Spl Box for a Gen 4 Mojo 15

[sittingheavy]

Hey Guys,

I'm trying to build a strictly burp box for a 2011 toyota sienna. I'm currently running a 15-cm15d4 memphis mojo on a hifonics hercules amp. The sub is in a prefab 4ft3 vent, no clue on tuning. I'm hitting 138 on the windshield on a termlab. I have plenty of room in the trunk, like 14ft3. We tested the res frequency with a sealed 12 and seem to be peaking out around 55hz. What should I be tuning the box to? I've mocked up a few boxes in winisd and really have no clue what looks good based off of what I need.

I can't seem to get a box to mock up properly in winisd. After messing with it the past couple days, trying to get the port area almost equal to sub cone area, this is what came out. Box is measuring 32"x36"x20" with the vent measuring 18.5" long x 10" wide x 11.2" deep. After vent and sub displacement, the box is coming out at 9.67^ft3 and tuned at 47.95hzSub and vent will be on top and at opposite ends of each other. Does this sound reasonable?

This is a screen shot of what I have mocked up with the t/s specs of the mojo, what data was input into winisd, and the transfer function graph. Any chance anyone would care to chime in on what is wrong? I appeciate it.

http://i.imgur.com/19aGneP.jpg

Click to read more...

 

[hispls 5,000+ posts]

Easiest would be to use a round external port. Sono tube would be great for testing. Go with 5 cube (or larger) box and get yourself a 10 or 12" round tube or pipe. Start with the port 22" long and cut off an inch at a time and test to see which tuning is best. Once you have a good length, reinforce it with fiberglass or buy a flared steel port or something more solid.

Testing multiple tunings is fast and easy with sono tube ports.

Or if you like to use a slot port, make a HUGE one, like 130 square inches tuned to 55hz then add 3/4" MDF to a port wall to tune lower a little at a time. This is a little more tricky but also a decent option to test different tunings fairly easily.

 

[Jeffdachef 5,000+ posts]

If you want to go for numbers, why not try modeling out a 4th order enclosure. Siennas have a lot of space.

 

[sittingheavy]

Easiest would be to use a round external port. Sono tube would be great for testing. Go with 5 cube (or larger) box and get yourself a 10 or 12" round tube or pipe. Start with the port 22" long and cut off an inch at a time and test to see which tuning is best. Once you have a good length, reinforce it with fiberglass or buy a flared steel port or something more solid.
Testing multiple tunings is fast and easy with sono tube ports.

Or if you like to use a slot port, make a HUGE one, like 130 square inches tuned to 55hz then add 3/4" MDF to a port wall to tune lower a little at a time. This is a little more tricky but also a decent option to test different tunings fairly easily.

Dude, Thanks so much. Building the box to 6 cubes with a 12" removable sonotube port. Had no idea people were using these **** things as ports. Makes things so much easier to tune. Thanks for the help, I really appreciate it.

 

[hispls 5,000+ posts]

Dude, Thanks so much. Building the box to 6 cubes with a 12" removable sonotube port. Had no idea people were using these **** things as ports. Makes things so much easier to tune. Thanks for the help, I really appreciate it.

I'd suggest reinforcing sono tube once you've settled on ideal length (and position in the box), but it's a very fast and cheap way to test.

Also if you find 6 cube box is too big you can shrink it by just filling it with bricks or blocks of wood or anything else hard. It's much easier to reduce volume than to add more (ditto with port length).

Good luck!

 

[wew lad 5,000+ posts]

iirc you can get up to about 20% "extra" volume by stuffing with boxes bigger than ~4 cubes so you have some wiggle room in either direction if needed.