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Discussion Starter #1
wife pulled the trigger on a system while I'm super busy at college, work, life.. but I'm going with it!

Yamaha 677
infinity mains, center, surrounds - primus

I just need a sub....

I have a dead space in the room to use... around 51 cubes.

Room size is 3400... 19x15x12

best of what I've read about ... I think I can fit two SI HT 18's with a crown xls 2500 pretty easily. Only real questions I have are if the xls 2500 is really worth it? I hate companies that have some bogus numbers and you bench test something totally different.
 

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Crown power amps are worth every cent (in my opinion). Reliable and a real company to support them.
You might consider a different alignment other than infinite baffle for efficiency sake though.
 

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Hmm, room gain doesn't start in earnest until below ~565/19 = ~30 Hz, so with a 17 Hz Fs driver, corner loaded sealed would be a good choice, especially for pipe organ symphonies and HT; though if size, material costs isn't a major factor and a < 80 Hz XO is used, a simple folded 'BIB' concept pipe horn will dramatically increase efficiency down to ~20 Hz or lower since you have high ceilings, then combined with room gain, then just one might yield enough peak SPL down low to damage the home, so with two you might can get by with a fairly low power amp: http://www.diyaudio.com/forums/full-range/66173-terry-cains-bib-why-does-work-does-anyone-have-those-fostex-craft-handbooks.html
https://speakerprojects.wordpress.com/cabinet-types/bib-loudspeakers/bib-calculator/

GM
 

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Discussion Starter #5
I made a thread over in the ported subwoofer section. I'm taking pictures and measurements inbetween doing my college reading =\ I'll end up updating it later tonight when the wife's back home. I really want to do a insane kerfed slot port but I don't have the space for it on the same plane as the drivers. A tough decision to be made there. (for me anyway)

As for damaging the house... doubtful, I built it personally. I skipped even using drywall and used 5/8 plywood 100% of the room. Screwed off with 2 1/2 screws. Exterior is sided and then reinforcing 1 inch strips nailed over every stud / seem / corner. But...

Things inside it? .... Definately doing to need to anchor down everything on the walls.... maybe re-fluff the attic insulation every other month..


Btw how did you come up with the numbers for the room gain ~30 hz ???
 

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It's half the speed of sound (1130 f/s) divided by the longest room dim. (29.736)
Hmm, the textbook I have says it ramps up below the room's lowest room mode, which of course can be very complex to calculate if oddly shaped, but a simple box is the longest parallel walls, or 19 ft in this case, so curious how you arrived at 29+ ft; and of course how close it gets to the theoretical 12 dB/octave below this point will depend on the room's/house's construction and how airtight it is.

GM
 

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Hmm, the textbook I have says it ramps up below the room's lowest room mode, which of course can be very complex to calculate if oddly shaped, but a simple box is the longest parallel walls, or 19 ft in this case, so curious how you arrived at 29+ ft; and of course how close it gets to the theoretical 12 dB/octave below this point will depend on the room's/house's construction and how airtight it is. GM
lol. The 29.736 (565/19=29.736) was the actual number room gain starts at. I assumed you rounded up to 30hz from this number in your example to him. You are correct, it is very complicated. I was just trying to give him a short version so he could try it out himself.
 

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Just putting it another way...
Room gain and room modes are different. I hope I'm not simplifying too much but:
Room gain is from room pressurization and is primarily function of room volume (ft3), air-tightness and boundary compliance.
Room modes are function of the room dimensions (ft).
Of course, room volume and dimensions are related.
 

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A wife who randomly buys HT equipment (especially if it's good gear!) is either a huge asset or a debilitating enabler in this hobby. lol. Glad to hear she's into it too, and I'm sure you'll both love the addition of those subs.
i agree with this.... super congrats.
 
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