Square Inches Of Port

[CleanSierra]

The calculator was shown to me by Bkolfo, whom I trust and is a knowledgeable guy. Its all based on stuff found I'm the Loudspeaker Cookbook. Small's formulas and such

He runs quite a bit of port as well I believe and has had good results. Isn't he also an AA dealer?

Edited December 2, 2013 by CleanSierra

[n8ball2013]

Im familiar with it all. What was used to determine too much port area was testing testing and testing without any swags. Thats how the rule of thumb came about. The loudspeaker cookbook has been around forever so its not ground breaking. Nor do people jgnore it. Theories can sometimes be flawed especially in a vehicle.

[CleanSierra]

N8, this is from pure curiosity on my part but I have a question. Is it with the higher powered systems where you've seen the too much port result in decreased output? Like 20K plus sub stage? Because I know that Real96SS got a little bump in output when he took a little port area out. But we are talking a lot 3 9Ks and 6 Team Fi subs in a 16V setup.

[g2shuck]

If it makes a difference I am hoping to clmap very close to 5k per sub after impedence rise. Wiring amps low lol.

[n8ball2013]

I hate saying this but its.all install dependent. I used to hang and know alot of hardcore spl guys. Like guys who had boxes stacked in their garage that they could pull out and show you the writing on the top of the specs and what score it did at what freq. Power didnt matter because they were overdriving their woofers anyways. Alot of street a b and c boxes that were done with one battery as well. Alot of ugly 2x4s in the ports extra baffles etc. They could range from a couple thousand watts to about 5k in most cases. Small time for us now but at that point it was big time. Alot of what theyd see was larger ports loss of cone control. Extremely peaky boxes and more woofers that went poof.

[Slinky]

I wish I was able to test this out without it being super expensive. I just don't see how the calculator is correct. I entered in 2 12's and 40 mm xmax with 38 hz tuning and its telling me a minimum of 166.54 sq in of port. There's no way 2 12's need that much port.

[CleanSierra]

I gotcha, thank you for the info I was definitely curious. So number chasing guys. They would have benefited from hugely peaked box at tuning I would think too I would think. But like you said, it would come at a cost.

[CleanSierra]

I wish I was able to test this out without it being super expensive. I just don't see how the calculator is correct. I entered in 2 12's and 40 mm xmax with 38 hz tuning and its telling me a minimum of 166.54 sq in of port. There's no way 2 12's need that much port.

40 MM of Xmax is seriously hefty.

And like N8 and myself said, you can surely get away with less in a vehicle cabin. Every vehicle is different and how much less depends on more factors than one.

And it's not super expensive to test. Build two or three boxes, that's just a couple sheets of wood for a couple of 12s.

Edited December 2, 2013 by CleanSierra

[n8ball2013]

Right the gsme was to peak your box at the same freq as your vehicles res freq.it.only had to play that one freq too. There.is no way I could ever consider anything over 20 sq in of port per cube for musical use. Even that scares me. My limit is really 17 to 18 for woofers that willplay music .

[g2shuck]

When I ran my two dc level 4 12a I had 72 square inches of port, and they sounded great and where no peaky. They have 23.5 mm of xmax. That calculator says they need 82.39 inches. So I was running roughly 15 percent less port area than that calculator says to and loved it. So if i do 250 square inches this time I will be about 17 percent less than the calculator. I think that will work out great on 5k clamped per sub with drivers side ported wall.