ported box slot vent

Port lengths you can choose from:                        

                         17" tuned to 47 Hz

These are based on your slot opening of 3 X 14.  If you looked at the VB graph I showed you in your last thread, at the top right it showed the Fb as 42 Hz.  That's the tuning frequency of the Kicker box that you're trying to duplicate, because I modeled it using the Kicker specs.  With your larger slot opening, the equivalent port length would be 22.5".  The extra port length takes away about .06 cu ft from your box net volume, which is negligible.

Here's a look at the response:  vb_response_kicker_cvr12d2.gif

Keep it at 2.25 in the program.  It is when you actually build the box that you add all the displacements into the total.  The program doesn't account for any displacements at all, but figures on net air volume alone.

When you work up your cut plan, you have to include the total volume of the port which includes not only the air but the walls that are used for it.  You'll also need to add for driver displacement and bracing you use.   Your gross volume should be the 2.63 cu ft you showed above plus the driver, port walls and bracing, which it looks like you didn't figure into it.  When you draw this out on paper it will be easier to calculate total port volume including walls.

Try to keep the volume error  within +/- 5% of the total 2.25 that you're shooting for.  That gives you about +/- 0.1 cu ft margin for error.

One wall of your port will be the box wall, so you don't count it as additional.  Just count the inner wall, which should be 3/4" MDF.  The total port displacement should be somewhat higher than what you posted...you might want to double-check that.  The driver is whatever Kicker says it is.  And you might want to add an MDF brace on the opposite side of the box from the port because you'll have an expanse there.

You might also look at modeling that up with the box you've been working on just to see what it would look like.  It would require all calculations over again.  But if you have the wood to work with, might as well start over, eh?

Isn't this your port dimensions and with a 22.5" length?