How do you determine port area?

[Cutdeluxes1]

I have a Memphis 1ohm qvc mojo that im building about for. I tried researching this but can't find any true results. Read that depending on your cone area's size determines the size of your port area? How does this work? And with volume displacement? I want to make this sub slam like I know it can. Any advice appreciated.

[RickyFriery97]

General rule of thumb is like 12-15 square inches of port per cube, I usually like 15-18 though

[BJD3]

The rule of thumb you'll likely get around here is 12-16 sq.in. of port per cubic foot.

RAM_Designs posted a while back a formula for attaining port area based upon cone area. I used it to calculate a couple boxes (all for myself) and found it was right in the 12-16 sq.in. rule for most boxes. I promptly forgot it.

Which method is the "right" method? Dunno. Logically, I would think port area would be more driver reliant than box reliant. However, I can't argue with results, especially when I'm only relying upon what I've read online.

[Ray]

15 is average for beefier subs

Bigger ie: up in the 18-22sqin is gonna start getting peakier.

If you want a flatter resp than stick with 14-15 its plenty on vent

[Ray]

Then*

[ryan916]

Here's a pretty cool calculator.

http://www.carstereo.com/help/Articles.cfm?id=31

[Cutdeluxes1]

Thanks a lot for the info. Ray I still want the design for the two lms ultras I talked to you a while ago about. My paypal been acting funny. So I really need to get with you on that.

[BassMunky]

nice