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-   -   Differents results from differents simulation sofware (http://www.diyaudio.com/forums/subwoofers/225178-differents-results-differents-simulation-sofware.html)

 sebDIY 7th December 2012 08:44 AM

Differents results from differents simulation sofware

Hi, I'm trying to understand, for my knowledge, how to do bass reflex sim. I've find formulas here: The Subwoofer DIY Page - Ported Systems: Frequency Response Calculations (Thank you Brian to share this)

I've put formulas into Excel and compare with others software. Excel gives me same results as BassBox PRO and WinISD. But if I compare to Hornresp and Akabak, I've seen some differences, sensitivity and fréquency response. Akabak and Hornresp gives similar results.

Here copy screen of Hornresp, Excel, WinISD. I've made perfect flat curve in Hornesp with Beyma Driver 18P1200Nd, ( http://profesional.beyma.com/ingles/pdf/18P1200NdN.pdf ) Vb 110 liters, Fb 50.14Hz, then same sim in WinISD and Excel (with Ql=7):

Hornresp sim:
http://data.imagup.com/12/1169543085.jpg
http://data.imagup.com/12/1169543174.jpg

Excel:
http://data.imagup.com/12/1169543214.jpg

WinISD:
http://data.imagup.com/11/1169543054.jpg

As you can see, differences in WinISD and Excel are : little bump , F3 is higher, sensitivity is lower by 3.5dB.

So, Which software say the truth?

 bjorno 7th December 2012 09:21 AM

Hi sebDIY,

Why not post your input screens. the only way for other DIY-members to find out why there are differences.

b:)

 sebDIY 7th December 2012 10:05 AM

Hi Bjorno, I have include the input screen of Hornresp in my first post, and repost all the frequency response, there was a little error, but nothing change: Akabak and Hornresp have the same flat response (or very similar), same F3, but WinISD, excel formula, and even Bassbox show little bump, higher F3, lower sensitivity.

 OMNIFEX 7th December 2012 06:18 PM

Hi.

I would put more trust in software designed to create reflex cabinets if that is the goal than, software designed to create horns. Upon looking at the parameters required for horn response to draw to its conclusion, it is evident that it is not using the traditional parameters used to create a reflex cabinet.

 Djim 7th December 2012 09:24 PM

Hi sebDIY,

Indeed, it would be much easier if you showed all input pages.
Maybe the difference in output level is because winISD uses Watts and HornResp/Akabak uses Voltage. The difference in response may be the result of the port volume.

 sebDIY 8th December 2012 03:50 AM

Hi Djim, it's very simple and quick to makes a comparison between Hornresp and WinIsd, even with UNIBOX which gives similars results as WinISD and BassBox. So everybody could see the problem by himself, it will be easier.

I've tried to use SPL voltage in excel. It's improves the comparison a little, but not totally and not for all drivers.

I don't see why software like Hornresp or Akabak couldn't do bassreflex sims.

If David McBean read this thread and can tell us if his software can do Bassreflex sims with accuracy or not? I will be interesting also to know why these differences.

 David McBean 8th December 2012 06:15 AM

Quote:
 Originally Posted by OMNIFEX (http://www.diyaudio.com/forums/subwoofers/225178-differents-results-differents-simulation-sofware-post3275012.html#post3275012) I would put more trust in software designed to create reflex cabinets if that is the goal than, software designed to create horns.
Hi OMNIFEX,

Hornresp uses a more sophisticated bass-reflex simulation model than WinISD.

While I don't know for sure, I would expect that in theory the Hornresp predictions should be the more accurate.

AkAbak and Hornresp use essentially the same model.

Kind regards,

David

 David McBean 8th December 2012 06:19 AM

Quote:
 Originally Posted by sebDIY (http://www.diyaudio.com/forums/subwoofers/225178-differents-results-differents-simulation-sofware-post3275597.html#post3275597) If David McBean read this thread and can tell us if his software can do Bassreflex sims with accuracy or not?
Hi sebDIY,

See my post #7 above.

Kind regards,

David

 OMNIFEX 9th December 2012 04:33 PM

Hi David.

I have a lot of experience with Eminence Designer that is a light version of Harristech’s Bass Box pro in which, sebDIY mentioned. I’ve compared Bass Box Pro to Eminence designer and the results are exactly the same.

The problem with Horn Response is that it does not offer the traditional parameters used for designing a reflex cabinet. If I need to convert the parameters in Eminence Designer in order for Horn Response to recognise the figures it is requesting, why would I bother with Horn Response to design a reflex cabinet?

Possibly, it would be better for Horn Response to have compatible parameters that reflect what manufactures offer when they sell raw drivers if Horn Response is looking to expand into reflex designs.

Cheers!

 Rademakers 10th December 2012 05:39 AM

Quote:
 it does not offer the traditional parameters used for designing a reflex cabinet
Which are?

Best regards Johan

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