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Attic build/treatment Sound Enhancers & Exciters (HW)
Old 23rd December 2010
  #1
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Attic build/treatment

I'm just getting started with my own attic build for a common mixing/tracking room. My roof is a little below a 45 degree pitch and meets at the peak. I'll be building an inner structure for isolation from the outer, and will be leaving a gap between that ceiling and the peak just so I can periodically check for moisture, pests, etc.

Still, there isn't enough height to build a flat ceiling all the way across, and I know that the angles will focus the sound somewhat.

So I'm trying get myself pointed in the right direction here. Nothing on this pic is exact, it's all proof of concept, but I'm wondering if a poly run down the center of the room in the focal point of the ceiling would help, particularly with broadband clouds to either side? I know that no matter what I should expect some focusing in the middle of the room, but will this help disperse at all or should I be looking in a totally different direction?
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Old 23rd December 2010
  #2
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Quote:
Originally Posted by 99zulu View Post
I'm wondering if a poly run down the center of the room in the focal point of the ceiling would help
I'd use thick (and wide) absorption there instead.

--Ethan

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Old 23rd December 2010
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That can be done.

And I'm all for turning the entire ceiling area, slopes and all, into an absorbing surface if that's what it takes. I just don't want to completely deaden the room if that can be avoided, so I'm wondering if some diffusers would help keep it a little lively in there, and on which surface they could be used to help do so while avoiding the focusing effect of the slopes?
Old 23rd December 2010
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Hey Zulu.

THe control room thread in my sig. line is quite similar to your build. Give it a gander if you have time.

Definatly employ a ridge and soffit vents. Insulate the rafters.

Being that my space is control only, far less is being done in regards to isolation, but you may still find some value in reading it.

Being that you are floating a structure up there, I would be very concerned about the heft of the level below's ceiling rafters, and their ability to shoulder such a heavy load. I hope they are 2x10's, and even then I would be weary.

good luck!
Old 23rd December 2010
  #5
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Thanks John,

The ceiling joists below the attic flooring aren't worrying me too much. They're 2x12s with two load-bearing walls running down the center of the house (either side of a hall-way splitting the 2nd floor front to back) and are spaced rather closely together. My house was built in the 1880s in storm territory; they just don't make 'em like this anymore.

Still, it's a valid concern and I'll pay attention and see what a couple contractor friends think about what I'm planning to do up there.

EDIT - hey, didn't realize that was you! I followed that thread, that's what originally got me thinking I should look at utilizing my own attic. Can't wait to see the build!
Old 24th December 2010
  #6
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Lightbulb

Quote:
Originally Posted by 99zulu View Post
I just don't want to completely deaden the room if that can be avoided, so I'm wondering if some diffusers would help keep it a little lively in there, and on which surface they could be used to help do so while avoiding the focusing effect of the slopes?
Without knowing the size of the room it's impossible even to guess. But generally, small rooms need to be more dead than live. The classic place for diffusors in a control room are on the rear wall behind the listening position. Or you can go nuts and put diffusors everywhere except at reflection points:

Hearing is Believing

--Ethan

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Old 26th December 2010
  #7
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Good point Ethan. I was looking for theory, but it's pretty tough to speculate without some dimensions. I'm primarily concerned with keeping the room alive while getting the modes under control, after which I'll start looking at treating to even out any weird bumps.

I'll get some dimensions shortly and try my hand at sketchup, that should help.
Old 1st January 2011
  #8
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I'm curious about load now. I've pulled up some floorboards and discovered that my joists are 2x8s...but double-braced all the way across, for actual floor joists of 3.5" wide by 7.5" tall, 16" on center. I was happy to see the double bracing but hoping for something a little taller as I plan to put a lot of weight over this space.

I have surprisingly low sound transmission from the rest of the house into my space, in fact walking around with a c-weighted SPL meter held arm's-length in front of and to my side I couldn't get it to register anything over 50db (radioshack, 50 was the lowest setting it just read "lo" most of the time) with music playing one floor below (at 80db in my listening position) and a kid screaming in the hallway. The only register I got was when a louder truck drove by (the house is inset around 40 feet from the street) and that got me up to around 58db max, assuming low frequencies.

I plan on drumming in this room and would like to isolate transmission from the drums into the bedrooms on the level below, at least by a reasonable amount. My thinking on the floor was to rip up the existing planking, screw down fire-rated OSB as the base, a layer (or two?) of carpet padding (to help dampen and float the upper layers) and on top of that an OSB-drywall-plywood-laminate sandwich, decoupled from the walls. However I'm getting concerned about weight, as I also planned on separate inner framing for my walls (both to allow the ceiling to breathe and to keep the inner walls de-coupled from the outer structure so as to reduce road and rain noise), and wanted two layers of drywall with gg between on that frame. Now I have no idea if the floor can handle the weight.

I'll have a contractor friend come in and give me an opinion, but if anyone here has some advice on ways I can cut down on weight while still maintaining some separation I'm all ears. I'm not going to assume I'll hit an STC of 60 if I need to cut some corners, but I'd still like to be able to drum and occasionally track in the evening without pissing off people trying to sleep right below me. Perhaps this just isn't feasible, but I'd like to try.

EDIT - I brought a kick and a floor tom up there and had my wife bang on them, she was consistent at around 95db about three feet from the kit. I measured back in the same music room and was getting a reading of 70db...totally unacceptable. I attribute the difference in playing music to good stands and broadband treatments and having these things positioned properly so that I was getting less sound in the attic from that room than I was getting in that room from the attic. The bass energy was mostly transmitted through the structure by the kit sitting on the bare floor, so I was seeing less transmission loss, hence my assumption for the need for a dampened, de-coupled floor.
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