bkolfo4

Well if you insist on using that box with the port and sub facing in different directions, my opinion is that is your best choice. If you blow the windows out of the camper, it is one cheap a$$ camper, so you need a nicer one anyway with a bunch of nice equipment in the back.

Hmmm. What voice coils, and what load on each amp? If you are running 4 ga from the amp and jumping to multiple coils/subs, it could make a difference. That could be up to 90 amps through the speaker wire. If you have each coil run back to the amp, no way. Even with 1 ohm coils all in parallel. 2000 watts at 1 ohm is only 45 amps. 8 ga would be more than enough, unless the amps are 20' from the subs.

With a 4th order, all the bass comes from the port. With a standard vented enclosure like you are asking about, the sound comes from the woofer and the port. With a 4th order, the port could be designed to open into the cab behind the seats, with the standard vented enclosure, the baffle needs to be a few inches back from the front of the bed so the full range of sound can make it into the cab.

Same ones that need 4 ga speaker wire to bring down the impedance rise

Unless you are burping or bass racing music, the BEST thing to do is not worry about it (PERIOD) Even when I competed, impedance did not factor into my box design. You design the box based on what you need from the subs. Then you select an amp that has enough power to do what you want it to. . .or take a chance and run at a lower impedance load than the amp is rated for.

Don't put 4 15's in that box unless the port can be external. . . You need at least 150 sqin of port, and really more like 200 sqin. Put 3 in there for now with 150 sqin of port.

What do you want to know? If you think you need more power, get a bigger amp or recone the sub as a Dual 1. Changing the box design may make a difference, may not. Depends on the actual design and what frequency you are burpIng at.

High Q. 1 cuft sealed with 12 oz of polyfill.

Dust cap will get warm with 800 watts. If it is getting REALLY hot or you smell glue melting, you are clipping that little 800 watt amp. The Q is rated 1500. Will it handle more? That will depend on the box design and type of material you are playing. My wife's car has a 12" Q on a Massive N2. Sealed box - been working great for a couple of years now.

Tuning freq needs to be a few Hz below the resonant freq, not the same.

Should be right there close.

Sorry - that was 100-120 per woofer

With SMDs, I would give up a little of the net volume to have more port area. 100-120 sqin would be what I would shoot for.

Never personally used the SP4, but I have talked to Scott about it. Should be a low end monster. Looking at the parameters, it should make a really nice home subwoofer. Large, low tuned cabinet with a 1000 watt plate amp would be killer!

Easiest way is to keep the same length and just change the width (cut down port area). As far as the tunings - 32-34 is great for music. SPL tuning will depend on the vehicle. SP4 is a great daily sub, but if you are going to compete a lot, BTL or Mayhem may be a better choice.

I am running the MTX shallow mounts. Have a pair on a AQ2200D at 1 ohm. I have abused the heck out of them and they are still going strong after 25,000 miles.

I misread too. 1 sub on 500 watts vs 2 subs on 500 watts - 2 subs will win unless you do something really stupid with the enclosure design.

It is actually .5" off because I forgot to factor in the .5" added by the thickness of the wood where it butts up against the other piece at the 90 degree turn. The way you have it drawn with the dimensions you listed, the port is only 4.5" wide. The pieces would need to be 15"/9.5", and 21.5"/16" for a 5" wide port that is 31" long. Why are you using .5"? You do understand the port can have a lot of pressure inside it just like the box. Round ports can be thin because they self brace by design.

The port in that drawing is only 25" long. Need another 6" to be 31" long (the port length is determined through the center of the port). Brian

Need more info. Is it 8 high x 5 wide, or 8 wide x 5 high? Is the port bending up/down, or left/right? Is the 12" dimension the inside or outside edge of the port? What are the external dimensions of the box?

Yes

I would go for 33-34 Hz. If he will not be competing, center the port between the two drivers.

The Fi IB3 is a great driver. I have 8 18's in my HT IB and it is the cleanest bass that I have ever experienced all the way down to 12 Hz (limited by the electronics).

If it is tuned at 40 and burpIng at 45, you are more than likely still in the spike above the tuning frequency. Your issue is that the burp may have a high impedance, but you may be ok at some frequencies with the lower tuning and playing music.