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  1. #1
    Join Date
    Jul 2008
    Location
    Kerr Lake, VA via Durham, NC
    Posts
    67

    Default Sub Box Question

    I am looking for pictures of a sub box that does not disrupt the kick panel/foot rest under the help. My dad is a huge fan of the diagonal foot rest and in order for me to put the sub in the boat, he won't let me take away that space. I am putting a 12" JL W6v2 that requires a 1.25 sqft sealed box. I have searched the forums for other pictures but really only found set ups using a faux wall and eliminating the foot rest all together. Has anyone seen this done or have pictures?
    Joey

    2007 LSV
    Gravity III w/ 750's and IBS, Acme 1433
    WS-420SQ, Kicker KM6500.2, JL e4300, JL 12w6v2, JL e1400D, Polk db651s, JL JX360/4

  2. #2
    Join Date
    Oct 2010
    Location
    Lake Wylie NC Area
    Posts
    772

    Default

    JPG,

    I do not have any specific pics of an LSV sub enclosure with the root rest left intact, but here is something that I find to be helpful. First determine what the max outside dimension of an enclosure can be in order to fit in the space you want. Then mock up a box out of cardboard for a test fit. Not only looking for how the enclosure will rest in its final spot, but will you be able to drop the completed enclosure under the helm and into its final resting place. You want to make sure the enclosure will fit past the seat and seat base, steering wheel, steering cable rack, etc. Better to know ahead of time while working with a cardboard box what needs to be removed or modified for the completed project to fit.

    Once you have the outside dimensions and basic shape, you can now determine what the gross internal volume is going to be. If you box is going to be a simple rectangle of wedge, there a a few good online calculators that will allow you to just plug in your height, length and width x material thickness (I recommend .75"). Hopefully, the gross internal will be more then you need and you can adjust down the dimensions to reach your target net internal volume. Dont forget to take the driver's displacement into account. Depending on the weight of the sub and the overall power you intend to drive it with, you may want to consider doubling the baffle board. Also, internal wall bracing and a support cradle need to also be factored in if needed.

  3. #3
    Join Date
    Jun 2008
    Location
    De Pere WI
    Posts
    4,164

    Default

    I used that exact sub in my supra 20ssv. probably very similar in the design and room under the helm. I didn't think there was enough room under there to do a proper sub box and keep the hump.

    fwiw, after eliminating the hump, there's quite a bit of room to push a box further back. I didn't even miss the few inches of room that it ate up and you can still use the sub box as a footrest. build an angled box under there and use a heavy duty grill and it should be a wash

    good luck..
    '06 Supra Launch 20SSV-gone but never forgotten

  4. #4
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    We do a lot of side-firing 7-sided sub enclosures (an irregular pentagon from the side perspective) that are mounted up on the hump so that you maintain the floor hump and have the full depth of foot/leg room under the enclosure. One angle exactly corresponds to the face of the hump (found by using an adjustable triangle and a square) and all other surfaces are either parallel with the sole or at 90 degress from the sole. The enclosure design and build is simple. The mounting bracketry is more complex since we use three mounting points for structural strength, we do not want to interfere with leg/foot room, we want easy removability for underdash access for the servicing boat dealer and the face of the hump is typically very thin fiberglass with little structural value. Since a 1.25 cu.ft. net is about 1.86 + cu.ft. external displacement this size of enclosure approaches the limit with a Moomba that is maintaining the floor hump. The Moomba doesn't have as much elevation between the underdash and sole as does a Supra of the same vintage.

