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Old 26th March 2009, 08:09 AM   #1
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Default Cone Excursion

I'm looking for a way to model or plot a speaker's cone excursion versus frequency for a given input power. I realize the cone excursion will depend upon T/S params, enclosure size and type, etc. but I am having a hard time finding an equation that includes all this. I have found PLENTY of references to the loudspeaker design cookbook and the PAR equation but I think it is only valid at the Fc of the system. I need an equation that is valid over all frequencies. Basically, I'm looking for the mathematics behind WinISD's cone excursion plots...Any help would be much appreciated!
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Old 29th March 2009, 04:19 PM   #2
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Hmmm, 100 views and no replies, this may be more difficult than I thought. I know the cone excursion plot of a sealed enclosure looks like a low-pass filter with the roll-off beginning above the fc of the box. But I'm not exactly sure what the roll-off rate will be or what the excursion will be before the roll-off depending on the input power.
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Old 29th March 2009, 05:51 PM   #3
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I can't answer your question directly, but there is an excellent resource available here:

Linkwitz Labs Electro-acoustic models

I know that this sight is best known for it's dipole speakers and theory crafting but don't let that throw you off there is plenty of good information to be had here.

Near the top of the page at the end of section A1 is a link to a spreadsheet that calculates the one way air displacement required at any frequency. Just at the end of that line there is a link to a GIF file which might provide equations that will eventually give you what you are looking for.

This link:

Linkwitz Labs Room Acoustics

has some good equations for calculating power required to reach a desired output level in a given room. Check Section C5
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Old 5th April 2009, 10:56 AM   #4
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WinISD alpha will plot the excursion to frequency graphs for a driver.

Does other things aswell, but you do need to know a lot about your driver...
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Old 5th April 2009, 07:18 PM   #5
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Have you checked unibox?
You might be able to figure out the math that drives it. Everything should be there.
Not sure how accurate they are, long time since I checked it.
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Old 8th April 2009, 11:47 PM   #6
Ron E is offline Ron E  United States
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Quote:
Originally posted by johnc124
Hmmm, 100 views and no replies, this may be more difficult than I thought.
For the most part, if you are smart enough to need the formula, you ought to be smart enough to figure it out or figure out where to get it. It's kind of a PITA to post complex formulas, and most people aren't gonna spend a half hour of their day posting something that you may or may not be able to use.
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Old 9th April 2009, 11:08 PM   #7
Ron E is offline Ron E  United States
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http://www.diysubwoofers.org/prt/ported3.htm

Note that the Pmax formula calculates power needed to reach excursion (Xmax+15%) Fairly easy to figure out Excursion for a given power from that...
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Old 10th April 2009, 02:45 AM   #8
HK26147 is offline HK26147  United States
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The Linkwitz site also has this:

http://http://www.linkwitzlab.com/im...edge-micro.gif
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