AJ Subwoofer Vent Equations and Formulas Calculator

Home Theater Sound Systems - Car Audio

Subwoofer Box Comparison Calculator:
Compare bandpass, sealed and vented frequency output graphs
for a subwoofer in one program.

Solving For Length of Vent or Port

subwoofer vent port length


diameter of vent (Dv)
number of ports (Np)
volume of box (Vb)
frequency of box (fb)
end correction factor (k)


diameter of vent (Dv)
= 0
= 0
number of ports (Np)
= 0
= 0
volume of box (Vb)
= 0
= 0
frequency of box (fb)
= 0
= 0
end correction factor (k)
= 0
= 0


vent length (Lv)

Other Units:

Change Equation
Select an equation to solve for a different unknown

Subwoofer Box and Speaker Enclosure
vent or port length vent or port length
minimum vent or port diameter minimum vent or port diameter

k values:
vent has one free end and one flanged  =  0.732
vent has two free ends  =  0.614
vent has two flanged ends  =  0.850

Lv  =  length of port or vent
Dv  =  diameter of port or vent
Dmin  =  minimum diameter of port or vent
Np  =  number of ports or vents
Vb  =  volume of box
fb or Fb  =  tuning frequency
k  =  end correction factor
Sd  =  surface area of subwoofer
Vd  =  driver displacement volume
Xmax  =  maximum linear displacement of driver

References - Books:

See 6 on reference page

Popular Pages:

Site Links:

by Jimmy Raymond

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