VituixCAD v2

[Reet]

Sorry, I do not understand your answer. What is over complicated? I am trying to follow the guidelines, but the guidelines are not applicable to my low frequency config.
Unless there are any guidelines that I have missed. Exactly what guidelines are you referring to?

What is unique about your speaker that makes the measurement guide not apply? Everything I've been leading you towards in past few posts is simply to follow instructions of the measurement guide.

Why is near field v2 useless?

What is so difficult to place it properly? Perhaps review details in aux - Near Field section.

You have not yet answered may question about the merger setup for v2.

No use talking about how to do things poorly so you'll need help from someone else to continue down that route.

[kimmosto]

...guidelines are not applicable to my low frequency config.

Guidelines are applicable with closed and vented LF designs which can be measured at near field and simulated with Diffraction tool. So you could follow instructions.

Don't try to over-complicate things, just follow the measurement guide for VituixCAD. For low freq, "v1" image is correct for 0 deg measurement, continue with far field for all other angles, leave the pipe in front of the driver as you intend for the far field measurements. V2 shows 90 deg far field, near field is useless measurement. Left image is correct for midrange far field, continue far field for all other angles, then move mic up to tweeter level and repeat for tweeter measurements.

Sorry, I do not understand your answer. What is over complicated? I am trying to follow the guidelines, but the guidelines are not applicable to my low frequency config.
Unless there are any guidelines that I have missed. Exactly what guidelines are you referring to?
Why is near field v2 useless? Far field is unreliable under 500Hz even out doors due to ground reflexes.
You have not yet answered may question about the merger setup for v2.

[Reet]

Don't try to over-complicate things, just follow the measurement guide for VituixCAD. For low freq, "v1" image is correct for 0 deg measurement, continue with far field for all other angles, leave the pipe in front of the driver as you intend for the far field measurements. V2 shows 90 deg far field, near field is useless measurement. Left image is correct for midrange far field, continue far field for all other angles, then move mic up to tweeter level and repeat for tweeter measurements.

I don't fully understand what you've done to measure the woofer, but there isn't a need to do anything different than any other driver. It may be better / easier to tip the speaker over on its side to measure the woofer in a forward facing position, and it looks like there is room between the pipe and speaker to place a mic for nearfield measurement. Diffraction should not be 90 deg, in the case of the woofer the egg shaped board is the baffle and it's measured straight on like any other driver.

In the crossover design, enter 90 deg tilt for the woofer, and other coordinates accordingly.

I need to describe what I have done so far. Please see the attached image. Version 1 is my initial measurements.
The high frequency/midrange (HF) measurements are the same in version1 and version 2.
In version1, I measured near field at the baffle surface and center of drivers on-axis, far field at 1m.
For the low frequency (LF), I did not tilt the speaker, I put the microphone 1m above at the driver on-axis.
All measurements were done outdoors, my rooms are too small to enable the recommended 4ms time windows.
I merged the near field and far field for both HF and LF to the best of my understanding.
I divided the merged frequency responses by the HF and LF on-axis diffraction patterns in the diffraction tool to create halfplane SPL versions.
Then I generated both vertical and horisontal directivity files based on the half plane HF and LF SPL files.
In the VituixCAD crossover I set the LF driver as tilted 90 degrees.
This scheme seemed to work rather well and I was able to adjust everything to get a straight SPL frequency response for the system.
However, the listening experience is such that I do not trust my measurements and design to 100%.
It could be room effects, but it makes me want to go through everything once more.

I got the impression that you recommend measurements rather than simulations.
That made me think of a low frequency measurement according to version 2 in the attached drawing.
In version 2 I measure the LF near field 90 degrees off axis near the baffle edge.
In this case the merger might need to be set up differently, hence my questions.

I actually tried to do this v2 measurement outdoors a few days ago but it failed, probably due to the temperature, 1 degree below freezing.
The driver suspensions and cone materials could behave differently enough at this temperature vs. room temperature to make the difference. Or even the microphone.
I made this judgement by comparing the HF measurement to the previous attempt in the summer, and they were quite different.
I need to postpone this v2 measurement project to the spring.

[Reet]

I don't fully understand what you've done to measure the woofer, but there isn't a need to do anything different than any other driver. It may be better / easier to tip the speaker over on its side to measure the woofer in a forward facing position, and it looks like there is room between the pipe and speaker to place a mic for nearfield measurement. Diffraction should not be 90 deg, in the case of the woofer the egg shaped board is the baffle and it's measured straight on like any other driver.

In the crossover design, enter 90 deg tilt for the woofer, and other coordinates accordingly.

