Front and Rear IB setup

[camusmuse]

First off thanks for the great forum, been lurking and reading for a while now. I'm not new to speaker building, but I am to IB.

I am currently working on my Home Theater and have both attic space and basement space for IB options, though the basement is probably the best option for my setup.

Basic breakdown of my room. Eight foot ceilings and about 2400 cu.ft.(basically same space in the basement) Front of room has built in shelving on the right and left sides on top of also built in cabinets all along the bottom(wall to wall) and space right in between the shelves for the flat screen on top of the cabinets. My "high" frequency speakers(left/center/right for BOTH front and rear, as well a single ceiling mounted speaker for the middle of the room), will play information down to around 40 or 50 HZ. I would like the IB to play as flat(and loud of course) as possible to fill in the bottom end, from that 40 or 50Hz *ideally* down into the 5hz range.

I have a pair of Crown PSA2 for the IB subs, two(soon to be three Parasound HCA-855a) for the high frequency drivers. The highs will be three way, with the tweets and mids passively crossed over and a ten or twelve(still havent decided on which yet)that will be active band passed between the IB and the mids/tweets. I also have a couple EQ options including a Behringer dcx2496.

Now for the interesting part.... I have a surround processor(Parasound AVC-1800 and a CSE 6.1 Center Surround Expander) that in addition to the"extra" high frequency outputs previously mentioned, also has outputs for both front AND rear subs. I have read here in several places that rear IB isnt the best idea. But for my application it would only operate when there is rear information.

The front IB will be in the center of the cabinets along the bottom of the wall in a horizontal line array "vented" to the basement(14.5"x72"), under the flat screen. Still havent decided on the rear, but most likely will do the same thing. I will either build a similar "built in" cabinet or do a manifold/single line array playing up through the same dimension "vent) 14.5"x72". Obviously 15's or 18's will have to be angled to fit between the joists.

Any thoughts, ideas, or opinions would be greatly appreciated.

[ThomasW]

Hi,

Seems like you have everything pretty well thought out.

As a result I don't have anything to add other than to say IMO targeting 5Hz is not all that important

[chrisbee]

I'd like to hear more about angling your drivers between the joists.

This isn't the normal way of doing thing. So I'm wondering what exactly you have in mind. It may not even be necessary if we understand more about your plans.

[camusmuse]

Thanks ThomasW, yeah....its been in the planning stage for far too long....lol. So do you think that I will have problems with front and rear IB if they are running some of the same information? I am thinking that the front will run both front and back and the back will just be "added" from the way the CSE integrates into the system(information gleaned from the rear channels). My best guess is that I will just have to build it to find out, but was hoping that someone might have a similar setup. As for the 5hz....I guess I just needed something to shoot for. I know that there is some information down there in certain movies, would be nice to get as much as I can out of a system such as this. But I would probably be happy to get down to 15Hz or even 20Hz, at least for a while.....

Chrisbee -- Well basically I need to keep as much headroom in the basement as possible because it is "finished"(or will be), but I am running a short soffit(5" or so)all around the room . Since I plan on running at least 15" speakers, or hopefully 18"s(finances permitting); they wont fit flat between the joists for a line array(4 front and back). In the front of the room the bottom cabinets(upstairs) will accommodate hiding the speakers, but in the rear I will either have to build a similar cabinet(REALLY dont want to), or drop the speakers down inbetween the joists which are standard 16"OC. So my thought was to add to the bottom of a joist, fill in the sides(obviously), and give enough linear dimension on a baffle board to fit the speakers. Then vent the IB through the soffit to the basement, and up through the floor with some cast iron grates. I have thought about running the back speakers upside down with the basket up in the joists, but I still dont think they will fit well enough, and I dont want the speakers to be visible at all from the basement. Need to get speaker(s) in hand before a final plan is determined, I suppose. Or a very detailed drawing with dimensions of the speaker....that being said....

Been doing alot reading since I first made this thread. Have pretty much decided on the Fi IB drivers(or whatever they are called when they come out with the "new brand name"). I have some car speakers with that basket design(old Eclipses) and was impressed with their performance. Plus Fi seems like a good place to do business.

[ThomasW]

There are a 1/2 dozen or so IBs with front and rear drivers, to date no one has had any significant issues.

Part of a successful install is understanding the relationship between the geometry of the room, the location of the listening position and the use of good bass traps

[camusmuse]

Thanks again for the info Thomas. Half a dozen huh? Kinda puts me in an exclusive club....I always was a bit ambitious....lol. ;D

If there was any way to get in contact with one or more of those that have done both a front and rear IB it would be greatly appreciated. PM, or emails are fine......"myscreename"@yahoo.com. If they decide to remain anonymous I certainly understand.

As always, any and all information would be greatly appreciated. Mainly just waiting for the new "FI" IB subs to become available, and maybe wait for a few people to try them out before I start my build thread.

I currently have (4)12" Peerless subs(the old ones from the 90's) in ported boxes....two front two rear....it gets loud, just not low..... Of course the boxes werent designed for the subs, they were just leftovers from other speaker projects or boxes that were parted out. And they are grossly underpowered with a OLD Parasound stereo amp. The Crowns would smoke them(well more appropriately my heavy volume knob would....lol). I ran two of the the old Peerless in a car audio setup, off an Autotek 7300...NO CLIPPING...and they released the magic smoke, but they did last about a week and sounded pretty good. Great speaker, just not alot of power handling. I think they might end up in a tube amp project...someday.

[chrisbee]

If you already have subs front and rear you are already an expert on whether these will work in your room. IBs are no different form any other sub in this respect. While you wait for drivers you can use REW (or similar) to double check the ideal positions for the IBs.