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I guess my question after re-reading the thread is: What is between the new HT space and the rest of the house? Is there another room? Are you going to be building another room between? If so, I don't think you will need to do anything in particular to isolate the HT, just having a couple of normal walls and good solid doors should do the job. bpape may have better advice, but I'd probably go with at most, staggered studs on the wall closest to the living spaces, and insulate the tar out of the rest of the area.

I doubt you'd have much sound leakage, unless you listen at reference levels regularly.

Building that way, with good insulation in all the walls, and good solid doors with thresholds, and perhaps some double drywall, would probably be cheaper too.

How close are your neighbors?
 

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Realistically, I'd just do double with Green Glue direct to the studs. If you're going to use anything else, just use hat channel or RSIC-1 with hat channel. Don't bother with RC. It's OK for vocal range but doesn't do diddly for low end and is also VERY easy to screw up and short out.

Bryan
 

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What Chris and I are wondering is... What are your plans for the space between second floor of the main house and HT space???? ...Are you building another room??? ...How are you going to access the HT??? ...From second floor through the open space above main house??? ...:huh:

Diagram Carton Rectangle Box Parallel
 

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The left hand side of that roof is walled up. It terminates into the living area of the second floor.

The right hand side may be walled up as well, as a firewall between the garage and living area.
 

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The left hand side of that roof is walled up. It terminates into the living area of the second floor....
I asssume ... is where you're planning to put a door to access the Ht room, Right???

The right hand side may be walled up as well, as a firewall between the garage and living area.

If you do that ... it will create an air gap between HT room and living area of second floor; that means ... "Don't worry about the sound disturbing the second floor occupants" :yes:
 

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On a short wall with a door in the middle RC or RISC is pointless anyway. RC makes it so that the wall has a bit of spring to it and separates it from the studs, RISC takes it a step further. The door frame and assembly will short out any of those benefits however. They are really only good on straight un-opened (meaning no doors or windows) walls like in a townhouse or duplex's shared wall.

A double wall would be a better option. Better than staggered stud also because there would be no demolition necessary. With to door on the theater side of the double wall it should help. A double wall with insulation and double drywall would probably get the STC rating up in the 60's. Sound could flank up through the roof or the floor though. That sound being low bass only most likely.
 

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OK, now I'm a bit more confused.

Let me state what I'm pretty sure of, then ask some more questions. (A floor plan of the entire second floor would help, I think.)

The new HT is going to be above the garage area. I assume the screen/display will be at the end furthest from the living areas.

How are you accessing the new HT room? Is there a stairway from the garage, or a door/opening direct from the living area 2nd floor?

That floor plan you're going to post :bigsmile: will really make things clearer, I hope.
 

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Discussion Starter · #29 ·
What Chris and I are wondering is... What are your plans for the space between second floor of the main house and HT space???? ...Are you building another room??? ...How are you going to access the HT??? ...From second floor through the open space above main house??? ...:huh:
In the new attached SketchUp file I ripped the roof off the space in question. It is standard web trusses. Considered modifying the trusses and putting a hallway thru (engineering actually worked out!) but too much money! Stairs will be going up from inside the garage. So the space between the main house and HT is about 26 feet of air gap. From David's last comment it sounds like I should be fine? I also attached a plan view showing the layout of the space above the garage (thanks Chris!).

Thanks for your patience. I should have provided a plan view from the start.

Duc

http://www.hometheatershack.com/gallery/index.php?n=1122
http://www.hometheatershack.com/gallery/index.php?n=1124
 

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Yeah...i think you have no need for special sound proofing in this space. Most people are lucky if they have a good wall between a bonus room/theater and their bedroom, but you have 26' of insulated attic space. That not only decouples the theater wall from the rest of the house, but gives a lot of time/distance for sound to be absorbed before it reaches the house. If you can still hear it after the fact, you can add OSB to some of those trusses and make some solid barriers.
 

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There would be some vibration transfer from the floor and wall into the studs. As long as you take care of that the rest of the house should be oblivious to what goes on in the theater room. You have quite a bit of built in soundproofing already.
- The double drywall layer will take care of the wall portion quite a bit.
- The floor structure, seeing that it's insulated will prevent the room below from resonating.

