Internal dimensions:

15" d

34" w

10" h

Port:

10" h

3" w

30" l

Sub displacement .1 cuft

Subs up, port sideways

2.1cuft after sub and port displacement

Leaving .1 for 45s, so 2 cubes net

Tuning guesstimate: 33-34 Hz

Side note: I would like to figure out how to calculate neccesary port area by the parameters of the sub, not by the 12-16 square inches per

cuft rule, might use areos if someone has a suggestion.

Anyone? If my information is unclear, retarded, or you just have a question, let me know. I really want to do this box up right, so any and all input is appreciated.

aeros for a general rule of thumb is about 9-13 sq inches of port compared to 12-16 for slot ports.

your calculations are pretty spot on. 2.08 cubes of net volume tuned to ~32.84 hz with 14.42 sq inches of port per foot. i guessed that it was a slot port using 3 walls however. that would only effect it with about a 1 hz difference either way

Thanks for the reply, but indecisive me has a new box! (Still for the 2 SA-8s of course with the .1cuft displacement per sub)

3/4" MDF of course

Subs up, (double baffle on top), port back, (slot)

Dimensions:

Inner: ---------- Outer: ---------- Port:

33.5" w ---------- 35" w ---------- 9.75" h

9.75" h ---------- 12" h ---------- 3" w

14.5" d ---------- 16" d ---------- 36ish" l

The port will be "L" shaped and the first part of the "L" before the corner will be double-baffled.

1.74ish cubes after port and sub displacements, and probably about 1.6 cubes after 45s and bracing.

33ish Hz?

Edited April 17, 201015 yr by Don Ganso

i'm gettin 1.77 cubes @ 32.59 hz. one more tenth of bracing puts you at 1.67 cubes @ 33.55 hz

i'm gettin 1.77 cubes @ 32.59 hz. one more tenth of bracing puts you at 1.67 cubes @ 33.55 hz

Close enough for me as this is just a daily box and 1 Hz difference one way or another in tuning isn't going to be noticeable.

Thanks again, time to get out the power tools....

Side note: I would like to figure out how to calculate neccesary port area by the parameters of the sub, not by the 12-16 square inches per

cuft rule, might use areos if someone has a suggestion.

Minimum Port Diameter

To calculate the minimum diameter of the port required to prevent port noises, you will also need to know the following:

Xmax = maximum linear displacement (mm)

Dia = Effective diameter of driver (cm)

Np = number of ports

Calculate the minimum port diameter from the following equations:

Sd = pi*(Dia/100)^2/4

Vd = Sd*Xmax/1000

Dmin = 100*(20.3*(Vd^2/Fb)^0.25)/Np^.5

where,

Dmin = minimum port diameter (cm)

Note: You CAN use ports that have a smaller diameter than that given by the equation above, especially if the ports are flared at both ends. However, at higher volumes, you may notice some port noise caused by the air rushing through the ports.

The Subwoofer DIY Page - Port Calculations