FI BL 18 box????

[jstaguy24 10+ year member]

Going to start a build on my FI BL 18 pretty soon. Just pulled a dual 15 wall out of the expedition. Now deciding which route to go with the 18. 7-8 cube ported box? Or I have a guy that can design me a 6th order band pass for it. (Which he recommends) Just looking for opinions. Have only ever had prefab preloaded band pass boxes in the past.

Click to read more...

 

[keep_hope_alive Premium Member]

i've built a few for this sub.

KHA does an SPL build - 1996 Astro Van

The van was slightly louder than the Silverado, on half as much power. Combination of the box and placement.

This went in a Silverado but I wasn't happy with the result due to loading - port should have been against the side wall.

A buddy put this in his Dakota, the silverado was louder and more musical

Go as big as you can for maximum efficiency. It can take 4kW RMS but it wasn't strong enough to overcome cabin pressure. We swapped an Alphasonic 12 for the 18 (same amps, same box) and the 12 was nearly as loud.

musically, the sub wants a low-tuned box and a large box.

 

[jstaguy24 10+ year member]

I have been planning on 8 cubic feet, tuned around 30hz. Sub up, port Back. Also trying to figure out a design I can swap the subwoofer baffle and have 2 mounts. 1 for the fi 18, and 1 for my 2 Memphis lvs 15's (once I get one of them repaired) might end up with 2 boxes, but don't have a decent place to store extras now. So trying for a design for 1 box for both purposes.

Sub will be powered by a Memphis mojo 2200. Could strap 2 if I wanted, but wanting to see what one will do.

 

[keep_hope_alive Premium Member]

you can do a swap-able baffle. build one layer for the box with a rectangular opening sized for the height of an 18 and the width of two 15. build a double layer sub baffle for both the 18 and the two 15. use bolts to hold them in place with the same holes for either. you can fit inside either so bolts are doable.

 

[jstaguy24 10+ year member]

you can do a swap-able baffle. build one layer for the box with a rectangular opening sized for the height of an 18 and the width of two 15. build a double layer sub baffle for both the 18 and the two 15. use bolts to hold them in place with the same holes for either. you can fit inside either so bolts are doable.

That is exactly how I was planning it. Original box design plan was throwing me off due to the slot port. I think I'm going to redraw it and have the slot port at the bottom, so the top is not hindered by the port

 

[keep_hope_alive Premium Member]

keep in mind you want even port loading on the cone for either configuration.

 

[jstaguy24 10+ year member]

keep in mind you want even port loading on the cone for either configuration.

I'm planning a port across the entire length of the bottom. 18" sub centered in box, 15" subs centered off each side.