So I'm building a box for a single 12, ported, that I'm having trouble figuring out what length to make the port. For those wondering I'm putting about 1200 w rms to the sub, its a HDC312.
Based on the instructions provided by Audioque they said to make the port length about 18" to give you 40hz if you use their formula of 16 sq inches per cu ft of box. So here's what I have to work with.
Box volume Gross: 2.98 cu ft
Displacement of sub: .15 cu ft
I used a couple of calculators but this one seems to be the nicer Car Audio - PORT Size Calculations and Formulas for WOOFER and Subwoofer BOXES
My problem is all of the calculators I use say to put in the volume of box. Do they mean Gross or Gross-sub or Gross-sub-port displacement? This all made a huge difference. I'm wanting to tune to 38 - 40 hz and based on these different possibilities I get crazy different numbers. Oh its a slot port 14 x 2.75.
Here's some of the stuff I came up with:
slot port 14 x 2.75
Using Gross volume: 38hz= 17.62 in
40hz= 15.26 in
Using Gross less sub: 38hz= 18.89 in
Using Gross less sub less port displacement:
38 = to long to possibly fit in my box
40hz= 23.25 in
Any help on this would be great. Thanks all again .... I wonder if I'll ever get this thing built lol