Custom In-wall Sub

Discussion in 'DIY Corner - Tips & Techniques' started by annunaki, Jun 29, 2009.

  1. annunaki Moderator

    annunaki
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    So a very good friend of mine wanted "bass in his space" but would not have any sort of enclosure on the floor. He is not a "bass head" by any means but wanted a sub for movies & such.

    After checking out his unfinished room, we determined the location and measured out some dimensions. Seeing as though the maximum depth for the entire enclosure could not exceed 4-5/8", this was not going to be easy.

    Driver selection was somewhat difficult mainly for the fact that the mounting depth was so little. I looked into some flat woofer designs, but these never modeled up well for a home application with a system capable of reaching the mid to low 20's(hz) at a decent output level.

    Ultimately I decided on dual JL Audio 8W1v2's. They are a known entity in terms of being fairly linear and they have a very minimal mounting depth with no rear pole vent. This allows close proximity placement to the rear of the enclosure with no harsh effects.

    The subs modeled up best in a 2.6ft^3 enclosure tuned to 24hz. This allows a-3db point anechoic of about 22hz. In room response will be a good bit lower. The other great thing with these drivers is that they only need about 300 watts rms between the both of them to reach full xmax as well as staying within the recommended power input.

    To get the proper volume in a wall, this enclosure is (externally) 4-5/8" x 40" x 62" and will form part of the wall itself. It will also be isolated using a high density high resiliency rubber/foam.

    Here are some pics from early in the process:

    Main layout 40" x 62" footprint:
    [​IMG]

    Vent piece prior to installation:
    [​IMG]

    Round over on internal vent piece:
    [​IMG]

    Bracing Layout internal:
    [​IMG]
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  2. adwilk Audioholic Ninja

    adwilk
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    Thats freakin awesome, man. I cant wait to see it finished up and hear some results. Really nice work as usual.
  3. FNG212 Audioholic

    FNG212
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    +1

    I'm very interested to see how this turns out.
  4. pjoseph Full Audioholic

    pjoseph
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    Looks great, this is going to be a great project.
    Is that volume of 2.63ft^3 for both subs?
  5. annunaki Moderator

    annunaki
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    That is correct. It is net volume after displacement.
  6. annunaki Moderator

    annunaki
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    Here are some minor updates:

    Here is a picture of the soon to be front panel of the enclosure. I have a 1/2" piece of MDF that will sit flush with the drywall that the woofers & grille will mount to. This also includes part of the vent opening.

    [​IMG]

    Here is an internal view again, adding a few 1" pieces of mineral wool wrapped in grille cloth to help dampen some resonance within the enclosure. I have more yet to add though. One can also notice the area that will include the vent opening has been painted.

    [​IMG]
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  7. annunaki Moderator

    annunaki
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    More updates:

    All Mineral Wool pieces installed:
    [​IMG]

    Closer shot of dampening pieces:
    [​IMG]

    Front of enclosure attached:
    [​IMG]

    Side view of woofer with baffle attached to front panel of enclosure:
    [​IMG]
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  8. annunaki Moderator

    annunaki
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    These will be the final updates until I get over to his home to finish up. At that point, I will post some spec's etc.

    The enclosure ended up being rather heavy. My estimate is around 120lbs+.

    Here are a few pics of the last updated pictures I took.


    Masked Baffles ready for Primer:
    [​IMG]

    Masked Baffles with woofers in view:
    [​IMG]

    Primed baffle with foam isolation strips to 'float' drywall on the front and prevent rattles:
    [​IMG]
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  9. adk highlander pessimistic optimist

    adk highlander
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    Hey Annunaki,

    Any updates on this. Very cool project and amazing skills you've got there. Please post more pics of the final install and thoughts when you can.

    thanks.
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  10. annunaki Moderator

    annunaki
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    I am waiting on some pics from the installation. It looks wonderful in the wall now that it is finished.

    It is a slowly progressing project. I was hoping to have pictures by now too.
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  11. Guiria Senior Audioholic

    Guiria
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    Very interesting design, will you be using REW or anything to measure in room response?

    I've got space behind my bonus room walls to do something in-wall and I've often thought of doing something, maybe even an IB subwoofer but then I always end up thinking "What if it doesn't sound good there???" That is such a commitment, kudos to your friend for pulling the trigger and gettin' 'er done.

    One more question, did you do any in-room listening tests with a box subwoofer where the subs will be placed before building the subs into the wall?
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  12. STRONGBADF1 Audioholic Spartan

    STRONGBADF1
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    I missed this thread...Very cool, annunaki.:cool:
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  13. fredk Audioholic General

    fredk
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    I missed it first time around too. Agreed, its cool!
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  14. annunaki Moderator

    annunaki
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    I will most likely do it the old fashioned way, measure & plot. :) It really is not so bad as I have created an excel spread sheet that does most of the work for me. I just have to take measurements.

    As for listening for best placement, with no wall coverings and bares studs & joists, a listening test would not do so well. The acoustics of the room would change so greatly once everything was closed up that t would not be as anticipated anyway.

    I did ad a feedback destroyer so we can flatten the response at the listening location(s). We have not done any set up yet however as his room is still partially under construction.

    The sub is in the wall though and the walls finished.
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  15. Rickster71 Audioholic Spartan

    Rickster71
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    Hi annunaki, your project really interests me.
    I'd really like to see how it's integrated into the wall framing.
    Very nice job!
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  16. annunaki Moderator

    annunaki
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    Rick,

    When I get the photos, you will be able to see it. It was an interesting way to do it but it worked very well. It was a difficult integration in a way, because it had to become part of the wall, but not become part of the wall for isolation purposes. If you catch my drift.

    Hopefully my buddy will get me his pics shortly.

  17. annunaki Moderator

    annunaki
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    I FINALLY received some pics from the install process of this enclosure.

    Here they are:

    Mounting Area:
    [​IMG]

    Enclosure in the wall:
    [​IMG]

    One of the mounting tabs from the top:
    [​IMG]

    Mounted prior to mud:
    [​IMG]

    Enclosure mounted dry walled & mudded:
    [​IMG]
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  18. Highbar Senior Audioholic

    Highbar
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    Looks great. Can't wait to see final install pics and a review of how it sounds. A great solution to a problem many have. Good work.
  19. GO-NAD! Audioholic Ninja

    GO-NAD!
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    Love it!

    Boy, that looks great already. I should consider something like this for my living room 2.1 system. I'm sure my wife would love to get rid of the subwoofer I have in there right now. I'm good with my hands, but I have NO idea how to design a subwoofer...
  20. lsiberian Audioholic Overlord

    lsiberian
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    Just steal this design. :D

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