# Bluegrass Basement Build



## patchesj (Jun 17, 2009)

Wow... My original thread was started almost a year ago and I'm just now getting ready to order framing materials!!! Hopefully all of this planning and thought will pay off. Here is the link to the original discussion:

http://www.hometheatershack.com/for.../19572-theater-unfinished-basement-space.html

I've ended up with a room-in-room design. We will be constructing 4 new 2x4 wood framed walls, approx 91" tall. Walls/ceiling will be 2 layers of 5/8" type X drywall with green glue.

There will be new ceiling joists run lengthwise in the room, resting on the new walls. The joists will sit in between the HVAC duct work on one half of the room. Unfortunately moving the HVAC trunk lines was too much of an effort to gain the additional ceiling height. The plan to locate the joists parallel with the duct work should help preserve head room and still provide an isolated ceiling. 

The door opening will be framed in to create a 36" door. I will be installing 2 doors (back to back "communicating airlock"). I will add additional mass to the "inside" door via MDF sheets.

There will be a dead vent located in the mechanical room with the opening in the rear theater wall. There will be a high volume (~500cfm) fan with variable speed controller, pulling air from one end of the open basement. A second dead vent will be located under the stairwell and feed exhaust air out into the other end of the open basement space.

Pictures to follow, comments/suggestions welcome (hopefully before I make any major mistakes!!)


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## Ted White (May 4, 2009)

Sounds like a good plan!


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## patchesj (Jun 17, 2009)

Photo's of raw space


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## patchesj (Jun 17, 2009)

Hopefully this helps give a visual of the space. A few things to note... 

The HVAC trunks are metal, wrapped in two layers of bubble wrap type insulation with an air gap in between layers. I am planning on cutting some MDF down and screwing it to the bottom of the floor joists to cover the flex runs (There are 3 flex ducts + vents above the theater). Not sure if anything can/should be done to better isolate the trunks.

I'm going to prewire for 7.1. Current plan is to have the equipment in the room, behind the front screen/false wall. I kept going back and forth on putting it in the room or in the closet under the stairwell. This still might change, but I think for wiring purposes in room would be easier. L/C/R/Sub would be wired direct to amps and not use in wall wiring. I would like to keep the pre-pro and source components in the room for easy access. If I put them in the closet, it will be a 20' walk + 2 heavy doors away...


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## patchesj (Jun 17, 2009)

I should also mention that the "outside" walls in the mechanical room (rear of theater), the long/center "outside" 6" wall, and the theater side of the stair well will all get a single 5/8" type X drywall.

The theater screen wall will be the short side with the stairwell.


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## patchesj (Jun 17, 2009)

Question on insulation. I am planning on putting R19 in between the existing floor joists, and then more R19 between the new joists, where I can (can't where the HVAC trunks will be). 2 of my walls will be 8-10 inches thick (double walls - long side wall and short wall against mechanical room). Should I use R19 in those double walls, or is R13 fine?

Also, what if anything should I put between the new ceiling and the HVAC trunks? the plan right now is to have a 1" gap between the drywall and ductwork. Should 1" cotton be used, or would the air gap be better than potential physical connection?


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## Ted White (May 4, 2009)

patchesj said:


> Question on insulation. I am planning on putting R19 in between the existing floor joists, and then more R19 between the new joists, where I can (can't where the HVAC trunks will be).


That's fine, as long as none of the insulation is compressed in an effort to get insulation into every nook and crannie.



patchesj said:


> 2 of my walls will be 8-10 inches thick (double walls - long side wall and short wall against mechanical room). Should I use R19 in those double walls, or is R13 fine?


If the walls are 2x4 stud, then double R13 would be fine. If you line up the studs, you can use R19 and span both stud bays.



patchesj said:


> Also, what if anything should I put between the new ceiling and the HVAC trunks? the plan right now is to have a 1" gap between the drywall and ductwork. Should 1" cotton be used, or would the air gap be better than potential physical connection?


The risk of conduction is huge. I'd use nothing unless you get 1/2" insulation board


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## patchesj (Jun 17, 2009)

and now the $64k door question. My "door" plan is to have an exterior MDF door (with threshold/weatherstrip) on the "inside" wall and a solid core interior door on the "outside" wall of the theater, but I'm begining to rethink this. Perhaps a solid MDF slab door with acoustic seals will be better on the "inside"?


