VituixCAD

[kimmosto]

2.0.125.1 (2025-05-31)
Main

• Auto update is using HttpClient instead of (obsolete) WebClient.

Enclosure

• Online database is downloaded for browsing and database update using HttpClient instead of (obsolete) WebClient.

Merger

• Raw LF response traces try to maintain line width, color and style set in Traces window while current session.

Replacing WebClient with HttpClient class may not have any effect, but it should be more modern. This version should be downloaded and installed manually if previous versions and server do not co-operate anymore due to newer PHP version 8.2 at the server. Co-operation is tested automatically by Auto update in every start-up, or can be tested manually by browsing Online driver database in Enclosure tool.

 

[Finnito123]

@kimmosto I was wondering if it is possible to export the filter curves and phase for the different drivers? I mainly use DSPs for crossovers. Since all DSPs use different methods to calculate the coefficients it would be beneficial to measure the DSP output and compare those to vituixcad output. I measure my designs in a community hall to get down to 80 Hz. Afterwards I would be happy if I could just check my DSP output... instead of remeasuring the whole speaker which is not possible at home and a lot of effort to do in the community hall...

Anyways big thanks for vituixcad i really love the software!

 

[kimmosto]

if it is possible to export the filter curves

User manual might tell you something about "File -> Export -> Filter response of Driver".
Impulse response window can create IR as wav, txt, ... for FIR/convolution gear.

 

[Stixx]

I have been working with the diffraction tool a lot lately, after eventually finding out how to properly name files for the angle parsing. 🤔

I added the directivity information to a lot of my projects…some based on measured data from previous times, some based on simulated data. I even went so far to reconstruct projects from german „HobbyHifi“ in VituixCad by generating frequency responses using SPL trace, enclosure, merger, directivity and calculation tools. Results in VituixCad using these methods are usually surprisingly close to the published curves in the magazine.

Now…I noticed that the spl drop for different angles in the response curves as calculated by the diffraction tool (based on the information given in the drivers tab) is somewhat different than what I can find in published data. I understand that the angle information is calculated based on a mathematical model…taking in mind baffle step, driver dimensions etc.

To illustrate my findings I shall add a few images:

 

[Stixx]

For comparision reasons the published data of another 6 inch driver.

Point is that the response curves seem to change only after about 1kHz and not much lower than 1 kHz whereas VituixCad exhibits (calculates) a drop of about 2dB @1kHz...
The influence of diffraction on a tweeter response curve is similar but maybe trickier since the falling slope of the response (downwards) is usually affected by the baffle step. Maybe you can share a few thoughts on this. Thanks!

 

[witwald]

The VituixCAD models of a driver's off-axis response are likely to be based on analytical equations that apply to a rigid piston in a baffle. An actual 6-inch driver is a flexible vibrating structure, resulting in its effective diameter at higher frequencies becoming less than its nominal diameter. At those higher frequencies, the typical 6-inch driver will have cone breakup modes, which cause it to exhibit non-piston behavior. Instead of moving uniformly, the surface of the cone vibrates in a way that creates complex radiation patterns that vary with angle and frequency.

Below is an example:

Source: Measurement and Visualization of Loudspeaker Cone Vibration,
by Wolfgang Klippel and Joachim Schlechter, 2006.

 

[hifijim]

Here is the actual measured polar response of a 6" driver (Purifi PTT6.5M) in a small cabinet. The baffle is only slightly larger than the driver. At 100 Hz the response is omnidirectional, but by 200 Hz we can see some directivity taking hold. By 1k there is a lot of directivity.

If this same driver had been mounted in a much larger baffle, the response would remain omnidirectional to a higher frequency. We would probably not see any directivity until 400-500 Hz. So baffle size matters.

Point is that the response curves seem to change only after about 1kHz and not much lower than 1 kHz whereas VituixCad exhibits (calculates) a drop of about 2dB @1kHz...

Published curves can represent a wide variety of test conditions. Some driver manufacturers have a unique way of testing their drivers and displaying the response. Others tend to follow a more standardized approach. It is difficult to compare our own measured (or simulated) results with manufacturer data unless we know exactly how the manufacturer data was produced.

j.

 

[kimmosto]

Maybe you can share a few thoughts on this

Calculator is able to calculate off-axis responses of ideal flat piston in infinite baffle. For example Sd=117 sq.cm, Dd=122 mm:

Simulation of conical shape is not available. Manufacturers usually publish responses in infinite baffle (to half space) or use some own box (e.g. Seas) or IEC baffle. Project baffle will be different almost without exceptions so using manufacturer's data is not proper method to design anything else than dimensions and cut-out holes.

Diffraction tool combines directivity of an ideal piston(s) and the edges of front baffle. Edge diffraction is also directivity component so off-axis responses start to drop at much lower frequency than with piston only in infinite baffle. For example 200x350 mm baffle with tiny Dd=1 mm driver in the centre, 'Ideal edge' unchecked. 90 deg would be flat 0 dB with 'Ideal edge' checked.

