Help with custom 15" Alpine Box
 

Noob here LOL. I am trying to build a custom sub box to fit in my Jeep. I want it to have a square port, The total box size is supposed to be 18" high X 16" deep X 28" long. My 15" Alpine Type R 1542 is going to be installed into it. I would like the box and sub to be tuned at 34HZ. I followed these directions to get some of the info I needed from WIN ISD. Some of the measurements didn't seem to correspond with the suggested ported box size from the 1542 Alpine users manual and really had me confused. The users manual suggests 2.9ft3 for the box size and only 1.5 for the port opening (Alpine Manual shown in pic). Seems very small. Other forums suggested up to 4.0ft3 for the box.Click image for larger versionIn the pictures are the WIN ISD results from me following the youtube video. The WIN ISD results also show my sub peaking at 42HZ when I want it at 34HZ. Any help would be greatly appreciated. Thanks in advanceAttachment 17654

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Here are higher quality pics https://drive.google.com/folderview?...WM&usp=sharing

Btw will be putting around 1050 rms to the sub