Is my IB plan OK?

[mx48]

I have a 20L x 11W x 8H (1760 cubic feet) room that is decently acoustically treated.

Here is my IB plan:
-4 Exodus DPL-15's ($520 + shipping)
-Attic mounted cube box at front of room between speakers. (Have a friend who will build it for me for about $125)
-Behringer EP4000 ($349)
Total about $1000.

Is this what I should be using? Should the 4 15's be enough in this room?

Pardon the newb questions but, well, I am a newb. Just started researching this the last couple of days.

Thanks
Moto

[weverb]

Moto,

Welcome to the forum. Since our master has left us children to watch over things, I will try and help some.

Usually he asks for a layout or pictures of the space. This will help with layout suggestions. Also, have you done any response measuring to direct you where to place the manifold? Also, is the room sealed or opened to other spaces. How large of an area (how big of an attic space) do you have for the rear wave?

As for drivers... I would look at the Fi IB318's. Two of them will out displace all four of the DPL drivers and cost less. I would plan on four, but you can start with just two.

www.ficaraudio.com

The amp you selected is good. You also need to look into some type of eq. You don't need it now, but just be prepared.

And as always.... Thomas consistently points out to read the FAQ section.

[mx48]

OK
The room is sealed. Bass traps in the corners floor to ceiling. One recliner and 65" Plasma on entertainment center which holds components. A sliding glass door on the left wall with double curtains, one being a lite blocking curtain. Rest of walls are 1/2" drywall.

My attic is 20ft x 40ft. 8 feet high in the middle sloping to 0 feet. It has vents on the eaves if this makes any difference.

I have a BFD for eq.

I will do some REW sweeps and find what is the best spot for the sub.

I may go with 4 IB318's, just have to decide to spend the extra money. I definitely will if I need to to get good bass!

Pardon me if my word useage is incorrect.
Thanks
Moto

[weverb]

You can start with just two 18's, but build the manifold to hold four or plan on a second manifold at a later date. Get the first two up and working first and then you go from there.

Maybe we should know a little more about your current set-up and what kind of levels you are trying to reach.

Maybe some of the other knowledgeable members will post more tonight (other side of the world).

[mx48]

Onkyo 806 with Emotiva XPA-3 for LCR (may go to a UPA-7 as I think the XPA is a little overkill).
My LCR is Polk 70's with CS2.
Polk 40's for surround.
Ultimately I want to go with either Seaton Sparks or JTR triple 8's across the front, but those will have to wait for more money and after I get the perfect sub .

I have a Seaton Submersive but had a time getting it into the correct position for flat response. It is off the back wall about 3 feet in to the middle of the room now. I still have a null at about 87 Hz.

I like the bass to vibrate my chair and the mids to give me that good punch in the chest. I also want to feel the really low bass. However, I don't want my ears to bleed from the mids and tweeters while this is happening so I tend to run the bass a little hot.

Moto

Edit: I forgot to say my room is carpeted on a cement slab.

[weverb]

Nov 30, 2009 11:04:00 GMT -7 mx48 said:

I have a Seaton Submersive.....

I would plan on four 18's then.

[ThomasW]

Nov 30, 2009 10:34:36 GMT -7 mx48 said:

My attic is 20ft x 40ft. 8 feet high in the middle sloping to 0 feet. It has vents on the eaves if this makes any difference.

I have a Seaton Submersive but had a time getting it into the correct position for flat response. It is off the back wall about 3 feet in to the middle of the room now. I still have a null at about 87 Hz.

I like the bass to vibrate my chair and the mids to give me that good punch in the chest. I also want to feel the really low bass. However, I don't want my ears to bleed from the mids and tweeters while this is happening so I tend to run the bass a little hot.

Moto

Edit: I forgot to say my room is carpeted on a cement slab.

Can you get to the suburbs of Atlanta? If so you may want to pay a visit to Paul and his system......

The Octagon

You might want to contact him via email. Tell him ThomasW recommended you guys having a conversation.

[mx48]

Man, I just read thru some of "The Octagon". That guy is WAY over my head!

I did come across on interesting idea. He uses multiple surrounds at different phases, apparently using a Behringer DCX2496 which is about $275 (although I could be totally wrong since this stuff is so far over my head). I wonder if a normal HT could do this using about 6 speakers and adjusting the phase?

As far as going there to see it, maybe. I live about 3 hours+ from Atlanta.

ThomasW, do you have his email address? (tried to send you a PM but I cannot send one to an Admin.

Thanks
Moto

[jman]

With a 7.1 receiver you can already adjust the speaker distance for the side and rear surrounds (distance is phase).

If you split the sides to 2 pairs, then you might need to adjust phase. However, if you use dipoles on the sides (my preference), then there's no need for additional adjustment since dipoles scatter sound along the side walls.

If you use 6 monopoles and want to tune them for 1 chair dead center, then there might be a reason to align their phase. Having multiple pairs of side surrounds is usually for serving multiple rows of seating. If you want more diffuse sound, use a dipole.

[mx48]

OK, after much searching with REW and my sub, the best place for my IB is on the right wall just above (5 feet from the floor) and just behind (2 feet form the back wall) my right front speaker.
Behind the wall is 3 hallways leading to front door, a large bedroom and kitchen.

Questions:
1) Will this create any unusual problems?
2) If I use a cube manifold will gravity cause any problems for the top and bottom subs?
3) I am supposed to make the smallest manifold possible. What size should this be for 4 IB318's? The hole cut into the room can be whatever size is needed.

Or:
I can use a rectangular manifold. Dimensions would be 23.5" deep x 45.5" High x 18.5" wide. Corresponding opening would be 44" x 17". This would solve the gravity problem.

Or (and this is the aproach I am leaning towards now)-
I have room in the same area to make a line array of at least 2 but can do 4 18" subs or a faceted array with 2 on each side. Do you need less subs for a line array or the same for the same amount of bass? Also will securing it to the 2x4's in the wall make it rigid enough, if not what does it take to make it so (I will of course build the array to spec. double 3/4 layer, 2x4 frame etc.).
Man theres too many decisions to be made .

Just to review:
-4 IB318's. All 2 ohms and wire them in series to create 2 4 ohm pairs.
-Behringer EP4000 amp
-BFD for eq
-1760 cf sealed room, carpeted cement with acoustic panels.

Thanks again.
Moto

[ThomasW]

I've been vacationing in the desert southwest. My only internet access was an Edge connection on an iPhone, so it was basically impossible to make meaningful forum posts...

I'm back home now so questions will be answered in a timely manner

No one can PM me. PM's tended to be abused for questions that belonged on the forum so I turned them off

Sorry I thought Paul's email addy was on his website
[e-mail]

If you could provide us with some pics, a floorplan or graphic reference of the room and proposed place for the IB installation that would make it much easier to help you.

4 driver line array or 4 drivers in a manifold, they put out the same SPL

Taller manifold with 2 drivers on each side is a good way to go. Doing 2 =2 driver line arrays has the potential to smooth out the in-room response over a single source.

[mx48]

Looks like I am going to go with a rectangular manifold in the attic. What size do I cut the holes for Fi ib318's.
I will have the box built before the subs get here as my boxbuilder is going on vacation.

Thanks
Moto

[ThomasW]

You get the dimensions from the Fi website