I need some advice on how to setup the merger tool for my project.
My low frequency enclosure is a CB, vertically oriented cylinder, 700mm long, 400mm diameter, and the 10-inch woofer is mounted pointing upwards in the top lid baffle.
My high frequency enclosure is a pipe crossing the face of the woofer, facing front, driver center distance to the woofer plane is 150mm.
My crossover frequency is 240Hz.
The front baffle/plane of the high frequency driver is placed at the perimeter of the low frequency enclosure, front side. See the PNG image included.
In my far field measurement I use a distance of 2 meters, the mic height is placed at the midpoint between the enclosure top height and the high frequency driver axis.
My near field measurements for the high frequency driver is conventional, on-axis center about 10mm from the dustcap. No problem to set up the merger tool for this.

My near field measurements for the low frequency driver is different. I measure at the edge of the top woofer baffle, i.e. 90 degrees driver off axis, just below and next to the high frequency driver baffle.

The merger tool manual says that the BS should not be checked, as I am not measuring on the front of the driver. I understand this.
I have generated diffraction responses from the low frequency baffle, distances 2m and 5m, 90 degrees horisontal tilt, see image below.
Should I include any diffraction response at all in the near field section, or in the far field section?

[Reet]

Let's say >1kHz, general use of diffraction applied to a neafield measurement would usually be <500Hz. . As well, any tweeter with anything other than a flat faceplate, off-axis not possible with diffraction tool. Main problem is that calculated diffraction uses a "piston model" for high frequency driver behaviour, reality is a fair bit different factoring cone shape, breakup effects, waveguides on tweeters, etc.

Sure, keeping in mind that calculated diffraction response lacks accuracy at high frequency

Please define high frequency.

[Reet]

Sure, keeping in mind that calculated diffraction response lacks accuracy at high frequency, and its a bit of an annoying tedious process if you want to do that for all off-axis data, since each off-axis diffraction response will need to be processed individually through the calculator tool, it doesn't support multiple files as "B response". Unless the cabinet width varies wildly, it may be easier to do nothing and just load in measurement data for slightly wrong cabinet for ballpark figure, with complete re-measure once the future cabinet is built. The result of a simulation with slightly wrong cabinet measurement may have just as much error as a bunch of math on simulated diffraction data.

For the above inaccuracies mentioned, VituixCAD measurement and design recommendations is to utilize calculated diffraction only for low frequencies, not to be applied to complete half space response.

Follow up question would be why would you want to? Regardless...

Half space data for a driver could be used in the diffraction tool for any future cabinet/baffle design.
Full space data is for the specific driver and enclosure combination where it was measured.
Right?

[Reet]

A real question, not so complicated after all..."How do I generate half space data?".

Follow up question would be why would you want to? Regardless...

1. Measure on infinite baffle. Perhaps "in-wall" installation would fall under this category. Would you need the merge tool in this scenario? Does your room still have a floor and a ceiling and walls? If so, answer is yes.
2. Manufacturer data is often half space equivalent, traced data could be one use case.
3. Approximation of half space can be obtained by dividing far field measured response in-cabinet by diffraction response, use the calculator too. Realize that the result of simulated diffraction is not incredibly accurate at high frequencies, and especially so off-axis.

I don't understand your question. Are you wanting to produce a half space result, or are you wanting to produce a full space result in your cabinet for crossover design? Merge tool simply spices two responses together, while retaining the amplitude and phase of the high frequency part. Whether the spliced result is half space or full space depends on the frequency response data you provide, and selection of baffle loss on the low frequency part.

I do not understand the above. How can I get real half space data under normal circumstances? It is impossible unless I have an infinite baffle, which is very difficult to find, at least in the country where I live. And if I did, why would I need the merge tool?

Generally speaking, the intended use of the merge tool would be to produce a full space response of a speaker measured in the intended cabinet for crossover design. Near field measurement data would be provided for the low frequency part, check diffraction response and load in the diffraction simulation for the low frequency part. Far field windowed data would be loaded to high frequency part. When done correctly, result is reflection free full space response, ie anechoic equivalent.

So there was the answer. It was not so complicated after all.
Thank you.

A follow-up question.
Is it possible to create half space data from a merged full space?
Does it work to use the calculator tool to divide the merged data by the cabinet diffraction response?

[Reet]

I don't understand your question. Are you wanting to produce a half space result, or are you wanting to produce a full space result in your cabinet for crossover design? Merge tool simply spices two responses together, while retaining the amplitude and phase of the high frequency part. Whether the spliced result is half space or full space depends on the frequency response data you provide, and selection of baffle loss on the low frequency part.

