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how many cuft per 18" sub?

2K views 54 replies 21 participants last post by  beatnbronco 
#1 · (Edited)
hey CACO, got another question and i've always gotten good feedback and answers on here so here's another one for you.

I'm building custom 18" subs, triple 3/4" slug OEM motors w/3" dual 3 ohm coils and punch hx2 baskets but i've never had 18's and never build an enclosure for them, i've never even heard a system w/ 18's so how much cuft per sub should i use? the subs are gonna be around 1500w rms and 3000 max. should it be vented w/a slot vent or aero? The box for my 15's has 1-8" aero and it rocked. I love low bass but i like to hear all levels too. So help me out with some suggestions on how big this box should be or if there is a site on the www like SSA that has examples of 18" boxes and the size of the box. I like to do my own work and don't want to pay someone to do it for me, i like knowing that I did it all myself but just need a little help with the size of box. Thanks and everyone have a great day:thumbsup:
shoot! i forgot one thing. I've been using stock alt w/big 3 upgrade. Should i buy an HO alt and get an additional battery? I'll be using around a 2200 watt rms amp to push the 18's and i have a RF p4004 pushing my components so i'm running 2 amps off a stock alt and 1 battery.
 
#3 ·
Go as big as you can fit. I prefer 8cu ft per 18". A slot port will be much easier for this big of a box.
 
#6 ·
^^this is the best answer so far
 
#10 ·
the area i have avail for box is 18hx52wx31d..i was going to use about 12cuft of that room but wanted to face 2 aero's toward the back but the back of the box is going to be butted up against my tailgate. i guess i could fire the aero's out the sides, there will be about 12" from the sides of the box to the inside panel..just need to get a design together and get on the calculator on 12volt..thanks for the input so far..any ideas about port area or ideas about port design lemme know, i still plan to use 2-8" aero's tho..anybody know how to convert a sketchup model to a pic so i can put it on here for opinions?
 
#12 ·
my corvette box in the rear hatch used a slot port @35hz and the sub only got about 5.5 cubes net... but it was amazing.
if I could have built the box bigger I would have.
I bet it would of inialated with 6.5 to 7 cubes net in my vette.

I have a re sx 18 - factory rated at 1K - but I fed it 1200 to 1400w with diffrent amps in the little enclosure and it took it like a champ. not shure if it will take the same amount of power in a larger enclosure tho...
 
#14 ·
You have to export the image from sketchup from each angle or whatever, save it to your computer then upload to photobucket
 
#20 · (Edited)
I say 4.5 minimum uless you are building for a burp. 6 cubes should give you plenty of extension into the lower 30hz region.
what 18s u know even sound close to good in an enclosure of that size, with out it being an super woofer with tons of power tuned LOW? his sub has an rms rating of 1500 rms, i don't think telling him he can go to 4.5 cubes mini would be good, cause he may just do that, and then will wonder why his setup doesn't sound worth shit. ima say this and be done with it, its all personal preference when it comes to enclosure size, besides the woofer itself and power.

ive been using 18's for years now, and im an 18" sub woofer whore, so here is a little biased rule of thumb i keep to myself


soft/Medi-Core 18's- 1000W rms(examples)(Re Sx, Fi SSD,Fi Q's, you get the idea
i like to be efficent on the lows, so with 18's like that which i have owned, i liked about 7-8 cubes each tuned to 30ish.

Beast mode 18's lol 2000w+rms(Treo SSX's.Fi BTL's,DD 95-9918s,DC lvl 4xl/lvl5, you get the idea) would work much better in an smaller box, generally because of the added motor BL and power being applied to the subwoofer, so dont pay attention to my sig box size for my btl's but

4.5-6.5 cubes each 18 tuned 30ish would be golden. the Treo Subs likes around 5 cubes each, but work way better than the others in the list @ 4 cubes.


just goes to show you that Decaf is right, every sub is different, and we need T/s parameters. but i just gave you my little ROT. ive never been dissatisfied with an enclosure ive done for all the 18's ive owned.
 
#22 ·
this is about it so far..needs more bracing and 45 the corners but i think that would be it..3" of baffle on the face to hold em in..the aero's will fire into the area right behind the wheel well bumps, could put some 90 degree bends outside the box to fire the vents up, something to think about, def different..anyway, any ideas about this box lmk if i need to change nething..hoping to find a 3000w rms amp to put to em, man i need another job!:runaround:
 
#40 ·
that's cool, i'm sure any 18", no matter what the parameters are will work in a 6 cuft box so that's what i'm gonna go with. i'll add some 45's and more bracing..thanks for all the help but i think that's about it for now unless everyone has more suggestions..lke i said, i've never even heard an 18 before, oh wait, i did hear 1 RF 18", the very first 18 RF ever made in a 6 cuft box pushed with a punch 45 but back in those days the max watts on that 18 was about 500w..other than that i've never, ever heard an 18, never even been involved with em, just had my 15" RF power dvc's that I need to sell local, i'd hate to have to ship them but I'll prolly cry when I do..thanks for all the help guys and take care till next time..you're awesome!
 
#41 ·
that's cool, i'm sure any 18", no matter what the parameters are will work in a 6 cuft box so that's what i'm gonna go with. i'll add some 45's and more bracing..thanks for all the help but i think that's about it for now unless everyone has more suggestions..lke i said, i've never even heard an 18 before, oh wait, i did hear 1 RF 18", the very first 18 RF ever made in a 6 cuft box pushed with a punch 45 but back in those days the max watts on that 18 was about 500w..other than that i've never, ever heard an 18, never even been involved with em, just had my 15" RF power dvc's that I need to sell local, i'd hate to have to ship them but I'll prolly cry when I do..thanks for all the help guys and take care till next time..you're awesome!
sounds awesome in the right install, gets loud and low.


your gonna be glad that you did get involved with them.


been using 18s for years now, although i have sold and used different size woofers, i always go back to 18's. cant explain it but i just do. i love em.
 
#42 ·
it kills me cuz i've had these 2 oem's sitting in the garage for a month and 1 is mounted to a punch hx2 basket..tried to sell my amp to buy the recone kits but i'm not that hard up for money that i'm gonna let something i paid 375 for go for less than 225 shipped, that's what i was asking and kept getting low balled so i ended the sell..i can't wait to get those things in my truck and finally hear the amp wake em up..the T10001bd should be a good break in amp tho..ttyl georgia boy!
 
#44 ·
I'm not reading all of this shit.

Build the box as large as you can with reasonable port area tuned in the 32-35hz region and it should be nice and loud and low.

Also, I'm about 45-50mins North of Columbus :)
 
#47 ·
only way i can go over 12 cubes is if i was to build over top of the wheel bumps but it won't be hard..or i could build behind the bumps all the way back to the tailgate and that will bring me close..i'll work on the design a little..this thread is dead now..got what i wanted..thanks for all the input everybody..later:hello:
 
#48 ·
just an update on my situation..got really lucky lately, found a shuriken 120a batt for $60, sold my T10001bd local for $200 and found 4 soundstream TSS6.5 comps for $30..the batt along with 2 of the comps will be going in my truck..bought a BNIB AP3k to push the 18's, parts should be coming in for those w/in the next week..i will get pix of the sub build and box build to post..later
 
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