Long port vs less port area
11-06-2010, 02:00 AM
#1
Long port vs less port area
The carstereos.com port calculator says a 12" with 32mm xmax needs 53.x" of port area when tuned to 31hz for it to reach full excursion. The port becomes really long. Is it better to have less port area for a shorter port or does the sub need to breath?
11-06-2010, 06:57 AM
#2
dont go by that unless you know you will reach xmax everytime...lol
it all depends on box size and amount of power being applied now and in future plans... if you have a 12" with 1000 watts of power without plans to upgrade... your sub will not reach xmax( keep in mind if you play below port frequency it may happen, but that is not because of port size)
assuming you are using a large box of 3 cu ft plus displacements you still will not reach xmax of 32 mm , rather you would be in a very safe area of the xmax curve
it all depends on box size and amount of power being applied now and in future plans... if you have a 12" with 1000 watts of power without plans to upgrade... your sub will not reach xmax( keep in mind if you play below port frequency it may happen, but that is not because of port size)
assuming you are using a large box of 3 cu ft plus displacements you still will not reach xmax of 32 mm , rather you would be in a very safe area of the xmax curve
11-06-2010, 10:49 AM
#3
It's a box for a new BTL 12 N2.
Port 3.75 W x 14.5 H x 45.375 D
1" MDF, 3" baffle, sub sits on 2"
Outer dimensions:
16.5" H x 24" W x 30" D
2.9559 cubes @ 31.03 HZ
I figured the xmax went up to 32mm with the hi xmax coil?
I'm trying to get the most out of it without killing it.
Also for SPL... same dimensions, just the port is 6.5" W x 25.75" D, for 3 cubes @ 50 HZ.
How do those look?
Port 3.75 W x 14.5 H x 45.375 D
1" MDF, 3" baffle, sub sits on 2"
Outer dimensions:
16.5" H x 24" W x 30" D
2.9559 cubes @ 31.03 HZ
I figured the xmax went up to 32mm with the hi xmax coil?
I'm trying to get the most out of it without killing it.
Also for SPL... same dimensions, just the port is 6.5" W x 25.75" D, for 3 cubes @ 50 HZ.
How do those look?
11-06-2010, 10:19 PM
#6
11-07-2010, 06:10 AM
#7
As for Barrie, no I will not be able to make it and the twins are still waiting on recones.
Last edited by DeadlySones; 11-07-2010 at 06:45 AM.
11-07-2010, 07:48 AM
#8
the more a sub travels, the more air it will move, which measures a hiher SPL number... but first you need the power to move the sub that much
loading, box size, type and tuning frequency determine your impedance rize which chages at every frequency
11-07-2010, 08:06 AM
#9
--SPECIAL ED--
Join Date: Aug 2010
Posts: 138
yes, but say you play wayyyy under tunning the sub moves alot and isnt very loud
also.. what kind of power will you be running to the btl
the 18s i have took 2 audiopipes at 1ohm to get moving with 3k on it it didnt move more then 3/4" inch
also.. what kind of power will you be running to the btl
the 18s i have took 2 audiopipes at 1ohm to get moving with 3k on it it didnt move more then 3/4" inch
11-07-2010, 09:35 AM
#10
you dont design boxes for daily listening to play below port... it just doesnt work that way..so dont even ask that question.
Last edited by MTA; 11-07-2010 at 09:40 AM. Reason: that is also the purpose of the subsonic filter on most subwoofer amplifiers
