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Old 27th November 2020, 06:05 PM   #2471
mehta is offline mehta
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Or how to get FR to follow impedance model, for example?
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Old 27th November 2020, 07:20 PM   #2472
Shaun is offline Shaun  South Africa
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Quote:
Originally Posted by mehta View Post
Or how to get FR to follow impedance model, for example?
You need to measure both impedance and frequency response. Load them to your driver, then you will be able to simulate the effects.
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Old 27th November 2020, 10:26 PM   #2473
mehta is offline mehta
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I'm using the impedance from the database.
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Old 27th November 2020, 10:40 PM   #2474
mehta is offline mehta
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I have the impedance loaded and the FR
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Old 28th November 2020, 01:23 AM   #2475
mehta is offline mehta
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Ok I've got it now. Thanks all, much helpful.

For some reason, in the nightclub industry where I worked before this year, it only became typical to use modelling software much later, and I found it easier to dial it all in by ear rather than mathematically/with measurements

I'm so amazed that there is this incredible free tool!! Very very happy with the quality of help I've gotten here! it's a great time to be doing this stuff. Being able to model biquads --- wow nice feature!!!

Last edited by mehta; 28th November 2020 at 01:24 AM. Reason: avoiding being an insecure braggart
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Old 29th November 2020, 03:11 AM   #2476
HammerSandwich is offline HammerSandwich
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Quote:
Originally Posted by kimmosto View Post
Another option is to enable inductance parameters: plain Le, basic impedance model or extended impedance model. It's 'Show effect of inductance' command in context menu of SPL chart. That's not exact fact either. Read user manual please.
I see odd behavior using the basic impedance model with multiple drivers in series. Best I can tell, parallel connections, plain Le, and extended models work consistently. This does not affect all drivers! 15W/8434 & NE123W-08 are good examples in the standard database.

To reproduce:
  1. Show effect of inductance.
  2. Plot to 20kHz.
  3. Select a driver with values for Z1k & Z10k.
  4. Increase the driver count.
  5. Note changes in HF impedance & corresponding FR.
15W appears normal with 1-4x drivers. With 6-12x, 10kHz SPL increases by 12dB.

NE123W shows strange results with 3x & 12x drivers but not the other configurations. Weirder, its HF Z increases, which is opposite to other drivers I've checked.
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Old 29th November 2020, 02:15 PM   #2477
kimmosto is offline kimmosto  Finland
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^Multiple problems in basic impedance model solver fixed/improved to rev 2.0.58.1 (2020-11-29)

Enclosure
* Initial values, constraints and parameters of basic impedance model solver improved to support all driver models, quantities and connections. May still fail with tweeters and illegal combinations of Z1k and Z10k.

Error message if basic model fails:
Attached Images
File Type: png VCAD2_Basic_Z-model_failure.png (3.1 KB, 135 views)

Last edited by kimmosto; 29th November 2020 at 02:19 PM.
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Old 30th November 2020, 01:12 AM   #2478
HammerSandwich is offline HammerSandwich
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Looks good! Nice work, Kimmo, and fast.
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Old 30th November 2020, 04:22 AM   #2479
smprather1 is offline smprather1  United States
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Hi Kimmo--


I am wondering if this is a bug. I exported a flat FR (no half-space response loaded) from a pseudo-infinite baffle diffraction sim (10000mmx10000mm). Shouldn't all of the off-axis angles be at the same level before beaming sets in? I don't have 'open baffle' checked, so I don't think there should be any cancellation from the back-wave.



Thanks!
--Myles



2020-11-29 22_13_39-Diffraction.png

2020-11-29 22_13_48-VituixCAD.png

2020-11-29 22_13_52-Inbox - mylesp@cadence.com - Outlook.png
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Old 30th November 2020, 06:57 AM   #2480
kimmosto is offline kimmosto  Finland
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^Diffraction tool is not designed for any kind of infinite baffle simulation. That wouldn't make much sense if we're talking about box/baffle diffraction to far field = intended purpose of the tool. In addition, DED model used in the simulation doesn't have exceptions for near field simulation within the edges.
So at the moment without adaptive constraints in dimension parameters user should take care that edge cannot rotate to the "back side" of virtual microphone with any horizontal or vertical off-axis angle. I can add adaptive constraints if that helps to avoid mistakes.
Flat rigid piston directivity simulation in Calculator tool is more suitable for simulation to half space only, though actual radiators are not flat rigid pistons i.e. result is not very valuable in practice.
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