I am helping my son build a sub for his car. We are using the Dayton Titanic MK III 12". According to winisd we need a sealed box roughly 1.65 ft^3 with dimensions of 10x16x24.5.
PE page http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-404&ctab=9#Tabs
The pdf on the PE site has plans for a sealed box for this driver at abut 1 ft^3. Are they just compromising the sound a bit to get a smaller box? The 1.65 will fit fine in his car so we are planning to go that route.
Other questions. The box would be 24.5 wide, 16 tall and 10 deep, but we may alter it a little. We are also planning on using two sheets of MDF on the front to stiffen it up a bit. Does it matter if the driver is in the center of the front of the box or is it better to offset it towards one end?
Should we use a router to round over the speaker cutout on the inside or would this even help?
Is there an optimal place on the front to put it?
Also, should we use some poly fill in the box or leave it empty?
The driver has a firm rubber ring around the driver. Will this seal the driver to the box well or should we still put some weatherstripping behind it?
Thanks for the help.
PE page http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-404&ctab=9#Tabs
The pdf on the PE site has plans for a sealed box for this driver at abut 1 ft^3. Are they just compromising the sound a bit to get a smaller box? The 1.65 will fit fine in his car so we are planning to go that route.
Other questions. The box would be 24.5 wide, 16 tall and 10 deep, but we may alter it a little. We are also planning on using two sheets of MDF on the front to stiffen it up a bit. Does it matter if the driver is in the center of the front of the box or is it better to offset it towards one end?
Should we use a router to round over the speaker cutout on the inside or would this even help?
Is there an optimal place on the front to put it?
Also, should we use some poly fill in the box or leave it empty?
The driver has a firm rubber ring around the driver. Will this seal the driver to the box well or should we still put some weatherstripping behind it?
Thanks for the help.
You'll probably get more responses on a car audio or PE's forum, but WRT box size, cars typically have a high room gain curve, so a high F3 with up to a 2nd order roll off (0.707 Qtc) is normally required for a ~flat response to the lowest frequencies which makes them way too small by HIFI standards. Indeed, depending on the vehicle's internal net Vb this driver's Fs may be too low to get the desired response without EQ unless a 'one note' boom-box response is the goal.
As a general rule, the driver's location in a sealed alignment can be wherever you want it until it becomes large enough with a high enough aspect ratio to audibly affect its response, so considering the sizes of the WLs a sub is reproducing it has to be too large to fit in a typical car. For the same reason, rounding over any edges of a sub is strictly for cosmetic reasons.
It's a good idea to either line the walls or lightly stuff a speaker cab to quell any spurious noise generated by the driver and add up to 1.75 lbs/ft^3 of fiberfill stuffing density to lower the effective box Q if required to get smoothest in 'room' response. Note that wool, fiberglass requires a lower max stuffing density to reach the point of reversal, with R19 fiberglass insulation being 1.5 lbs/ft^3. Don't know about wool: http://web.archive.org/web/20021007....cyberglobe.net/caraudio/resources/fiberfill/
Assuming by 'ring', you're referring to a rubber gasket on the back side of the mating flange where it touches the baffle, then I don't see why you'd need any other gasket, but if in doubt, read the instructions that either came with it or DL from PE. If it's on the front only, thern you'll need a good quality rubber/cork gasket or similar to get a good seal that can handle the environmental extremes a vehicle is exposed to.
GM
As a general rule, the driver's location in a sealed alignment can be wherever you want it until it becomes large enough with a high enough aspect ratio to audibly affect its response, so considering the sizes of the WLs a sub is reproducing it has to be too large to fit in a typical car. For the same reason, rounding over any edges of a sub is strictly for cosmetic reasons.
It's a good idea to either line the walls or lightly stuff a speaker cab to quell any spurious noise generated by the driver and add up to 1.75 lbs/ft^3 of fiberfill stuffing density to lower the effective box Q if required to get smoothest in 'room' response. Note that wool, fiberglass requires a lower max stuffing density to reach the point of reversal, with R19 fiberglass insulation being 1.5 lbs/ft^3. Don't know about wool: http://web.archive.org/web/20021007....cyberglobe.net/caraudio/resources/fiberfill/
Assuming by 'ring', you're referring to a rubber gasket on the back side of the mating flange where it touches the baffle, then I don't see why you'd need any other gasket, but if in doubt, read the instructions that either came with it or DL from PE. If it's on the front only, thern you'll need a good quality rubber/cork gasket or similar to get a good seal that can handle the environmental extremes a vehicle is exposed to.
GM
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