    David

  5. #5
    Join Date
    Jul 2008
    Location
    Kerr Lake, VA via Durham, NC
    Posts
    67

    Default

    David, I have considered the side firing sub with the idea of basically replacing the kick panel/foot rest with the box to utilize more space. I understand bass is better heard as a reflected sound, but does too much get lost going towards the bow of the boat when facing the outside wall of the boat? I guess the better question is, what are the pros and cons you have found in a side firing sub configuration?
    Joey

    2007 LSV
    Gravity III w/ 750's and IBS, Acme 1433
    WS-420SQ, Kicker KM6500.2, JL e4300, JL 12w6v2, JL e1400D, Polk db651s, JL JX360/4

  6. #6
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Quote Originally Posted by JGP54321 View Post
    David, I have considered the side firing sub with the idea of basically replacing the kick panel/foot rest with the box to utilize more space. I understand bass is better heard as a reflected sound, but does too much get lost going towards the bow of the boat when facing the outside wall of the boat? I guess the better question is, what are the pros and cons you have found in a side firing sub configuration?
    The answer depends on the particular boat, how refined your ear is and what your personal objectives are. But here are a few of the more basic acoustic guidelines.
    If there is no separation between the helm compartment and under the bow seating consoles then that extended cavity acts as more of a counter-productive bass trap. If applicable to your boat, you can add the separation and sectionalize the two compartments easily. If you cannot or choose not to add the isolation then I would probably avoid side-firing.
    In an open field environment, bass energy dissipates rapidly without reinforcing planes, especially as the frequency lowers. So you can use all the leverage you can get to assist with the bottom octave of bass material. Otherwise the bottom octave takes a very steep decline. Side-firing takes advantage of the under helm cavity (provided it is isolated per the above comments) by creating a resonant chamber (much like the body of an acoustic guitar behaves as an amplifier over a certain frequency range) and by making use of the hull as a reinforcing boundary.
    Now when side-firing the helm chamber has a slightly non-linear impact. This assists the deep bass output but serves to filter some of the upper bass or bass transients. In contrast, direct radiating offers a little better bass attack and pitch definition but without as much deep bass compression.
    A well-designed bass-reflex enclosure provides another 3 dB of output (equivalent to doubling your amplifier power) plus it will give you another one-third octave of bass extension before reaching its half power point as compared to a sealed enclosure. So if running bass-reflex the advantages of side-firing exist but are somewhat minimized. If running a sealed sub enclosure in an open air environment (accelerated deep bass roll-off) I like to get all the deep bass leverage possible and would prioritize the attributes of side-firing.

    David

  7. #7
    Join Date
    Feb 2012
    Location
    St. Albert, Alberta, Canada
    Posts
    169

    Default

    Quote Originally Posted by JGP54321 View Post
    I am looking for pictures of a sub box that does not disrupt the kick panel/foot rest under the help. My dad is a huge fan of the diagonal foot rest and in order for me to put the sub in the boat, he won't let me take away that space. I am putting a 12" JL W6v2 that requires a 1.25 sqft sealed box. I have searched the forums for other pictures but really only found set ups using a faux wall and eliminating the foot rest all together. Has anyone seen this done or have pictures?
    These are my two 10's.
    I'm 6'8" and they don't interfere with my leg room at all!!
    Just another idea for you.
    ImageUploadedByTapatalk1356652907.771653.jpgImageUploadedByTapatalk1356652925.993827.jpg


    Sent from my iPhone using Tapatalk
    2010 MOOMBA LSV
    340 CAT
    ACME 1235
    3100#'s




  8. #8
    Join Date
    Feb 2008
    Location
    Traverse City, MI
    Posts
    2,388

    Default

    How do those sound? Muffled at all?

  9. #9
    Join Date
    Feb 2009
    Location
    Wausau, WI
    Posts
    436

    Default

    I didn't read through all the replies but here is what I did in my Outback. Fit above the hump. (1) 10" JL Audio W6 in a sealed box, facing towards the side of the hull. Still have the leg room.

    Matt

    2003 Outback, Assault EFI, (6) Polk Audio DB651s, JL Audio M6600 amp, JL Audio M1700 amp, JL Audio 10w6v2 subwoofer

  10. #10
    Join Date
    Feb 2012
    Location
    St. Albert, Alberta, Canada
    Posts
    169

    Default

    Quote Originally Posted by ian ashton View Post
    How do those sound? Muffled at all?
    A little bit, but they shake the boat good enough for me, and those cubbies are a pain to get into, so the storage loss was no big deal. When you open the v-drive lockers up they sound a little clearer.
    2010 MOOMBA LSV
    340 CAT
    ACME 1235
    3100#'s




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