I'm going to be making some under seat speaker cabinets for my other car. The problem is there's only 60mm of space below the seat.
I've been told the best stuff for making speaker cabinets is MDF as it is an acoustically dead material. Because of the lack of height I want to
use a thin sheet of the stuff. Is 6mm too thin?
The bottom panel will be against the carpet so won't resonate as if it were in free air. The baffle will be braced internally some how too. Do
I need to sacrifice some internal volume to make the baffle plate thicker?
Assuming you have a small space you wont be able to fit a powerful driver in there... so I wouldnt worry too much...
IMHO 6mm would be ok, assuming you have some form of internal bracing....
I built a BIG sub years ago using 1.5" MDF... it weighs the same as the moon!
Dont forget that most car speakers dont really have an enclosure as such....
So if you are clever with your design you could use GRP....
Bracing is the name of the game then...make some inner bracing between the bottom and top faces of the box (the biggest walls) and that will stiffen the box considerably.
What sort of driver are you intending to use and how are you mounting it?
(I'm assuming a small sub facing up under the seat?)
Personally I'd use a min. of 12mm MDF - IMHO 6mm is too thin and will resonate too much. The drop in internal volume is not worth worrying
about, the enclosure stiffness is.
That said 60mm is very little space to start with so you're not going to move much air either side of the driver and probably need to think about
designing in a reflex port of some kind.
Another option might be a bass tube mounted on the behind or just in front of the seat. These can produce quite good bass detail when driven properly
and mounted securely. And you could probably fit one either side of the car to bolster the overall sound level.
I would make the base of the enclosure in Fglass, that woay, you would be using as much as possible of the room available by following the contours of
the floor, then use the MDF for the sides and top, and use ribs to strengthen...
Search youtube for custom sub enclosures...
quote:
Originally posted by nick205
What sort of driver are you intending to use and how are you mounting it?
(I'm assuming a small sub facing up under the seat?)
Personally I'd use a min. of 12mm MDF - IMHO 6mm is too thin and will resonate too much. The drop in internal volume is not worth worrying about, the enclosure stiffness is.
That said 60mm is very little space to start with so you're not going to move much air either side of the driver and probably need to think about designing in a reflex port of some kind.
Another option might be a bass tube mounted on the behind or just in front of the seat. These can produce quite good bass detail when driven properly and mounted securely. And you could probably fit one either side of the car to bolster the overall sound level.
Dedicated bass drivers would be much beter, but if you have the Kenwoods to hand then worth a try. Again a low pass filter would help seperate the
sound, bu TBH the seat will cancel a lot of the upper frequencies out by itself.
Shame you can't buy MDF tube as the bass tube approach seems idela for the vehicle. You could always cut and glue a lot of MDF rings together to
make one 
Seeing as you have the materials and skills an GRP cabinet could work well, certainly would maximise the cabinet volume in the space available - i
guess it depends how much time, effort and money you want to throw in.
quote:
Originally posted by nick205
You could always cut and glue a lot of MDF rings together to make one
Cracking speaker cabs 
I've made a few speaker door pods this way too - can be labourious, but it's worth the effort.