If you were to build the equipment room where the screen is, you would have even more separation. I don't know if that would work though seeing that you would have a door or doorway with a curtain on your front wall (space issue?).
 

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Discussion Starter · #32 ·
Framing is underway this week.:bigsmile: Will post pics this weekend.

Ventilation duct work will be installed next week. I have read several posts about reducing sound from the ducts: flex duct and labyrinth or baffle. The HVAC contractor will be using flex duct. My question is on the labyrinth design and location. I've read about mdf box around the duct for some distance (15 feet??) and packing the space between box and duct with insulation. Correct?

Please see the attached rough sketch of the room. Outside the sides of the room is the remaining taper of the roof. It may be possible to wind the duct through the open web of truss work as illustrated in green. Building a box around the duct may be possible but I think challenging. Is another option to build the labyrinth behind the screen wall as shown in red and run a long straight section back to the inlet/outlet vents in the room? Or does the straight run re-introduce noise issues? I'd have more room to maneuver in the open attic space behind that wall.

Other options??:huh:

Duc
 

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Without the box, just bending the flex duct won't help much with mid and low frequency isolation.

When you do the bends, you don't have to come all the way back at 180 degrees. You can just run a few feet, bend 90 to go up or down, then run, bend again, etc. Might be easier to do the boxing that way.

Bryan
 

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Discussion Starter · #34 ·
Thanks for prompt reply Bryan. Attached is another duct run design along the side of the room. And this does look easier to build. Due to space constraints of the the trusses I'm limited in how long the runs can be along 2 of the 3 axis. Using this design the numbers would roughly be:

90bend - 90bend - 30"vert up - 90bend - 4'horiz - 90bend - 30"vert down - 90bend - 90bend - 4'horiz, etc.

I can get 15'+ with that design. Will that accomplish the isolation objective?

Also, I've read about using a larger box at the end of the run and a large grille to help reduce face velocity of the air flow. Is that advisable? Effective?

Thanks much. Duc.
 

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That would work great.

The general 15' is assuming 3 5' runs with 3 90 degree bends. What you've laid out is actually better - though more work.

Bryan
 

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The more bends the more sound attenuation (from room into HVAC). Line the ducts with linacoustic or SUPERDUCT RC or other HVAC acoustical material and you'll be pretty happy. A silencer could save you a bit of duct work though. A silencer is basically constructed like a car's muffler.
 

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Yup. A silencer can work very well over a lot of the range - but still doesn't deal with the bass getting through very well.

Bryan
 

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Discussion Starter · #38 ·
A few construction progress pictures.
First, the linked picture shows the original truss space with camera flash illumination.
http://www.hometheatershack.com/gallery/index.php?n=1086

Second picture is from relatively the same position with framing of walls and subfloor now completed. A little better illumination with the temp construction lights. In the floor is a small box for wiring, controllers, etc. from the equipment room in the background. There are pvc pipes exiting to either side of the room. The equipment room has similar boxes at the very outside edges of the room with another pvc connection between them.

Third picture is one of the ventilation duct labyrinth's nearly completed. I had hoped to complete both of them (supply & return) this weekend. My advance measurements were spot on but assembly took considerably longer than anticipated.:sad: Actual duct work will be installed next week.

Duc
 

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Nicely done. Add in the flex duct and a bit of insulation to fill in the gaps and that should be about as quiet as you're reasonably going to get.

Bryan
 

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Discussion Starter · #40 ·
Wow, over a month since my last post. Time flies. I've been working on the all the electrical wiring which took considerably longer than I expected. I should have expected that! Passed the rough-in electrical inspection yesterday! :bigsmile: HVAC duct has been run. I still need to get the insulation in and finish the front panels on the mdf boxes.

I'm about to finish up the conduit runs for speakers and cables to the projector before I start with insulating the wall/ceiling cavities. Any recommendations or advice on projector location? I know throw distance of the projector is a factor, but otherwise is it advisable to be closer to the screen or further back? Overhead or behind the front row?? Screen will be about 18-19' from the back wall with a door in the middle of that wall.

Also, how much clearance should I factor for an anamorphic lens assembly? My ceiling will be rather low at about 7'8" or a bit less. A riser would shrink that even more in the back of the room. So I'm thinking I want to mount the projector as close to the ceiling as possible?

Duc
 
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