port area question

[broosky333]

when building a ported box....how do you calculate the ideal port area for each sub...cause i've heard ported enclosers that sound like sh*t and then i have heard some that are superb. i was just wondering if there was an easy way besides asking the manufacterers to figure the port area..........

[Chris from MI]

All depends on what type of port you are doing and what frequency you want the box tuned to. It will depend on what sub you are running and what results you are looking to get when deciding on a frequency. If you go to this site http://www.bcae1.com/ and option number 110 is enclosure calculations. It has a calculator that will figure it out for ya.

[Ranger SVO]

I just wanna add one thing. Because at port tuning frequency, the port makes almost all of the sound, I always recommend larger is better, to a point. Always try to put a port in that will keep vent velocity to a minimum. I like to use WINISD to get me there. If a single 4-inch port will work, then in my opinion 2 3-inch ports have slightly more area and will perform better.

Just my 2 cents worth

[JeremyC]

http://www.linearteam.dk/default.aspx?pageid=winisd

Here is a link were you can download WinISD, or WinISD Pro.

[geolemon]

when building a ported box....how do you calculate the ideal port area for each sub...cause i've heard ported encloserethat shound like sh*t and then i have heard some that are superb. i was just wondering if there was an easy way besides acting the manufacterers to figure the port area..........

Whoa!
Two issues here!

I hope you aren't for some reason believing that port opening area has to do with the sound quality of a vented enclosure?
Port area won't affect sound quality until you get to a point where your port is so insufficiently small, that it begins making huffing or chuffing noises...

...there ARE a great many things that affect sound quality in a vented box, and surely that would contribute negatively - but funny port howling noises due to insufficient port opening area I'd list near the bottom of "things you are likely to encounter".

The #1 culprit: the design of the vented enclosure - including the designer not tuning the box to the customer's taste and expectations, the designer not taking cabin gain into account, or the designer not taking into account internal displacements like sub displacement, port displacement, or bracing displacement.

The #2 culprit: The design of the subwoofer. Does your box designer know what subs are fundamentally compatible with vented enclosures? Or did he just "Design up a box" given some specs that came with the sub?
Looking at Qts and/or EBP is key, in deciding on a sub that'll work in a vented box.

The #3 culprit: The construction of the enclosure. I've seen flexy boxes, I've seen leaky boxes, I've seen boxes with the port jammed up against the side of the trunk, or a hockey bag and enough dirty laundry to live on in a month stuffed into the trunk on top of hte sub... I've seen boxes that've gotten wet... I've seen a lot. It all boils down to "did you build this box to realistically work in that trunk, given what else is going to be going on in that trunk?"

Bottom line is -
If you are worried about the SQ of a vented box - address THAT.
If you are worried about port opening area (maybe for maximum SPL?), address THAT.

But to me, it sounded like you were correlating one to the other...

[GlassWolf]

http://www.bcae1.com
right menu
find section called "basic enclosure calculators" and scroll down past the sealed portion to the ported portion of the page.
That tells you everything for figuring port area.