Air Space Question?

Grimster74
Grimster74 Posts: 2,576
edited December 2008 in Car Subwoofer Talk
Getting prepared to start building the sub enclosure for my car. After taking measure measurements for the size of the SEALED enclosure this is what I've come up with. By the way, I'll be using dual MM2124's wired as a 2 ohm load which according to Polk suggest an air space of 0.88 cubic foot per sealed enclosure. After measuring the space I have to work with the measurements are as follows: 35" wide, 15" high and I can go as deep as I want but I prefer to keep it under 9". After calculating the internal volume I've come up with roughly (per enclosure) 13" high x 16" wide x 7.5 deep / 1728 = 0.90 cubic foot. The sub enclosure will roughly be a shaped as a square filled with poly fill. My question is, should I make the enclosure's internal volume larger and if I did, would I benefit anything from it. I had planned on going by the recommended Polk specs but I just wasn't sure if anyone could tell me what a larger internal volume would do. Thanks for your help in advance.

Rob
Money Talks, Mine says Goodbye Rob!!!!
Post edited by Grimster74 on
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  • Grimster74
    Grimster74 Posts: 2,576
    edited December 2008
    Okay, I've been doing some research today and it never even crossed my mind to factor in the driver displacement. I've looked everywhere on Polks website and for the life of me can't find this info anywhere for the MM2124's. Anybody know what the driver displacement is for this subwoofer? Thanks again.

    Rob
    Money Talks, Mine says Goodbye Rob!!!!
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  • McLoki
    McLoki Posts: 5,231
    edited December 2008
    With external dimentions of 13x16x7.5 and working with 3/4" material I come up with 0.57899 cubic ft. (as you mentioned - that is not taking into account driver displacement either) Seems a bit small for a 12" sub to me, but that is not based on anything scientific....

    BTW - if you have not seen it - This is a great page to help figure out box volumes and port sizes (you have to scroll down to see most of the information)....

    Michael
    Mains.............Polk LSi15 (Cherry)
    Center............Polk LSiC (Crossover upgraded)
    Surrounds.......Polk LSi7 (Gloss Black - wood sides removed and crossovers upgraded)
    Subwoofers.....SVS 25-31 CS+ and PC+ (both 20hz tune)
    Pre\Pro...........NAD T163 (Modded with LM4562 opamps)
    Amplifier.........Cinepro 3k6 (6-channel, 500wpc@4ohms)
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  • MacLeod
    MacLeod Posts: 14,358
    edited December 2008
    This is the best tool Ive every found for coming up with the best box size and shape.

    http://www.bcae1.com/spboxnew2.htm
    polkaudio sound quality competitor since 2005
    MECA SQ Rookie of the Year 06 ~ MECA State Champ 06,07,08,11 ~ MECA World Finals 2nd place 06,07,08,09
    08 Car Audio Nationals 1st ~ 07 N Georgia Nationals 1st ~ 06 Carl Casper Nationals 1st ~ USACi 05 Southeast AutumnFest 1st

    polkaudio SR6500 --- polkaudio MM1040 x2 -- Pioneer P99 -- Rockford Fosgate P1000X5D
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  • Grimster74
    Grimster74 Posts: 2,576
    edited December 2008
    McLoki wrote: »
    With external dimentions of 13x16x7.5 and working with 3/4" material I come up with 0.57899 cubic ft. (as you mentioned - that is not taking into account driver displacement either) Seems a bit small for a 12" sub to me, but that is not based on anything scientific....

    BTW - if you have not seen it - This is a great page to help figure out box volumes and port sizes (you have to scroll down to see most of the information)....

    Michael

    Those dimensions are the internal dimensions, not the external.
    Money Talks, Mine says Goodbye Rob!!!!
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