VituixCAD v2

[kimmosto]

About a week ago I already tested adding delay (in mm) to all rows in LF near field response list. That could be quite adequate addition to Merger tool assuming that directivity information included in far field measurements is "good enough" also for LF part. Entered delay would be travel difference between port and main/cone surface to typical listening position at e.g. 2-4 m.
Adding simulated directivity of radiating surface to 90 deg for top, bottom, side and rear ports/passives would be another helpful addition. That can be significant especially with passive radiators. Effect can be calculated using existing 'Diam mm' column (when BS is unchecked), though ports can be rectangular.
Baffle step exists on-axis when radiating surface is in front panel, but very close to zero on top, bottom, side and rear radiators. Existing BS checkbox takes care of that.

I will add those two features to the next revision. Using main program is a bit too complex so let's try simpler one first.

[Reet]

Time locking of near field measurements takes care of internal delay compared to main/cone radiator

Thank you for your response. I understand, that internal time of travel from driver cone to port exit is accounted by locking the timing, however I am thinking about the additional time of travel from port exit back to the driver location once the signal leaves the cabinet, so near field is represented as single point in space measurement. When measuring driver and port exit individually, physical location of mic may differ by 0.5m or more on a large cabinet, so this is what I was expecting to address with a simple additional delay, in the same sense that Hornresp includes an "Acoustic path length between outputs" in its calculations.


It makes little difference in <100Hz range, but as we know there can be significant output up to 500Hz+ that affects overall response through the merge frequency range. An example of some data provided to me by another user for a TL speaker. Here, the delay value of the TL output >200Hz has significant impact on the combined result, so just trying to confirm that the normal locked timing process is providing the expected result.


It sounds like I could take a step further and process each near field response individually with diffraction and delay through the main program if I want to go the extra length on this process. Thanks for this idea, I will explore a little more.

[kimmosto]

When processing nearfield measurements, for woofer nearfield and port or TL exit, does it make sense to incorporate some delay to the port output if it's located a significant distance from the woofer? ...

Time locking of near field measurements takes care of internal delay compared to main/cone radiator, but as we already know, that's the easiest part in this merging puzzle. Significantly better summing of near field responses would require directivity/baffle loss simulation of each radiating surface, location X, Y, Z, rotation R and tilt T. With this data LF near field measurements could be transformed to far field, and then merged to far field HF measurements. Merger tool can do the last part but nothing more. Diffraction tool can simulate directivity for individual radiators i.e. convert ports etc. to far field with off-axis, and main program is able sum dual plane far field data with X, Y, Z, R and T parameters. I have done it few times to reduce some errors, but the procedure is not very easy. All those features integrated in Merger tool would be nice, but it's quite big change and probably more difficult to understand and operate.

[kimmosto]

2.0.111.4 (2024-03-18)

Main

• Parameter min and max limits read from crossover variant before the value to prevent limiting between default min and max.

Enclosure

• Total SPL max trace in SPL chart limited with real power of driver instead of power to Re. Note! Result depends on 'Show effect of inductance' setting.
• Max length of vent increased to 9999 cm.
• Max diameter of vent increased to 112.8 cm, 9993 cm^2 as area.
• Max number of vents increased to 50.

Convert IR to FR

• Output file format selection changed from radio buttons to list box.
• Added LMS output file format.

[Snickers]

Max port length of 500cm while still simulating longer ports.

I was simulating a huge infra bass subwoofer. When I lower the tuning or increase the port diameter to the point where the length passes 500cm, the simulation seems to still work as intented, but the port lenght shown on screen never passes 500cm. As this equals a pipe resonance of 34Hz, it is not a big deal, but still what is shown on screen is incorrect. Also, with a quarter wave calcelling path, a 5 meter port could be useful up to just above 50Hz, so some might look for a solution like this.

[Reet]

When processing nearfield measurements, for woofer nearfield and port or TL exit, does it make sense to incorporate some delay to the port output if it's located a significant distance from the woofer? Physical distance from port exit to woofer nearfield location can sometimes be in the range of ~1m. I've always processed the port and woofer nearfield together in the IR - FR tool, pressing "near" on the woofer impulse, and port output is always very slightly delayed anyway, but perhaps there could be some benefit to providing additional delay to the port output if the physical distance is significant? For something like a TL, there is often still significant output in 200-500Hz range, so the phase / delay of the response can make a significant difference in the merged result.

It can be done of course by adding delay in the calculator tool, however if this process makes sense as "common practice", perhaps it would be a good addition to the merger tool, to allow individual delay adjustment of each response in the "low frequency" portion.

