Loudspeaker design using Open Office Calc (or Excel) - diyAudio
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Old 4th November 2008, 09:17 PM   #1
pelanj is offline pelanj  Czech Republic
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Default 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 y-coordinates for a certain x-coordinate, as the x-coordinates 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.
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Old 4th November 2008, 09:52 PM   #2
pelanj is offline pelanj  Czech Republic
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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
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Old 4th November 2008, 09:55 PM   #3
simon5 is offline simon5  Canada
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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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Old 4th November 2008, 10:21 PM   #4
pelanj is offline pelanj  Czech Republic
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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
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Old 4th November 2008, 10:37 PM   #5
pelanj is offline pelanj  Czech Republic
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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.
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Old 4th November 2008, 11:07 PM   #6
simon5 is offline simon5  Canada
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Great, show us your work when you're finished !

We like to try new free software !
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Old 5th November 2008, 12:11 AM   #7
Ron E is offline Ron E  United States
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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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Old 5th November 2008, 12:24 AM   #8
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Thorsten Loesch's OB spreadsheet

http://www.fortunecity.com/banners/i...o/Xlbaffle.xls

dave
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Old 5th November 2008, 03:34 PM   #9
Helmuth is offline Helmuth  Netherlands
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Hi,

I use winISD pro freeware professional software. Not fot exel or openoffice.

To design:

closedbox
bassreflex
closedbandpass
ventedbandpass

winisd-pro
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Old 5th November 2008, 04:37 PM   #10
pelanj is offline pelanj  Czech Republic
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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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