Sealed
Vented
Enclosurewith Passive Radiator
4th-orderBandpass








Parallel6th-Order Bandpass
Series6th-Order Bandpass
8th-OrderBandpass


Subwoofer Simulator allows for 1, 2 orall 7 types of subwoofers to be simultaneously simulated, however, onlyone instance of each type is supported in the current softwareversion. The next version will be more flexible and have lotsmorefeatures.


I have made thegraphing part of subsim to show multiple curves in one page only sothat users may clearly see the relationship between each curve. This isnot only educational for beginners, but also informative for knowledgeddesigners. Moreover, all curves corresponding to each box type areshown on the same page, which allows for easy comparison of box designs.
The currentversion of subsim does not automatically adjust the extremes of theY-axes. However, all X-axis and Y-axis maximum and minimum values maybe easily changed by clicking the supplied Up/Down buttons or Up/Downkeys for keyboard bashers.
SubwooferSimulator plots:
- System SPL and phase
- Cone and port speed
- Cone and port excursion
- Group Delay
- In-Room frequency response (given the user's room transfer function)

and lets the user save the graphsin FRD/ZMA (textual) format. The format allows for postprocessing with any text editor and other audio software such as theones from the FRDGroup. The format is also used by commercial software such asSoundEasy, LEAP, LspCAD etc. FRD files are simply text filescontaining, for example, the following data.

Frequency (Hz)Magnitude (dB)Phase (degrees)
10.00080.00090.000
11.00082.00085.000
12.00083.00080.000
......
...
...


Writing Bitmap screenshots ishandled by Subwoofer Simulator simply by clicking on the graph space orby going the long way of clicking on the File / Write Screenshotdrop-down menu.
In order to help the user distinguish which curve is which, the userhas the option to change the color of each curve. Colors areautomatically saved when a simulation is ended or when subsim isclosed; the last saved colors are loaded everytime subsim is opened.
Clicking anywhere outside the graph space recalculates everything.

2.3. Create/Load/Save Project Files, DriverFiles, Box Files..

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Projects can be saved and loadedfor convenience. This greatly saves time in re-entering designparameters or making derivatives of a known good design. Exceptfor which sub-windows were open, everything is saved in one file, theprogram even remembers graph colors and axis extremes. Graphcolors are automatically-saved just before ending a session with theprogram or complete program closure. Graph colors can be resetjust in case the corresponding settings file becomes corrupted. Enclosure and driver details can be separately saved and loaded as well.


Using measurements of the user'slistening room, subsim can show the effects of which with a candidatesubwoofer design. Subsim simply adds the transfer functions of bothsubwoofer and room then displays the results.

When any of the checkboxes in theGraph Options | Available Curves tab is checked, moving the mousepointer anywhere on the graph space enables curve tracing. At thebottom-left-hand corner of subsim's window, the correspondingmagnitude, phase and frequency of the mouse pointer's position isdisplayed. Depending on which Y-axes are selected to be shown and whichY-axis is selected, users will see, for example, '88.123dB/-90.456degat 30.789Hz.' Any of the visible Y-axis may be selected for curvetracing simply by clicking on the desired Y-axis type.

Not all woofers come with enoughThiele/Small parameters. To compensate, Subwoofer Simulator cancalculate the requried parameters.. given a set of extraparameters.

Box volume, Vb, port radius, Av,port length, Lv, and box resonant frequency, Fb are interrelated to oneanother. I have made subsim to behave as follows.

Enclosure Part-Changed by adjustments of any/all of:-Notes
Fb
Vb, Av, Lv, PR parameters, number of vents/PRs
Lv
Vb, Fb, Av, number of vents
+m
Fb, number of PRs
PR Parameters
number of passive radiators
to reflect a single equivalent PR

Physical port length isinfluenced by end-correction, (and user defined values for) speed ofsound and air density. Subsim calculates the effective port length byadding 0.850*Av (for flanged end) and 0.613*Av (for unflanged end) tothe physical value, Lv. Please seeCylindrical Ports and Flared Vents for more details.

3. Quick Startup Guide
3.0. Double-clicksubsim.exe and then click on File / New Project



3.1. Enter driverThiele-Small parameters or load a pre-saved driver file.



3.2. Enter simulationparameters and then select which enclosure type to simulate.


3.3. Click on Boxes /Vented to bring up the Vented-Box Details window. Enter yourenclosure's parameters and then select which curves to plot.




.. Quitestraight-forward. There really is no particular order, which maymake Subwoofer Simulator's user interface a little 'different' to someusers.

4. Notes
- Enclosure optimization isdisabled and completely removed from the program. The code works,but is 'randomly' unstable, so I need to work on it some more.

-- Upper frequency roll-off isdue to voice-coil inductance, butremember that the SPL curves are only accurate up until Cone Breakupsets in. For subwoofers, Cone Breakup happens well away from thepassband of interest.

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-- Radiation is intohalf-space. Subtract 6dB from the plotted SPL to obtainfull-space radiation, however, remember that Baffle Diffraction is notsimulated. The easiest way to subtract 6dB from the SPL is byhalving the voltage input.

-- I have built SubwooferSimulator to use the most commonly used measurementunits in this subject. However, to help you convert from onemeasurement unit to another, you may download Factor Conversion Tool.

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-- multiple woofers may be usedwith the program simply bymanipulating the T/S parameters of the woofer used. The single-wooferequivalent T/S parameters are:
For x woofers in parallel:
Revc= Revc/x
Levc=Levc/x
Fs=unchanged
Vas=x*Vas
Qms=unchanged
Sd=x*Sd
Bl=unchanged
For x woofers in series, as above, but:
Revc=x*Revc
Levc=x*Levc
Bl=x*Bl

-- Please see Thiele-Small Parameters and Dual Voice-CoilDrivers for DVC simulations.

-- for an isobaric configuration,the effective parameters are:

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For parallel voice-coils:
Revc= Revc/2
Levc=Levc/2
Fs=unchanged
Vas=Vas/2
Qms=unchanged
Sd=unchanged
Bl=unchanged
For series voice-coils, as above, but:
Revc=2*Revc
Levc=2*Levc
Bl=2*Bl

-- Project/Woofer/Box/Color filesare saved in binary format. Iwas going to use text mode saving/loading but this created anincompatibility with Windows machines which use the comma (,) as thedecimal separator (as I program using the full stop (.) as the decimalseparator). Text mode would have given the user the option to manuallyedit the project files using any text editor, but the incompatibilityproblem was unavoidable in text mode.

-- Subwoofer Simulator displayspeak or one-way excursion curves.

-- Input FRD files must not haveany comments whatsoever -- theinput files must only contain data or the program will refuse to acceptyour room measurements.

5. Things To Come

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I had originally decided tocontinue updating Subwoofer Simulator with active filters, equalizersetc., but I thought it is time to combine both Subwoofer Simulator andCrossover Simulator into one loudspeaker simulation package.

6. Download Details

Speaker Box Cad Programs Pdf

SubSim ZIP File
size =
851kB
Uploadedon May, 2002

Subwoofer Simulator is FREEWARE!
Kindly email me to arrange commercial use.
Please email me if you'dlike to donate any sum of money.