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Old 8th September 2019, 06:21 PM   #1461
kimmosto is offline kimmosto  Finland
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New built of 2.0.24.0 has been available for 3 hours. Minor improvements to logic and weighting factors of intensity calculation to support new off-axis recipe with constant angle steps.
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Old 9th September 2019, 05:25 AM   #1462
kimmosto is offline kimmosto  Finland
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Rev. 2.0.24.1 (2019-09-09)

* Added sanity check to frequency response loading in Drivers tab. Ver 0 deg coverted to Hor 0 deg. -180 deg converted to +180 deg. Duplicate directions are not loaded to response list. Warning and request to verify Angle parsing : Integer multiplier setting in Options window if duplicate directions are found.
* Minor improvements to logic and weighting factors of intensity calculation to support new off-axis recipe with constant angle step.
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Old 9th September 2019, 06:59 AM   #1463
kaameelis is offline kaameelis  Estonia
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I had question. Is VituixCAD able to optimize DSP biquad filters?
Is there any limitations or precautions for this kind of optimization?
If for example I had 4 biquads per speaker connection, can I put them all together to optimization or this will not give reasonable result?

One more: is possible on VituixCAD to merge vented speaker enclosure vent/port near field measurement and bass speaker near field measurements? Old SpeakerWorkshop made it based on vent and speaker areas.

Last edited by kaameelis; 9th September 2019 at 07:10 AM.
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Old 9th September 2019, 09:17 AM   #1464
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by kaameelis View Post
I had question. Is VituixCAD able to optimize DSP biquad filters?
Is there any limitations or precautions for this kind of optimization?
If for example I had 4 biquads per speaker connection, can I put them all together to optimization or this will not give reasonable result?
It is possible to optimize b0...a2 parameters without technical limits how many biquads are optimized at the same time. BUT initial parameter values should be quite close to final = initial response close to target before optimizer is started because Nelder-Mead algorithm is aggressive and there's no constraints or artificial intelligence (restarts etc) in the sequence.

My recommendation is that filter should be designed with generic active blocks such as But/Bes/L-R/1st/2nd order LP, HP, Peak/Notch, All-pass, Shelf etc. if dsp configuration application supports them and acoustical target is possible to reach with generic blocks. The reason is simple: biquad parameters are almost impossible to adjust manually by human.

One possibility is that filter is designed initially with generic blocks, and fine tuning using some non-standard slope/shape is done with single...only few blocks which are converted from generic active block to biquad(s).

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Originally Posted by kaameelis View Post
One more: is possible on VituixCAD to merge vented speaker enclosure vent/port near field measurement and bass speaker near field measurements?
You probably mean summing of port and cone signals to total near field response which is usually merged with far field response or response? If yes, for example image on home page and user manual shows one example where near field response of port and mid-woofer's cone are summed and then processed with diffraction simulation to make quasi far field response and finally merged to far field measurement(s). Port response is loaded to LF response list and scaled with diameter or area.

Click the image to open in full size.

Last edited by kimmosto; 9th September 2019 at 09:21 AM.
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Old 9th September 2019, 10:48 AM   #1465
kaameelis is offline kaameelis  Estonia
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With biquads is all clear. I had biquads basically ready and working in DSP, but as amount of them is limited, I need to fine tune them for better SPL response. So I will test it soon on VituxCAD.

With response merge/summing not so clear. If cone and port near field responses are defined both in Merger tool, in Low Frequency section, then automatically is made merge of all 3, port, cone and gated HF measurement?

Last edited by kaameelis; 9th September 2019 at 11:10 AM.
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Old 9th September 2019, 12:11 PM   #1466
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by kaameelis View Post
If cone and port near field responses are defined both in Merger tool, in Low Frequency section, then automatically is made merge of all 3, port, cone and gated HF measurement?
That's the idea. This video might be revealing: VituixCAD Merger.

Directivity of low frequency part is inherited from time windowed far field measurements. That could cause some irregularities to directivity result especially if time window has not been Hanning.
I usually solve that problem by using simulated directivity below ca. 150 Hz with wide blending range. That is possible with double merging: quasi far field LF responses with simulated directivity are merged with measured (gated) far field responses merged with near field LF responses That procedure is not documented in help files, but experienced users probably guess or know how that is possible with existing tools.

Last edited by kimmosto; 9th September 2019 at 12:14 PM.
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Old 9th September 2019, 03:34 PM   #1467
kaameelis is offline kaameelis  Estonia
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Actually biquad optimization is more complicated than measurement summing.
How is possible to define min and max limit for biquad coefficients in optimization? Usually coefficients cannot be bigger that +/-1 or +/-2 depending from coefficient.
I tested it on tweeter where I had 2 biquad sets for HP filter, 1 set for low shelf and 1 for peaking EQ, based all on MiniDSP Biquad calculation xls sheet.
Optimizing of all 4 biquad sets together make no sens, I get big mess. Also optimization of one biquad set make no things better. Only optimization of one coefficient in biquad set make some sense, but also difficult to get result.
Or this kind of optimization in real life is not possible, as type of filter represented by biquad can be changed during optimization. Opposite to passive component filter where type of filter or component (capacitor or inductance) is not changed, only component value is changed.
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Old 9th September 2019, 05:42 PM   #1468
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by kaameelis View Post
Also optimization of one biquad set make no things better. Only optimization of one coefficient in biquad set make some sense, but also difficult to get result.
I have got some results with single biquad (all coefficients optimized), but as already mentioned, initial situation should be close to get any better than original. Also frequency range should be carefully set, not too wide or narrow.

Component/block parameters have internal constraints but they are not yet enabled and shown in the program because usually they just make working more difficult and slow. Manual adjustment becomes faster when number of configuration parameters increases. I agree that constraints would help with biquads, but I don't have enough faith to test it. Changes to get decent result quickly are close to zero, with or without constraints.
I trust more traditional methods; using and optimizing blocks with f, Q and gain parameters.
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Old 9th September 2019, 06:35 PM   #1469
kaameelis is offline kaameelis  Estonia
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Can blocks with f, Q and G be converted to biquads in VxCad?
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Old 9th September 2019, 07:10 PM   #1470
kimmosto is offline kimmosto  Finland
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^Yes. Selected 1st-2nd order generic active block can be converted to single biquad block by clicking BiQ menu button with Ctrl-key pressed. 3rd...8th order generic active LP/HP blocks need 2...4 target biquad blocks. Select source block, Copy Biquad coefficients command from context menu, select target biquad blocks and Paste Biquad coefficients command from context menu. DSP system with correct sample rate should be selected before this operation to get correct coefficient values. Not so difficult imo.
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