I'm planning on building a sub box to fit two Infinity Perfect 10.1 subwoofers under the strut tower brace. I am going to build just a normal box out of 3/4" MDF, then cut ends to fit flush with the brace from 1/2" MDF. I have never built a sub box before, but am very crafty with wood. My questions are these:

1) The subwoofers have 6" mounting depth. Does this include the excursion, or will the box need to be deeper?

2) Each subwoofer requires .75cu ft. How much space does each subwoofer itself take up?

3) How do I attach the sides to each other? Nails? Glue? Should I use silicon on the inside to fill cracks? Do I need to use fiberform?

4) What else do I need to know?


Thanks.

 

I would personally see if Infinity has a box design in the instructions or on their website and base my box on that. Your choice of 3/4" MDF is correct, as that will cut down on resonances and panel flex. I recommend that you either build a brace between the subs connecting to the back panel, or build a partition between the subs; that back panel will be fairly large and could possibly flex some. Any panel flex will cause a decrease in sub output.

1.) If the subs require 6" mounting depth, build for 6.5-7" to allow room for the pole vent (hole in the backside of the speaker used for cooling) to do its job.

2.) Enclosure volume: Some companies recommend a box size that already takes into account the displacement of the woofer. Others do not. My suggestion is to reverse engineer an Infinity design, using a formula like:

assuming 3/4" MDF:

(width - 1.5") + (height - 1.5") + (depth - 1.5") / 1728"

1728" = 1 cubic foot (12x12x12).
*The 1.5" subtracted is for two pieces of MDF.

3.) I have built a few sub boxes in my time, and I have found that doing simple butt joints with a high quality carpenter's glue (like the Elmer's stuff) or even liquid nails works very well. Glue it and screw it together with approx 1.5" screws. And don't forget to pre-drill and countersink the screws. MDF likes to crack.

4.) I highly recommend bracing the back wall of the enclosure, and it is probably best to separate the airspaces for each woofer to minimize interaction. Don't forget to take into account the lost airspace of the bracing. It is imperative that the box be completely airtight. This can be ensured by using caulk or some similar material around all the seams in the inside. Run a bead of caulk around the seams, then press it in with your finger. Do not caulk the woofers. it will most likely void your warranty. You may wish to seal the terminal cup though, those have been known to leak.

For carpet/vinyl, use something like that 3M super 88 adhesive. It's like contact cement but I have had good results with it.

If you prefer a little extra low bass extension, add a little bit (no more than like 10%) to the enclosure volume.

You may wish to put little blocks of wood around the edges inside the box and use those for a larger glue surface and for screws.

Hope this helps

 

exactly what I needed to know! Thanks a ton