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## Ted White (May 4, 2009)

I would flip this scenario.

Use your big, bad door on the inside as this inner door needs more isolation. Use aftermarket seals to ensure this first line of defense is as solid as possible. 

The outer door has less work asked of it, and could be the exterior door you mentioned.


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## patchesj (Jun 17, 2009)

Sorry, must not have been clear.... I was planning on an exterior style door on the "theater" wall with an interior style door on the "basement" wall. But I think we are on the same page. I'm just trying to see if it make more sense from a cost/performance perspective to use a solid MDF fire rated Exterior style door with integrated threshold/weatherstrip vs. MDF slab interior style door and add seals. Either way I'll be adding mass to the door.

If one were to go the interior style door route, those door frames don't usually have a threshold installed. Is it best to install a wood base under the doors (on the floor, maybe a .5x10" plank or something?) to ensure a good seal?


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## Ted White (May 4, 2009)

My point was that if you have two door options, place the more massive and more sealed door on the interior theater side, as this door will need to do more work.

In this case, the interior solid core slab + MDF + seals would be the more formidable door. I'm guessing this would be heavier, and certainly more acoustically sealed.

The aftermarket seals have a drop down door bottom and engage to a smooth surface, so a strip of Oak or similar would work well. The seals can't "seal" to carpet or tile (tile has grout recesses and more likely to fail).


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## patchesj (Jun 17, 2009)

Interesting door seal kit with a "saddle" for under the door. I wonder how that saddle compares to the standard threshold on an exterior type door?

http://enoisecontrol.com/acoustic-door-seals.html

Pricing on doors: looks like an exterior 1 3/4" fire rated MDF door is about $30 more than a standard thickness solid MDF interior style door. I'm guessing the door frames/hinges on the exterior door will be a bit beefier which is good. What about using the exterior style door as my "theater" side door. Then add a 3/4 MDF layer to the airlock side, and use an accoustic door seal/sweep set as a secondary seal against the new MDF layer?

I would still use a solid MDF interior door on the basement wall as my secondary door, but just use off the shelf weatherstrip on the jambs and a simple sweep on the floor.


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## Ted White (May 4, 2009)

The saddle (threshold) isn't mission critical at all. I have one in my theater and would not do it on the next.

You could certainly use the exterior door and add MDF for mass. You could / should consider a damping compound in that scenario. You might also try and have a listen to determine if you want / need the afermarket seals. If the door is really well installed, you might get by.


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## patchesj (Jun 17, 2009)

Hopefully I'll have a bit of green glue left over for the door sandwich. I guess that's the benefit of "aftermarket" seals, they can be added at any time....


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## Ted White (May 4, 2009)

Exactly. If you can take the conservative "wait and listen" route, that's best.


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## patchesj (Jun 17, 2009)

Construction started this morning. Was able to get all 4 walls framed and the door opening on the 6" wall down to the right size. Put up insulation and 5/8 firecode on the "middle" wall for the stairwell. Installed the MDF covers over the vents to the first floor. Put R19 fiberglass between existing floor joists. Installed all of the electrical boxes. On tap for tomorrow, build MDF enclosures for all electrical boxes, run wiring, install new ceiling joists, finish insulation in walls and new joists.

I do have some construction concerns. The walls are all tied together and to the concrete floor. There still seems to be some "play" in the top of the walls. I can get some movement out of them, this isn't unexpected seeing how they aren't tied to anything else and there are no joists in place yet. However I would like to get them fairly solid. DC-01's are the obvious answer here, but being an idiot I didn't order any before now and my schedule is going to need to stay on track. With 2 of my isolated walls sitting in front of poured concrete, I was thinking about attaching some wood block to the concrete and then using a metal bracket to tie the isolated wall to the block. This should give stability to the wall and I would imagine the metal bracket to 10" thick concrete wall would be OK as far as isolation is concerned. Thoughts?

Hopefully pictures Sunday or Monday.

Oh, and 5/8 firecode is HEAVY. I'm not looking forward to carrying it 100 feet from the garage to the back basement door.


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## Ted White (May 4, 2009)

You won't have play once all the drywall is on. 10 years ago I built my room with separate floating joists and I removed temporary screws holding the top plates to the original joists. The room gets really solid the more drywall is added.