Generally speaking, the intended use of the merge tool would be to produce a full space response of a speaker measured in the intended cabinet for crossover design. Near field measurement data would be provided for the low frequency part, check diffraction response and load in the diffraction simulation for the low frequency part. Far field windowed data would be loaded to high frequency part. When done correctly, result is reflection free full space response, ie anechoic equivalent.

The choice is yours. For speaker design, purpose would be the latter, to create an anechoic equivalent response of drivers in their cabinet.

I am sorry, I do not understand your answer. How can you get both?
Please clarify.

[Reet]

The choice is yours. For speaker design, purpose would be the latter, to create an anechoic equivalent response of drivers in their cabinet.

I have a fundamental question about the merger tool.
I have read the manual, but reading and understanding are not the same, unfortunately.

Is the merger tool producing a half-plane SPL trace for the driver without diffraction, or a full space SPL trace for the driver in the enclosure taken at the mic position?

[Nil L]

Thanks for the advice. Perhaps I didn't use all the possibilities. I will try to learn how to use existing opportunities.

[kimmosto]

It’s not a good idea to mentally calculate the denomination that will limit the optimizer’s search.

First you ask more constraints (for limiting XO frequency) and then you don't like or want them. What is the logic?

I have seen program(s) having many times more constraints (including XO frequency) and targets than VCAD. For example LspCAD 6. Problem is that entering multiple constraints and targets could take much time - more than manual initialization of component values, and some small detail in settings could prevent optimizing totally. That is very frustrating.
Initialize network and component values with brain and mouse wheel or optimize response of each individual driver with target, and then fine tune on-axis, LW, ER and SP with optimizer so that bad decisions e.g. with XO and impedance are prevented with constraints which are available during that phase. This method leaves you full control and you won't change to powerless passenger in that vehicle.

[Nil L]

Thanks for the advice. I am aware of this possibility. It’s not a good idea to mentally calculate the denomination that will limit the optimizer’s search. To teach a program that can do this faster than any brain seems to me to be the best idea. But this is not a problem at the moment. In case of arbitrariness of the optimizer, I deprive him of the laurels of the winner and manually do everything normally.

[kimmosto]

...can be limited to adjustment of a single driver circuit by limiting components to optimize.

This is primary method to keep crossover frequency within proper range. Another very good option is to limit component values of passive network. Parameters i.e. component values have min and max constraints. For example series coil of the woofer >= 1.2 mH and/or series cap of tweeter <= 10 uF could maintain some sense in XO freq while total on-axis is optimized.

All this is very natural with active OPA and DSP projects because frequency is main parameter of LP and HP filters. Just limit freq with min and max constraint. FIR projects use transfer functions which are created with target responses having XO freq selected by user.

[Reet]

Optimizer doesn't design the crossover for you, only to adjust part values to achieve the target goal you've provided. Options already exist to limit frequency range of optimization, and define high pass / low pass target to optimize individual driver response. Optimization to overall power and axial response doesn't care about individual driver responses, but can be limited to adjustment of a single driver circuit by limiting components to optimize. Best results if driver response is already in the ball-park of target to begin with and appropriate circuit topology is in place. It's an excellent time saving tool.

[Nil L]

kimmosto,
The optimizer may suggest cutoff frequencies as a result of its operation that should never be used. For example, 600 hertz for two drivers. The tweeter should never play down to 600 hertz. The play of percentages between axial response and power response doesn't help. Offer. Add a parameter that limits the frequency range in which the optimizer can search for the best option. Each driver has its own range. Or a common range for all drivers.
The same thing happens with the level of individual drivers. The optimizer decides that the tweeter level can be 5 dB higher than the midbass level. It would be good to set a range of levels at which the optimizer can play. Each driver has its own range. Or a common range for all drivers.

[Reet]

Great changes, the change in resonant frequency with Fs should make for a bit better agreement when comparing actual measurement to simulation.

FWIW most of my reflex designs use slot ports, when comparing actual measurement and impedance to the simulation, I find Qp around 20-30 is proving better agreement with real world results. Possibly the values I had used for Qa and Ql were bad, or perhaps Qp suggested by Kristian accounts for port ends but still assumes an otherwise perfect port, not accounting for bends, laminar flow vs turbulent flow, back pressure or other factors restricting port efficiency. I'm no expert on the subject though, just trying to determine best values for accurate simulation.

[JonMarsh]

Very useful updates!

