View Full Version : how to calculate???

04-16-2006, 07:37 PM
i need a box that is 3.5 after diplacement my port has to be 50 sq inches in vent and 15.25 long and 29.4hz how do i calculate the length of pieces for the vent and the length to make the tuning proper???

04-17-2006, 11:21 AM
well, to make the "length of the tuning proper" it sounds like you already know. you just said 15.25" to get 29hz.

when making the port you measuer down the center of the port to get it's length. i don't know the dimensions of the port opening...to get 50sq". but if one port wall is the box wall, then you need to subtract 1/2 of the port's width from it's length. also need to keep the end of the port the width of the port away from the back of the box...or any other wall. (ex: 4" wide port needs to stay away 4" from the back of the box.)

once you figure out how much building materials are going to go into making the port walls, add the port volume, along with all materials, to get the total port volume and add this to the size of the box to compensate for port displacement...also add sub displacement.

it would help to know the dimensions of your box.

04-17-2006, 05:22 PM
It sounds to me like you're asking the wrong questions.