Pairing IB with smaller 5.1 surround speakers

[larryw]

I've been reading about the wonderful world of IB for a while and I'm ready to start planning my own system. I have a decent projector and a 126" screen in a 17x12x8 room with great light control and a soundbar. It's not a dedicated home theater but I'll be able to put in some sound treatments but I would rather avoid large speakers. I don't listen to movies at "11" but would like the ability to experience LFE on movie nights. My question is this: 

Can I successfully pair something like the Take Energy 5.1 speaker system (with the appropriate receiver) with an IB box built with two 18" drivers and a Behringer EP2000 amp (a crawl space mount in front of the screen is possible)? Most of the time the small sub would work (tv shows, the kids watching something) but when I want the up the experience, would I be able to hear the dialogue and enjoy the ELF at the same time? The Take Energy satellites only go down to 115 hz but the sub covers 33 - 150 hz. If I did pair these speakers with IB would I want to lower the crossover for the IB and use the included sub to fill in the gap?

Thank you for any advice, 
Larry

[ThomasW]

Hi,

Issues using an IB with restricted bandwidth mains involve the potential to create a hole in the frequency response if a standard 80Hz or so XO point is used. Combine that with a potential to 'smear' the stereo image unless the IB is located on axis with the main speakers.

Whether of not the current sub can be used depends on how it's wired. Is the sub fed via the sub out from the receiver, or does the sub have a crossover so it feeds the main speakers from the main output of the receiver?

Do you have a floor plan or picture of the room with the location of the speakers and proposed location for the IB. If so that would be handy

[larryw]

I don't currently have the 5.1 speakers yet. I had planned to wallmount the satellites on the wall behind my couch on either side, the front speakers on either side of the screen and the center under the screen. I have plenty of space in the crawlspace to mount the IB manifold in front of the screen. 

[thedude306]

Looking at those drivers, they are going to cross over at 100+hz, too high IMO. Most likely they will start to roll off at 120hz. It's going to take some work with the sub to get it and an IB to blend OK so you don't have a dead spot in that 70-110 hz range.

[ThomasW]

You can run the IB higher than the normal XO point provided the sub is centered between the mains.

Those higher frequencies from the sub will roll-off at a steep rate so EQ will most likely be needed to avoid having a hole in the FR

[larryw]

Thanks guys for your replies. So it sounds doable but it would be better to step up to speakers like the Elac Debut B6 which is rated down to 44hz. One of the bigger issues is I would prefer to wall mount my main/center speakers since the path through the room is directly in front of the screen but every speaker I get excited about has a rear port.

[ThomasW]

The Elac port tuning is going to be below the crossover point to the IB sub. This means you can plug the port and it won't have a negative effect on the sound quality.

[larryw]

ThomasW,

That would be great if I could wall mount those speakers. I've read some about plugging the speaker ports, but how does one know that "the Elac port tuning is going to be below the crossover point to the IB sub?" 

And thanks for helping someone new to the world beyond soundbars

Larry

[ThomasW]

The tuning point for ported speakers is always the lowest frequency the speaker can play