Contents of the BOXPLOT.DOC file
Box Plot For Windows 3.0
By Rick Carlson
For Sparta Sound Co.
SHAREWARE VERSION 1.0
Box Plot is a Microsoft Windows based program that shows
the frequency response and maximum Sound pressure level
of a given Loudspeaker/Box Combination.
This Version of Box Plot requires Microsoft Windows 3.0
or later to run. A math coprocessor is not required but
really helps speed things up if you want do alot of
iterations on the box parameters.
(Turn off Auto Plot on slow machines).
If Terms like Qes, Fs, Vas are unfamiliar to you, then
this program will be difficult for you to use. It is intended
for the audio hobbyist or professional interested in building
there own speaker enclosures, or modifying their present
If you are interested in building your own speakers, I would
suggest that you subscribe to Speaker Builder Magazine. It
is a good source of information on this subject.
Box Plot is based on a program called Boxresponse, which
was published in Speaker Builder magazine a while back. Box
Plot adds graphical output, MS Windows compatability,
printing, file storage, and a couple of other new features to
the original BASIC version of Boxresponse.
This Program was designed to allow 'almost' real time
update of the response plot as box parameters are changed.
This is usefull when trying to shoehorn a speaker into a non
optimum box. Many different combinations of box parameters
can be tried in a short period of time. If Auto Plot is
turned on, then clicking on the OK button of the BOX
Parameters dialog box will replot the response curves.
Speaker parameters are entered into a dialog box. When
done, click on the OK button to save the parameters. The
Parameter names are the Thiele Small Parameters specified on
most good spec sheets.
Box Parameters are entered in a dialog box. When the OK
button is clicked the Box Parameters dialog box stays on the
screen. To close the dialog box click on the Close button or
use the system drop down menu (upper left of dialog box) to
close the box. The reason the dialog box stays on screen is
to make it easier to edit parameters and see the effect on
There are 6 types of boxes that can be modeled with Box Plot.
Simple sealed Enclosure.
Closed Box with first order equalizer:
Sealed box with first order filter. The first order
filter usually provides subsonic attenuation.
Closed Box with second order filter:
The second order filter is usually an active filter
placed before the power amp. This filter can be used
to extend the low end, or modify the response of an
Box with tuned port.
Vented Box with first order eq:
First order Eq is more usefull here than is a sealed box.
Vented Box with second order eq:
Same as sealed box.
The comments field is a text string, 255 chars long that
can be used to annotate the graph.
This box will show the vent length based on the present
box/ speaker combination.
When the Auto Plot menu item is checked, anytime a speaker
or box parameter is changed, the graph will be regenerated.
This keeps the graph up to date with the latest parameters.
This also may be annoying on slower machines so it can be
This will reset all parameters to some predefined settings.
The settings are based on nothing at all, just some numbers
that wont do real wierd things. (The speaker parameters are
from a well known manufacturer.)
This will save the speaker, box, and comments in the specified
file. (Registered Versions)
Read a file on the disk. The default file extension is .SPK
but has no real significance.
This will print the response curves as shown on the screen
along with the speaker and box parameters. (Registered versions)
In the Unregistered shareware version, files cannot be saved
and the response curves cannot be printed. Please register
to recieve the complete version, as well as updates and
bug fixes, as they become available.
To register Please send $25.00 to
62 Fox Trail Rd
Sparta, NJ. 07871
I will send out a disk with the complete version, and some
more on line documentation.
If you have suggestions, comments, bug reports or just feel
like writing please do so.
Let me know what other kinds of programs would be usefull to