First off WinISD is a freeware program put out by the fine people at www.linearteam.org
They do have a DONATION for use with Pay Pal, if you use this program and find it helpful send them a few bucks to help keep this type of software free and available!
Onto the useage.....
As soon as you open the program it will pop up with a window open inside of it, this is called the "Plot Window". There are a few tabs in this window, the gain, Phase Plot, SPL and Group Delay. For most purposes the only ones that will concern us are the Gain and the SPL (providing you know what amp you will use!).
The first step is to hit the "New" Icon/button in the programs main window. A box will pop up and have to radio buttons. The "Program Database" button has many subwoofers in its database. If you see your Subwoofer in the database go ahead and select it. If not you will need to enter all the T/S Specs yourself by clicking the "NEW" button. After you enter your own Drivers specs then you may use the "Own Drivers" button!!
We will continue as if we have to enter our Subwoofers numbers.
So we go ahead and hit "NEW" button. Another window pops up with a bunch of blank boxes. This is where you will enter in you T/S specs for the sub you have. All information is not always needed, but the more the better. Here is a cut from the DIY Subwoofer site I find useful:
Fs = resonance frequency of the driver. In free-air, the driver's impedance will peak at this frequency.
Pe = (EDIT:RMS!)Thermal capacity of the driver, in Watts. If continuously driven above its rated Pe, the driver may prematurely burn out and fail.
Qes = Electrical Q of the driver at Fs. Qes is a measure of the driver's tendency to resonate at Fs, based on its electrical characteristics, e.g. magnet strength, magnetic circuit characteristics, etc.). The driver's overall resonance characteristics are usually dominated by Qes.
Qms = Mechanical Q of the driver at Fs. Qms is a measure of the driver's tendency to resonate at Fs, based on its mechanical characteristics, e.g. surround compliance, the compliance of the spider, weight of the cone, etc.
Qts = Total Q of the driver at Fs. Qts is a measure of the driver's tendency to resonate at Fs, based on its overall characteristics. Qts can be calculated using the equation: Qts= Qms*Qes/(Qms+Qes))
Re = DC resistance of the driver's voice coil. Re is less than the driver's rated impedance (normally 4 or 8 ohms).
Sd = Effective surface area of the driver. Roughly equal to the area of the cone plus 1/3rd of the surround.
Xmag = [DUMAX] Excursion limit due to the magnetic limitations of the driver's motor. Xmag is defined as the displacement at which the BL product has fallen to 70% of its value at the cone's rest position.
Xsus = [DUMAX] Excursion limit due to the driver's suspension. Xsus is defined as the point at which the compliance of the suspension has decreased to 25% of the value at the cone's rest position.
Xmax = Linear (one-way) travel of the cone. Xmax is used to determine the maximum linear SPL capability of the driver, and can be defined in a number of ways. The DUMAX definition is objectively the best one, and it is defined as the shorter of the Xmag and Xsus values, in each direction of cone travel. This definition is more useful than the older definition of Xmax, which was solely dependent on the length of the voice-coil vs. the length of the gap.
Vas = Equivalent air compliance. The volume of air that has the same compliance ("springiness"as the driver's suspension. Because less air is more "springy" than more air, a large Vas represents a "loose" suspension
Vd = Peak displacement volume. Vd = Sd*Xmax
I found and added these:
BL = The product of a drivers gap flux density and the length of the voice coils conductor in the gap. (measured in Tesla meters)
Le = The electrical inductance of a speakers voice coil. (measured in mH also known as millihenries)
Z = Nominal Ohms (rated or how you will run this sub if DVC!)
Dia = Cone size genius!
The bare minimum information that must be entered is the first three fields (Qts, Vas, and Fs)
You will want all of these parameters to use WinISD effectively! You should be able to attain the T/S Specs by the Subwoofers manufacturer website or they should have come in the box with the Sub. If you dont have it get it!
Before you enter your T/S Specs you will need to enter a name for your Sub, so do it. It should be under "Driver Name"
Enter you information into the boxes. Check the units the use to the units given to you by the manufacturer. Sometimes the units may be different, but dont fret! Click on the unit of measurement in the WinISD progams box. Viola! It changes to adapt to the specific measurement you have! The VAS, XMAX, Diameter and SD measurements allow this flexibility!