[Quza]

Small bug report:
When switching between crossover variants VituixCAD resets the Z position of a speaker to the default limit of 2000 if the value entered was bigger than this.
Reproduce by:
-increase Min/Max values to 5000
-enter Z 4000mm
-switch to different crossover variant and back
-Z is 2000mm again

This isn't a huge deal for designing loudspeakers, only a little annoying when simulating subwoofer arrays

[Nil L]

kimmosto,
There is a suggestion about the space to the right of the crossover cirquit. Now it is possible to disable one graph out of six. After disconnecting, the space remains empty. If you turn off 4 graphics, the remaining 2 can be placed one above the other. Then the detail of the remaining graphs will increase. There will be 2 times more horizontal space and 1.5 times more vertical space. It is rare that you need to see all 6 charts at the same time. And two at once very often. It is possible that three at once is even better, but it is not clear how to arrange them.

[Snickers]

kimmosto


I find these drawings extremely informative in regards to the end correction function. They seem to fit rather perfectly with practical testing.

Do you think these could be added to the user manual?

[JonMarsh]

As a former college of mine was fond of saying, "I'm in violent agreement with you!"

[kimmosto]

I found it worked "well enough" for a pair of 10" passive radiators I had without documentation.

Sometimes solver is able find very good match, but it may require solving of extended impedance parameters too. Here is an example with Purifi PTT6.5X04NFA with two passive radiators. So we can simulate accurate impedance response if we have the same system as actual for calibrating T/S and extended impedance parameters Not much sense imo but it's there.

[kimmosto]

If the chosen port length or diameter was not calculated very accurately, and this only became clear after the final assembly of the speaker with the crossover, I assumed that using the Enclosure Tool I could look and select more correct port sizes. Or disassemble the box and increase its volume.

For example effective volume and End correction are parameters which cannot be calculated with reasonable amount of data so simple box+driver simulators cannot calculate accurate vent length for certain resonance frequency. End correction should be estimated by user. We can use some experimental values, but internal supports, curved vents, flares, vicinity of internal walls etc. makes estimation difficult. Here is commonly used guide for end correction. So tolerance of length is ca. (2.227-0.732)*Dv. Value range in VituxCAD is 0.60-2.40. Of course we could also ask if certain resonance frequency is very important and constant...


Still trying to say that box+driver simulation will not be very high class science no matter how much we add features into software.

[Nil L]

Reet, kimmosto, I read the manual and understood what it was for. Thank you.

[Reet]

I found it worked "well enough" for a pair of 10" passive radiators I had without documentation. I was able to at least get usable enough parameters to put them to use with confidence, but I wasn't that particular about Qa, Ql, etc. for that purpose.

For a bass reflex cabinet however, I think it is easy enough to just measure dimensions and port as a starting point. Again, I don't think exact value of Qa, Ql is that important, use real world measurements of the driver, port, impedance, etc. to determine if the system is underdamped, overdamped, has internal reflection issue, etc.

[kimmosto]

Right. This is how it works. 1) Load Z overlay(s) to graph.

2) Then you can select correct overlay from solver window.

Anyway, I'm quite sure that solver is not able to find solution because it requires almost exact match. That is quite rare in real life.

[Reet]

Where's your impedance overlay to solve with? Read the manual.

https://kimmosaunisto.net/Software/VituixCAD/VituixCAD_help_20.html#Radiator_type

Scroll down a bit, you'll see "Solving parameters of passive and bass reflex radiators".

[Nil L]

What "select button" and solver?

If you click on the field or button to the right of the field marked with a red arrow, you cannot make a selection.

If the chosen port length or diameter was not calculated very accurately, and this only became clear after the final assembly of the speaker with the crossover, I assumed that using the Enclosure Tool I could look and select more correct port sizes. Or disassemble the box and increase its volume.

[kimmosto]

The Enclosure tool has a solver to fit the appearance of the impedance curve to the target. But when I press the file select button, the file system explorer does not appear.

What "select button" and solver? Calculate T/S or Bass reflex or Passive radiator? Everything I have tested works here as designed.

There is a ready-made enclosure with a driver and a port, and there is a measured impedance in this box. T/S driver parameters are included in the database. The shape of the proposed impedance curve is not similar to the measured one.....

