I thought is would be a smart idea to post my project before starting to get a green light from the experienced people here at CarAudioForum.
I just got my 2012 Subaru WRX and I want to put my sub in the back. The Rex is a hatch with a lot of contour and curves on the side of the trunk area. I plan to make a fiber-glass and MDF box so I can utilize all of the space available in the trunk. There is not a lot of room when the back seats up so my old box isn't a good option.
Here is some background information about the build. I am putting in an Apline 10" Typr-R. I have a 3D model of the trunk interior to get my volume almost exact. I used foam boards to trace and cut the contour of the car interior at different locations. Then I took photos, imported them into my 3D modeling program, scaled them, and traced them.
Here are the details and numbers:
-The fixed dimensions of the box are ~13" tall and ~28" wide. The depth is my only variable. I want a ported box with as little depth as possible (so as little volume, but still the correct amount). Alpine recommends a box volume of 1.1 cu.ft.
-I want to achieve a ported enclosure tuned to ~35hz. I can fudge the frequency a bit and I am open to recommendations, 35hz sounded like a good number to shoot for.
-I've never used a round port before, but I understand that they are more prone to whistling/chuff noise. I decided to shoot for a 4" Diameter port with flared ends.
-I used an free-online calculator at AJdesigner (Link HERE
) to find the recommended volume and port length. Here are the numbers it gave me:
Volume (base on the sub's Qts=0.53 and Vas=21L) = 1.83cu.ft
Port Length (single 4" port, end correction of 0.5) = 13.12"
So here are a few questions I have about the build:
1)Alpine manual recommends a vent enclosure volume of 1.1 cu.ft, but the AJdesigner calculator recommends 1.83 cu.ft. What should I use? The 1.83 box extends about 12" into my main trunk space, 1.25 extends about 8", and 1.1 extends 7"
2)Will a single 4" flared port work okay for my this build? Do I need to go larger diameter and/or more ports?
3)Can you have a turn in a round port (similar to how a square vent makes a 90deg turn at the back of the box). Is this okay to do?
I really appreciate the help!