I would not use the bracing you propose. Better to have a couple of screws hold the system. The screws have less surface area for conduction.


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## patchesj (Jun 17, 2009)

Here's a shot of the block/bracket idea. This is attached in the middle of the long left wall. It makes a huge difference in the stability of that wall. I see your point about the drywall adding strength as well. Will this bracket really transmit that much sound to the concrete wall? The bracket is 2" wide. It's still easy to take out...

Thanks.


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## patchesj (Jun 17, 2009)

Picture updates on progress:
Stairwell wall being insulated








Stairwell drywalled








3/4 MDF covering vent locations to first floor (also insulated with R13)








First wall up








R19 between existing floor joists








2nd wall








4 walls up, framed in doorway








Started installing electric boxes.









Getting ready to put up floating ceiling joists, finish locating electrical boxes, install conduit to projector outlets, build MDF enclosures for electrical boxes.


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## Ted White (May 4, 2009)

There are two issues we'd like to consider:


The conduction of the component.

The overall flexibility of the wall.

Bracing limits the independence and therefore flex of the framed wall, you start losing LF performance.

Personally, I started the drywall off on the lower walls and the ceiling center. That stiffened things a lot. Then I pulled out the temporary screws that were through the top plate into the joist. Then I completed the drywall work. Not an efficient drywalling plan, but that's what I did. I also had my floating ceiling joists mounted on top of my top plates. 

The DC04 piece you mentioned is a lossy connection, which retains some flex.


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## patchesj (Jun 17, 2009)

Thoughts on using these brackets to secure the joists to the top plate?


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## bambino (Feb 21, 2010)

patchesj said:


> Thoughts on using these brackets to secure the joists to the top plate?
> 
> View attachment 22023


To me those look like an acceptable choice for tieing the joists to the wall.:T


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## patchesj (Jun 17, 2009)

Finished the ceiling joists, ran wire for the surrounds, conduit for projector, additional bracing for the projector mount, built enclosures for all electrical boxes (took way longer than I expected), started insulation in walls. 

Hooked up a sub and ran some low freq sweeps to check for noises. My large return duct has a slight buzz in it. Very faint but annoying. Might try picking up some ice guard (sticky asphalt stuff, think generic dynomat) and try to lay some on the bottom side of the duct tomorrow. I doubt it will be buzz after the drywall goes up, but will be impossible to fix later.


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## Ted White (May 4, 2009)

Good looking bracket. Duct buzz may need a surface application of pipe wrap or such. Surface damping.


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## patchesj (Jun 17, 2009)

Framing is complete, in room wiring complete, insulation 95%. Need to dampen the duct work a bit this afternoon and then finish up the insulation. Drywall starts tomorrow.


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## patchesj (Jun 17, 2009)

Boxed in Projector connections and 3" conduit















Sub hooked up for some rattle testing








Rear of room








Front of room 








From outside








Conduit entering HVAC/equipment room, also showing boxed wall for dead vent inlet/exhaust to room.


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## bambino (Feb 21, 2010)

Looks to be coming along nicely! why only brackets on some of the joists?


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## patchesj (Jun 17, 2009)

Hard to see in the photo's, but from the projector box to the door I doubled up on joists. Because of the HVAC ducts I couldn't hit 16" on center for all of them so I decided to play it safe and nailed/glued 2 joists together. I used 6+ nails in each pair, plus the added width they aren't going anywhere... I was able to get 16" OC for all of the points that might fall on a drywall edge, except for the extra wide return duct, so I have a 2x4 in there to get a surface to attach to. The clearance from the joists to the ducts was too close to use those brackets too.


Ordered my mic and pre-amp for REW today. Going to try to get some LFE measurements after drywall is up to design a resonator for the peaks to build into my rear seating platform (planning on 6" tall platform, 6' wide, entire width of room).


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## Ted White (May 4, 2009)

Nice backer boxes. Nice build. Thanks for taking the time to keep us in the loop.


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## patchesj (Jun 17, 2009)

1st layer drywall done in room. I'm glad I'm covering it with the second... 2nd layer green glued and on ceiling and back wall. Tomorrow moving more drywall down to basement (ugh x2), going to install drywall on outside main wall while I have the lift, finish 2nd layer in theater.

That will leave the HVAC/equipment room drywall and dead vent construction for the weekend. I still haven't finalized my dead vent plans, have a pretty good idea but need to get it all sketched out and dimensioned.

