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Discussion Starter · #1 ·
I am a finishing a theater and have a space under the stairs that measures out to approx 90 cu ft. Would that be enough room for a small infinite Baffle setup using 12s. Or would I be better off using the space for a ported enclosure.
 

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Elite Shackster
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90 cu ft is enough for an IB. You may have to use 15's rather than 18'a, but you will still get all the performance you will need. With 90 cu ft, you could use upto 8 x 15" IB315's and the system would take 500 watts per driver.
 

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Discussion Starter · #5 ·
That is great news. I may make a temp baffle to just test the one Dayton 15 hf driver I have to see how it would sound. If I were to make the baffle 2 1/4 thick is there a reason that I couldn't mount the drivers flat along the wall. Now I just wish someone in Salt Lake had a infinite baffle I could hear.
 

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Elite Shackster
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Be aware that in an IB installation the cabinet has little to no effect on the sound of the driver, you just get the raw sound. If the driver isnt designed for IB use it likely wont sound right.
 

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Discussion Starter · #7 ·
I am aware of that. I thought I read were someone had modeled the Dayton ib sub and the hf sub was the same.
 

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Discussion Starter · #8 ·
One other thing I was going to mention was that in another thread you mentioned that you can port a large enclosure and virtually turn it into a large llt. Would that be a possibility with my 90cuft space. If that is possible which would be better and if the llt better what all would I need to do to prep the space. Thanks in advance for any info.
 

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Elite Shackster
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It has been done before. The principles dont change when you increase the scale, and porting simply uses the rear wave of the driver to increase output. You would need likely need to make the space more like a normal enclosure though as a room or attic space etc is usually pretty leaky. Ive never tested what a leaky enclosure on that scale would be like when trying to build an LLT.

The best thing to do is model it based around the enclosure size you have and see how it looks. The system will be very efficient though and wont need much power at all.

As for the choice of drivers, I would need to model them and see how they compare. I am not on my own computer right now, so will try get to it later.
 

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Elite Shackster
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It may well be better to panel out the space so you know the exact volume and have full quality control over the enclosure. Do you have a favourite driver you are considering then?
 

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Discussion Starter · #16 ·
I don't know too much about any of the drivers is ther any that would be better then other with that large of a space
 

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Elite Shackster
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Well, if your running cabs that large, I would take a good look at IB drivers. You wont need a super high power handling motor and a higher Qts motor would be my preference as well. A pair of Fi IB318's for example, in 90 cu ft, tuned to 15hz and given 500 watts, will deliver over 120db in room flat to around 13hz and models to not even need a HPF.

Thats stellar performance, and the IB drivers are cheaper than ordinary drivers as well, which is another bonus. Only needing 500 watts total power means both your drivers and amps will run cool which in turn contributes to nice clean output. If you wanted to run to 10 hz you easily could, depends what you want to do really.
 

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Elite Shackster
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There is that. But with such a large space something like a pair of 12's wont cut it IMO. Getting a pair of 15 or 18, which is what I would personally aim for, is really going to push that budget unless you buy much cheaper drivers. He could of course use a single 18, in which case I would lean even more towards the IB driver, purely for sound quality goals. I think a single IB318 tuned to 12 hz in 90 cu ft would work well and the system will only need 250 watts.

I just think that in such a large cabinet, a normal driver isnt going to sound right (think of a sealed sub with a .3-.4 system Q :sick:) and the IB drivers will be the most suitable for this application.

There is then always the option to add in the second driver in the future and tweak the tuning if needed etc etc.
 

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I just think that in such a large cabinet, a normal driver isnt going to sound right (think of a sealed sub with a .3-.4 system Q :sick:) and the IB drivers will be the most suitable for this application.
Bear in mind that Q is two things - mechanical and electrical. IB drivers manipulate Q mechanically but you can just as easily manipulate Q electrically with equalization. We can shape the frequency response any way we like, and that's all Q is. bviously you don't want to throw away efficiency before equalizing, but beyond that, any sufficiently low Q is fine.

Generally we shoot for a low Q box because a box mechanically raising Q tends to color the sound.

Room lift is also another factor in the Q we actually perceive. It`s a mechanical factor, and likewise it can be EQ`d down electrically.

once equalized I'd extremely be surprised if you could tell the difference between a naturally .4 Q box EQ'd to .6 Q and a naturally .6 Q box, if they`ve got the same frequency response.
 
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