ported/vented box for 2 kenwood kfc w3011

Yes, I did check with WINISD for the port diameter and length.  That is what it recommended for my box volume.  There will be 2 ports, and the vent mach is at .05 according to WINISD.  The only thing it did not recommend was the dimensions of the box itself, which I had to research and find how to manipulate.  Just to clarify, and please excuse me if I am being a little anal about this but, if I put 1" x 1" bracing inside the box, do I just put it along the length of the bottom dimensions of the box or both the top and bottom?  Also, if I go with the center brace, will this be a negligable volume displacement as well?  Should I do both, or is just one method ok?  If just one is ok, which is better?

Much appreciated.

If your design is with two ports, go ahead and put a solid center baffle in that box.  That will give good bracing stability in the most critical areas, and the ports will be distributed one to a woofer as appropriate.  And because of the box depth, the "stick" brace as DYohn suggested from side to side would also be important.  Measure the cubic inches of the baffles for displacement, but as DYohn suggested, the quantity is neglible.  There is no reason to have a common chamber box when two ports are incorporated, and the need for bracing is addressed with the common baffle wall.

You have plenty of room on a box of that width to place the ports away from boundaries.  They can be toward the outside or inside, either will do.

What's the tuning frequency?  About 35 Hz?  Re your earlier thread (***edit: topics merged***), I don't expect these subs to perform as you hope in a vented box.  I could be wrong, of course, so post a thread when you have it all hooked up and let us know how the performance is.

Edit:  I was doing some other things as I wrote this and missed your reply to DYohn's reply, but to answer about the bracing:  yes, it is critical to brace side to side in a box that size.  The brace should be from center to center, not along the bottom or top.  It is the center area of any baffle expanse that is most prone to flexing.  Here is an illustration I made a while back that shows the critical areas of a box that need to be stabilized (yellow areas):

In your case, using dual ports, I suggested a solid center baffle separating the two drivers/ports rather than what's illustrated here.  Center point bracing (as shown) is best, but just using an additional length of 1 X 1 wood along all edges is much better than using no bracing at all.

Stevdart, yes the tuning is at 35 Hz.  WINISD shows I should be able to hit a 35 Hz note pretty flat with these subs, so I am going to try it out.  Hey, if Solobarics are meant for sealed and sound good in a ported box, hopefully these will to.  It will be a little while before I build it, I got to wait until this semester at aschool is over (college.) 

Are you suggesting that I put a center brace with no holes in the middle?  I was going to do the "common chamber" because WINISD shows it will be more SPL this way instead of "seperate chambers."   I was going to use 2 ports because WINISD shows I will get less vent mach using 2 instead of 1, but the difference is only .04, so I might just use one instead.  But, how would I use the center bracing that way?  If I just use one port 6" Diameter, How would I brace the box then?  With the 1" x 1" along the edges?

Sorry, I wish I had more time, got to go to work.

• thanks.

I was thinking that I could use a 6" precision port tube and cut it to around 11" long and have a .09 vent mach.  Would I get much vent noise from this mach #?  Also I was thinking that I could use 2 of the center bracing boards with a 12" circle cut out of them on each side of the port, which would be in the middle.  How does that sound?  With 2 of these bracing boards in the middle, will the volume displacement still be negligable?

Have any of you tried the Precision Port Tubes from Parts Express?  Is there any difference between using them and regular PVC tubing from Home Depot for the port?  If there is not a big difference between them, then I will use PVC tubing for the port, but how would I mount that to the box...there is no flange.

Here is a link to the Precision Port Tube:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=268-352

Thanks.

Hello.  Stevdart, I have decided to take your advice on putting a center brace in my box to seperate the chambers, and port each chamber with a 4" x 10" port.  However, with my box being only 37.5" inches wide (maximum,) and the Precision Ports requiring about a 5.25" diameter hole for each port, this only leaves me with about 1" inch space between the driver and walls on the outside of the box.  The box is only 15.5" inches tall (maximum.)  Will this be ok because I keep reading how you should have a port's diameter away from any wall and the driver.  WinIsd suggests using this size port (It is the one that I can fit) to have an acceptable mach noise (.10).  If this will not work, then maybe I could face the woofers up, and put the ports facing the trunk.  How would that work?  Has anyone ever tried that?  How did it compare to the woofers facing the trunk?

Thanks!

Did you mean to say "between the port tube and wall..."?  I can't think of any reason this would cause an acoustical problem.  Just be sure you have 4 or 5 inches of free air extending straight out at port's end.

Well, I meant that between the port and driver, and between the port and side and bottom walls there will be about an inch of wood.  Also, yes, there will be about 8 inches between the inside port end and the back wall.  However, there will only be about an inch or so between the bottom and side of the box.  I am guessing by your response that this will work out for me.  Thanks for your help.

two 2" X 5" ports are completely different tuning than one 4" X 10" port.