Is this box too big?


  • Member
    peter_euro on #160

    I am building this system for somebody else, it is a 69 Camaro. I am putting this box completely out of the way (there will be a loading board hiding it and hopefully minimizing the trunk rattle). The box is basically 1.5in MDF with glass bottom. Is this box too big (comes up to about 4.5 cu ft)? The sub will vent to the interior through perforations in rear deck. 600 watts max off PA amp.

    http://www.sounddomain.com/ride/2213485


    Member
    simon5 on #2564

    What woofer are you going to use? Then we will be able to answer your question.

    I guess it will be 6th order bandpass?


    Member
    peter_euro on #2565

    @simon5 wrote:

    What woofer are you going to use? Then we will be able to answer your question.

    I guess it will be 6th order bandpass?

    BP? no, it is a sealed box

    http://www.sounddomain.com/ride/2213485/3

    single AV15 wired to 4 Ohm


    Member
    simon5 on #2566

    No the box isn’t too big. It’ll be perfect.


    Member
    Admin on #2567

    Yep, that should work quite well. You can’t really go too large on a sealed enclosure.

    John


    Member
    peter_euro on #2568

    @stryke wrote:

    Yep, that should work quite well. You can’t really go too large on a sealed enclosure.

    John

    wow, great to know… I was gonna run Winisd on the box but I do not think I have to anymore… I have migrated here from CAF where I was getting mixed comments on the box size. I hope this is going to be a one nice sounding Camaro after the dust settles. BTW, the entire trunk and sheetmetal under the parcel shelf will be cotated in firewall liquid deadener and the sub box hidden behind a wall, this is why the box does not need to be finished anymore. Do you guys think that any bracing is necessary with 1.5in MDF?


    Member
    Admin on #2569

    Hi Peter,

    You shouldn’t need bracing if you use 1.5″ MDF. I believe the stiffness actually goes up 8x when you double the cross sectional area. Making sure the box is secured down and has no rattles will be more difficult than anything else.

    In terms of box volume, 4.5cf sealed with no box fill will give you a Qtc of .66 with an F3 around 34Hz. Box fill will bring the Qtc down even more but F3 will go up slightly. In any case though, the larger box is a benefit. The larger the enclosure, the less power you need to drive the woofer to the same excursions. This means you don’t need as much power to get the same volume. Less power means less heating of the VC and less distortion as well. That is a good thing. In a sealed box, no matter what the size is, your output is equal to how much the woofer moves. The less power it takes to move the woofer, the better off you are.

    John


    Member
    peter_euro on #2570

    @stryke wrote:

    Hi Peter,

    You shouldn’t need bracing if you use 1.5″ MDF. I believe the stiffness actually goes up 8x when you double the cross sectional area. Making sure the box is secured down and has no rattles will be more difficult than anything else.

    In terms of box volume, 4.5cf sealed with no box fill will give you a Qtc of .66 with an F3 around 34Hz. Box fill will bring the Qtc down even more but F3 will go up slightly. In any case though, the larger box is a benefit. The larger the enclosure, the less power you need to drive the woofer to the same excursions. This means you don’t need as much power to get the same volume. Less power means less heating of the VC and less distortion as well. That is a good thing. In a sealed box, no matter what the size is, your output is equal to how much the woofer moves. The less power it takes to move the woofer, the better off you are.

    John

    Then it looks this thing is ready to go… The box will be mounted rock solid to the trunk floor (thus the lip on the rear of the box) and to the rear seat seatback sheetmetal. This is after second skin firewall goes under it and on top of the glass bottom. I got these things covered pretty well (I know the drill by now a little…. 😀 )

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