[dbbarron]

Any thoughts on building an Acoustic Door for a home theater?


Perhaps a fir frame (.75 thick (use 1x3s)) covered with high mass MDF (3/4 or 1"). Will have to route a channel in the long edges to accept a wood member for the hinge screws.


Fill cavities in frame between panels with fiberglass batting.


Q: Is green glue effective as glue? I.e., can I glue the MDF panels to the frame using green glue? Will this assist with damping/isolation. Otherwise I will have to screw each panel to the frame with green glue along the joints.


Anyone care to estimate STC?


What about same idea, but three layers! (perhaps use thinner MDF).


As the door gets thicker, will have to taper inwards (like a vault door) so it can operate. Maybe use multiple layers per above and a staggered door frame; just like a vault door.


Any other thoughts on how to attach two high mass panels separated by an air gap filled with damping material? (and still acheive function of a door - i.e., support its own weight when held by hinges along an edge.)




db

 

[Terry Montlick]

Use a solid, dense core with no air space. When you create a shallow air space within a door, you are making things worse, not better. You are building in a mass-air-mass resonance which will transmit sound, and work against your efforts to attenuate such transmission via increased mass.


- Terry

 

[dbbarron]

Terry:


The high mass solid door was my 'gut' impression for the best door with special emphasis places on seals all around.


Then I saw a few STC studies on the web (seemed to be legitimate source/testing lab) that suggested that a metal door, hollow core had a higher STC rating than a solid core wood or MDF door - even better if the metal door was stuffed with fiberglass.


No details on the door itself were given; i.e., construction, etc. Perhaps the metal faces were somehow isolated and high mass; I would normally think this hollow core metal door would simply be a large resonant cavity. But, if the faces are massive enough, and the construction somehow isolates the faces, and if the cavity is filled with an absorbant material......etc.


Will post URL should I find it again - just looked and I neglected to bookmark it; need to use Google Notebook more diligently.


db

 

[Terry Montlick]

db,


Metal acoustical doors are not just hollow shells, but have layers and cores which are generally proprietary. See for example:

http://www.doors-ambico.com/products/s_acoustic_cut.asp


- Terry

 

[asolutions]

Be sure what you use is a heavy solid core door. You are looking for mass. But dont forgot acoustical door seals (automatic door bottom, threshold, jamb seals and perhaps cam lift hinges). There is no acoustical door on the market with an STC value above 40 that does not come with seals. You can purchase them seperately from the doors themselves.


However if you have the money ($2,500 - $3,000) you cannot beat an actually profesionally made acoustical door.


Also regarding the question on Green Glue - it works great but the name is misleading you CANNOT use it as a glue to adhere multiples layers of boards - you would have to use screws with it.


Dave Ingersoll

Acoustical Solutions
http://www.acousticalsolutions.com

 

[ScottJ0007]

Here is a link on how I am doing an acoustical door in my theater...

.... My acoustical door link ....

Not that this is the "best" solution, but maybe it will give you some ideas...


- Scott