these informations in page 4 of the "VituixCAD Measurement Preparations.pdf" in Basic Rules


Here is the link if needed : https://kimmosaunisto.net/Software/VituixCAD/VituixCAD%20Measurement%20Preparations.pdf

Hope It help
 
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I have some questions related to positioning the microphone for far-field measurements (or which "convention" is implemented in Vituix). I guess the answers should be in the manual (downloaded from the Vituix CAD website), but I could not find it, so please bear with me... or just tell me the page number of the manual so I can look it up.

For a multiway loudspeaker, what is the convention adopted in Vituix regarding the height of the microphone (for far-field measurements)?

For example, how do I place the microphone for on-axis measurements of the drivers in a three way loudspeaker with the three drivers stacked on top of each other?
  • Do I set the microphone at the level of the center of the tweeter for the tweeter measurement, at the midrange level for the midrange measurements, and at the woofer level for the woofer?
  • Or do I set the microphone at some level that is "centered between the three drivers"?
  • Something else?

Also, when it comes to off-axis measurements (both vertical and horizontal), what is the Vituix convention regarding the direction of the angles (positive vs. negative anglues)? I remember we had this discussion before, but I can't find it anymore, and it seems this did not make it into the manual.

Typically, one would be looking to measure ear level along the listening axis and then off axis would be at that same height. This is because the primary design is addressing the sound arrival at your ears. This might be on the tweeter axis (tweeter height level) or between the tweeter and midrange depending upon your design and loudspeaker placement. As you change your listening position (up or down), a certain amount of lobing will be introduced between the drivers; this is inescapable. Another important thing to keep in mind is that you want to assure that your measuring distance allows for adequate driver integration as this will provide you a more accurate representation of the farfield reproduction. Realize that the more vertical rotation at each horizontal rotation that you have, the closer you will bet to a true power representation; but this becomes impractical so we do our best to emulate this with the horizontal rotation and then perhaps a limited number of vertical rotational measurements.

The common convention horizontally is that from the listening position or measurement position looking at the loudspeaker, your left is labeled as negative degrees and your right is positive.

Hope this helps,
Jay
 
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Could be because measurements are not done in VituixCAD but with other software's and this other document is a guideline how to get data to work with


For me it make sense to separate the manual describing in detail all the functions of VituixCAD and the guides for measurements in other softwares or in general terms


One way or another I am glad Kimmo provided that in addition of the user manual.
 
Could be because measurements are not done in VituixCAD but with other software's and this other document is a guideline how to get data to work

Yeah, but the data must correspond to the conventions implemented in VituixCAD. The measurement geometry assumed by VituixCAD is crucial information that should be in the main documentation manual. Skimming through the manual, I didn't realize there is another document that has the info I was looking for, so I simply assumed the information is not available in the documentation.
 
The measurement geometry assumed by VituixCAD is crucial information that should be in the main documentation manual.

Multiple measurement help documents is needed in order support different measurements programs; CLIO, ARTA, REW etc. because data processing is different for all of those.

This is probably repeating, but main program does not require certain measurement geometry. Each driver instance in XO has X, Y, Z, R, T parameters which affect to calculation of delay/phase and SPL attenuation, and selection of off-axis angle measurement from response list in Drivers tab. User can measure all drivers at single elevation in horizontal plane and single Xmm in vertical plane, but then all drivers should be parameterized X=0, Y=0, Z=0, R=0, T=0 in order to disable geometry calculation by the simulator. In addition, user have to scale SPL and delay differences between drivers if measurement distance is not equal to simulated listening distance.

Drivers' geometry parameters are shortly explained in user manual. Really easy to test how location (X,Y,Z) affects to phase response and SPL at listening distance (set in Options). Just single wire XO is needed.

Better user manual is possible for sure, but I will not do big changes to document structure as long as German translation is not done. It's delayed since 2018-10-05. One possibility is to move forward without German version.