I have a subs up port back box that was my first ever built box. it houses two SI ht-15's and dementions are 20.5" H x 49" W x 21" D. my port on each the right and left start out as 3"x19" along the back of the box then meet in the middle to combine into a 6"x19" port out the front no center divider down the center. I tuned the box as basically treating each side as it's own box with a 3"x19" port all the way. My question is when the two meet together in the middle to the 6" does this somehow change tunning? my tune should have been 30hz. but it seems more like 34?
Current setup: 2 Obsidian Audio 18's with 8 layer aluminum spl coils and spiders
Power is via 2 car audio bargain CAB-1600.1's strapped @1 ohm. ..also in my spare bag of goodies is...
2 Stereo Integrity HT-15's
1 Stereo Integrity HST-15
2005 Tahoe which I nicknamed the william hung.... because she bang! Haha!