Jl Audio 18" X2 Install Update/Questions

[BlownEARdRUMS 10+ year member]

Well I have finally started on box planing... So far I have a measurements of: h-13"Xw-20.5"Xd-27"... With that measurement I get 3.224 Ft3, which is just about perfect for sealed single enclosure, but my first plan was, h-13"Xw-36"Xd-18" which gave me 3.788 Ft3,which is really close to the ported requirement of, 4 Ft3. Now the 18" is too small so I need to make that about 2 inches longer, so If I do that, I hit the 4 Ft3 mark... I know that these are SPL subs and not SQ but I wanted to exploit what SQ they do have by using a sealed enclosure, but I am so close the ported requirements that I think I should just go ported and gain some more db's. What do you think? I want to keep the 36" width so that there is minimal movement and so the boxes can just squeeze them in between the strut towers, but if I go sealed I cant keep that measurement. and have to change it to 20.5". I also would like to mount my 2 amps on top of the boxes next to the subs so if I go sealed, I cant do that. All the signs say fuk it, go ported, but if I do, I need to tune ports and I don't know that if this enclosure design would still use JL's port length and Hz tuning, and I have no clue what goes into tuning a ported enclosure. (Ported mesurements- h-13"Xw-36"Xd-20")

Any Help/Ideas/Suggestions?

Thanks

Brad

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[Trixter 10+ year member]

by going through your numbers you have to remember to use the internal box dimensions and also to account for sub and port displacement. if the net volume is the same as the recommended volume, then you will be fine with the same ports they recommend.

 

[bumpin_blazer 5,000+ posts]

also wondering if those are internal or external measurements? that sub is what .68cuft displacement?