solved

[PositiveCrew]

solved

[PositiveCrew]

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[Triticum Agricolam]

I'm not sure what you used to calculate your port tuning, but your ports are going to have to be a lot longer than 5" to tune to the low 30's. More like 24" long to get to 32 Hz, exactly how long will depend on how much net volume you have left.

[SkarredSierra]

youll be louder if u run ports back.

[PositiveCrew]

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[Triticum Agricolam]

It told me 10.4" for port length. Since I had to make two ports, I figured I would just divide that length in half and it would work out.

What program can I use to determine port tuning and everything?

My last box for a single 18" was built by a professional and was 37hz with 6" wide x 2" tall x 10" deep of port.

....

That's not how port tuning works. The right way to do it since you are using two ports is to divide your net volume is half and calculate what the tuning would be for that. So lets assume you have 13 cu ft of net airspace to work with and are going to use two 9" x 10" ports. So you would calculate what you need for 6.5 cu ft of space and one 90 sq in port.

The port calculator here works well enough: http://www.carstereo.com/help/Articles.cfm?id=31

How much power were you running to your last box? A 6" x 2" port for an 18" sub is ridiculously small, you basically had a sealed box. Your builder may have been "professional" in name, but its unlikely his was "professional" in results.

[PositiveCrew]

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[bassl0va]

Could go for a sealed box?

[Triticum Agricolam]

Yeah the more I look at it, the more I realize I was ripped off.

I asked for 120 square inches of port, and ended up getting 12 square inches (he calculated port displacement, not area). fml

Thank you for your help!

All of these calculators are showing like 20" - 30" of port depth.

Obviously with this box, once I go down 14.5" inches, I'm sitting right on that wedge that sits above the wheel well, which is an issue.

Should I scrap the entire idea, and just run 3 of the 15s? Or is there some way to get this all to work?

And if I need the net volume to calculate port length and such, is there an easy way to do it other than guessing? Because I need the port displacement in order to get net volume, but I need net volume to get port length, right?

Calculating port length while accounting for port displacement for net volume is definitely a tricky thing. You can do it through a lot of trial and error or you can use something like Torres box calculator. Torres isn't going to be able to account for the steps in your box to clear the wheel wells, but you could fudge the numbers a bit in Torres to come up with a port dimension that will work.

As far as just running 3 15's goes, it might be the right thing to do in your case. If you were really creative you might be able to make four 15"s fit somehow, but it will be tough. Since this is your first box it might be better to make things easier on yourself and drop back to three subs, which you should have plenty of room for.

[PositiveCrew]

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