ported box help

[d2freak82 10+ year member]

First of all my sub calls for several different enclosures, 1 calls for 2 4" diameter ports, at 14" long, and tuned to 33hz, the other calls for 3 4" x 14" ports at 40hz, I'm not sure which to use for everday listening.

Second I've been beating my head against the wall trying to find, and figure out the conversion for round ports to square ports, thus far this is what I've figured out. for the 2 4" x 14" at 33hz, the face area would need to be 25.02in^2 and I'm guessing the port length stays the same at 28 inches total, that's my big question is does the port length remain the same?

Also, I punched in these numbers for the port on RE box calc, either it's off or I'm nuts... with the above idea holding the port length the same, I designed an enclosure with this in mind, and then made the box fit my subs box volume... it showed it pulling 22hz? WTF I'm so lost

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[bonesninja 5,000+ posts]

a slot port and a round port require diffent lengths for the same tuning

 

[d2freak82 10+ year member]

okay well my figures are coming from the 2 4" x 14" 33hz round port, where the surface area of one is 12.56 multiply 2 = 25.02

so I need to make my slot port face equal to that from what I understand, so my plan was to make it 16.67 (5/8 is close) x 1.5" is this correct?

and where do I go from there to find out the port length?

 

[d2freak82 10+ year member]

should I just find a tuning freq that I want and use winISD to determine the port length? and if so what is a good freq I've heard 37hz

 

[Cloak559 10+ year member]

Subs? Power? Vehicle?

 

[d2freak82 10+ year member]

the subs are 1999 hcca 15d, takes 4ft^3, port diam 4", length 14", in a 96 grand am?