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Building speakers/IB sub

post #1 of 9
Thread Starter 
I'm planning on building my own theater setup.

I'm thinking of going with a Fi IB 12. Not sure what to power it with, and am unsure of my receiver right view.

Then my second concern is building speakers. I'm looking to go with a 2.1 setup for right now into a 7.2 eventually.

So I just need help with IB sub enclosure, and how to build up the other speakers, or should I go with my own IB and use something like the Polk Monitor 70?
post #2 of 9

12 is on the small side for IB.  It will work but normally you would want a little more displacement.  What is the size of your room? 

 

Additionaly IB works best in pairs opposed to cancel out vibrations and trust me there will be vibrations......

 

I posted this in your other post too:

 

Cult of the Infinitely Baffled

post #3 of 9
Quote:
Originally Posted by Pj0312 View Post

I'm planning on building my own theater setup.
I'm thinking of going with a Fi IB 12. Not sure what to power it with, and am unsure of my receiver right view.
Then my second concern is building speakers. I'm looking to go with a 2.1 setup for right now into a 7.2 eventually.
So I just need help with IB sub enclosure, and how to build up the other speakers, or should I go with my own IB and use something like the Polk Monitor 70?

There's a lot there. An IB build, speaker build, and the other items as well. The diy loudspeaker crowd here is superb, they'll have to cover that, but I can help for sure with the IB.

A front loaded IB array, or manifold IB? I'd recommend a manifold if your situation permits.

Unless you absolutely need the 12 due to size constraints, you'd be vastly better off with the 18 for a variety of reasons...., specifically the Fi IB3-18. I'm unsure of your room cubes (HxWxD), however it's likely you need four 18s (there's a discount for four also) and you can power them with a Behringer EP4000 (or equivalent). If you have the space, ideally you should split them into two separate-two driver manifolds.

Some more room and usage details would be really useful. any room dimensions, pics?
post #4 of 9
Thread Starter 
Unfortunately due to size issues I'm stuck with a 12.

I still live at home with the parents so that's why I'm sticking with a 2.1 for now. Plus I need my speakers back because the TV speakers are getting on my nerves! I want to say my room is 16x8x16, but I can measure and get exact measurements.

I know a 12 won't get that low that I want, but for now it will be enough. Plus I have to master my skills so this is good.
post #5 of 9
I believe the 12 has the same excursion, so perhaps it'll go as deep. However, the 12 is much less sensitive than the 18 and the 18 doesn't cost a great deal more. If you're wanting to stick with only one driver, I'd consider a sealed approach.

The exact room measurments aren't nessesary, what you listed is fine.
post #6 of 9
Thread Starter 
I was thinking IB because if the ability of the ability to go lower on less power.

Right now will be one driver, but you think sealed will perform better then IB?
post #7 of 9
Quote:
Originally Posted by Pj0312 View Post

I was thinking IB because if the ability of the ability to go lower on less power.
Right now will be one driver, but you think sealed will perform better then IB?

That reason, is an outstanding reason and one I speak of often.

IB, when executed and optimized correctly is superb. However, if I was limited to one driver, I'm not sure if I would utilize an infinite baffle alignment.

Typically, one employs more drivers when implementing an IB approach to subwoofing. I'm not well versed on a single IB driver configuration, but perhaps there are some workarounds. High-passing the IB, even quite low, ie., somewhere 20 and below, could get some of the output back and maybe closer to what a single sealed sub would do.

It's a typical IB power conundrum. With a sealed you have an acoustic limiter, and you can have more power on tap above the knee, without concern below the knee. With the IB, you power according to excursion capability, with the sealed you power more according to thermal capability.

You could easily hit Xmech with the IB, yet still be way under the thermal limitations. This is good and allows a very low compression, highly responsive system. But typically you make up for the lower power handling with additional drivers. With a small sealed you have all the power availed to the driver both above and below the knee. This is due to the back-pressure associated with the lowest frequencies, inherently limiting the driver. This must be overcome with a strongly EQ'd response, boosting the power needed below the knee to overcome the incredible pressure involved with the deepest frequencies. Thus, properly designed, the thermal limits are encountered prior to the physical limits. Exactly opposite of the IB, whereby the physical limits of excursion are encountered at quite modest power levels.

Tell me, how close to the proposed IB location is the primary listening position?
post #8 of 9
Thread Starter 
I'm only 3-4 feet away. Not that far away.

I might rethink the IB until I can support multiple drivers. I might just go with sealed until I can. If that's the case I will have to rethink my sub choice.A
post #9 of 9
Well there's many others here that are quite savvy in this regard, maybe more discussion will flesh out a better option.
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