Linearteam WinISD Pro

Entering your own drivers

If you want to create your own drivers, open the New Project window (CTRL-N is a shortcut), click on the "New" button next to the down arrow of the drop down on the New Project window. This opens up the Driver Editor window:

Again, driver editor is split into several tabs, which we will discuss now. Let's begin with first "General"-Tab.

Most of the parameters in "General"-tab are self-explanatory, but perhaps short explanation is in place anyway.

• Manufacturer is the name of the company who actually made the physical driver, e.g. name of the OEM factory.
• Brand is the marketing name of the driver.
• Model is type marking on the driver.
• Data provided by field is by default filled by user name.
• For comment field, you can enter your own findings about particular driver.

At bottom of the driver editor window, there is a "Auto calculate unknowns" option. As you'll later notice, it is very great help when entering parameters. In fact, it is recommended that you enter as few parameters as possible, because then Driver editor will ensure, that your data is in perfect accordance with Thiele/Small-model.

In Parameters tab, you enter the Thiele/Small Parameters of the driver that you wish to add to your database. If you wish to change the mathematical units in which your parameters are given in, simply click on the unit and WinISD will toggle through the available units and make the conversion for you. For instance, if you put a speaker diameter of 8.0 in., and you'd rather have that value in cm, mm, etc., simply click on the value (in. in this case), and watch as WinISD converts it over for you. The area and distance systems are used for Ports and 1w/1m (SPL) measurements.

All of the drivers that you create are automatically saved in the \drivers subdirectory (folder) of your \WinISD directory (folder) and, as such, will not be deleted or overwritten when you update the WinISD database from the WinISD home page. The driver name that you provide will be the actual name of the file in the \drivers directory, so don't include any \'s or anything else in the driver name that would be illegal as a Windows file name.

The bare minimum information that must be entered is the last three fields of first subsection (Qts, Vas, and Fs). Note that you won't get anything else but minimum set of graphs with these three parameters, so be sure to enter all relevant parameters. As you enter the parameters, driver editor will continuously check if new parameters can be calculated from parameters, which you have so far entered.

Parameter status is indicated by different colors. Green means user entered parameter, Blue means calculated parameter. Black means not entered nor calculated parameter. You can change entered parameters anytime, and the editor will re-calculate all calculated parameters all over again.

Important note for 0.50a7 and above:
The driver editor won't accept erraneous entries anymore. Your data must be perfect (i.e. not over-defined by entering "too much" parameters), for you to be able to save it. If you try to enter too many of them, editor will display an error dialog when you try to save the data.

In above tab, you can enter dimensional information of your driver. It shows then approximate displacement volume DVol. It is probably most accurate that can be obtained using just these dimensions. Most evident neglected volume is the driver frame. On the right, there is illustration for what most dimensions mean. Only one which is not illustrated, is the voice coil diameter, VCd. See also Thiele/Small-parameters section in articles.

The suggested procedure for entering driver parameters is following (check first that "Auto calculate unknowns" option is checked):

1. Enter Mms and Cms

This gives fs. If either is not available, then enter fs and other parameter.

2. Enter Sd, Bl and Re

Now, you should get all but Qms (and Qts), Vas. Please note that Vas may not match exactly what is specified by manufacturer, because exact value of Vas depends on environmental parameters. See FAQ.

3. Enter Rms or Qms.

Either one will do, although I tend to prefer Qms over Rms, because it can usually be measured in driver measurement procedures.

4. Enter Hc, Hg and Pe.

If Hc or Hg or either is available, then enter Xmax and optionally either Hc or Hg if available.

5. Enter number of voicecoils.

This procedure is most accurate. Also note that it also calculates true SPL (1W/1m) value. So it might not match the marketing SPL value, which is generally somewhat vague. Not in all cases, though.

6. Correct Znom, if necessary.

If there are several voicecoils, then you must be careful when entering parameters in that case, because many manufacturers give Bl in voice coils in series, because it yields double value for Bl against parallel connection. If driver manufacturer gives Qes, Bl and Cms or Mms, then you can check how Bl is specified. For that, you can enter following parameters to calculate Re: Qes, Fs, Mms or Cms and Bl. Connection mode can be changed by changing the combobox selection. The driver editor then converts Bl and Re values accordingly.

Equivalently, you can check for Bl by entering:

Qes, Fs, Mms or Cms and Re (for desired connection mode).

If you enter resistance for parallel connection and get about half of advertised Bl, then you know, that Bl was specified that way.

Like in Driver-tab in project window, you'll probably noticed the driver icon in bottom of the driver editor window. you can drag the driver object into some project by just dragging the icon.

Worked example of entering driver data into program

For example, Let's enter a entry for Scan-Speak 21W/8555-00 driver, which has following specs:

So what specs should be entered?
Based on guidelines given above, let's enter fs, Mms, Qms, Re, Bl, Sd, Le, Xmax and Pe. If you have incorrect unit displayed, just click on it until it matches with driver data units. As you enter the values, note how driver editor continuously calculates missing fields.
After entering those specs as suggested above, we obtain following entries in editor window:

As you can see, we got ourselves some of the specs what weren't even specified by the manufacturer. Calculated SPL 1w/1m spec matches also quite well, which is not the case with some of the brands. If you compare calculated Vas against manufacturer's spec, you'll notice that it matches quite well. So we can be quite confident that our data is reasonably correct.

When you have entered all the specs, you can check the "Advanced parameters"-tab, and see some statistics of your entered driver (calculated from the parameters we just entered):

There, we can see, that this driver is definitely not suitable for horizontal mounting, Gloss is almost 10 percent! Also, using single woofer like this doesn't certainly be an SPL subwoofer, maximum predicted closed box SPL at 20 Hz at maximum excursion is only 83.7 dB. You can also see the air properties, which WinISD used when it calculated missing fields.

Finally, you can click "Save"-button to save the entered data. Driver editor suggests a filename for our driver.

This page originally written by JJ Richard (JJRichard@linearteam.org) and revised by Janne Ahonen (janne@linearteam.org)