Need a box design/specs for single sa-8 ASAP

[braapboogcafish 1]

i pieced together a simple system for a friend of mine and installed everything, only thing left to do is make the box and slap it in there!

we both a totall newbs at sub enclosures and already failed miserably at making one for this sub (long story short, it turned out to be a fart box. box is sub forward port back which makes it interchangeable in positions 5 ways which we like a lot) so i need you guys to help us out on a box design/specs, i dont wanna be pushy but we need the specs by tomorrow because he really wants to build a box thats right and hear his sub how it should be already. hes a carpenter so the woodworking skills and tools are all here and ready.

the max space we have to work with is 20" wide 18" deep and 18" high. Getting a amp that can do 400-500 at 4 ohms and 1000+ at 1 ohm (hifonics brz1200.1). well be at rms power for the sub and more so im thinking .65-.8 tuned to whatever is the most musical, 32-35hz? i was told to not go over 12sq inches of port area? well use any nice box specs that you can come up with as long as it stays within our goals. idk how you guys come up with your specs but if u want just use the re calc (if its accurate), that way you can just list the numbers here and i can type it in myself and get the dimensions for the wood cuts.

the truck is a extra cab 2008 f-150. not enough space to fit a enclosure under the seats so pls dont suggest that. the 2 spots in these pics below are the only ones that he wants his sub, he has kids and uses his truck for work. also trying to avoid a "sub up" design, just so it doesnt get damaged as easy.

here is the spot where he doesnt mind the sub/box being (seat is not in box ready position)

now u can see here that with it open it frees up some box space

here is a top pov

directly behind the center console was our original idea but we decided against it because of size restrictions, were still open to using this spot if a box in our desired specs can fit there.

i appreciate the help and i know he does too. he told me to tell all of you thank you for all of your input and help with this build.

[stealth 113]

when were you told not to go over 12 square inches of port??? i said to try 14. try building a standard l port instead itll be fine with many options to position the box.

how about i give you the numbers to punch in the RE CALC since you are familiar with that.

[braapboogcafish 1]

i didnt say it was you who said that . some others. but that doesnt matter. normal slot or L port are both fine with me. he just wants a good box.

id take those calc numbers gladly

[stealth 113]

plug these numbers in the RE calc. these are the RED numbers

19

9.5

14

14

0.75

1.25

12

after displacement you should be tuned to 33-34hz. you should have around 13.3 square inches of port per cube. and cubic ft. net should be approx .75 cubes.

this box should do well with 400-600 watts. according to jacob. you should be able to hit somewhat lows but it should be musical. try it out and let us know on HCA.

[stealth 113]

if you look at RE calc STEP 2 shows the cuts you would have to make to piece the box together. id suggest you cut all those pieces out, then write what piece is what with a pencil so you dont get confused.

[braapboogcafish 1]

^exactly why i asked for numbers to put into the re calc, idk if u can get any easier than that. Thanks Alex, hes gonna be relieved and stoked to know we got a solid box to build.

funny though you found this thread before you seen that i wrote the same thing on HCA.

so with those numbers i got

square port area of 10

0.849 ft^3

32.9hz

is that right? then with .1 sub displacement it will be .749? ...just checking

Edited May 11, 2011 by braapboogcafish

[braapboogcafish 1]

also i was wondering if and how adding 45s in all the corners would affect the box? just asking because we want to do that.

[stealth 113]

you can add 1 very small one in the L angle of the port.

[stealth 113]

and yeah those numbers are correct. you generally you want 12-16 sq inches of port per cube. but since your box is less than 1 cube, it has only 10 sq inches of port.

[braapboogcafish 1]

ok gotchya thanks again man. i have such a strong drive to get good at building sub enclosures, once im good at it will just add to my love for car audio. next im gonna build a better ported box for my v3 mag, its basically 3ft^3 tuned to 32-34 right now, too big!!! gonna shoot for si spec (2ft^3) or up to 2.5ft^3 tuned to 31-34. Also gonna do a sealed box for the mag too, listened to my friends 12 in a sealed box today and it sounded so clean and crisp! Makes me miss how my mag sounded sealed.

