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Old 18th July 2019, 01:19 PM   #1341
DBMandrake is offline DBMandrake  Scotland
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Quote:
Originally Posted by mbrennwa View Post
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.

Quote:
Originally Posted by kimmosto View Post
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.
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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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Last edited by DBMandrake; 18th July 2019 at 01:32 PM.
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Old 18th July 2019, 02:32 PM   #1342
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by DBMandrake View Post
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.
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Old 21st July 2019, 12:42 AM   #1343
johnsurnamerobinson is offline johnsurnamerobinson
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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)
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Old 21st July 2019, 06:26 AM   #1344
tcpip is offline tcpip  India
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Originally Posted by johnsurnamerobinson View Post

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.
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Old 21st July 2019, 06:33 AM   #1345
kimmosto is offline kimmosto  Finland
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How to start

Few video lessons
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Old 21st July 2019, 11:44 AM   #1346
johnsurnamerobinson is offline johnsurnamerobinson
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Got it.Problem seems is that I was trying to work `theoretically` rather fron actual measurements.
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Old 21st July 2019, 11:53 AM   #1347
johnsurnamerobinson is offline johnsurnamerobinson
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May I ask kimmosto how long have you worked on this ! seems very comprehensive (esp for freeware)
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Old 21st July 2019, 11:56 AM   #1348
tcpip is offline tcpip  India
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Originally Posted by johnsurnamerobinson View Post
May I ask kimmosto how long have you worked on this ! seems very comprehensive (esp for freeware)
I like that "especially for freeware" tailpiece. I guess you have similar questions about Linux, Apache, Postgres and the rest of them?
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Old 21st July 2019, 12:17 PM   #1349
johnsurnamerobinson is offline johnsurnamerobinson
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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)
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Old 21st July 2019, 12:30 PM   #1350
tcpip is offline tcpip  India
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Originally Posted by johnsurnamerobinson View Post
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.
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