Jerry can placement (?)

    Quote from Stafford


    there was a thread on this a couple years ago if anyone feels like searching, iirc I did the math on the internal volume of the jerry can and there was no sub on the market that would come close to working well with it. Need more air plus all the issues mentioned above with rattling. If it was a good idea to build sub boxes out of metal that's the way they would be built.


    Mounting inside the vehicle and storing gas in it would make me worry about fumes.


    Remember the volume off the top of your head? I've got a couple older 10" kicker solobarics sitting around and if memory serves they only needed .66 ft^3. I'd think line the thing with dynamat and you'd at least have a 1/2 decent enclosure.

    Quote from clendaniel

    Remember the volume off the top of your head? I've got a couple older 10" kicker solobarics sitting around and if memory serves they only needed .66 ft^3. I'd think line the thing with dynamat and you'd at least have a 1/2 decent enclosure.


    http://www.delawareja.com/foru…37083.msg302491#msg302491

    Quote from clendaniel

    Remember the volume off the top of your head? I've got a couple older 10" kicker solobarics sitting around and if memory serves they only needed .66 ft^3. I'd think line the thing with dynamat and you'd at least have a 1/2 decent enclosure.


    I think if you lined the can with Dynomat it would help but the key is you want the speaker moving the air, not the enclosure. Metal will transmit vibrations too easily, and would create a lot of distortions. If you did it you would also want to put some internal support to make it all more rigid.

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    Quote from deadfeat

    I think if you lined the can with Dynomat it would help but the key is you want the speaker moving the air, not the enclosure. Metal will transmit vibrations too easily, and would create a lot of distortions. If you did it you would also want to put some internal support to make it all more rigid.


    You all are way over thinking this.


    Jeeps and fine audio are pretty much mutually exclusive.


    The 6" sub crammed into my center console adds tons of depth.


    Is it acoustically correct. No.


    But it sounds great so why worry.

    Quote from deadfeat


    I think if you lined the can with Dynomat it would help but the key is you want the speaker moving the air, not the enclosure. Metal will transmit vibrations too easily, and would create a lot of distortions. If you did it you would also want to put some internal support to make it all more rigid.


    Hence why I said "1/2 decent" Not ideal but I think you'd be surprised....remember as you said the speaker is moving air and as long as it's sealed the volume will not change, the shape might but the volume will not. My suggestion of dynamat was simply to dampen the vibrations given the sheetmetal however I think you'd be impressed with the stiffness of the older GI cans.


    Agree 100% with Keith, as a young and dumb teen I had way too much money into a stereo in a CJ....yes, a CJ. With the hardtop on it was 'ok' at best.

    I dont know. I have a box I built to fit behind my rear seat with a 10" in it and that along with oversized alpines in the sound bar and some crap (supposed to be good but I think they are crap) polks in the front running off an alpine head unit with a plug and play amp to the highs and a rockford 1000w amp to the sub. My jeep sounds pretty damn good cruising down the highway with the top off. The problem I run in to is that you need more lows with the top off while moving vs stop and go or top on so I end up adjusting the sub alot. Im kind of a stereo snob though. If I cant crank pantera then Im not a happy camper :mrgreen:
    .
    As for a metal sub box, maybe if you made a box and that was used as a shell to fit over it but then you would run into a depth issue.

    Quote from Tonka


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    Metallica sounds so weak on my upgraded stock system. I want to upgrade but I'm afraid to start adding amps and subs with the soft top and my love for leaving the top down.

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    Quote from DJS DAD

    Metallica sounds so weak on my upgraded stock system. I want to upgrade but I'm afraid to start adding amps and subs with the soft top and my love for leaving the top down.


    Hmm, your right, its harder in a jk because its more open and Im not sure you can put the amp under the seat with the fold down feature. Tj's are easy, the box I have is so snug behind the seat that you cant move it and Im going to put a chain around the roll bar anyway so I can lock up my toolbox and power tank so ill probably add somthing to the box that I can run a chain through. Its not theft proof but you also cant just grab it and run.
    .
    Im trying to think of what you could disguise a sub box as so it looks like somthing that nobody would want. Like an old bald spare with a ugly hubcap

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    Take a flexible plastic cup, fill it with water. Squeeze the cup. Water will flow out of the cup, demonstrating that the internal volume of the cup has gotten smaller. The surface area of the cup has not changed, and the plastic has not contracted.


    Point is, with a given surface area, you can have different internal volumes with a different shape.

    Quote from Erock


    Take a flexible plastic cup, fill it with water. Squeeze the cup. Water will flow out of the cup, demonstrating that the internal volume of the cup has gotten smaller. The surface area of the cup has not changed, and the plastic has not contracted.


    Point is, with a given surface area, you can have different internal volumes with a different shape.


    Yeah but your example isn't comparable to what Ian and others were saying. A plastic cup is not a sealed container. A better example woud be a capped bottle of water. No matter how much much you squeeze or twist it the internal volume of liquid will not change.

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    Quote from Kuntryboy816

    Yeah but your example isn't comparable to what Ian and others were saying. A plastic cup is not a sealed container. A better example woud be a capped bottle of water. No matter how much much you squeeze or twist it the internal volume of liquid will not change.


    That's because water is considered a non-compressible fluid. Either way, that's not the point of my example. The point is that when the container changes shape, the volume can change. Take a bottle filled with air and you can squeeze it and reduce the volume.


    Try this one...think of a zip lock bag, when it is completely empty, the internal volume is zero. If you fill it with air, the internal volume has increased, the shape has changed, but the surface area has not changed.

    At its simplest think of 1cm^3 of clay. No matter what shape you make that clay...be it a sphere, cube, cylinder, or model of Geoff's manhood that clay will always displace the same volume.

    correct, but it can have drastically different surface areas when you mold it into different shapes, and you are talking about a non compressible solid. the jerry can is hollow and the air inside is compressible, introducing pressure differences...different concept. the volume of the steel used to make the jerry can will remain the same, but the volume of the air space inside the can will change
    we all agree that the can will flex, the question is why? when the sub is pushed out due to the magnetic field, the air pressure in the enclosure drops. there is now a presssure difference between the inside of the box and outside of it. lower inside, higher outside...this will effectively "suck" the sides of the jerry can in, trying to equalize the pressure difference. when the sides are sucked in, it reduces the internal volume.

    Quote from Erock


    correct, but it can have drastically different surface areas when you mold it into different shapes, and you are talking about a non compressible solid. the jerry can is hollow and the air inside is compressible, introducing pressure differences...different concept. the volume of the steel used to make the jerry can will remain the same, but the volume of the air space inside the can will change
    we all agree that the can will flex, the question is why? when the sub is pushed out due to the magnetic field, the air pressure in the enclosure drops. there is now a presssure difference between the inside of the box and outside of it. lower inside, higher outside...this will effectively "suck" the sides of the jerry can in, trying to equalize the pressure difference. when the sides are sucked in, it reduces the internal volume.


    Yes, you are correct on the interior volume changing...I was thinking about it last night and you're correct the total surface area in my example can (and does) change significantly where, in the example of an empty water bottle, unless the plastic stretches or shrinks the surface area will not change while the interior volume does. I think what it comes down to for this use is the likelihood of the can actually flexing. The old GI can that I have is pretty damn heavy gauge sheetmetal and has reinforcing ribs pressed into the flat areas. I suspect that while the flex may occur it would be minimal. Gonna stick with my original assertion that it'd be '1/2 decent'....not ideal but not terrible.

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