What is the problem? Recommended procedure is that after you have actual box, you measure SPL and Z responses, tune if needed, load responses of accepted box+driver to Drivers tab in the main program, design XO with simulator and configure or build XO. That's it. There is no need to override parameters in driver database or try to imitate measured Z response with Enclosure tool and driver database or worry about "normal" parameter differences between (possibly old) datasheet and actual driver samples you have. All that is just extra work after cabinet is accepted and measured for XO simulation.

T/S parameters could have quite large tolerance and changes while burn-in, but that does not cause much or significant effect to box volume. Vent length needs some tuning almost without an exception. Qa, Ql, Qp and Qm of passive are kinda irrelevant. Main target for filling is not to get certain Q. It's to damp possible resonances due to standing waves down to acceptable level. No more.

...many people have this situation.

Why they make this a problem if at least some datasheet version is available and driver is already purchased. Parameter measurement needs driver and some test box or mass(ses). That can be done if T/S parameters are totally unknown or designer suspects that difference to datasheet is radical and wants to verify values of his driver samples before building prototype box (though measurement does not represent global exact values or average).

As already told, Enclosure tool or any other basic box+driver simulator has very narrow purpose. It's not to give accurate impedance curve or filling density, location or Q factors or vent length, location or diameter and so on. Unfortunately it's much less so don't try to put all hopes for it.

[Nil L]

kimmosto,
The Enclosure tool has a solver to fit the appearance of the impedance curve to the target. But when I press the file select button, the file system explorer does not appear. Second. There is a ready-made enclosure with a driver and a port, and there is a measured impedance in this box. T/S driver parameters are included in the database. The shape of the proposed impedance curve is not similar to the measured one. I tried to use the parameters Qa, Ql, Qp to match the appearance of the proposed curve to the measured one. This improved the similarity, but not completely. Then I went through the Table and Ql options on the Align tab. And I repeated the adjustment of the Q parameters. This brought the curves even closer. Then I added 20 liters to the volume of the box of 180 liters. But still the curves were not the same. Question. Can a program do this work on a button solve? If you give her a file with actually measured impedance with amplitude and phase. And using as fitting variables all the parameters that I used and possibly the TS parameters. Because the TS parameters from the manufacturer were created in 2011. Since then, something has changed, improved, and so on. And many people have this situation. After all, there is an actually measured impedance curve. Based on it, you can select the size of the port, the volume of the box (slightly), the frequency of maximum output of the port, and the transient response.

[kimmosto]

New build of 2.0.111.3 has signal limits of 400 Vrms and 80 kW. Switching from P to U signal was not yet fixed in Enclosure.
The same limits in Power dissipation window.

P.S. Enclosure tool is already quite difficult to maintain and update. Too small changes to remember how everything works so number of bugs has increased. Tool is already overshoot for box+driver design though database browser is nice and useful imo. Product quality is done with something else than "volume and vent calculator". Basic simulation with T/S is far from adequate for much more than purchasing decision and preliminary values of those two. More complex radiator concepts are not supported. According feedback users don't seem to see much more than box simulation.

[kimmosto]

2.0.111.3 (2024-02-14)

Enclosure; Add/Edit driver, Calculate T/S

• Parameter limits adjusted.

---

2.0.111.2 (2024-02-13)

Enclosure

• Fixed trace values in Power chart. Calculation was using wrong impedance variable.

[Reet]

kimmosto Just in case you haven't noticed, the latest beta releases of REW are now including an API for external integration. I know you have stated that you have no intentions to include measurements within VituixCAD because perfectly good software already exists for that, however perhaps there is some opportunity for integration there. I'm not asking for anything, just want to put it on your radar.

https://www.avnirvana.com/threads/re...eleases.12981/

https://www.roomeqwizard.com/help/help_en-GB/html/api.html

[JonMarsh]

well, I am guilty of designing stuff with 4 PR's per cabinet... and I figured 8 would be really over the top!

[kimmosto]

Directivity chart uses Ref. angle you have selected from here

It is saved to project's vxp file to be project dependent.

[tktran]

Hi,

I noticed today that my Directivity Chart uses the 15 degrees axis as the Reference. Have I accidentally changed an option that made this so?

eg.


I have the most recent release of VituixCAD2.

[kimmosto]

Limits look overshoot but it's mostly just keeping voltage and power units compatible down to Re=2 Ohms in Enclosure and down to 4 Ohms in Power dissipation window.
Significant part of (paying) VituixCAD users are pro audio so power amps 1-7 kW are possible. Enclosure tool does not directly understand multiple power amps while simulating multiple drivers so for example 9 drivers need 3||3||3 correction and voltage signal x3 or power signal x9.

