Line array vs ported..

[Rodny Alvarez]

Hey guys,

4 RL-p 12s or 15s for the ported box and 4 RL-p 15s for the line array.
My room is 2.122 cubic ft.
If I go with the line array I will have to build two, one on each side (2 15s on each one) what I don't understand on a IB set up is how far the back wall needs to be from the sub? I know you need x amount of space for the back wave, example... so if you have 1000cft of back space and the back wall is 15ft from the sub, now you have 1000cft of back space but the wall is 3ft from the sub, what will be the difference between the two?
what I want to know is at what distance the back wall needs to be before it will affect the response of the subs?
I read and posted some ? in the cult , but I want to hear some comments from you guys.
For the ported box I have about 20cft air space total, it will be 12ft in front of the listening position. It will be about 12ft wide x 19" tall and 16 deep.
Does it matters here how far the back wall is from the sub?
I want to build a L shape square or rectangular ports, is this OK?
I watch a lot of movies and listing to some music, I will have to say about 90% movies 10% music.
Want to hear and feel the bass

[jagman]

The volume in the back space should be 10 x the combined VAS of all four drivers. You can do 4 x the combined VAS, but 10 x is better. 4 RL-p 15s in an IB should rock your world. Just ask Darren. The output will be more than sufficient to meet your needs, and the SQ will trounce the ported sub. Add to that the fact that you don't have to build the enclosure and your decision is made for you.

[Sonnie]

Rodny.... are you meaning to decide between a manifold or line array IB... or are you actually considering a ported box sub?

If I remember correctly in your room... I would go with the manifold route on the left side since you pretty much have unlimited attic space behind that wall.

[Rodny Alvarez]

Sonnie wrote:

Rodny.... are you meaning to decide between a manifold or line array IB... or are you actually considering a ported box sub?

If I remember correctly in your room... I would go with the manifold route on the left side since you pretty much have unlimited attic space behind that wall.

When i put my sub on the left side it didn't sounded good, I guess because of the shape of the room
I can't do the manifold because one of the subs will be to close to the wall for the back wave.
I'm not sure if I go with the two line arrays I will have some phasing problems because of the room shape
The subs on the sides will have to be flat not angle.
My SVS is on the right side of the room behind the RF main.
Slide1.JPG
The right side is open to the attic next to the door and the stairs.

[Rodny Alvarez]

Here is another view..
Don't pay attention to the box this is just so you can get a idea of the room.
Slide1.JPG

[JCD]

If I remember correctly, the ideal IB actually has subs in two locations directly behind the front L/R speakers. They aren't done as often simply because a manifold is supposed to be easier to build/implement.

As for the phase of the respective subs -- as long as everything is equidistant, then I'd think you'd be ok. It'd be the same as adjusting the phase of a manifold IB.

JCD

[Sonnie]

Did you post these design images over at the Cult and what did ThomasW say about them?

[Rodny Alvarez]

Thanks for the help,
I will do the line array on each side.