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Acoustically Treating a Bomb Shelter

Seriously.  My house came with a 1960s era bomb shelter.  It's a total of 2,200 square feet of Cold War Era awesomeness, basically divided into two 51X21 long rectangular rooms.

It's under a pool and pool house, easily 15 feet down. Hard concrete walls. Huge metal out swing doors that could keep out Bob Dylan looking for a string bean. 

We turned one big room into a giant pantry, wine cellar, and storage room.

The other I softened with hardwood floors, sheet rock (with foam insulation) on walls and ceiling, in that it could make an excellent apartment, being 1000 sf by itself, not counting the kitchen and bath.  And has two entrances, one at each end.  Very airy with good ventilation (and expensive filters).

It's this (now) 50 X 20 room iswhere my listening area is.  Ceilings are 14 foot sloping down (the short way on the rectangle) to 12 feet.

I've divided it into three areas of roughly equal area.  One end has a power rack and tons of free weights and whatnot.  On top of the hardwood is a protective layer, hardwood, and then rubber horse stall mats.  Kitchen and bath beyond that.

The other end is an emergency bedroom, with flip down Murphy beds, etc.  Area rug where the wife does yoga.  At its end are double metal doors, then stairs, then another metal door.

The middle third is my listening area.  Speakers and subs on the higher-ceiling side, although I could flip it.  Set up in the classic 60 degree triangle with a leather couch facing the speakers.  Chairs to the side, and a table I use as a desk behind the couch.  Area rug.  Decor: think Andy Warhol meets Austin Powers.

My thought is I don't get a lot of reflection from either the right or left side, due to the width of the room, and the stuff in each room.  I suspect I mainly get reverb off the back wall.  And perhaps the ceiling, although it is sloped up to the speakers.

I'm thinking all I need is some absorption on the back wall, immediately behind the couch/table (so facing the speakers), as I sit closer to the back wall than the speakers.   Perhaps something on the ceiling about 2/3 of the way across the room.

Thoughts?  I'd like to be informed a tad before I get involved with GIK or one of those groups.

davetheoilguy
mahler123
3,050 posts
 

You might want to go the whole Atmos route, but since you already have the Arcam (I am assuming it’s a 5.1) you should start there first

hsounds
129 posts
 

Hey, I would contact Acoustic Fields. They have different levels of things down to DIY depending on your budget. Maybe absorption up to 9 feet from the floor on the sides. Then quadratic diffusion on the front/ ceiling starting at the absorbers/ and the back. I don’t know if you create a faux ceiling at 10’ or just dart wrapping the ceiling down to the absorption foam. I say leave it to the experts. 

wolfie62
352 posts
 

Melamine Foam. It’s what you want.

koestner
626 posts
 

I would treat it for radiation blocking as well, you never know.

davetheoilguy OP
111 posts
 

It's 2.5 feet of hard concrete and steel under ~15 feet of dirt under a swimming pool or deck.   Pretty sure it's a giant Faraday cage, too.  Cell phones go completely dead, something I very much enjoy.

So, I think we're OK with radiation.  ;-)

On the serious point, my playing with Dirac Live on the Arcam/laptop and a brief online consultation told me the same thing.  Nothing is needed on the left or right side, due to the length of the room.  All that is needed is either diffusion or absorbtion on the back wall, immediately behind the listening area, together with a bit directly above the sofa on the slanted ceiling.  Also pulling out the speakers about two feet from the forward wall (which I had already done).

I have a large (5' x 5') oil painting on the back wall.  I'll see if acoustic foam hidden underneath in the void works.

The slanted ceiling is apparently ideal and a bit of a mini-ampitheater. 

 

 

 

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