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Venue remodel: Sub bunkers?

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Helge A Bentsen:
Depending of the amount of reduction needed, I've had pretty good results using MDF/drywall in a sandwich construction.
A inner shell of MDF with enough space for the sub(s), two layers of drywall and one outer layer of MDF with as little as possible physical connection to the rest of the stage. Easy to build and easy(ish) to modify later down the road. Also made the stage floor of the same sandwich type, put a pair of SB1000z under there and it worked well.


Tim Weaver:
If sand worked before, what about using a CMU block wall that is internally filled with sand. Cap this with the drywall, or drywall-mdf sandwich.

CMU blocks are pretty easy to knock out with a sledge if you later need to reconfigure. I know years ago we would use similar construction in dance clubs to make mounting platforms for the turntables. This would decouple the TT's from all the vibrating wood that made up the DJ booth.

dave briar:

--- Quote from: Helge A Bentsen on June 21, 2021, 05:00:24 PM ---Depending of the amount of reduction needed, I've had pretty good results using MDF/drywall in a sandwich construction.
A inner shell of MDF with enough space for the sub(s), two layers of drywall and one outer layer of MDF with as little as possible physical connection to the rest of the stage. Easy to build and easy(ish) to modify later down the road. Also made the stage floor of the same sandwich type, put a pair of SB1000z under there and it worked well.

--- End quote ---
I like the sandwich idea. No 2x4ís needed.  Bunker thickness is somewhat limited by the need to keep the stage as low as possible to maintain view lines from under the mezzanine.
Curious how the two layers of drywall in the stage deck are holding up?  Iíve been looking at using two layers of 3/4Ē HDF glued and screwed to the joists. Drywall would certainly add mass but drywall underfoot is not a ďnormalĒ application Iíve ever heard of. Just curious.

dave briar:

--- Quote from: Tim Weaver on June 21, 2021, 07:22:30 PM ---If sand worked before, what about using a CMU block wall that is internally filled with sand. Cap this with the drywall, or drywall-mdf sandwich.

CMU blocks are pretty easy to knock out with a sledge if you later need to reconfigure. I know years ago we would use similar construction in dance clubs to make mounting platforms for the turntables. This would decouple the TT's from all the vibrating wood that made up the DJ booth.

--- End quote ---
Thatís a pretty practical solution. There is sufficient room to the back and sides of the sub-cluster so CMU block could fit. Sand is cheap.  Building it during stage construction would be easy. Knocking it out and replacing it with the stage deck on would be more difficult.  Great idea though.

Helge A Bentsen:

--- Quote from: dave briar on June 22, 2021, 12:54:42 AM ---I like the sandwich idea. No 2x4ís needed.  Bunker thickness is somewhat limited by the need to keep the stage as low as possible to maintain view lines from under the mezzanine.
Curious how the two layers of drywall in the stage deck are holding up?  Iíve been looking at using two layers of 3/4Ē HDF glued and screwed to the joists. Drywall would certainly add mass but drywall underfoot is not a ďnormalĒ application Iíve ever heard of. Just curious.

--- End quote ---

MDF forms the outer layers of the sandwich, so people are  performing on top of a solid surface. It's 1" MDF top/bottom with two layers of 3/4" drywall in-between, feels very solid to walk and perform on. Certainly  more  solid than most regular stage decks.  The sandwich floor is on top of 2x4" beams/legs not  connected to the sub bunkers. We used industrial carpet on top for less HF reflections from the floor and vacuum the  stage regularly.
I have no data on how effective this solution is, it was conceived as a cost effective solution using available materials and for ease of installation.
I've had several performers comment on how little sub there is up on stage after we did this compared to past experiences in the same room.

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