SUB FOR MY LIVING ROOM

hello ALL.
I WANT TO BUILD A SUB FOR MY LIVING ROOM. 20HZ - 100 HZ. 120-130 DB.
I WANT to BUILD a cubo box.
THE Problem is. he STERT in 40HZ. AND I WANT THE SUB to go Under 20 HZ.
Which Modifications i need to do to the box? to go uder 20 HZ.
it is for my Living room.
the Drivers I have is.
RCF L18-p200. cubo 18
OR DRIVER DAS G35a cubo 15
OR JL AUDIO 12W7 cubo 12

Which one will go lower in a cubo box?

OR do you have a Better plan to build.

Sorry on my poor English.
eli.

my amp is 1500W in 8 ohm. power isnot the Problem.

How big is your living room? The reason I ask is most boxes like the cubo need space to operate correctly. For home use reflex cabs normally do the trick. The thing is certain box designs drop very low but have reduced spl where others give good spl but dont drop too low. Id go for a reflex design like the B&C sub 18 design which will excell with both music and movies.

20hz isn't realistic with these components.

Tony they will do 20hz but at about -30db smiley36 . 30-40hz for a living room is abit more reallistic which you can get from a reflex enclosure.
There are designs that will drop down lower but this requires large boxes but like Tony said not with those drivers.

build a stepped horn and you'll get 20hz

Only if you use a chassis speaker with that kind of spec.

saul wrote: build a stepped horn and you'll get 20hz

With a lab 12, bit big though.

edit- can you see the picture as it aint showing on my computer.