ok, im desining a box for a 12" XXX, my maximum dimensions are 14" x 33" x 19", the recomended box size is 2.1 cubic feet for the sub. i want to tune at 28hz. one thing im confused about is how to port it, i was orginally planning to slot port it, however it seems that the box would take up alot more room if i did that. what confuses me is how come if i were to use a 4" diameter tube as a port, it would only have to be 17.64" long, according to this: Port Size Calculation
why is it so much smaller when using a round port than a slotted port? is there any advantage to using each? help is much needed, as the gained trunk space would help alot if i could build a smaller box because of porting with a tube..

thanks

 

if you are set on using a box 2.1cf @ 28hz. try going with 36 sq" of port 53.5" long. you are most likely going to have to use the slot port type of port becase you will not be able to fit a single round port in that box.

the length of the port is dependant on 3 things.
1. port area, to find the area of a round port : (3.14 · (radius2)) and to find the area of a slot port its hight x width
2. size of box, make the box larger the lenght of the port is decreased, make the box smaller, the lenth of the port increases
3. tuneing, make the tuning higher the lengh of the port become smaller, make the tuning lower the length of the port becomes larger

if a round port has the same amount of area a slot port ( with all else being equal ,tuning ,box size) then there lengths of the 2 differnt types of ports will stay the same.

 

i also got some advide from people on the caraudio.com forum, and i think im going to go with 3 3" diameter ports totaling 32.52" long, would 3 3" ports be enough port diameter for an xxx? these are the kits i was planning on buying:
http://www.partsexpress.com/pe/pshow...68-350&scqty=3

 

3 3" areos should be enough area

 

are you sure, becuase it wouldnt be much of a problem to go with 4 3" ports, i would if there is even a chance that thre might be port noise with only 3 3" ports

 

Hey Hoful

I was wondaring if you can help me with a design for my XXX 15" the spcs are

RE 28.0HZ, RE 1.9DVC, QMS 4.68, QES 0.55, QTS 0.49, SD CM2 810, VAS 123.3, XMAX 1 WAY 32MM, BL 17.1, SPL 1W/1M 17.1, SPL 1W/1M 88.7,

I have about 17" high, 34ish wide and I guess as deep I need. I listen to Rap bass in the music and on RE web site sealed is 2.0 ~ 4.3 cft take your time and Thanks clown 78

 

i just looked at the maximum space you have to work with and how exaclty do you plan on fitting those 32.5" long ports in your box?

 

pm me. im sure we could work something out

 

i thought that it was 32.5" long with all 3 ports combined? please tell me im right, i just built the second box, and ordered the 3 port kits (max of 17" per kit)

 

nope each port must be that length