Eclipse Thiele/Small, difficult to find!

If you're entering parameters into a design program, Vd will be auto-calculated if you have some other parameters entered.  Try this:  in the blank driver editor box, enter the values Xmax and Sd.  You will see two calculated values appear:  Dd and Vd.

Here an example of a database I filled in the other day.  The values in green are entered by me, the values in blue were calculated by WinISD:  autocalc.jpg

If you're looking for volume displacement of the whole driver installed for the purpose of calculating airspace, the value Vd will not give you what you want.  In the example above, the actual displacement of the sub, front-mounted to a 3/4" baffle, was listed as .07 cu ft...where in the pic you can see that the value of Vd is only .045 ft^3.  This is something I do a lot of guesswork on;  comparing given displacements for several subs and making a call for a particular one I don't have info on.  And, if you are doubling the baffle face, the displacement would be less by the cu. inches of the extra cutout hole.

Yes, that may be why.  Here's what I found for the 9122.  It may not be 100% accurate but it should be close enough for modeling work.

Fs=27Hz; Qts=0.30; Re=3.8; Vas=90.6 liters; Xmax = 3.81 cm (one way); Sd=335 cm^2

That's a very suspect Qts parameter for a sub touted as being engineered for use in a small closed enclosure (https://www.cbrstereo.com/browseproducts/Eclipse-Titanium-Series-12--Subwoofer.HTML).  Here is a page from the Eclipse site:  https://www.eclipse-web.com/sw9100/sw9122.html

Looks like .30 is what it is, but I wonder how the coils were wired for that measurement.  Usually they're run in series, then measured, so set your program as 2 coils in series (just before you hit "save").  Also, change the Fs to 22 Hz as shown here.  You'll find that this change makes it easier to work with.

For a vented box, try 1.25 cu ft, tuned to 26 Hz with a 4" round PVC port 37" long.  And it will probably lower the power handling capacity to about 500 watts.  The port itself will probably take up about 0.3 cu ft displacement, and the driver looks to be about 1.2 or so...it's a big one.  If you double the baffle thickness, reduce the driver displacement by about 0.05 cu ft.  You'll only change it to 1.15 by doing that, so really, an actual displacement measurement might be in order for this.  Good luck if you try that!

That's what they say.  If the EBP is 68 as it shows with the Fs changed to 22 Hz, then that is a gray area that can go either way.  Personally, if it is correct (I'd still rather have an actual measurement of this sub) I would tend to work it up as ported.

Sealed doesn't look very good given what we have to work with, though.  But if you are intending on powering with 700 watts, then sealed is how you should go.  Look at a 0.9 cu ft box response and check the SPL chart.

Lots and lots of variables there.  What I did was, using the program: 

• Bring up several of the drivers already loaded into the database.  These drivers were entered at one time or another by the program's author, and I think just because he started the exhausting project, he resoved to come to some sort of a collection of drivers that he could rightly call a "database".  So, figuring he was punching in parameters from various sources for the ones he finally put together, you can assume that it's probable that some of them are in error.  And, you can assume that he didn't sit there and tweak the program to get results different than what the program figured on its own.

With that, know that some of what you bring up to look at might not be entirely accurate.  But in the long run after you've looked at many, you will see consistencies in the response curve with both sealed and ported enclosures.  Oh, and you should always click on the "Show parameters" tab when you bring them up.  The program will always seek the flattest possible response curve.  Going from that, you can know that it is desirable to have a flat response.

• You will see some that stick out as oddities.  High peaked response above the 0 line or box sizes way too big to be reasonable are cues that the woofer was poorly engineered.  Look at the parameters of all of these and you will start getting a feel for what looks odd.  If the program can't provide a decent-looking somewhat flat response with unlimited space for the enclosure, then there's something about the woofer you don't want to have any part of.  If it turns out to be a well-known sub or otherwise is important to you, check sources to find if the parameters were entered correctly.
• You will notice that the low end of a vented box drops off much more steeply than a sealed, but provides a higher power range to the lower frequencies.  From that, you can know that for SQ it is desirable to have a gently sloping curve rather than an abrupt nosedive.

Look at DYohn's published ported response on page two of the thread Can a ported design sound sealed? for a picture of a beautiful SQ curve, for vented.

•  With any sub there will be one response that looks the best with the amount of airspace that is available in the vehicle.  A response for SPL will peak in a band of frequencies from about 50 to 80 Hz.  An SQ vented response will extend to very low frequencies and drop off below audibility.

• A sealed response looks like it doesn't provide the deep bass of a ported, but the variable you have to assume is cabin gain.  This will provide a boost in frequencies normally around the area of 50 Hz, of a probable 6 dbs or even higher if you are building for that purpose.  You have to use your mind's eye to a degree to picture what it might look like if it were actually tested in the car itself.

When modeling for ported, I look for a reasonable box size and a reasonable port length.  If I can't get a port length that can fit into my imagined box without bending it twice or more, I'll look either to use a sealed for the sub or use a different sub altogether.  Once I establish my size boundaries, I'll play with the tuning frequency over and over, watching the port length, and watching what it does to the response curve.  I would want it to hit 40 Hz nice and loud (but not as loud as it hits at 80 Hz).  Then I would look to see that the slope curves down consistent with the majority of other ported boxes that I've looked at, and not drop precipitously downward.

For sealed, I want the same requirements as far as box size, and no more than +1 db peak over the 0 line.  The deeper bass in real life comes out at more power than the curve indicates.  But the one thing to look at, which I covered in the guide, is F3.  Look at where F3 is on all modeled subs.  I'm not happy with an F3 of 40 Hz because I wouldn't consider that "nice and loud".  Mid-30's or lower is better.

With all of them, there are limitations.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

You need to change your chart to make it more realistically useable.  You shouldn't be looking at -30 db.  Right-click on the chart, select properties, select Transfer Function Magnitude.  Change the start and end to -6 db and +6 db.  Or you could use -12 and +6 db.  No more than that is necessary.

Are you working on that Eclipse sub?  Check your database editor for parameter input.  Fs is 22 according to the Eclipse site I linked to on page 2.  Fs shouldn't read that high, it should come up at 55 Hz with the default sealed response for the .707 alignment.

That's why this sub looks so bad sealed.  But we have insufficient parameters to work with.  This is a case where hearing from the experienced re: that particular sub would do a world of good.