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View Full Version : is a 4" port enough for a 12" bm???



~Magick_Man~
01-13-2007, 12:31 AM
i am building a box tomorrow and it turns out i have the room to make it a ported box so i want to go that route.

the box will house 2 12" si BM's
there is no good area to place 2 ports next to each other so i am planning on seperateing the 2 subs and each chamber will have a 4" pvc port

does this sound like it would work?

i will have some pictures of what i am trying to do in a little while

Thanks,
~Magick_Man~

~Magick_Man~
01-13-2007, 12:52 AM
here is the basic idea i have right now.
it might change a bit but that is pretty much it.


http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso1.jpg

http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso2.jpg

http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso3.jpg

http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso4.jpg


so if i dont make 2 seperate chambers will the subs really utilize the area in the middle?


Thanks,
~Magick_Man~

xluben
01-13-2007, 12:55 AM
you need double that port area.

have fun trying to make it fit :(

bdawson72
01-13-2007, 12:58 AM
heh, that truck will be happy after you are done though

~Magick_Man~
01-13-2007, 01:00 AM
you need double that port area.

have fun trying to make it fit :(

:crap:

i am using a port calculator and for 2 4" ports in a 2 cube box tuned to 34 it says they need to be 26.xx"

is that each?

if it is then that *****.
because i can fit in up to 14" long ports.

would i be better off with 2 3" instead of 1 4" ?

~Magick_Man~

10W3dodge96
01-13-2007, 01:26 AM
heh, that truck will be happy after you are done though


Yeah that guy is going to be very happy.:D

NoLimit
01-13-2007, 01:33 AM
heh, that truck will be happy after you are done though

:)

~Magick_Man~
01-13-2007, 01:49 AM
this should be a little better.

25sq-in of port per driver

http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso5.jpg

http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso6.jpg

http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso7.jpg

http://i65.photobucket.com/albums/h202/magick_man9579/Box%20for%20other%20justin/iso8.jpg



~Magick_Man~

10W3dodge96
01-13-2007, 01:50 AM
did yo use those port tubes on NoLimits box?

~Magick_Man~
01-13-2007, 01:54 AM
did yo use those port tubes on NoLimits box?

no i used a mdf slot port on his.
i am trying to stay away from that on this box because i dont want to mess with angling the port like it is on your box.

and i have a ton of 4" pvc pipe so i might as well use some of it.

~Magick_Man~

xluben
01-13-2007, 01:55 AM
um, what's the volume of the box (after displacement) and how long are the ports?

adding two ports like that (and keeping them the same length) is going to make the tuning A LOT higher (10hz +) possibly.

PatFitz9
01-13-2007, 01:58 AM
yeah, thats probably not going to work... the port calc is EACH port, so adding more is just making your problem worse

~Magick_Man~
01-13-2007, 01:59 AM
um, what's the volume of the box (after displacement) and how long are the ports?

adding two ports like that (and keeping them the same length) is going to make the tuning A LOT higher (10hz +) possibly.

i dont have the exact number yet but i have about 2.2ish per driver after the port is taken out.

i was looking at a single 4" at 11.xx" long which would supposedly give me 34hz with a 2cube box
now i am looking at 2 10.12" long with 2cubes after displacement which should give me ~36hz

i will end up with as close to 2.0 per chamber after the port and sub is taken out.

~Magick_Man~

~Magick_Man~
01-13-2007, 02:00 AM
yeah, thats probably not going to work... the port calc is EACH port, so adding more is just making your problem worse

yeah i figured that.
i was using one at 11.xx long shooting for 34hz
now i am using 2 at 10.12 (i think) shooting for 36hz

~Magick_Man~

~Magick_Man~
01-13-2007, 02:03 AM
so i guess the real question is will 2 4" ports 10.14" long in a box 2.0 cubes after displacement give me a 36hz tuning?

i am judging this off the port calculator from carstereo.com

~Magick_Man~

xluben
01-13-2007, 02:05 AM
http://www.psp-inc.com/psp-inc.com/cgi-bin/port_length_calculator.cgi

volume: 2
tuning: 50
port dia: 4
no. of ports: 2
length: 10.62

:crap:

~Magick_Man~
01-13-2007, 02:15 AM
:mad:
wtf
that is gay

do you know if the box volume you put in includes the port displacement?
the other site said 2 at 10.14" each gave you 36hz with 2.0 cubes after displacement.

~Magick_Man~

xluben
01-13-2007, 02:19 AM
http://www.carstereo.com/help/Articles.cfm?id=31

entered the same things, and got...........

10.62 inches!

don't know what you're doing.

btw, pi x r^2 x length / 1728 for port displacement.

~Magick_Man~
01-13-2007, 02:28 AM
hmm i guess i entered it wrong.

well shoit...
i think i might just build a sealed box since i dont think i can squeeze in enough port area to have no port noise.

~Magick_Man~

10W3dodge96
01-13-2007, 02:32 AM
hmm i guess i entered it wrong.

well shoit...
i think i might just build a sealed box since i dont think i can squeeze in enough port area to have no port noise.

~Magick_Man~


So your going to have to go with a Sealed Box.

PatFitz9
01-13-2007, 02:33 AM
you entered it in for one port... why can't you just have one port? it's probably not enough, but you can see if you like it

~Magick_Man~
01-13-2007, 02:37 AM
it looks that way.
or tune it to 50hz....

if i go sealed i can fit both subs on one side and you wont have to move your amp or anything else which would be a plus.

and i would almost bet money that the pair of bm's sealed will be louder than the r's ported.

~Magick_Man~

~Magick_Man~
01-13-2007, 02:38 AM
you entered it in for one port... why can't you just have one port? it's probably not enough, but you can see if you like it

well from what i am told a single 4" port wont be near enough port area for one sub.
and i dont want to build this thing then have it make bad port noise.

~Magick_Man~

10W3dodge96
01-13-2007, 02:41 AM
Why dont you make the ports like I made them on my Boxes?

PatFitz9
01-13-2007, 02:46 AM
i'm sure 2 boxes would fit on one sheet of MDF. it just takes some more cutting time.

mazdakid
01-13-2007, 11:04 AM
couldnt you just face the subs and ports differently and have more room for port length?

Duke
01-13-2007, 11:10 AM
1 4 inch port works just fine for a 12. If there is too much port noise, just stuff it and called sealed. Unless you can figure out how to get dual 4s in. PVC elbows ftw.

Duke
01-13-2007, 11:16 AM
If the ports are facing down, there shouldn't be an awful amount of port noise.

10W3dodge96
01-13-2007, 04:50 PM
Man if this box can be ported it will kill the type R's ported

NoLimit
01-13-2007, 08:16 PM
Why dont you make the ports like I made them on my Boxes?

because you just cut holes? lol

pvc is your best bet in this application

those BM's are still gonna pound :D

squeak12
01-13-2007, 08:24 PM
When using more than one port, you need to divide the box volume by number of ports and then calculate.

2 cubes net
2 4" Aeros

Calculate what you would need for 1 4" port with 1 cu. ft. net.

~Magick_Man~
01-16-2007, 09:31 PM
well i ended up building the first box i posted with a single 4" port per driver and i am happy to report there is no noticeable port noise when installed in the truck.

the fact that they are down firing might be contributing to this but in any case i have been informed by the new owner that "OMG THEY ARE SO LOUD, and with no port noise"

so i guess i dodged the bullet this time.

~Magick_Man~

~Magick_Man~
01-16-2007, 09:32 PM
oh and thanks to everybody that helped me.

~Magick_Man~