The inside of my box is 11.75H x 20D x 37.5w

I will be using 3 4" Precision Port

I cant change anything because the box is almost done and its waiting for the subs to get here.

If someone could tell me how long the ports should be to tune to 32 thats what I need to know.

Thanks guys

Edited March 29, 201213 yr by rhconcepts

wow really guys, not even a recommendation for a online port calculator.

nice box

Here is a recommendation: more port area. You don't have enough. Carstereo.com for a tuning calculator.

Thanks I'll try it out..I have a build log here if you want to see more

So if I'm sitting at 5.09 - the subs .35 = 4.74 do I need to take out more for the space that the ports will use?

or do the calculators figure that out for ya?

And how good is http://www.psp-inc.com/tools.html ? like it because it shows what I need for ports with a flare.

For Aero ports that is the best calculator. For PSP I think you have to subtract for ports. But most others will automatically take them into account. If you're on a computer download Torres calculator.

Edited April 2, 201213 yr by Mathew

For Aero ports that is the best calculator. For PSP I think you have to subtract for ports. But most others will automatically take them into account. If you're on a computer download Torres calculator.

Ok thanks. I see now I wont get my 32 and thats fine. My car peaks at 45 so Im going to try tuning to 36 or so.

From the end of the port to the back wall how many inches are needed?

The site says you just need a gap. But rule of thumb is diameter distance so 4 in. You can get away with less but I wouldn't go much less IMO.

The site says you just need a gap. But rule of thumb is diameter distance so 4 in. You can get away with less but I wouldn't go much less IMO.

Sweet deal thanks, can you tell its my first bow with round ports lol.

Here are my ports uncut, I think they come 17" long

Yeah precision all come 17 with flares included. I just used my first one in a box.

Yeah precision all come 17 with flares included. I just used my first one in a box.

I don't care for the lip on the inside of them.

makes it easier to seal buy gluing around the lip to the box. I also used expanding foam but I prefer over kill.

Well its done and subs are in but I have a problem. The ports are uncut and the box should be tuned to 34 but peaks at 28hz. So I cut the ports to tune to 40 and now it peaks at 32hz. We think its from the back hatch acting like a port its self because its 4-5 inches from the box. So 32hz is good 40hz dips alot and peaks again at 50hz. The only thing I can do is make a new box with subs and port up but go with a slot this time. Maybe Ill do that just to have a music box.

This time, use more port area that wasn't enough.

This time, use more port area that wasn't enough.

I dont understand? that is what the calculator called for to tune at 34Hz. I can get two more 4" ports in the box and cap the center port. Do you think that will help?

I wasn't referring to length, but area. Seriously. The 8" mids I am working on a design for right now require a 4" aero. Obviously subs will take more if you want to keep the port velocity down.

I wasn't referring to length, but area. Seriously. The 8" mids I am working on a design for right now require a 4" aero. Obviously subs will take more if you want to keep the port velocity down.

Got ya,, Do you like I should try adding 2 more ports and cap 1 off? That would be 4 4" ports at 17-18 inches. Or should I start over?

Are these 12's? Sorry if I missed it.

I wasn't referring to length, but area. Seriously. The 8" mids I am working on a design for right now require a 4" aero. Obviously subs will take more if you want to keep the port velocity down.

Got ya,, Do you like I should try adding 2 more ports and cap 1 off? That would be 4 4" ports at 17-18 inches. Or should I start over?

Pretty hard to add ports since they take away from box volume....which perhaps you never accounted for either which would make that box rather small. Before starting over a review of what you have and what you plan would be in order.

Are these 12's? Sorry if I missed it.

Yes 12" BL

And I think after the ports Im sitting at 4.09 cu