[stealth 113]

yup, philip posted some numbers, but he is missing 1, i think because he is posting from his phone. but i think his box will be very close to the one i gave you.

[braapboogcafish 1]

yea he only posted 6 numbers so i couldnt really do anything with it since its not a complete design for that calc.

also i was wondering if sub displacement brings the tuning higher or lower?

Edited May 11, 2011 by braapboogcafish

[xiihustleix 6]

if you look at RE calc STEP 2 shows the cuts you would have to make to piece the box together. id suggest you cut all those pieces out, then write what piece is what with a pencil so you dont get confused.

Very good idea

yea he only posted 6 numbers so i couldnt really do anything with it since its not a complete design for that calc.

also i was wondering if sub displacement brings the tuning higher or lower?

Correct me anyone if im wrong, but that shouldnt affect the tuning just the internal cu ft of the box.

[stealth 113]

if you look at RE calc STEP 2 shows the cuts you would have to make to piece the box together. id suggest you cut all those pieces out, then write what piece is what with a pencil so you dont get confused.

Very good idea

yea he only posted 6 numbers so i couldnt really do anything with it since its not a complete design for that calc.

also i was wondering if sub displacement brings the tuning higher or lower?

Correct me anyone if im wrong, but that shouldnt affect the tuning just the internal cu ft of the box.

it does affect tuning. making your box space smaller while keeping the same port area and length will raise tuning. not significant enough to hear by ear in this case.

[stealth 113]

11 more posts to go jack3d. lol

[altoncustomtech 773]

if you look at RE calc STEP 2 shows the cuts you would have to make to piece the box together. id suggest you cut all those pieces out, then write what piece is what with a pencil so you dont get confused.

Very good idea

yea he only posted 6 numbers so i couldnt really do anything with it since its not a complete design for that calc.

also i was wondering if sub displacement brings the tuning higher or lower?

Correct me anyone if im wrong, but that shouldnt affect the tuning just the internal cu ft of the box.

Yep, it will affect the tuning. For a given port, if you add space to the enclosure (like putting a sub in with a smaller displacement) it will lower tuning. If you use up more space, you will raise the tuning. However, in MOST cases it's not going to be audible but it's the reason why several of the books out there on enclosure design and building suggest building the enclosure on the large side. It's easy to add some wood blocks or something to take up some space and bring the tuning up to where you want it, it's really really hard to add space.

[xiihustleix 6]

if you look at RE calc STEP 2 shows the cuts you would have to make to piece the box together. id suggest you cut all those pieces out, then write what piece is what with a pencil so you dont get confused.

Very good idea

yea he only posted 6 numbers so i couldnt really do anything with it since its not a complete design for that calc.

also i was wondering if sub displacement brings the tuning higher or lower?

Correct me anyone if im wrong, but that shouldnt affect the tuning just the internal cu ft of the box.

Yep, it will affect the tuning. For a given port, if you add space to the enclosure (like putting a sub in with a smaller displacement) it will lower tuning. If you use up more space, you will raise the tuning. However, in MOST cases it's not going to be audible but it's the reason why several of the books out there on enclosure design and building suggest building the enclosure on the large side. It's easy to add some wood blocks or something to take up some space and bring the tuning up to where you want it, it's really really hard to add space.

Now that i think about it that does make sense, thanks for correcting me.

[lymen 0]

This box get built, and if yes, how'd it sound on 4-500watts?

[braapboogcafish 1]

Damn sorry for not replying sooner. It sounds great and has great output, i like it a lot, slams in my 2000 xj. I like it so much I'm actually doing a .7 tuned to 31-32ish. just a bit less size than the sa8 box, and lower tune since ill be using a skar vvx-8.