Somthing wierd with WINISD

[mobeious 10+ year member]

Ok im designing a box for my 2 XXX 12's im going to do 2.25@32 per woofer since imma be throwin 2k to each woofer.... if i plot my box at 5.5 cubes with 82.5 sq of port 32hz my length is 31" on port but how im doin the box is subs up port back with the port from top of the box to the bottom and i was going to do a divider in the port so that gives me 2.25 and 41.25 sq on each side then my vent length goes to 42" ..... i know Fs of a box goes up and down with size of the box but i mean **** just adding a divider to separate the port added 10" to the port

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[helotaxi 5,000+ posts]

Yep. The relationship between port area, box volume and port length is not a linear one.

 

[mobeious 10+ year member]

so is it ok to stick with 31 on length or 42

 

[PowerNaudio 10+ year member]

you can stick with the 31" inches of port length, but then again your tuning is going to change to what ever that port length and enclosure volume is.

 

[helotaxi 5,000+ posts]

When you split the box you change the required length for a given tuning. It is the same reason that using 2 ports would require longer ports than a single port with the same area as the sum of the two.