Maybe Someone Can help Me

[chadpcb]

Here is my idea.

I am designing a ported box for my Dodge Dakota extened cab. The box is to hold 4 12" Kenwood Kfc-w3013. Don't ask why Kenwood I have always like Kenwood. It is a clam shell style box with the ports on top firing into the roof. The box is actually 2 boxes bolted together to form the clam shell. 2 12's on each side.

Now heres the issue.

Winisd says that for a 4cu.ft box I need a port of 14.5 x 2.75 by 21.09L with a vent mach of .08

Bass Box says for the same box I need a port 14.5 x 2.75 by 15..29 with a vent mach of .11

Which is right both have a box tuning freq of 31hz.

Here are the specs on the sub itself if this helps.

Z=4

RE=3.4

LE=1.65MH

SD=.051 SQ.M

BL=10.5 TM

VAS=83.7LITERS

MMS=183.0G

FS=25HZ

QMS 8.250

QES=.910

QTS=.820

XMAX=15.1MM

SENSITIVITY=85DB

FR=34-300

Any help to shed some light on this will be helpful and thank you in advanced.

[zx10intn]

if i remember correctly(havent used it in years), winisd doesnt take into account the volume lost by the port... that may be the discrepancy

[chadpcb]

I thought that might be the case but.....

Bass Box Pro accounts for displacement of the speakers and port.

Winisd figures the port base on the VB you enter, so to figure the extra displacement from subs and port you follow the following formula....

WP + BT x HP X LP / 1728 = (displacement of port) + SB + SB = (Total Displacemnt) + VB = Total VB

14.5 + .75 x 2.75 x 21.09 / 1728 = .51 + .072 + .072 = .654 + 4.0 = 4.654 Total VB

WP= Width of Port BT= Board Thickness HP= Hieght of Port LP Length of Port

SB= Sub Displacement VB= Volume of Box

I am not sure if I am over analizing this....... Could be me just being anal not sure......