Mic and pre-amp got here today, wow fast shipping from parts express. Depending on weather might try to get some open air measurements from my mains and sub outside.


From outside:








Doorway towards back left corner








Back wall








Front wall








Mmmmm green glue. One bucket down.








Backside of front wall, temp blower in the hole for the dead vent


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## patchesj (Jun 17, 2009)

Forgot to mention that I sealed up all of the wall and ceiling joints before starting the 2nd layer of drywall. Had some grey and some white, makes the photo's look like there are giant gaps...

Also, for the dead vent I'm planning to put the supply vent in the top hole and return the bottom. They will be pulling/dumping air from the main open basement space. The plan is for the dead vent "box" to attach to the backside of the "inside" drywall and not touch the "outside" wall in the HVAC room. Is this correct, or backwards?


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## Ted White (May 4, 2009)

Looking good, man. Your description of the Dead Vent puts it in the center of the wall, then? That can work if you have it built with massive damped sides, top and bottom. You don't want to risk sound leaving the DV and dumping into the middle of your wall cavity.


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## patchesj (Jun 17, 2009)

Drywall 99% done..

From outside








Front wall, slot at bottom left is for dead vent. Just a temp blower for now.








Back wall








2 layers 5/8 Type X with green glue, 2x4 wall, air gap, 2x6 wall, 5/8 type x









Still need to cut the outlet boxes in the 2nd layer of drywall, but I'm going to try and keep these as small as possible. For tomorrow, work on dead vent design/construction, finish drywall on the HVAC room side.


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## patchesj (Jun 17, 2009)

Ted White said:


> Looking good, man. Your description of the Dad Vent puts it in the center of the wall, then? That can work if you have it built with massive damped sides, top and bottom. You don't want to risk sound leaving the DV and dumping into the middle of your wall cavity.


This is the side shot of what I was thinking. The red is the drywall, brown is the 2x4, green would be 3/4 MDF. 









Basically going to invert for the exhaust, and have an initial 90 bend on the supply so the exhaust/supply will be sitting next to each other.


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## patchesj (Jun 17, 2009)

Of course it's dawned on me that I could build the dead vent inside the theater, behind the false screen wall. That would be my least favorite option as it would take up space back there that might be used at some point in the future, but it would probably be the best performing option.


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## Ted White (May 4, 2009)

I have one dead vent inside behind the screen wall, and another outside my theater in the equipment room. 

I misunderstood you before. I thought you were installing a DV on between the drywall layers in the wall cavity. You're shooting straight through. That's great.

The build is looking great, BTW


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## patchesj (Jun 17, 2009)

Ted White said:


> I have one dead vent inside behind the screen wall, and another outside my theater in the equipment room.
> 
> I misunderstood you before. I thought you were installing a DV on between the drywall layers in the wall cavity. You're shooting straight through. That's great.
> 
> The build is looking great, BTW


Just to clarify, am I thinking correctly that the MDF will be tied directly to the back of the double drywall/interior wall framing? And then leave a gap around it for the exterior drywall? Or do I want to try and decouple the MDF from the interior wall somehow. No idea how, maybe a "Slip" fit trim piece like the communicating door jambs will have?

Blue would be sealant..


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## patchesj (Jun 17, 2009)

Hmm. I'm getting a bit nervous here.. I know the room isn't close to done yet, no mud/tape, no doors, no carpet, no treatments, but.. I can still hear footsteps on the hardwood floors above the room. There is certainly a difference between the unfinished space and the inside of the room, but I was anticipating it would be a little more dampened than it is. Am I worrying too much and just need to wait, could I have done something wrong, or is this just expected?

:scratch:


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## Ted White (May 4, 2009)

A few things:


Is there a chance the new floating joists contact the original joists?

Is there a chance any of the conduit is touching both surfaces?

Has the Green Glue been drying for less than three weeks?
Footfall vibrations will be conducted into all of the joists and then to whatever the joists are in contact with. So without the door, you may be hearing this from the outside the theater.

Regarding your dead vent, you might consider damping the piece that travels through the walls. For example adding scrap drywall and leftover GG to the exterior of the component that travels in between the two walls. I would not attempt to decouple as you have pictured. 