After your done adding the info hit the "OK" button. Then hit the "close" button right afterwards. Your driver has now been entered into "Own Drivers" database!
Now go Back and Hit the "NEW" button on the main window. On the popup box select "Own Drivers" your Sub should be there! Select it and hit "NEXT" button. Now select the number of drivers you will be using. Then you have a radio button choice of "normal" or "ISO-BARIK". If you know what ISO is then good, if not look it up. For our use here we will be going with the "Normal" Choice. Now hit the "Next" button again. Now another screen. This screen tells you the EBP or Efficency Bandwidth Product. If its towards the top its best suited for vented/ported, the lower is for sealed. When its fairly close to the middle you can go either or, it will sound just as good in either! For my use here I will be going with a Vented/Ported enclosure. Then I hit the "Finish" button.
Now a totally new window pops up and the "Plot Window" actually has a line on it. This is where the program gets all tricky on everyone. The program automatically comes up with an "ideal" box size for you, and in this case vent/port
size/dimensions also. The window with the tabs on it, goto that window now. Click on the "box" tab. The first box will
have the box size. Note that you can click on the units to change it into FT^3 if you like! You can also change this box size, the plot screen will reflect any/all changes no matter what you do! I sugguest you either A) use the box size given or B) use the Manufacturers reccomended box size.
The next box on the "box" tab is the tuning frequency. It all depends on what you want to do. One note wonder, SQ, SQL, SPL- WHAT DO YOU WANT??? Some people for SPL purposes tune as high as 70Hz!! This creates a sharp gain, but it kills the muscial aspect of the install. Im an SQL type of guy, so Im going to tune my box to 35Hz. If I was soley SQ I would go around 25-30Hz. On with it!
Next click on the tab marked "Vents". This is where it gets even more interesting! Now you can change the number of vents, size of them and even the shape! The round vents are geared towards PVC pipe cut to lengths. The square vents are geared towards cut wood or a "Slot Port" if you add the tall dimension and can 'play' around with the other dimension. When you start to change this around you will want to note the length of the port changes. Keep this in mind when designing! Make sure its not to long and will fit!!
So by now you SHOULD have noticed by manipulating these various numbers you can make a larger "GAIN" in the plot window at specific Frequencies. This 'gain' will make the box louder at the specific notes. This is desireable but has its negatives also. Choose wisely in how you do this.
If you added the SPL part back in the T/S Spec window at the begining you can now Plot the estimated SPL. This is the fun part of the program! This allows you to get an IDEA fo what you will be doing. Click on the "Plot" tab. Now tell it how much power you will be feeding the subs in RMS (Must know what amp your using by now!). Then select how many feet away the Mic will be. Then goto the "Plot Window" and click on the "SPL" tab. There it is!
Now you can SAVE this project by clicking the "Project" button. Nit the "Save" button and enter a file name. If you like to get the cold hard numbers hit the "Show as Text" button. At that point you can copy it to the clipboard or save it. This will allow you to print your info.
For example here is my data I came up with:
Driver : ED 12k.44
Vas : 53.7
Qts : 0.41
Fs : 26.39
SPL : 0.00
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Project by : RH
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Number of drivers : 1
Box type : Vented
Box size : 42.5 l
Tuning frequency : 35.00 Hz
Vent : 1 vent(s)
0.510 m length for each
0.102 x 0.102 m rectangle
Relative
Freq Gain SPL
[Hz] [dB] [dB]
10.00 -39.40 -39.40
15.00 -26.09 -26.09
20.00 -16.88 -16.88
25.00 -9.78 -9.79
30.00 -4.07 -4.07
35.00 0.14 0.14
40.00 2.33 2.33
45.00 2.85 2.85
50.00 2.65 2.65
55.00 2.28 2.28
60.00 1.94 1.94
65.00 1.65 1.65
70.00 1.41 1.41
75.00 1.22 1.22
80.00 1.07 1.06
85.00 0.94 0.94
90.00 0.83 0.83
Anyhow thats about it! If anyone has any extra input please feel free to E mail me: