Over the years I've had probably a dozen people ask me to model speakers for them using WinISD after they couldn't get it to work. So I figured I'd post a little how-to guide explaining how to get it set up.
Step 1: Download the program. I prefer the Pro Alpha version because it has more features. Get it here: LinearTeam
Step 2: Find the T/S specs of the woofer you want to model. For this demonstration I'll use the new Stereo Integrity TM65 mkII since it's one I haven't done before.
Re 3.2 ohms
Fs 69 Hz
Qes 0.90
Qms 3.0
Qts 0.69
Le 0.03 mH
Sd 136.9 cm^2
Vas 5.5 L
Mms 25 g
BL 6.2
Sensitivity (2.83v/1m) 88 db
Xmax 9 mm
Xmech 13 mm
Step 3: Open WinISD and click the New Project in the upper left. A small window will appear asking you to select a driver for the project. WinISD comes with the specs of a bunch of speakers, mostly pro audio stuff as you can see by scrolling through the list. But the TM65 is not there, so we'll add it by clicking New, just to the right of the drop down menu. This will bring up the Driver Editor screen. In the General tab, just add the name for it so you'll be able to find it in the list later.
Step 4: Select the Parameters tab. This is where you'll add the T/S parameters you found and where most people have issues with this program. The thing about T/S parameters is that they're not all just independent numbers. There are set mathematical equations that can be used to calculate certain parameters by using other parameters. WinISD has all these equations built in and must use them to calculate as many of the answers as it can, or it will give you errors and not let you save it. For example, Qts = Qes * Qms / (Qms + Qes). For the TM65 with Qes of 0.9 and Qms of 3.0, that means Qts = 0.692307 repeating. SI rounded it to 0.69 for display, but if you plug in 0.9, 3.0, AND 0.69, it will give you an error because 0.69 is not the completely correct answer to the equation. You must let the program do it by itself. The easiest way to make sure you don't screw something up is to hit Tab a couple times (i.e. more than once) after each number you type in (which will appear green) and see if any other numbers are automatically calculated (which will appear in blue). As you can see from this picture, the only values that I plugged in are Qes, Qms, Fs, Vas, Mms, Re, and Xmax. The program calculated everything else. (I also plugged in Le but it's not necessary for modeling low end response). So of the 13 parameters provided by SI, I only needed to add 7 of them and let it figure out the rest. Anything that still says 0.00 is not necessary for the modeling.
![Image]()
Step 5: Hit Save down at the bottom and save the driver. You don't need to edit anything in the other two tabs. Then close this window.
Step 6: Click New Project again, and scroll down the drop down menu and find your newly added speaker. Hit Next. Select how many drivers you'll be using. If you're modeling multiple subs in a common chamber enclosure or IB, select how many you'll be using. Otherwise, just use 1. Normal configuration. Click Next.
Step 7: Select box type you want to model. Based on the driver's parameters, whatever is shown here at first is the program's recommendation based on Efficiency Bandwidth Product. This isn't to say it can't work in other enclosure types, but if the little bar graph in the middle is pegged way at the top toward ported or way at the bottom toward closed/sealed and you were planning on doing the opposite, that should throw up a red flag that you're probably not using it in the best way. For the TM65 mkII, its specs lend itself a bit toward a ported enclosure, but it's in the middle of the spectrum enough that it should work fine sealed as well, which is how I figure most people will use it, so we'll go with closed for this demonstration. Click Next. For Alignment, as the program says, if you don't know exactly what you want here, just click Finish.
Step 8: At this point, you should have a graph of the Transfer Function Magnitude of the speaker in the optimum box size calculated by the program. You can see this by clicking the Box tab. For the TM65, this appears to be 0.665 cubic feet. And per the graph, in this enclosure, the woofer will be 3db down (purple line) right at 70Hz.
![Image]()
But now let's say you're like most people and want to use these in a door. Take some rough measurements of the length, width, and height of your door and find the volume. For my car, the door is around 2 cubic feet. You don't have to be real precise here because doors will be leaky and they're already a huge volume for a small 6.5" speaker. So you can change the box volume all you want to see how the anechoic response will change. This is also where you can find the total Q of the setup, Qtc. If you're after a certain target Q, say .707 or .5, you can adjust the volume to find this.
Step 9: Let's get a better idea of power handling, output potential, and low end performance. So far all we have is the shape of the response curve. Click over to the EQ/Filter tab and add a high pass filter. The TM65 is known to be good on the low end so I'm going to set a really low crossover for this demonstration - 40Hz/12dB. Hit Apply. Now click the second drop down menu at the top of the graph, scroll down to Cone Excursion, and click that. This will show you how much the cone will move with any given power at any given frequency. A red line depicts the driver's xmax. To find out how much power your speaker can take with a given crossover setting, go to the Signal tab of the driver window and use the top left box to apply higher amounts of power until the highest point on the cone excursion graph touches reaches the Xmax line. For the TM65, this looks like 145W. Note you can do this in a different order as well. Apply the amount of power your amp can put out and then use the cone excursion graph to find what high pass you need to keep the driver from exceeding xmax. Or like I just did, apply the crossover you intend to use and then use the cone excursion graph to find the max power it can take with that crossover.
![Image]()
Step 10. Now let's check output potential by selecting the SPL graph. This will show you the max anechoic output potential of the speaker with your power and crossover settings. Looks like about 106db at 1m in this case.
![Image]()
So there you have it. Use these steps to get an idea of how different speakers can perform. It is important to note that WinISD does not take cabin gain or power compression into account. These graphs will not tell you how the speaker is going to sound or how loud and low it's going to get in your car. I think it's best used as an apples to apples comparison of multiple drivers. I don't look at one speaker and think, "cool, I can cross the TM65 at 40Hz and it'll play 106dB in my car." I model multiple speakers and use it to compare. "Driver A will play 3dB louder than Driver B with the same amount of power" or "Driver A won't be any louder than Driver B but will be able to extend 20Hz lower."
![Image]()
So here's a couple of 6" drivers all modeled in a 2 cubic foot door with a 40Hz/12dB high pass and the amount of power applied to make it hit xmax. Without concentrating on the actual numbers since they'll be different in a car, I can see that the AE TD6H will be the loudest above 225Hz, the Exodus Anarchy will have the lowest extension, and that at 70Hz, the SI TM65 mkII will be 4dB louder than the B&C 6NDL38. I also see that the 6NDL38 can take the least amount of power of the 4 speakers due to the low crossover. Finally, I can tell that the TD6H and 6NDL38 start rolling off much earlier than the other 2 and would benefit from a ported enclosure. The program told me this when I was selecting box type - the little EBP graph was pegged at the top for both of these, indicating they should be used ported.
![Image]()
Now here's the same 4 drivers, same 2 cubic foot door, but now all have an 80Hz/24dB crossover and 150W applied. I can see that with the same input settings the 6NDL38 exceeds the output of all the other speakers at all points on the graph because of how sensitive it is. The Anarchy that looked arguably the best on the previous graph is now 3-4dB below most of the others because it's so inefficient. The overall shape of the graphs relative to each other is still the same.
These are some examples of how I'd use the program to compare speakers.
The other main use of this program is figuring out tuning for ported enclosures. If you select ported during project creation, the driver window will also have a Vents tab. With that and the Box tab, you can mess with tuning. Give it a box volume and port size/length, and it will give you tuning frequency. Or give it a volume and desired tuning, and it'll give you port size, etc.
Step 1: Download the program. I prefer the Pro Alpha version because it has more features. Get it here: LinearTeam
Step 2: Find the T/S specs of the woofer you want to model. For this demonstration I'll use the new Stereo Integrity TM65 mkII since it's one I haven't done before.
Re 3.2 ohms
Fs 69 Hz
Qes 0.90
Qms 3.0
Qts 0.69
Le 0.03 mH
Sd 136.9 cm^2
Vas 5.5 L
Mms 25 g
BL 6.2
Sensitivity (2.83v/1m) 88 db
Xmax 9 mm
Xmech 13 mm
Step 3: Open WinISD and click the New Project in the upper left. A small window will appear asking you to select a driver for the project. WinISD comes with the specs of a bunch of speakers, mostly pro audio stuff as you can see by scrolling through the list. But the TM65 is not there, so we'll add it by clicking New, just to the right of the drop down menu. This will bring up the Driver Editor screen. In the General tab, just add the name for it so you'll be able to find it in the list later.
Step 4: Select the Parameters tab. This is where you'll add the T/S parameters you found and where most people have issues with this program. The thing about T/S parameters is that they're not all just independent numbers. There are set mathematical equations that can be used to calculate certain parameters by using other parameters. WinISD has all these equations built in and must use them to calculate as many of the answers as it can, or it will give you errors and not let you save it. For example, Qts = Qes * Qms / (Qms + Qes). For the TM65 with Qes of 0.9 and Qms of 3.0, that means Qts = 0.692307 repeating. SI rounded it to 0.69 for display, but if you plug in 0.9, 3.0, AND 0.69, it will give you an error because 0.69 is not the completely correct answer to the equation. You must let the program do it by itself. The easiest way to make sure you don't screw something up is to hit Tab a couple times (i.e. more than once) after each number you type in (which will appear green) and see if any other numbers are automatically calculated (which will appear in blue). As you can see from this picture, the only values that I plugged in are Qes, Qms, Fs, Vas, Mms, Re, and Xmax. The program calculated everything else. (I also plugged in Le but it's not necessary for modeling low end response). So of the 13 parameters provided by SI, I only needed to add 7 of them and let it figure out the rest. Anything that still says 0.00 is not necessary for the modeling.
Step 5: Hit Save down at the bottom and save the driver. You don't need to edit anything in the other two tabs. Then close this window.
