varying port diameter

[Alex JB 10+ year member]

Hi folks,

I was wondering if there is any rule of thumb or web site you'd recommend for understanding how a varying port diameter effects the tune of a port/box?

e.g. having a 4" port with a restriction down to 3" in it or the other way round, a 3" port with a 4" dia bulge in it.

Even understanding what would a 2 stage port diameter would do would help (4" dia for x lenght then 3" dia for y length)

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[Alex JB 10+ year member]

Basically I'm trying to consider how to lower the peak (seems around 40Hz) and increase the lower frequency response of my ported enclosure that I tried to tune to 32Hz.

I'm considering decreasing the CSA of the port to lower the tune and adding egg crate foam behind the subs and/or polly fill stuff to the rest of the space to mimic larger net volume.

 

[Alex JB 10+ year member]

no one?

put the egg crate foam in tonight, will see tomorow...