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Author Topic: Making use of the volume of air above a drop ceiling?  (Read 3186 times)

Offline Gregory Thompson

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Making use of the volume of air above a drop ceiling?
« on: October 25, 2011, 09:42:39 am »
I have a small space roughly 8' wide, 8' drop ceiling, 11' deep.
I think the room is around 11 or 12 feet tall (I used to have the measurements somewhere) so there's about 100 cubic feet of unused space up there (aside from some HVAC ductwork running above the drop ceiling)

wondering if there's a simple way to make the space up there into a bass trap.  Currently there is a batt or 2 of Roxul AFB stuffed up there.
The ceiling's been stiffened up with 2x2 sheets of sheet rock laying on top of the ceiling tiles.

perhaps opening a hole into it and tuning it like a helmholz resonator with the Roxul up there will trap a specific freq or range of frequencies? 
-Engineering for a living since 1994
-Currently freelancing for ABC Television (and that can change at a moment's notice)

Offline boggy

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Re: Making use of the volume of air above a drop ceiling?
« Reply #1 on: October 25, 2011, 10:14:18 am »
I have a small space roughly 8' wide, 8' drop ceiling, 11' deep.
I think the room is around 11 or 12 feet tall (I used to have the measurements somewhere) so there's about 100 cubic feet of unused space up there (aside from some HVAC ductwork running above the drop ceiling)

wondering if there's a simple way to make the space up there into a bass trap.  Currently there is a batt or 2 of Roxul AFB stuffed up there.
The ceiling's been stiffened up with 2x2 sheets of sheet rock laying on top of the ceiling tiles.

perhaps opening a hole into it and tuning it like a helmholz resonator with the Roxul up there will trap a specific freq or range of frequencies?
Of course you can build excellent bass trap in this void. Use fluffy rockwool (low gas flow resistance, 30-35kg/m3) to fill it. For surface below it use some sort of binary diffuser, 1D or 2D.



Example of 1D binary on the ceiling (IN Radio, Novi Sad, Serbia):



Sorry for non-straight slats above, this is a craftsman's mistake!  :-[

EDIT: Please, bear in mind that about 100 cubic feet of fluffy rockwool may be pretty heavy, then try to build frame strong enough to support it.
« Last Edit: October 25, 2011, 06:35:50 pm by boggy »

Offline Gregory Thompson

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Re: Making use of the volume of air above a drop ceiling?
« Reply #2 on: January 29, 2012, 03:10:49 pm »
I wound up doing 2 things:

1) making the majority of the ceiling into OC 703 panels that fit into the drop ceiling frame, in the space above I put two layers of Roxul AFB and other leftover insulation from the original room install.
2) Re-hanging 2 of my Realtrap Mondo Traps as an angled cloud over the mix position.

Much improved bass response across the majority of my room.
-Engineering for a living since 1994
-Currently freelancing for ABC Television (and that can change at a moment's notice)