Getting a box built

[mazzasec 0]

Well I got a design for the box I want and I am having a shop build it today. This is it.

17"H x 42"W x 24"D, 8.174^3ft gross vol. Slot port, 15.5" x 5" x 15.92"Long@37Hz. After all displacement, 7.048^3ft net

What do I need to change the port to too get a tuning of 35hz?

[shizzzon 461]

Well... since you are typing in specifics all the way down to a 1\1000th of an inch, to reach 37hz tuning, the length should be 15.460", not 15.920".

So, to retain that port area and tune down to 35hz, the length(including the width of the baffle it exits out of) needs to be - 17.990", or just make it 18" long. Subtract the thickness of the baffle from 18" to find the length of the port itself.

However.... in slotted ports, the entrance of the port is NOT where the active length starts at.

Usually, you would take the internal width of the slot, divide in half then add that to the length of the port to determine it's beginning active length.

So.... if your slot port is 5" wide, then 2.5" before the entrance actually acts as part of the port IF AND ONLY IF one of the walls of the slot port is the wall to the box itself.