Also original max limit of passive radiators was logical error because typically one active driver needs 1-2 passives so 24 passives is proper max limit. It's not necessarily wise decision because vented is usually easier and cheaper with large enclosures having enough room for relatively short vent. Vented small boxes are more difficult so 1-4 passive radiators is tempting solution.

[Reet]

Some lunatic on DIYAudio asked for higher max power and at least 12 passive radiators. I'm not going to ask why.

[JonMarsh]

Downloaded this morning... before seeing this! But, um, 40kW? Wow! ;^)

[kimmosto]

2.0.111.1 (2024-02-10)

Main

• Show ±45 deg in context menu of directivity chart enabled for Polar chart.
• Generator's default maximum voltage increased to 283 V.

Power dissipation

• Maximum voltage increased to 283 V.
• Maximum power to 8 Ohms increased to 10 kW.
• Maximum power to 4 Ohms increased to 20 kW.

Enclosure

• Maximum signal voltage increased to 283 V.
• Maximum signal power increased to 40 kW.
• Added current (A) trace to Power chart.
• Maximum number of passive radiators increased to 24 pcs.

[Reet]

Marketing speak for reducing assembly steps and parts cost

[mecedo]

...have you listened to the Diapason Adamantes acoustics?

From their speakers description:

...a newly designed, thick printed circuit board is directly connected to the loudspeaker terminals to ensure the most direct and fastest possible transmission of the electrical signal to the speaker membranes. According to the minimalist interleaving concept, only a few components were used to enable the most direct and fast transmission of the electrical signal...

O M G !!!!

[kimmosto]

have you listened to the Diapason Adamantes acoustics?

No..

[Nil L]

kimmosto, have you listened to the Diapason Adamantes acoustics? If yes, then say something about it.

[kimmosto]

Some balancing problems exists also with very small speakers with small wave guide, because small box itself creates directivity with diffraction.
This is existing commercial design with 4" woofer and 1" dome. Diameter of circular wave guide is just 100 mm, and depth 20 mm. LW is normalized with slope = -0.13 to get ON slope to 0 to the graph and PR table.

This produces PIR slope = -1.476 and SP slope = -2.40.

Both numbers are clearly off my previous specs so I would have to tilt on-axis up by ca. slope=+0.4 to full-fill my own standards. I will not do that because too much heated treble creates "quasi resolution" i.e. actual resolution achieved with bad method such as excessive on-axis level on tweeter's range. Sound edges and bling-bling would sound clear, but it's not natural and relaxed for long listening periods. So this speaker will have compromise; small tilt up but ON slope < +0.3 and LW slope < +0.1. Much less tilt would sound too dull and muffled in decent room acoustics. Target environment is probably worse so all good I hope.

Heated treble wasn't rare in Finnish speakers when popularity of wave guides increased few decades ago. That became a standard long time ago. Nowadays hifi enthusiasts have noticed that room acoustics (mostly with diffusers) is proper cure and too large and deep wave guides are not. I can see positive attitude towards wave guides on international discussion forums, but expecting that people start to listen and hear that more than just linearity of some calculated curves is needed.

[kimmosto]

Where does the determination that a certain slope is preferred come from? Last I knew, Toole, et al. left that specific question open when they developed their preference scoring. Is there another group that has carried on this research?

In this thread it's just my experience and opinion. I guess someone educated has tried to find some range for preferred slopes, but as I mentioned earlier, there are many variables which makes difficult to recommend range for a single variable such as PIR slope or SP slope compared to ON/LW slope "as a scientist".

Harman's earlier listening room was quite large and it had mostly (styrofoam?) diffusers on the walls and ceiling. That is not typical listening environment making me think that it could provide (too) narrow sight and results are not very representative. RT60 was maybe ca. 400 ms, but EDT was not published. We all (at least should) know that RT60 does not tell anything about achieved acoustical resolution so it's kinda worthless as a number. EDT and spectrum tell more.

Back to slopes. Strength of directivity is one tool to increase acoustical resolution, but it's not good method if e.g. DI=0 dB at LF and > 10 dB at HF. Steep DI slope with small DI at LF is not compatible with rooms having good EDT at mid...high to get good acoustic resolution on wide frequency range with any speaker concept. High DI at HF could help with bad and harsh acoustics, but then order of improvement actions is reversed. Really wrong imo. spinorama.org and many members (including webmaster) on ASR don't seem to care or understand anything about this. They just look linearity of ON, LW and especially PIR curve because "Olive's PR says so", and say wow! for straight lines. Almost no one protest against e.g. Neumann KH 150 which sounds dull dead with burned tweeter in living room having some (painted) acoustic panels on the walls and ceiling, and large carpet on the floor. Sound is unworthy almost everywhere outside on-axis. Ok, it's near field monitor, but also in that group very unbalanced in decent listening environment though it is said to be "one of the most flat frequency responses ever seen". And it's not the only one. March Sointuva, Buchardt P300..S400 etc. look the same concept.

