I know, Free-Air Subwoofer Box IS a bit of an oxymoron, BUT, it will be a BIG box - easily the size of a trunk - about 18 cubic feet. I have a 2013 Fiat 500 hatchback. I plan to build a box to seal off the back seat (remove back seat) and hatchback area from the base of the window line down (the box will enclose the entire area of the back seat and hatchback from the base of the windows down to the floor). The two 10" free air subs will be mounted on the vertical front surface of the box just a few inches in back of the back of the front seats. The box will be made of 3/4" MDF with bracing as needed to make it very solid.
My question is about sound dampening. I will be doing that on the two car doors and the floorpan. If I wasn't sealing off the back of the car w/ a sub box, of course I would be installing sound dampening materials back there also. But I wonder if it will really be needed if I seal/box off the entire back end of the car. Or maybe I should be installing sound deadening materials on the two surfaces of the sub box that will be contiguous with the interior of the car - maybe on the inside of the sub box (the top and the front where the subs will be mounted).
Any thoughts would be greatly appreciated.
My question is about sound dampening. I will be doing that on the two car doors and the floorpan. If I wasn't sealing off the back of the car w/ a sub box, of course I would be installing sound dampening materials back there also. But I wonder if it will really be needed if I seal/box off the entire back end of the car. Or maybe I should be installing sound deadening materials on the two surfaces of the sub box that will be contiguous with the interior of the car - maybe on the inside of the sub box (the top and the front where the subs will be mounted).
Any thoughts would be greatly appreciated.
With only the woofers playing (sub enclosure installed), run a low frequency sine-sweep through the woofers. If you hear any noise (resonating panels, etc...) from the vehicle, determine whether it's going to be a problem or not and if it's a problem, determine the best way to kill it (damping, bracing, soft filler between panels...). For road noise entering the vehicle, you'll have to determine if it's bad enough to add damping material.
if you are sealing the boot space, you might also want to check out the water bung (assume the fiat500 has one). the pressure from the to 10" subs going flat out ought to be enough to pop it out.
Or... you can build in an internal tube and a sliding vent over it to create an external tuned port (may need to drill the hole a bit bigger) to impress your friends/foes even more when stopped at the lights with the press of a button.
What Perry mentioned, a can of space filler is likely to be a requirement to have handy to sort out all the various rattles throughout the rest of the car.
That sounds like you may build a reasonable amount of pressure in the car, as it is fairly new should be OK but sometimes the the rubber seals around the boot and doors may also leak - or there is a softer patch or kink in one of the bends which leaks.
Are you sure that your drivers are designed to be 'free air' (or rather the term 'infinite baffle')? Many drivers with grunt like to have a bit of pressure or they might 'flutter' - a bit like the back pressure of a turbo engine and people putting big bore exhausts on their cars being detrimental to performance. 10" cone sizes sound a bit small and I think you'd be better to seal them somehow.
Or... you can build in an internal tube and a sliding vent over it to create an external tuned port (may need to drill the hole a bit bigger) to impress your friends/foes even more when stopped at the lights with the press of a button.
What Perry mentioned, a can of space filler is likely to be a requirement to have handy to sort out all the various rattles throughout the rest of the car.
That sounds like you may build a reasonable amount of pressure in the car, as it is fairly new should be OK but sometimes the the rubber seals around the boot and doors may also leak - or there is a softer patch or kink in one of the bends which leaks.
Are you sure that your drivers are designed to be 'free air' (or rather the term 'infinite baffle')? Many drivers with grunt like to have a bit of pressure or they might 'flutter' - a bit like the back pressure of a turbo engine and people putting big bore exhausts on their cars being detrimental to performance. 10" cone sizes sound a bit small and I think you'd be better to seal them somehow.
I'm with reverse, 10" are small for infinite baffle, but if they are then what your doing sounds awsome. I'm a big fan of sound damping as much as whats practical, flexing panels are never desired.
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Yes, they are Infinity Kappa series specifically identified as being free-air subwoofers. I had these installed as free-air in a Mercedes sedan for many years in a 1-1/2" thick slab of MDF mounted and sealed to the back deck. And the Benz' had a big trunk (boot). They sounded AWESOME. Best sounding set of subs I've ever had. Since then I used a couple sealed box setups - they sounded very nice, but NOT as great as my old free-air subs. One thing that was nice about the Mercedes was that the back deck and between the back of the back seat and trunk was solid steel - no openings at all between the trunk and the passenger area - primo for mounting a set of free-air subs on the back deck.
Thanks for all the input.
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