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View Full Version : Ext. Cab Box Design: 2.5 cuft @ 34hz (2 12" Alpine Type R's)



SSS 18734
02-26-2009, 03:01 AM
Here is a design requested by kfx450r. The box turned out to be 2.65 cubic feet (per chamber) after all displacements, tuned to 35.3 hz. There are 72.5 cubic inches of port. I made this one pretty quickly, so anyone is welcome to chime in with improvements/comments.

Final Dimensions are:
W 50"
D 16"
T 18 1/4"

Start off by constructing the base, sides, back, double baffle, and the ports, in that order.
http://img25.imageshack.us/img25/310/95293983.jpg

http://img25.imageshack.us/img25/6807/56884543.jpg


You should make these double baffles before you put the port in. Sorry about the confusing order of these pics. Simply mark an "x" from corner to corner to get the center of the baffles. Make sure to get these cuts and the ports very precise. Also, "diameter" should read "radius."

http://img7.imageshack.us/img7/4852/92807811.jpg

Finally, make sure the box is nice and sealed, then attach the front.
http://img8.imageshack.us/img8/2410/37602062.jpg


If you use this, post a build log for me, please!
-SSS

Lakota
02-26-2009, 11:54 AM
Subs up, ports up?

Moe Lester
02-26-2009, 11:59 AM
Put a divider in the port. Also on assembly it would be easier to go Base > Back> Front/Ports > Top > Sides (front meaning the sides the subs are mounted to.) It is not fun squeezing a baffle between two pieces that are already attached. The tolerance may be tight, and your glue can get pushed or scraped away squeezing a piece in like that.

kfx450r
02-26-2009, 12:16 PM
Thanks alot for the box layout. As for the other posts, would it be better to face subs forward and port up? Or subs up port forward? Either way wouldnt make a diff to me. Im not TOO worried about glue getting squeezed or pushed away, I usually screw a box down real good then put some silicone/caulking around every joint and smooth it out for maximum air tightness.

da box king
02-26-2009, 12:21 PM
how much do you charge, or is it free :)

My box program is on my comp 100 miles away and I need a box design for 2 15" hdc3's

Moe Lester
02-26-2009, 12:21 PM
There is really no way to tell which firing direction will be best for you. The current design will work fine and if you are not planning on competing in all out SPL competitions i would not worry about it. The glue is what holds the box together, not the screws. However if you do assemble it in the order he has listed it will be much more of a pain piecing it together. If your cuts are straight and you lay a nice glue bead there is no need for caulking.

I still stress putting a divider between the ports. Alot of turbulence will be created at the intersection without one.

kfx450r
02-26-2009, 12:42 PM
There is really no way to tell which firing direction will be best for you. The current design will work fine and if you are not planning on competing in all out SPL competitions i would not worry about it. The glue is what holds the box together, not the screws. However if you do assemble it in the order he has listed it will be much more of a pain piecing it together. If your cuts are straight and you lay a nice glue bead there is no need for caulking.

I still stress putting a divider between the ports. Alot of turbulence will be created at the intersection without one.

What do you mean a divider between the ports? Like a sheet of MDF going down the middle of the port all the way making it 2 chambers? Or like a brace.

SSS 18734
02-26-2009, 01:55 PM
Okay, thanks for the tip Moe. I'll fix this when I get back from class.

I'm doing these for free when I have spare time. As long as people post their builds if they use my design, I'm happy! I'm trying to get better at sketchup :)

Lakota
02-26-2009, 02:41 PM
I would at least fire the subs forward. Firing the subs up is a good loss in my truck.

SSS 18734
02-26-2009, 03:58 PM
Here is a revision. After all displacements, this box will be:
2.43 cubic feet
34.3 hz
Ports are each (14.5" x 2.5") x 27.25" long, for a total port area of 72.5 square inches.

http://img187.imageshack.us/img187/8103/99812727.jpg

http://img21.imageshack.us/img21/5230/76087540.jpg

Moe Lester brings up a good point. You'll want to start by assembling the base, the back, and one of the sides. Then assemble the double baffles and the ports. Lastly, attach the front, followed up by the remaining side. Make sure your cuts, especially your baffles, port divider, and port walls are very precise, as this type of box is easier to mess up than others.

Lakota
02-26-2009, 04:15 PM
I've also had 2 Type R 12's in my truck. They did a 150.0 @ the headrest and 151.x in the kick :)

kfx450r
02-26-2009, 05:35 PM
Sweet thanks for the revision, even brought the tuning down a little which i was wanting but not enuff to have you revise the layout.

SSS 18734
02-26-2009, 09:03 PM
Yeah, I figured I might as well fix that since I was already redoing the ports.

Stitch
02-27-2009, 07:08 AM
mind me asking what program you are useing to draw?