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Thread: Another subwoofer thread

  1. #1
    Senior Member Azmodon's Avatar
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    Another subwoofer thread

    After getting the diffuser on I needed a new project... with 8 days till the final races... and after seeing 514's build, and many many hours of youtube, I decided to give it a shot. Having never built an enclosure before, why not jump in the deep end with a 4th order band pass?

    First Idea
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    needed more air volume above and below, but didn't want it to be taller, so I added air columns to the rear - the port on the right side is tuned to the resonant frequency of the sub.
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    converted to 3D for cutout patterns
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    laid out
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    cut out Monday night
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    Parts arrived last night at 6pm
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    Box 90% done by 3am
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    Tonight's wiring and final assembly + resin coating

    (calculations for the nerds)
    Sub requirement for ported = 1.1ft^3 minimum / sealed = 0.6ft^3 optimal
    Resonant @ 38.4Hz
    displacement = 0.07ft^3

    Octagon volume at bottom = 2(1+2√) x 4.55in^2 x 2in = 0.11569ft^3
    Lower chamber = 35x16x3 = 1680 / 1728(in^3 to ft^3 conversion) = 1.208ft^3
    Expansion box = 6.25x13.875x2 = 173.4375/1728 = 0.1ft^3
    supports = 0.003ft^3
    Total = 1.423 - 0.07 - 0.003 = 1.35ft^3

    Port size needed = 2 x 2.875 @38Hz = 5.97"
    Port dimensions = 2 x 2.875 x 6" + chamfered edges

    Sealed chamber = 35x14x1.75 = 857.5 / 1728 = 0.4962ft^3
    Expansion box = 17.25 x 2 x 5.75 = 198.375 = 0.1148ft^3
    expansion box entrance (volume of the cutout between the chamber and the expansion area) = 0.5x1.75x17.25 = 15.09375 = 0.0087ft^3
    supports = 0.0008ft^3
    Sub face displacement offset by dished area
    0.4962 + .1148 + 0.0087 = 0.6197 - 0.0008 = ~0.62ft^3


    Last edited by Azmodon; 09-19-2018 at 02:02 PM.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra SV automatic: 7.1 L/100 km ... 39.9 mpg (Imp) ... 14.1 km/L ... 33.3 mpg (US) ...


  2. #2
    Senior Member MrMicra2015's Avatar
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    your AMAZING.....excellent , quick , work...but its going to weigh and your gonna go slower!!!...although i do miss my 2 10" subs in the 99 civic ......#old and lazy#

    what CAD system do you use?...all i know is microstation
    have you run the power wire from the battery?

    did u use 514 route?
    2015 Micra S (manual)
    no A/C /no power options/ block heater/4x 2 Ohm speakers...all factory stock in 2015
    Feb 2015 build
    9,999 purchase price + tax..no additional 1600$ because it was a 2015 purchased in 2016
    so receipt says $8,399....+1600 .... so they look good i guess...for a brand new car!

  3. #3
    Senior Member Azmodon's Avatar
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    I have some LT version of autoCAD at work, fairly terrible but handles 2D fine. I have a license for Inventor2008 at home thanks to a former employer who put my name down as the owner of the license rather than the company's name with me as a user.

    I've already added ~50 pounds of sound proofing through out the car and doors, the box is about 25, subs ~18... It's like having a small passenger at all times, no biggie.

    I actually used the grommet 514 used for power, for my demon eye control (pics in projector thread). I picked up a 3/8ths cable gland though and am just going to drill another hole next to that one

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra SV automatic: 7.1 L/100 km ... 39.9 mpg (Imp) ... 14.1 km/L ... 33.3 mpg (US) ...


  4. #4
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    Nice !

    LoL i made a new box too.
    I pass from 10 low profile to 12in alpine sub. Need 1.25 sealed enclosure, so have to made new one completly different...

    AND don't forget if you want used your spare tire make a hole for the ex bolt. Have a great story about that hahaha



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