Step 6: Click New Project again, and scroll down the drop down menu and find your newly added speaker. Hit Next. Select how many drivers you'll be using. If you're modeling multiple subs in a common chamber enclosure or IB, select how many you'll be using. Otherwise, just use 1. Normal configuration. Click Next.
Step 7: Select box type you want to model. Based on the driver's parameters, whatever is shown here at first is the program's recommendation based on Efficiency Bandwidth Product. This isn't to say it can't work in other enclosure types, but if the little bar graph in the middle is pegged way at the top toward ported or way at the bottom toward closed/sealed and you were planning on doing the opposite, that should throw up a red flag that you're probably not using it in the best way. For the TM65 mkII, its specs lend itself a bit toward a ported enclosure, but it's in the middle of the spectrum enough that it should work fine sealed as well, which is how I figure most people will use it, so we'll go with closed for this demonstration. Click Next. For Alignment, as the program says, if you don't know exactly what you want here, just click Finish.
Step 8: At this point, you should have a graph of the Transfer Function Magnitude of the speaker in the optimum box size calculated by the program. You can see this by clicking the Box tab. For the TM65, this appears to be 0.665 cubic feet. And per the graph, in this enclosure, the woofer will be 3db down (purple line) right at 70Hz.
But now let's say you're like most people and want to use these in a door. Take some rough measurements of the length, width, and height of your door and find the volume. For my car, the door is around 2 cubic feet. You don't have to be real precise here because doors will be leaky and they're already a huge volume for a small 6.5" speaker. So you can change the box volume all you want to see how the anechoic response will change. This is also where you can find the total Q of the setup, Qtc. If you're after a certain target Q, say .707 or .5, you can adjust the volume to find this.
Step 9: Let's get a better idea of power handling, output potential, and low end performance. So far all we have is the shape of the response curve. Click over to the EQ/Filter tab and add a high pass filter. The TM65 is known to be good on the low end so I'm going to set a really low crossover for this demonstration - 40Hz/12dB. Hit Apply. Now click the second drop down menu at the top of the graph, scroll down to Cone Excursion, and click that. This will show you how much the cone will move with any given power at any given frequency. A red line depicts the driver's xmax. To find out how much power your speaker can take with a given crossover setting, go to the Signal tab of the driver window and use the top left box to apply higher amounts of power until the highest point on the cone excursion graph touches reaches the Xmax line. For the TM65, this looks like 145W. Note you can do this in a different order as well. Apply the amount of power your amp can put out and then use the cone excursion graph to find what high pass you need to keep the driver from exceeding xmax. Or like I just did, apply the crossover you intend to use and then use the cone excursion graph to find the max power it can take with that crossover.
Step 10. Now let's check output potential by selecting the SPL graph. This will show you the max anechoic output potential of the speaker with your power and crossover settings. Looks like about 106db at 1m in this case.
So there you have it. Use these steps to get an idea of how different speakers can perform. It is important to note that WinISD does not take cabin gain or power compression into account. These graphs will not tell you how the speaker is going to sound or how loud and low it's going to get in your car. I think it's best used as an apples to apples comparison of multiple drivers. I don't look at one speaker and think, "cool, I can cross the TM65 at 40Hz and it'll play 106dB in my car." I model multiple speakers and use it to compare. "Driver A will play 3dB louder than Driver B with the same amount of power" or "Driver A won't be any louder than Driver B but will be able to extend 20Hz lower."
So here's a couple of 6" drivers all modeled in a 2 cubic foot door with a 40Hz/12dB high pass and the amount of power applied to make it hit xmax. Without concentrating on the actual numbers since they'll be different in a car, I can see that the AE TD6H will be the loudest above 225Hz, the Exodus Anarchy will have the lowest extension, and that at 70Hz, the SI TM65 mkII will be 4dB louder than the B&C 6NDL38. I also see that the 6NDL38 can take the least amount of power of the 4 speakers due to the low crossover. Finally, I can tell that the TD6H and 6NDL38 start rolling off much earlier than the other 2 and would benefit from a ported enclosure. The program told me this when I was selecting box type - the little EBP graph was pegged at the top for both of these, indicating they should be used ported.
Now here's the same 4 drivers, same 2 cubic foot door, but now all have an 80Hz/24dB crossover and 150W applied. I can see that with the same input settings the 6NDL38 exceeds the output of all the other speakers at all points on the graph because of how sensitive it is. The Anarchy that looked arguably the best on the previous graph is now 3-4dB below most of the others because it's so inefficient. The overall shape of the graphs relative to each other is still the same.
These are some examples of how I'd use the program to compare speakers.
The other main use of this program is figuring out tuning for ported enclosures. If you select ported during project creation, the driver window will also have a Vents tab. With that and the Box tab, you can mess with tuning. Give it a box volume and port size/length, and it will give you tuning frequency. Or give it a volume and desired tuning, and it'll give you port size, etc.