Combination of 200x350 mm baffle and 6" driver Dd=122 mm:

Unfortunately these simulations don't not have much value. Diffraction should be minimized with adequate roundings and wave guide(s), and drivers measured in the project enclosure for crossover design.

 

[Stixx]

Thank you Kimmo. In fact I compared the manufacturers responses (taken most likely in an infinite baffle) to the simulation.

Unfortunately these simulations don't not have much value. Diffraction should be minimized with adequate roundings and wave guide(s), and drivers measured in the project enclosure for crossover design.

Truth. Actually building and measuring would be and is the next step. Thank you for your response!

 

[b_force]

Diffraction should be minimized with adequate roundings and wave guide(s)

Should?
In some practical cases, function simply follows form.
Is that "da besT"?
I guess not, but sometimes it simply goes that way.

Quite some speaker drivers will have very different off-axis behavior compared to an ideal piston behavior.
So I completely agree that in the end measurements are really needed to know what's going on.
But it's still a good way to know what's roughly going on and what can be expected.
It's also good as a learning tool of course.

 

[b_force]

At 100 Hz the response is omnidirectional, but by 200 Hz we can see some directivity taking hold. By 1k there is a lot of directivity.

I think the term "directivity" might be a little confusing for some people in this context.
While it does technically affect overall directivity, the underlying physical principle here is actually baffle step behavior (along with some diffraction effects)

This is probably obvious to some, but I just thought it might help to clarify it a little.

I personally would prefer to call it "an higher directivity index" as well.
Although I think it's not necessary true with just the bafflestep at play.
Theoretically we can stay at just pure constant hemispherical dispersion.

Practically speaking, I also wouldn't classify 1-1.5dB as bafflestep/directivity behavior just yet.

 

[witwald]

Here is the actual measured polar response of a 6" driver (Purifi PTT6.5M) in a small cabinet. The baffle is only slightly larger than the driver. At 100 Hz the response is omnidirectional, but by 200 Hz we can see some directivity taking hold. By 1k there is a lot of directivity.

At 200Hz, that 6-inch driver's diameter is only around 1/10 of the wavelength of sound. As a result, wouldn't the driver still be an omnidirectional sound source when mounted in a small enclosure?

 

[hifijim]

I rather expected it to be omnidirectional even higher than 200 Hz, but the data shows that is not the case. The 90 degree curve is 2 dB less than the 0 degree curve at 200 Hz, and that means there is some amount of directivity. It is not an omni source. @kimmosto 's ideal piston simulation also shows that with a 6" driver in a small baffle, we would expect the 90 degree curve to be about 2 dB less then the 0 degree curve.

 

[Stixx]

Practically speaking, I also wouldn't classify 1-1.5dB as bafflestep/directivity behavior just yet.

Although in a lot of cases the baffle step of a 6 inch driver in a cabinet of, say 220mm width is more than that...to the degree of 2,5 - 3 dB. This obersavation is based on measured data.

 

[DualTriode]

Hello @kimmosto and All,​

​

I am attempting to avoid retesting everything. The measurement software that I use is Audio Precision APX500. I do not want to switch to ARTA or REW if not necessary. I see in the VituixCAD change Log that VituixCAD will import Audio Precision WAV and TXT files.​

​

Is anyone familiar with the process? Is there a tutorial for using Audio Precision measurement software like there is for ARTA and REW?​

​

"The change log shows an update to input Audio Precision WAV and TXT files​

2.0.101.1 (2023-04-03)​

Convert IR to FR

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

Thanks DT

I see on the purifi speaker website that they commonly use VituixCAD to illustrate crossovers for their drivers. Time to VituixCAD a spin.

 

[DualTriode]

Hello All,

I sat at the coffee shop yesterday sorting through the several VituixCAD documentation / help packages.

I see that the file formats and structure are critical.

REW, CLIO, ARTA, SoundEasy ..... and APx500 software do the impedance and acoustic measurements then export the measurement data files. VituixCAD imports the measurement data for crossover simulation and modeling.

Apparently the VituixCAD 2 software will import measurement files; impedance and Impulse Response files made with the Audio Precision APx500 software. I will need to sequence the measurements, save the measurement files in compliance with the VituixCAD 2 file structure and naming conventions.

First I will download the available example measurement files and give them a spin for a couple of days to get a better hands on feel of how the files upload into the VituixCAD software.

Thanks DT

 

[wonderfulaudio]

Hi,

In previous versions of Vituixcad when using the defaut driver the polar plots were +-180 degrees, but the recent version has only +-90 degrees.
How do I enable +-180 degrees polars for the default driver?

Thanks and Warm Regards,
WonderfulAudio

 

[hifijim]

Put your cursor in the phase plot, right click... one of the options is "show +/- 90 degrees"... this toggles between +/90 and +/-180.

 

[kimmosto]

Unchecked Half space and Corner in Options are also required

 

[machine1747]

Hello @kimmosto and All,

Is it possible to add an EPDR curve to the impedance window in the enclosure function to make the job easier。