6 re 8's. box plans

[req 5,000+ posts]

ok, i got a grandam with an empty trunk (friends car)

he is looking at getting 6 re-8's for it. he has a PPI 6ch 100w per channel amp.

perfect, no?

heres the picture

now, each box is 1.5 cubes, problem is i need to know how big the slot port should be when tuned to 35hz with 11mm Xmax.

we are gonna build the base and the port outta MDF for ease of construction and because it would require less fiberglass =)

the rest will be solid fiberglass to the contour of the trunk.

i know how to get everything else made up, i just need to know how low profile the ports can be to make them that flat\long and not too deep into the enclosure.

i was thinking of making it about half way into the enclosure, prolly 2-5" tall and 10-20" long

anyone have a calculator that i can use to calculate the INSIDE volume of the port where i can give it dimensions and a freq and it will generate somthing near that size? or maybe a formula that i can play with?

it should look really nice when he gets the $300 to pay for it all!

on a side note, isnt it like buy 3 get one free for the 8" re's? so he can buy 5 and get the 6th free- and it would only cost ~$250? //content.invisioncic.com/y282845/emoticons/inlove.gif.6846f78f06b405429ef3a00129788a2a.gif

what do you all think?

Click to read more...

 

[req 5,000+ posts]

noone knows anything about anything then i suppose?

not even a 'good luck?'

 

[saywhat? 5,000+ posts]

theres a lot of math involved.....jmac will come soon...may have to pay him

 

[req 5,000+ posts]

i just need a calculator and\or formula that i can use to figure it out =\

 

[goinpro 10+ year member]

to the best of my knowledge they are not doin that deal anymore with the buy 5 get 1 free...but u can always ask it wont hurt...

 

[saywhat? 5,000+ posts]

talk to mark //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif i always reccomend this guy as he was a huge help with me.

 

[LoneRanger 10+ year member]

http://www.caraudio.com/vb/showthread.php?t=63426

 

[req 5,000+ posts]

http://www.caraudio.com/vb/showthread.php?t=63426

WEEE thanks! this should help alot! i wonder why i couldnt find it on the search tho //content.invisioncic.com/y282845/emoticons/tomatoface.gif.6507032fedd1868ec0a6a447bb29a18a.gif

i still have this problem though. i DONT have the dimensions of the box. its going to be FIBERGLASS... i know its gonna be 1.2 cuft @ 37hz (for MY box) and 1.5cuft @ 35 for his box. but- how the hell do i fugre a SLOT style port without the box dimensions?

The formula to figure the displacement of a slot port is ((W+T) x H x D), where W = width, H = height, D = depth and T = board thickness.

im building the port and the bottom of the box from 3\8 mdf. so thats .75 - but where do i get width and height? and how the hell does this number (when i get it) have anything to do with the tuning?

is there another calculator to figure out what the port volume\tuning ratio is?

none of this is actually stated *clear* anywhere. its always PORT VOLUME or TUNING. i dunno, im just confused... //content.invisioncic.com/y282845/emoticons/up2something.gif.dd110ecf3ae4b76050d87598f2f8de7c.gif

on the JL audio site;

Where Av is the cross-sectional area of the port (in square inches),

Lv is the length of the port (in inches)

and Vb is the enlcosure's net volume (in cubic inches).

*courtisy of JL audio

i dont know the ports dimensions, so how on earth am i supposed to figure out the tuning?

 

[Dogmeat]

Uhmm...unless math has changed......3/8" = .375....... 3/4" = .75

What I want to know is when you get a fluid designed box how can you acurately calcute the volume without building it and filling it with water. I mean all the smooth shapes don't really fit a formula very well.

Side note Good luck

 

[req 5,000+ posts]

eaither use water, or sand or somthing else using a container taht you know its internal volume, and basically count how many cups. u use an 8-count measuring cup ;

1 US cup = 0.008 cubic foot

box is gonna be 1.2 cuft so;

1.2 \ .008 = 150 cups

my measuring cup holds 8.. so;

150 \ 8 = 18.75 times.

ill most likely use packing peanuts. as long as you dont push them in, and let them retain the space between... its fairly accurate. i tested it with a 1cuft box, i filled it with water using the measuring cup system, and then i used peanuts, and it was almost exactally the same. so it works fine.

i still dont know how to measure a slot port without having the box dimensions or the length\width\height of the port though... anyone off the top of their head have a 1.2cuft box tuned to about 37hz? rofl.

and i just multiply it out

(sorry about the number, i was in a rush and just wrote .75... i forgot the 3)

 

[supa_c 5,000+ posts]

pointless post. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[req 5,000+ posts]

well ****. i suppose im never gonna build my box then eh?

 

[supa_c 5,000+ posts]

if you learn that stupid formula maby.

 

[req 5,000+ posts]

ok. then help me out for a second.

instruct me on how to use a formula that isnt around. when i do NOT have the height\width\depth of a FIBERGLASS box that is not made yet. and i do NOT know how big the port should be?

all the formulas ask me to enter dimensions i do not know. so enlighten me. ive been searching for like 5 freaking days now.

only numbers i know are;

37hz

1.2cuft

11mm xmax

 

[supa_c 5,000+ posts]

just think up an enclosure that is 1.2ft^3.

http://www.the12volt.com/caraudio/boxcalcs.asp

fiddle around with this site, it might help you, but it wont solve the problem if you dont know how to do the formula.