Hi all, I put this box together last summer, because I wanted something a little more 'custom' looking, and seeing that I never used my backseat- a fiberglass box in its place seemed the best bet. I posted this over on the termpro forums for some help too, and haven't had a whole lot of responses, so I figured I'd post on here since there seems to be a lot more fiberglass specific threads.
Here are some pics of its construction (I set them up as links to make it better for the 56k people):
My old box:
Mostly with the framework:
Framework done, ready for fabric:
With just the one layer of fleece:
After that, I added 2 more full layers of the chop matte fiberglass from the inside; and 1 more layer of chop matte on the outside to try and keep it from flexing. To me it seems pretty solid.
Then I wrapped it in my finishing cloth:
Finally a pic of it installed in the car:
Now to my questions; when I switched to this box, I lost about 3-4 dB on an older, portable Audiocontrol meter (the two readings were done almost a week apart, so I know there will be some variation anyway). Plus now it does seem overall just a tad less powerful (I also went from 2 batteries to just 1 between the two runs).
Obviously I made the port easily removable, and made a gasket for it to seal perfectly when screwed in, so I can vary port length. My actual questions:
1.) Is this box too big for these 12" Atomic ELE's?
2.) About what length port should I be running?
3.) Is my port too big? (I can pretty easily make a smaller cross sectional area port)
4.) Any suggestions or changes I should make to make it louder (I don't intend to compete in any organized events like dbdrag, but I do sometimes go to small local competitions)?
BTW- here are the sub's specs (well this is for the dual 2 ohm, I've got a dual 4; but the rest is the same):
Revc (ohms ) 1.80
Fo (Hz) 50.7
Sd (sqM) 0.055
Bl (TM) 20.06
SPLo (dB) 92.43
Xmax (mm) 10
Dvc (mm) 75
Qms (m.q.) 5.38
Qes (e.q.) 0.37
Qts (totQ) 0.35
Vas (liter) 32.4
Cms (uM-N) 75
Mms (gram) 130
General size for the box (since I have no way to calculate volume at all)- these are all outside measurements:
The box itself is about 48" wide, 24" deep, and 26" tall. The port is currently 6" wide and 13.5" tall; and can be a maximum of 13.75" deep before it hits the back wall.
I know if it were triangular (instead of the curvy front) it would be ~8 cu ft considering the port, but not taking into account the internal bracing or subs; but the box slopes back so much on the top sides, that it should be a good bit less than that, but I don't know for sure.
Any help is appreciated!