my sealed box is too big

whgarrett1394whgarrett1394 Posts: 217
edited May 2013 in Custom Fabrication
A friend made me a nice enclosure for my subwoofer yesterday. Unfortunately it is about 1.25ft^3 too big

Can I use that expanding yellow foam you get at the hardware store to fill up extra volume?

Or would it be better to place a bunch of 2x4's in it?

Or another idea if anyone has one. Thanks.
Post edited by whgarrett1394 on

Comments

  • cnhcnh Posts: 13,310
    edited March 2013
    Get a sheet of insulation foam and cut it into a number of pieces to fill the space. Some of that Pink or Blue foam stuff they sell at Home Depot/Lowes (2" thickness). Stuff it in there till NOTHING can move!

    cnh
  • whgarrett1394whgarrett1394 Posts: 217
    edited March 2013
    Thank you for the reply cnh. The insulation foam doesn't act the same as polyfil does it? Won't it still let the waves through? Just asking cause polyfil is thought to help make a sub enclosure react as if it were bigger than it is. I thought i needed something dense that wouldn't "give". Thanks again.
  • cnhcnh Posts: 13,310
    edited March 2013
    I see what you mean. Should have read "more" carefully, you need some of that stuff Larry used T.F.66.

    Something like Black Hole? Take a look at their site

    http://www.blackhole-america.com/five.html

    There are some others as well. Do a search for the SDAs Larry, Toolfan66, modded!

    cnh
  • JstasJstas Posts: 13,451
    edited April 2013
    The foam will work but even if you let it expand and cut it back, it's still going to end up expanding.

    You can use the foam sheets that Constantine suggested too but...gonna be hard to get the in the speaker hole.

    I'd just use chunks of wood or MDF either glue or screwed or screwed and glued in to place.

    As far as stuff acting like polyfil, polyfil doesn't really take up space. It just slows down air flow like a fat lady stopping just inside the doors at WAL*MART. That's why it makes the box seem bigger than it is. The foam Constantine suggested is close cell foam and therefore, solid but lightweight. It'll work just fine. The hard part is securing it. Hence the reason I prefer MDF or just wood.
  • FaceFace Posts: 14,712
    edited April 2013
    Or just build a new box...
  • whgarrett1394whgarrett1394 Posts: 217
    edited April 2013
    Thanks for the advice. I am way too stubborn to get a new box. I filled each side with packing peanuts and sealed it off with Great Stuff. I will let it cure for 48 hours before i attempt to secure the subwoofer. I like the fact that it
    is large enough to mount both amplifiers and crossover to it.
  • whgarrett1394whgarrett1394 Posts: 217
    edited May 2013
    WOW....I am such a beginner when it comes to this stuff! I finally tested out the box. Sounds alright but there definitely needs to
    be some kind of gasket between the enclosure and the basket. I can hear air leaking.

    I also don't know what to do about the wood. Paint or carpet. Both just sound like more work then I care to do. May just keep it natural. Fuction before fashion for now.

    I bought the crossover today. Audiocontrol 2xs. It is fixed for 90hz @ 18db/octave. I will see how that sounds.
    I can get different modules from Audiocontrol if it is too low.

    Gotta figure out how to upload picks so I can show off my first stereo system.
  • jon sjon s Posts: 922
    edited May 2013
    Sealed cabinets are not that dependent on box size as compared to ported designs... Actually, a larger box size lowers the Qtc, i.e. gives you a tighter bass response. What size/brand of driver are you using? I can calculate the proper box size if the the T.S. parameters are available.

    Stuffing a box with polyfill or acoustic foam will actually lower the Qtc even more, so that might not be a good idea.
  • whgarrett1394whgarrett1394 Posts: 217
    edited May 2013
    Thanks Jon, :cheesygrin:

    The driver I am using is an MbQuart pwd304. The box was originally 3ft^3. It's probably around 1.25ft^3 now.

    I was worried that with all that volume I might easily over extend the driver, so I decided to fill the extra space.
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