Quote:
Originally Posted by
mjaudio 
Hey Keager,
With your infinite baffle is there a lot of noise outside your house? I always wondered that about infinite baffles that are located in the attic or sub area.
I was quite concerned about this prior to my quad 18 attic IB system. Above all else, I wanted to maintain a neighborly decorum, and certainly didn't want the sound contaminating the area around our home. Our neighbors aren't on top of us, but the home closest tothe IB end of the house is about 60-70 feet away.
Sound outside the structure isn't typically a problem.
I've really examined this at my place, and there's several components that seem interact and determine the result.
De-correlation, ... the LF/ULF outside is significantly lacking in the correlating energy in the power region and thru the midband. This seems to be crucial for the audible cues that construct the remaining spectral energy of the playback, and without it, and only hearing the LF there's very little recognizable sound. It's simply not something that fits our normal range of sounds we encounter.
Secondly, but not necessarily secondarily important, is the diplolar nature of the subwoofer energy
outside the home.
Imagine for a moment, you build a stand alone listening room out-building. You build a state of the art IB. It's a killer, mammoth IB array, flush mounted in the front wall in the modestly sized room. The rear room, that the IB baskets are located in, shares a common outside wall with the listening room. Well, when the IB is operating full tilt, both the primary room, and the rear wave room have equal amounts of the energy,
except it's opposite in polarity. While standing outside in the yard, being exposed to both sides of that wall, the energy nulls to a large degree. It doesn't cancel entirely due to any structural deviation strengthening or damping one panel moreso than the other, however it is quite effective at nulling a considerable amount of energy.
I've noticed more than anything, that resonances play the largest role in energy reaching my closest neighbor. At first I had a small vibrating gable end that needed additional security. Then I found the next item, etc, etc. I stopped after I addressed four items, it's relatively well damped outside. what you hear is huge transient induced movements of the entire structure, but you don't hear much defined tonality. The biggest LF eggres I have noticed, is via a 10 foot wide, triple-pane sliding glass door off my listening room to the back yard
, yeah I know.
The cool thing about the attic IB is you can throw enormous amounts of damping/absorption at it (attic insulation), and the inherent shape of the sloped roof reflects many of those wavelengths down into the dense fiberglass/cellulose absorption material. I've added a lot of extra absorption up there, the decay time up there is tight, for sure. I'd planned on a pressure based diaphramatic absorber experiment up there (tuned plywood right near a rigid 703 panel), but I'm nursing some serious health issues that often side line me and limit my exertion.
All in time. It's low on the list, ...actually it's not even on the list but I've thought about it
IB noise outside?
Not typically a problem.
Good fences, makes for good neighbors.
Well, dipole bass,
from an IB, makes for good neighbors too.
Thanks
