Hi all

I am looking for advice on a design for a single ported enclosure to carry a 13W7 sub.

The enclosure would be sitting on the rear right hand seat, directly behind the driver (Right hand drive in Australia).

There are a couple of things I need to clarify first...

• Is the recommended internal volume of 2.375 cubic foot too small for this sub? If so, what would be a better size.
  
• Here we only get 18mm thick MDF (about 0.71"), so to make the front baffle stronger, should I just glue and screw two together? - Will it start to rattle / vibrate loose?
  
• If I make the box to JL's specs of 2.375, I would have to change the outside dimensions of the box to be (19.7" x 19.7" x 17.7") with the 17.7" being the height, as that is the height from the seat to the bottom of the window. Would this work and, would this change the way the box functions and is tuned? (port will probably be wider so the overall length would probably also need to be longer?) - And with this design would it be ok if the sub would be below the slot port, not next to it like how it traditionally is done?
  
• The height of 17.7" of the sub box is not fixed, just preferred, the max height of the box would probably about 20-21"
  

Concept 1, something like this...

• My other idea is to have the box be around 19" x 19" x 17" (externally), and have no internal ports, using external ports instead... BUT this could create further complications/questions, like how many and what size ports to use (I am guessing round PVC ports would be the easiest, or would external square MDF ports also be a good option?) - And do i need flared ends? - Also, the ports would drop down to feet level, would this make a noticeable difference to the loudness? (see pic)
  

Concept 2, something like this...

My space is quite limited as it is in an Isuzu pickup truck, (Australian model so much smaller that the F250's ect you have in the states)

Any other concepts / ideas will be much appreciated.

[i have not actually purchased the sub yet, just ensuring that it will work, other wise I will go with the 12" as it only "needs" 1.75 cubic ft. - but would like to make the 13 work if possible]

Some extra info..........

Vehicle : Isuzu D-Max

Location in the vehicle: On the seat behind driver (Right Hand Drive car)

Space available (19.7" x 19.7" x 17.7") or (50cm x 50cm x 45cm):

Subwoofer make and model: JL Audio 13W7

Subwoofer Size: 13.5"

Number of Subwoofers: 1

Type of Port (Kerfed, Slot, Aero, etc.): Either Slot or external

What type of music do you like?: I listen to basically anything with heavy bass and some dubstep depending on the mood hahah.

Tuning Freq (Hz): JL enclosure specs say 35Hz, but that seems a bit high? Would prefer 30Hz

Volume : Again, JL recommends 2.375 Cubic Foot but is that large enough?

Is the recommended internal volume of 2.375 cubic foot too small for this sub? If so, what would be a better size.

The folks at JL are generally pretty smart fellas, if they recommend 2.375cuft I'd imagine the driver would perform pretty well. That said you can adjust net volume and tuning to better match your goals if your goals differ from what JL's goals when recommending the 2.375cuft enclosure.

Here we only get 18mm thick MDF (about 0.71"), so to make the front baffle stronger, should I just glue and screw two together? - Will it start to rattle / vibrate loose?

Yes, glue them together. As long as the sheets properly bond with the glue they should not rattle loose. Use bracing within the enclosure as well.

If I make the box to JL's specs of 2.375, I would have to change the outside dimensions of the box to be (19.7" x 19.7" x 17.7") with the 17.7" being the height, as that is the height from the seat to the bottom of the window. Would this work and, would this change the way the box functions and is tuned? (port will probably be wider so the overall length would probably also need to be longer?)

Changing the dimensions is fine, however the change in port height will however require you adjust either width to keep port area the same, or adjust port length to keep tuning the same.

And with this design would it be ok if the sub would be below the slot port, not next to it like how it traditionally is done?

If I understand your question correctly no it doesn't matter.

If you are going ported, I would recommend sticking with a standard slot port.

Given this is going in a smaller sized truck with limited space is a ported enclosure a necessity? Might be easier to go sealed and still get good performance especially if you are limited on space.