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MultiWay Conventional loudspeakers with crossovers 

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4th November 2008, 10:17 PM  #1 
diyAudio Member
Join Date: Jul 2008

Loudspeaker design using Open Office Calc (or Excel)
After researching the free speaker design software available, I am trying to make some OB modeling in Calc/Excel. It is very easy to digitize FR and impedance plots shown in speaker datasheets. It is quite easy to compute amplitude response of a given type crossover (have not tried phase yet  should not be much of a problem, too). There are baffle influence simulators, whose output can be easily imported to Calc/Excel too.
There is only one big problem  I do not know how to "graphically" add FRs in Calc/Excel. The problem is, each data range has different number of points, so I cannot add easily ycoordinates for a certain xcoordinate, as the xcoordinates are different in each data range. Is there an easy way of doing it? What is the formula behind XLBaffle  it should not be difficult to implement in Calc/Excel  where could I find the theory? Such a spreadsheet would be very nice for crossover design from the real measured response shown in speaker datasheets  I guess I could get much closer to the final result than with textbook formulas. 
4th November 2008, 10:52 PM  #2 
diyAudio Member
Join Date: Jul 2008

I forgot to mention a few things  so that the post is also useful for someone else
I capture the plots to the clipboard directly from the screen with MW Snap http://www.mirekw.com/winfreeware/mwsnap.html Then I paste from the clopboard to Engauge Digitizer for FR and impedance plot digitizing  it is as easy as it gets (and free ) Do not forget to use log scale on X  http://digitizer.sourceforge.net/ I get exported plot as a series of numbers  that is easily imported to Calc/Excel  two columns separated by comma. Crossovers are easily computed from circuit theory using ideal components  needs a little math, though. It is easy to include any kind of compensation circuit  LR transform, dipole compensation, etc. I yet have to find some theory for baffle diffraction and ultimately, some LF room influence should not be that difficult to compute either. It should be also easy to add simple sealed and bass reflex box and driver modeling with TS parameters. Most of these things can be done by Basta!  but I'd like to have a little more flexibility event at the expense of more work. And what is most important  learn the math behind traditional loudspeaker design. I will be glad to share my spreadsheet when I come to something useful. Right now it is just killing time during a business trip 
4th November 2008, 10:55 PM  #3 
diyAudio Member
Join Date: Nov 2004
Location: Québec, Québec

Before reinventing the wheel, I'd suggest you look at Unibox, a subwoofer design tool built in Excel.
It may give you some great ideas. It can't do Open Baffle AFAIK OTOH. Good luck !
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4th November 2008, 11:21 PM  #4 
diyAudio Member
Join Date: Jul 2008

Thanks for the suggestion  I will check it out. The main purpose is of course not reinventing, but learning and understanding
update: Through unibox I have found what I was looking for  FRD's Frequency response combiner Now I can combine frequency plots till eternity 
4th November 2008, 11:37 PM  #5 
diyAudio Member
Join Date: Jul 2008

The definitive answer to anyone searching for a similar thing as I did, have a look at:
http://www.pvconsultants.com/audio/frdgroup.htm I knew that site before  but I underestimated its potential. 
5th November 2008, 12:07 AM  #6 
diyAudio Member
Join Date: Nov 2004
Location: Québec, Québec

Great, show us your work when you're finished !
We like to try new free software !
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5th November 2008, 01:11 AM  #7 
diyAudio Member
Join Date: Jun 2002
Location: USA, MN

you could make a passable sim with the equations at www.diysubwoofers.org
As far as matching frequency response for adding, you can't unless you normalize the files to contain the same data points  which is part of what the FRC does.
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5th November 2008, 01:24 AM  #8 
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5th November 2008, 04:34 PM  #9 
diyAudio Member
Join Date: Oct 2008
Location: Winterswijk

Hi,
I use winISD pro freeware professional software. Not fot exel or openoffice. To design: closedbox bassreflex closedbandpass ventedbandpass winisdpro
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5th November 2008, 05:37 PM  #10 
diyAudio Member
Join Date: Jul 2008

WinISD is OK, I use it from time to time  but is does not allow to use real measured data  that is why I needed something else.
I have first results  SPL Tracer and SPL viewer do not work on my PC. Tracer behaves strangely after selecting "trace" and does not trace anything, viewer crashes with an error message while trying to load a response to view. FRC kind of works I am just playing with it. 
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