[kimmosto]

2.0.110.0 (2023-10-28)

Main

• Added window for creating project folder and subfolders with driver list. Two folder hierarchy options: Project name\Data folder\Driver name or Project name\Driver name\Data folder. Far, Impedance, Merger and Near folders can be created for each driver as parent folder or subfolder. Optional common folders: Datasheet, Diffraction, Drawing, Enclosure, Export and Room. Window opens with File->New command or wizard button in Drivers tab.

Enclosure

• Effective box volume depends on Qa. Resonance frequency decreases by adding damping material i.e. decreasing Qa. Simplified Vb calculation and tooltip of Qa text box are compatible with UniBox 4.07 by Kristian Ougaard: Vb=Vphys*(1+0.9/Qa^0.9). No fill: Qa=120, Minimal fill: Qa=80, Walls covered: Qa=20, Heavy fill: Qa=5.
• Added tooltip to Qp text box. Values are compatible with UniBox 4.07 by Kristian Ougaard: No flush ends: Qp=70, One flush end: Qp=80, Two flush ends: Qp=90, One flared end: Qp=120, Two flared ends: Qp=140. Note! End corr should be adjusted manually too.

User manual is not yet updated for project folder creator. Maybe in few days...

[kimmosto]

Program should also warn and ask if directories are the same: "Output filename crashes and overwrites input (HF) file. Press OK to add 'VXM ' prefix to merged files. Cancel to change output directory or file extension.". Hopefully it actually works like that...

[kimmosto]

Suffix such as _mrg is possible with "root-filename hor/ver angle.txt/frd" only. For example I cannot use suffix due to CLIO QC and Outline table. 3D balloon naming conventions accept prefix, but own directory for merger results is safer, more logical and mentioned also in user manual.

[Reet]

Previously VituixCAD would append a _mrg suffix to the file names when merging, which I preferred, Regardless, the current process is to create a new folder for the merged file output, folder selection with new folder button is available when you save.

I humbly request that the merger Tool would offer an output file name and path dialog, not to overwrite and corrupt my input data.
Is this difficult to do?

[Reet]

Imagine the woofers have their own enclosures

Sorry, I misunderstood the intent of your question. Kimmo has provided an excellent response. With each driver in its own enclosure, why would you not measure each driver individually? Measuring as a pair necessitates both horizontal and vertical measurements, while also locking driver locations in place and the other distance errors mentioned. Measuring a single driver allows for accuracy of SPL at any distance, some flexibility in driver separation in the crossover simulation, and in many cases you may get very good results with only horizontal measurement set. So my recommendation is to always gather data for individual drivers.

[kimmosto]

Magnitude of possible problem when measuring both midwoofers of MTM at once depends on measurement distance. No problem if you can measure at 2000...2500 mm i.e. normal far field listening and simulation distance. Then you just add single driver instance to X,Y,Z=0,0,0 mm and load data including both Ms for it.
But there will be magnitude and angle error and differences between M drivers if you are forced to use much shorter measurement distance due to limited room height and time-window requirements. Here is one example with measurement distance of 1000 mm and M-M=300 mm. Acoustic averaging reduces error in the sum at mic, but there will be some remaining error compared to measurement at 2000...2500 mm.

It's certain that acoustic summing by the simulator with recommended method (=measuring single driver only) is not free of errors, but it enables more freedom when selecting measurement distance and simulation distance. It also enables playing with driver locations if mechanical construction is modular and adjustable.

[augerpro]

Imagine the woofers have their own enclosures

[Reet]

Driving just one speaker will affect cabinet alignment - bass response. So nearfield should be completed with both drivers connected. Far field >300Hz measurement should be relatively unaffected by measuring only one driver connected.

[augerpro]

Just wanted to confirm with Kimmosto a question on measuring symmetric driver layout such as MTM. Specifically vertically. Is it correct that there is no difference between measuring with both woofers at the same time, versus measuring each one individually? The SPL and phase should sum correctly either way?

[kimmosto]

I wonder if it would be useful for the auto-alignment buttons to align the cabinet with inclusion of the filter? I believe this is something bnilsson11 above was looking for.

The reason for adding Cs was to enable simultaneous tuning of box volume and series capacitor with too small closed box compared to driver's Qts to get closer to ideal Qtc=0.7-0.8 to half space. Tuning is quite subjective process in practice because we cannot specify "ideal" target which is reachable in every case. Designer is probably forced to make some compromise; combination of tolerable hump, dip and high pass. Ls is just extra to show possible hump at upper bass.
Tuning has been possible without passive components in Enclosure tool, but it's slower requiring export of SPL and Z, and loading SPL to main program with XO. 'Feed speaker' has been available for Z only, but of course it would be possible for SPL too. In that case difference between separated and new integrated passive components would be few seconds / iteration.
So auto align with passive components could be a bit overkill compared to advantages.