Speakers with very strong directivity such as tractrix horns with cardioid bass or dipole panels change the game so that they are not usually listened casually / much off-axis. No one cares (to say) if balance is bad or otherwise strange to 70...180 degrees off-axis.

Opposite end is flush mounted wall speakers which are almost omni to half space. See the following spinorama. Sound is very good, balanced and open to very wide and tall area also in decent room acoustics. Slope of on-axis can be balanced to negative to get PIR slope close to "good" value for full space concept. Sound fills the room and balance stays stable due to very small slope of DI.


So I encourage to listen and compare and use own brain rather than just reading n' believing Olive and Toole.

[tktran]

Here is my speaker, hand tuned by IIR DSP:

I'm also using XT25 (BG60) variant, but without waveguide.

Some comments about the top octave- IMHO fine tune to taste (ie. personal listening room acoustics, hearing preferences, musical program material)

[kimmosto]

Do you mean that the calculations in this comparison are different from what is shown in the preference rating window of VituixCAD?

Slope results are the same with all three equations, but SM results are not. Olive's equations (9) and (10) have some built in intentional biases or unintentional mistakes. SM result depends on slope. Slopes close to 1 and -1 give better SM result than slopes close to 0 with equal variations. NBD has the same problem, but NBD prefers slope=0. Equation 9 has NBD_PIR so result is not perfect with perfectly linear PIR.

Custom equation (the last one) eliminates slope from SM and NBD result, and has separate slope targets so it is the only equation what I can recommended for speaker designing.

More information in user manual: https://kimmosaunisto.net/Software/V...ference_rating

[Reet]

Start here:

https://shop.cta.tech/products/standard-method-of-measurement-for-in-home-loudspeakers

https://patentimages.storage.googleapis.com/95/03/0a/a4a8dbd7d8042c/US20050195982A1.pdf

[draki]

Will somebody explain a little these new (at least to me) charts please? 🤔

[augerpro]

Where does the determination that a certain slope is preferred come from? Last I knew, Toole, et al. left that specific question open when they developed their preference scoring. Is there another group that has carried on this research?

[Reet]

Some statistics with subjective classification: green=good, orange=maybe, red=bad. Calculations done with "custom" preference rating due to better math.

Do you mean that the calculations in this comparison are different from what is shown in the preference rating window of VituixCAD? For my speaker, PIR slope is -1.311, SP slope -2.159, so I will put it on the border of "maybe" and "good" category based on this chart. Bringing down the high frequencies in the top octave puts it in "bad" category.

[Reet]

This type of construction is still a bit complex to me, however I may attempt something along these lines for the next build.

[Reet]

You seem to have fitted carpeting which reduces reflected power at HF. Have you measured acoustical parameters at typical listening area? I'm interested in EDT and T20 spectrum. ARTA is good in that task. Probably REW too.

I am fortunate to have quite a good listening space. Eventually the carpet will go and I will have to rely on some heavy rug and tapestries. We also have 100 house plants, and the space behind the listening location is not a flat wall, but open stairwell. It is also a large enough space that I can listen at nearly 5m distance.

I'm not well experienced with RT60 type of measurement and interpretation, but I will be setting up for measuring a few more speaker drivers in a week or two, and will plan to investigate this topic a but further then. The waveguide on the XT25 also assists in distortion at 2kHz range by providing a bit of boost to forward facing angles. I find the overall sound balance of this speaker to be very good, neither bright nor dull, "just right".

[kimmosto]

Active 2-way with S-S 18WU-4741 and D3004-660000


Prototype cabinet. Final will be rounded to smooth DI and "mute" time domain.

Point is again that PIR and SP slopes are very good without wave guide. Very shallow wave guide could smooth DI, but too deep could tilt too much.

[kimmosto]

For a reference to previous table; Avalon style floor standing 3-way with Seas L22RNX/P, Seas MCA15RCY and Scan-Speak D2904-600001 classic soft dome. Preliminary box finishing without rounded bevels.

Indicates that modern 2-way near field monitors with deep (or any) wave guide are not far from useless crap especially for casual listening if room has acoustic panels, soft carpets etc.