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Discussion Starter · #1 · (Edited)
I happen to have a 20 foot long vacant room behind my home theater and have always wanted to build a large sub for movies.. I have been thinking..... Couldn't I have a truly huge sub and only expose part of it to the home theater room? So it would take up about 0 space in my home theater but could be as large as desired in the other room. Maybe a 20 foot long by 24" wide sonotube buried in concrete or something - who knows... Thoughts? Any suggestions on design with basically unlimited space like this? I have always heard that the more volume you have, the lower the frequency you can get.. With today's drivers and amps, is there a diminishing point of return here what would make subs over a certain cubic foot just dumb?

Google "under floor horn subwoofer" for inspiration. :)

I was also thinking that the infinite baffle subwoofer would not be great because the wall would vibrate so badly....
 

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Discussion Starter · #3 ·
How wide and long is your HT room and how far from the back wall is the seating position? What is your budget for drivers and amps?

18' wide, 30' long, 8' tall. The room is actually an L shape. the back opens into another 15'x15' room. Seating is about 16 feet back currently.

Budget is < $2000 for the sub and will buy whatever amp is needed to power it.
 

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Discussion Starter · #6 ·
The first thing you should do is put the Martin Logan sub in the middle of the back wall and see how it sounds from the seating position. This should give you an idea of what to expect before you start cutting holes in the wall.
Perfect, I currently have the sub along the front wall were I would cut a hole in the wall.
 

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Perfect, I currently have the sub along the front wall were I would cut a hole in the wall.
My mistake, for some reason I though the extra room was at the back. If it's at the front then the sub is where it should be. How does the sub sound from the seating position?
 

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Discussion Starter · #9 ·
My Martin Logan Descent sub is going under and needs repair as there is a buzzing sound. It was excellent for music, but not enough sound pressure for Home Theater. I had to buy a buttkicker. It does a good job, but is sometimes annoys me to death when sound engineers put low frequencies for things that are not supposed to vibrate you - such as musical crescendos when there is a dramatic scene kissing scene - or a simple scene change. I was once vibrated hard for 25 seconds - My friend and I just about stopped the movie.

After much learning much about IB subs here - I have the bug. I have made up my mind to do an IB sub and shore up the wall to reduce the vibrations. I will be ordering components near the end of November for a build to start Dec and finish at the end of Dec - My company has a mandatory vacation period one week at the end of the year - so the idea is to spend that week finishing up the subs and be ready for a new year of bass. :T

My current thoughts on setup are the following based on what I have read here:

  • Behringer 1124DSP
  • Behringer EP4000
  • 4 Fi IB318 18" drivers ( I have over 50 * VAS behind the wall - so I am good there)
  • 2 Manifolds mounted under the projector screen space about 4 feet apart
This appears to be what many people have gone with in the threads. I do have extra money in the budget - any recommendations on what might be better/more flexible/higher quality than the above(not that anything is really needed above and beyond the above - but hey).

My main goal is to have something that is great for music that also works for HT. I have a Magnepan setup right now and they are not the best HT speakers and blending the Magnepan 3.6 and subwoofers is near impossible. But I have read that IB subs are different in that way. I really hate one note bass and bass heard that is the result of cabinet resonances and do know what a sub is supposed to sound like. My biggest fear with and IB sub is that it is going to shake the front wall badly - and that will affect the sound. The front wall is a staggered stud wall and as such is more prone to vibrations.

I'll start a new build thread once I get the materials.

Seems like there is a great lack of audiophiles in the Chicago area compared to many other big cities. Anyone in the Chicago Area that may be willing to give me a taste of what an IB sub sounds like?

Thanks,

-Brent
 

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I run a subwoofer in the the next room. It is a patio that was enclosed to make a sun room. It is a Danley Sound Labs DTS-10. It fires through the wall into my home theater room. It is powered by a Behringer EP4000.

 

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M
  • Behringer 1124DSP
  • Behringer EP4000
  • 4 Fi IB318 18" drivers ( I have over 50 * VAS behind the wall - so I am good there)
  • 2 Manifolds mounted under the projector screen space about 4 feet apart
That sounds like a good start.

I might suggest a MiniDSP instead of the 1124DSP. Nothing wrong with the 1124DSP - but tweaking a MiniDSP is much less painful.
 

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If you're doing advanced biquad filters you can actually EQ under 10Hz if you generate the biquads coefficients another way.
 

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I was going to say... Is there any content besides a sound engineers elbows hitting the desk in any content anywhere?
There is SOME content, particularly during explosions, launches, things like that. You can see it in a waterfall like Spectrum Lab....... I believe that Hurt Locker has a scene "..... Irene" that has helicopters that have some 8hz content. The last time I cranked it up I tripped a breaker. :)

I'm all for sub 20hz content, but much below 20hz is quickly inaudible. Ear sensitivity is just much lower.

I've vibrated walls by playing a Space Shuttle launch that has sub 20hz content - you can feel it, but not so much hear it.
 

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It also comes in handy for pipe organ that does 16Hz. Pick up a copy of Pomp and Pipes and feel the bass.
 
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