More modern and recommended way to cut response hump due to high Qts and limit excursion is to use active filter. That is able to adapt in every case, and does not require ~1 mF bipolar cap.

[Reet]

That is a useful addition to the enclosure tool, for inclusion series inductor, resistor or capacitor. Alternative would be to revert back to the old "include crossover" option.

I wonder if it would be useful for the auto-alignment buttons to align the cabinet with inclusion of the filter? I believe this is something bnilsson11 above was looking for.

[kimmosto]

2.0.109.2 (2023-10-05)

Enclosure

• Fixed response calculation with 'Show effect of inductance' unchecked. Bug since 2.0.109.1 (2023-10-01).

Did not require multiple full range calculation loops. Just few intermediate variables. Anyway, this passive LCR filter option was really challenging with all three impedance models and flat fake frequency response option.

[Reet]

Biggest problem with traced data is the minimum phase aspect, lacking proper timing information between multiple drivers in a project makes for just guess work at best for initial crossover design. My recommendation would be to mount the driver on a baffle and measure real-world results, same for T/S parameters, depending on manufacturer, datasheet information can be quite unreliable. But, if you must continue with traced data, I have assembled some document a while back that may help you, but pay close attention to the text in bold on the first page.

https://drive.google.com/file/d/1j9leycXJNvUmYZxQNVqg8U13mMRHh8Iw/view?usp=drive_link

I don't fully understand what you're trying to accomplish. Enclosure tool already shows low frequency half space response of the driver. You can merge the cabinet response with manufacturer response to get some idea of actual response in your cabinet fairly easily. Export SPL in enclosure tool, merge with traced manufacturer response with merger tool, select "no baffle loss". Result from this is half space response, load this into diffraction tool half space response, check box for "full space". Result here is expected result in cabinet, of course with much inaccuracy of manufacturer and simulated data, and result is minimum phase. Correct process is to install driver in your cabinet and measure real world result for crossover design following measurement guides available.

The manufacturer's SPL data contain the driver behavior over the whole frequency range, such as cone breakup, etc.
My purpose is to include the driver behavior "preview" in the project to help me evaluate my crossover design at an early stage.

Thanks, I will try your suggested workflow.

BN

[kimmosto]

Driver+box calculation does not work properly with rev. 2.0.109.1 if 'Show effect of voice coil inductance' is unchecked. I have tried to avoid multiple full range calculation loops - first with selected inductance model and mechanical system to get correct impedance curve and transfer function with passive filter, and then mechanical system with plain Re to create fake flat SPL response which can be multiplied by transfer function of active and passive filter stages (with actual impedance response of course). This option is terrible mess

I have to make some plan; either remove passive filter option to the next revision or duplicate calculations in Enclosure - which probably takes few days... a week. Earlier link between Enclosure tool and main program calculated twice in Enclosure and once in the main program to include passive stages

[Reet]

Obviously a newbie question:

If I take a halfspace SPL chart from a driver manufacturer's site, and use the "Trace SPL" tool to make a SPL file, is there any way I can use this data for a bass reflex enclosure in the Enclosure Tool?

BN

I don't fully understand what you're trying to accomplish. Enclosure tool already shows low frequency half space response of the driver. You can merge the cabinet response with manufacturer response to get some idea of actual response in your cabinet fairly easily. Export SPL in enclosure tool, merge with traced manufacturer response with merger tool, select "no baffle loss". Result from this is half space response, load this into diffraction tool half space response, check box for "full space". Result here is expected result in cabinet, of course with much inaccuracy of manufacturer and simulated data, and result is minimum phase. Correct process is to install driver in your cabinet and measure real world result for crossover design following measurement guides available.

Sorry to post more than one question at a time...

I am comparing the halfspace SPL from exported an enclosure project I made a few weeks ago with the Scan-Speak W22/4851T00 driver, to what I get today.
I use a bass reflex enclosure auto aligned to QB3/SQB3.
My previous halfspace SPL was flat down to the normal f3 drop.
Today for the same alignment I get a rise of +1dB before the drop.
Has anything changed in the algorithm in the updated versions?

BN

Obviously a newbie question:

If I take a halfspace SPL chart from a driver manufacturer's site, and use the "Trace SPL" tool to make a SPL file, is there any way I can use this data for a bass reflex enclosure in the Enclosure Tool?

BN

[kimmosto]

2.0.109.1 (2023-10-01)

Enclosure

• Fixed response calculation with passive filter. Bug since yesterday.
• Added total impedance with passive filter to Impedance chart. Traces are disabled if passive components are not enabled.