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View Full Version : Will this work?

Umbra
11-20-2013, 04:54 AM
I've got two Rockford Fosgate Punch He2s (12") in a shoddy sealed enclosure I was given. The spec sheet for the subs (http://www.crutchfield.com/S-BE0EgOJcXjh/p_575RFP3212/Rockford-Fosgate-Punch-HE2-RFP3212.html#details-tab) lists the ideal sealed volume at 1.25 cubes (each) and the box is apparently 1.64 cubes w/o sub displacement (I thought it was just under two, I just redid the math and I'm shocked).

Suffice to say I need a new box. I wanted to try ported, but now that I realize just how small the box is, a proper sized box should give me a dramatic increase anyway. I'll leave that as a fallback, but I digress.

I want to build a box for the trunk of a 02 Hyundai Elantra. The problem is it has an odd shape, so I've designed a hybrid box that's part wedge, part rectangle and I wanted some experienced opinions.

Here's the trunk, you can see what I've named "the cave" at the back:

http://31.media.tumblr.com/c6e7201d75184f086e95ccc145506085/tumblr_mwjzlz72Ok1r153evo1_500.jpg

and here's my design:

http://25.media.tumblr.com/7136e027440720d16acbf45badbc6124/tumblr_mwjzlz72Ok1r153evo2_500.png

That's the view from the left side. Imagine that sliding into place and spanning 38" across the middle of the trunk.

I try to make efficient use of the back of the trunk by filling up the cave with a wedge shape, but then continue forward with a box as tall as I can make it so I get my desired volume.

Each sub calls for an ideal 2 cubes each for ported. Here I've got 4.27, leaving room for roughly .14 for the displacement of the subs and a little for the aero ports I'd like to make out of PVC pipe using the heatgun method for flaring. By adjusting the depth of the "square" part of the box I can add or subtract a bit in case I need to stick some bracing in there or something.

Mainly I'd like to know if such a design would work, or if it fails do to acoustic principles beyond my comprehension. I'd also like the know what size aero ports I need and all the measurements that go with them because I know very little of them. I'd also like to know what would be a good frequency to tune to. It says 35hz at the bottom of the page I linked. From my understanding that's a good balance between SQ and SPL. When it comes to bass heavy music I listen to more Dubstep, DnB, EDM, etc. than rock or more traditional genres. So somewhere in the 32-35 range? Also bracing. I'll probably need some, but where and how?

Thanks for looking. Any help would be fantastic. After making this thread and realized just how small the box I have is I'm itching to fix it.

azimuth
11-20-2013, 11:26 AM
Not sure you have counted for enough displacement. Port area can't be too small even with aero ports. Aeros can go outside the box though, if necessary. Tuning depends on the sub more than an arbitrary tuning. Orion subs slam tuned at 40 hz ported. I like low tunings personally. That means longer ports though as a negative aspect in design. I've done ported subs in small, low tuned boxes. Elemental designs subs comes to mind. Diamond audio d6 12 did really well in 1.5 cubes at 33hz. It depends on alot of aspects

basswiigee
11-20-2013, 11:31 AM
yeah its seems like you are going to make it harder than it has too be and thats not a small trunk you should see my little cobalt trunk!!! lol and i slammed 4 12's in it sealed....

azimuth
11-20-2013, 12:56 PM
You're trying to make it easier than it needs to be to build a top notch ported system. You're the one that said how many SF your design was, and I'm saying that you'll have more displacement than your box design allows with ports, bracing and subs to still get 2 cubes per sub. I guess "any" help isn't appreciated. Maybe you should stick to sealed. Lol