Jeffdachef 5,000+ posts
Gunz That Turn on Nunz
Quoted from quentin jarrel, owner of dss
"So basically the 12-16 port area thing is just a simple guideline, The real method is to find the minimum square inches of port area.
Thiele Small's formula
dv = 39.37 (fb x Vd)^1/2
dv= minimum port diameter of vent in inches
fb= box tuninf frequency in hertz
vd= cone displacement in cubic meters (one way xmax in meters times cone area(SD) in meters)
for one BL 15
xmax= .018 meters
sd= .081 meters^2
tuning= 32 hertz (per you)
dv= 39.37 (32 x .018 x .081) ^1/2 (^1/2 means square root)
dv= 39.37 (.046656)^1/2
dv= 39.37 (.216)
dv=8.5 inch diameter port per sub
dv=56.72 square inches
for two BL 15's you need (2)dv. So you need 113.44 square inches of port or more."
"So basically the 12-16 port area thing is just a simple guideline, The real method is to find the minimum square inches of port area.
Thiele Small's formula
dv = 39.37 (fb x Vd)^1/2
dv= minimum port diameter of vent in inches
fb= box tuninf frequency in hertz
vd= cone displacement in cubic meters (one way xmax in meters times cone area(SD) in meters)
for one BL 15
xmax= .018 meters
sd= .081 meters^2
tuning= 32 hertz (per you)
dv= 39.37 (32 x .018 x .081) ^1/2 (^1/2 means square root)
dv= 39.37 (.046656)^1/2
dv= 39.37 (.216)
dv=8.5 inch diameter port per sub
dv=56.72 square inches
for two BL 15's you need (2)dv. So you need 113.44 square inches of port or more."