I am going to build an enclosure for my 2 Havoc 18's in my 07 mazda cx-7. Each will be run off an saz-1500d, probably strapped. I have a few questions, as I suck at ported boxes.

I have calculated total gross of 12.34 cu ft. I assume this is enough for 2 Havoc 18's?

I actually want to do a "convertable" box. I want to run sealed for daily, and have a port package to run for spl. I am thinking to run with aeroports, as these will work in my mind to be easily removable. Suggestions or ideas?

I want to tune relatively low(in the 20's to 30's) for the ported part of the build. Suggestions or ideas?

Can I use a TL on my setup right now to find my resonant freq and tune the new build accordingly, or does the resonant freq change when my build changes?

Right now, I am running a single Havoc 18 sealed @ 5.69 gross~ approx 4 net. I have major flexing, but doesnt hit a meter worth a crap. Hit 139.7 legal last year. I am hoping to get a ~10db gain by going with this build, am I being unrealistic? If I posted in the wrong forum, feel free to move it, I posted here to hear from the wonderful, amazingly intelligent folks at FI/Ascendant. My main questions are with the build itself, I know a db gain is hard to estimate, but I figured approx 6db for doubling power and woofers, and another 4 for porting... or am I all screwed up?

Thanks,

Rob

Edited June 27, 200817 yr by cx-7heaven

This is the shape I need to use due to space restrictions. I do NOT want to fire the subs into the glass. Any ideas?

why do you not want it firing into the glass

You see the box in my sig? My hatch flexes a lot anyway, for fun I had turned the box to fire back, and I thought it was going to shake the hatch apart! That was with 1 18 on 1500 sealed....... what do you think 2 18's on 3k ported will do?

Have you thought about walling it?

As far as the box idea I have, it has changed a bit. That sketch will be my sealed box, and then I will build a removable extension that will be bolted to it and carry the subs and ports. What I am really looking for is a size in cu ft and port area/size whatever. I have no clue as to tuning a ported box, so if someone happens to have a good box building program out there to run the numbers with, that would be awesome. With my new plan, I can probably go as high as 20 cubes if I have to, so cu ft wont be a problem anymore( for the ported build)