Working on a box for my 12" alpha. Ported, 2.5 cubes~ tuned to 32 hz.
My question is when using winisd, i selected 2.5 cu ft, and i went and worked out my box sizing, and i put in 32 hz tuning frequency and i like the graph i see.
Now, i went to port sizing to see what i needed for this size box, and i obviously had to adjust it a bit 'cause the length of the port was deeper than the box by quite a bit. So i ended up with 2 ports @ 2.25x2.25 square shaped, and 8.8" long each, which brings my "vent mach" to .14 which should eliminate whistling.
NOW, should my volume from the beggining be less driver volume? or excluding driver? And also, should i use an estimated volume of the port (including just the actual port material, or the interior of the port too?) for the initial box volume, in order to get the correct tuning frequency.
W/ two ports 2.25x2.25 and an Alpha in 2.5cuft, you are going to get HORRIBLE port noise.
Second, The volume WINISD uses is your NET volume. So, less port and driver displacments.
Third, The port displacement will include the wood that makes up the port. For example: If you are building a box w/ a 12" internal height and a 2.25" wide slot port opening w/ 3/4" material and you port needs to be 12" long. (12"x2.25"x12" port) You will consider the port displacement to be 12"x3"x11.25".
So, you port displacement will be 0.234cuft.
Oh, And for that Alpha, try around 12-15sq inches of port per cuft.