Porting for a BL12

[chris4490 0]

I got an email from nick at Fi today saying "Personally I do not think that you have enough vent area for a single 12 with 2 2.5" ports. Typically we run 2 3" aeroports on a 12" sub and it works fine." Now I have a fiberglass box that has pre-molded 2.5 inch ports that have flares on both ends for easy breathing. now, theres are adjustable with addition of pvc piping. Will there be problems with the sub if I use the 2.5 inch pvc and just extend it a little for breathing purposes?

Thanks for your help guys, I'm electronically savy, just not to specifications like porting and such.

Chris

[KU40 173]

Yikes, that's only 10 square inches! I don't doubt you'll get port noise with that. Unfortunately what you suggest, extending the ports, will not help the matter. You simply need more port area. Is there any way to add another port hole or two, or else simply expand the holes already in there to fit a larger diameter port in each?

[chris4490 0]

How about this?

I take the box and add 3 inch ports as suggested through the bottom where it is wood and not fiberglass? It is on stilts and would have air to breath.

Heres the basic set up before I have completely installed it (I just built the board to hold the amps today.)

Im going to add 1 inch risers ontop of the 2x4s already raising it.

These were my initial ports, 1 on each side. I sealed them because I thought the JL sounded better sealed.

Heres the bottom where I would add the 3 inch ports. How many do I need?

I think Nick recommended something like this- http://www.parts-express.com/pe/showdetl.cfm?Partnumber=268-350

Instead of going with multiple ports should I go with one larger size than a 3 inch?

Thanks again,

Chris

[chris4490 0]

I forgot. I did the math and it comes out to be roughly 1.9 cubic feet.

[Duran 387]

I forgot. I did the math and it comes out to be roughly 1.9 cubic feet.

I would use 22-30^in of port area.

[chris4490 0]

That would be a 3 inch port about 4 inches long correct? {(pi)*1.5^2=28.3in^3}

[chris4490 0]

Im sorry. theres supposed to be a multiply by 4 in there as well and that puts out 28.3

[Duran 387]

That would be a 3 inch port about 4 inches long correct? {(pi)*1.5^2=28.3in^3}

9.42^2 in.

[chris4490 0]

Excuse my illiterateness but does that mean 2 3inch ports at 9.42 inches?

[tripslipfall 0]

How about this?

I take the box and add 3 inch ports as suggested through the bottom where it is wood and not fiberglass? It is on stilts and would have air to breath.

Heres the basic set up before I have completely installed it (I just built the board to hold the amps today.)

Im going to add 1 inch risers ontop of the 2x4s already raising it.

These were my initial ports, 1 on each side. I sealed them because I thought the JL sounded better sealed.

Heres the bottom where I would add the 3 inch ports. How many do I need?

I think Nick recommended something like this- http://www.parts-express.com/pe/showdetl.cfm?Partnumber=268-350

Instead of going with multiple ports should I go with one larger size than a 3 inch?

Thanks again,

Chris

What kind of tuning are you trying to get?

Edited June 28, 2009 by TRiPP3R

[Duran 387]

Excuse my illiterateness but does that mean 2 3inch ports at 9.42 inches?

No that means 9.42 square inches of port area.

[chris4490 0]

The inside is about 1.9 cubic feet and im trying to get around the recomended 32Hz.