Just seal it to the back of the drywall as you have indicated. Good idea to have the outer drywall layer slightly oversized so the component does not touch the outer drywall (or framing) and seal that with quality sealant.


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## patchesj (Jun 17, 2009)

Ted White said:


> A few things:
> 
> 
> Is there a chance the new floating joists contact the original joists?
> ...


From the HVAC room I can look down the length of the floating joists, across the room. There is around 1" gap at the tightest spot (around ductwork). There is some fiberglass insulation that is touching the ducts and the new floating joists, looks fairly loose and just laying across both surfaces.

The conduit is secured between the floating joists and about 12" away from the original joists, so I don't think that's it either.

The green glue has been in place < 48 hours.... I guess I'm just impatient. I figured the double layer and floating joists would be more effective on it's own, regardless of green glue.

I'm starting to think that the majority of the sound is flanking via the door way. The completely undampened interior of the room is not helping...

Thanks for the advice on the dead vent. Still sketching it out. Funny, I'm a "techy" but I still prefer paper and pencil when laying out speaker boxes/wood projects.


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## Ted White (May 4, 2009)

Over the years many have described things sounding worse after 48 to 72 hours. I have no actual data, but anecdotally very wet Green Glue may be quite conductive until the water leaves and the long chain polymers start forming.

There's no doubt that the floating ceiling that you (and I) have is the best method to decouple.


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## patchesj (Jun 17, 2009)

Thanks Ted, I'm beginning to feel better about it... Of course, having a 2 year old stomping around upstairs is a pretty tough test


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## Ted White (May 4, 2009)

Whew... That IS a tough test...


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## patchesj (Jun 17, 2009)

Ready for final sand on the drywall mud. Going to start on the false wall next. Trying to souce OC 703 local, need to get some materials to cover the entire front wall and build corner traps. Also planning on some 2'x6' panels to cover wall and ceiling first reflection points. 2" of OC 703 should work for that, right? My first reflection points on the right wall falls on the door. There was no way around this. So the door will get a panel on the inside, then green glue and additional 3/4 MDF on the outside (in the air gap).

Paint is going to be "Cafe Ole" in flat, trim/door in "Coffee Bean". Not sure on carpet yet, but I figure earth tones will be good. Wife shot down Grey/Black scheme.


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## Ted White (May 4, 2009)

How are you building your screen wall?


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## patchesj (Jun 17, 2009)

Very simple... Going to have 2 2x4s running floor to ceiling on the left/right edges of the screen (behind the screen border. Then 2 2x4's horizontally between the vertical members, again behind the screen border. This will give me a nice solid mount for my screen. Going to frame up some removable panels to fill in the "holes" on the left/right (about 20" wide floor to ceiling) bottom of the screen (30" tall and width of screen) and wrap them in some black material (doesn't need to be AT, but will not be solid). The screen "wall" will be about 20" off the actual front wall and give me space to put my mains and sub back there (AT screen).


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## Ted White (May 4, 2009)

I used steel studs years ago. I was concerned about warpage.


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## patchesj (Jun 17, 2009)

Hadn't thought about steel studs. Need to look into that. Would also make my plan of magnets to hold the panels a bit easier...


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## Ted White (May 4, 2009)

Stays flat, fast to install.


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## patchesj (Jun 17, 2009)

Started thread to cover acoustics. Figured that would require it's own thread and isn't "construction"....
http://www.hometheatershack.com/for...29764-advice-basement-theater.html#post268699


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## patchesj (Jun 17, 2009)

Room is 99% done... Well, I guess it will always be 99% done. This type of thing seems to be never ending! Pictures below are of the rear riser stuffed with fiberglass. Framed in screen wall. 1 3/4" MDF "inside" door. More of the framed screen wall, and front wall with 8lbs RockWool, then covered in black burlap.


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## patchesj (Jun 17, 2009)

Projector mounted, wiring termination point in the equipment room, building the 2 dead vents.


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## patchesj (Jun 17, 2009)

Back of the room. Foam corner pieces and more rockwool absorbers on the walls. Room is fairly dead even without the carpet and padding down yet.


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## BuSdRiVeR (Nov 14, 2010)

I've been following your build recently because you, too, are in Kentucky. Where abouts? It's looking great!


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## patchesj (Jun 17, 2009)

I'm outside of Lexington. 

Watched Book of Eli on BD (on my new Oppo BDP-83!!) last night. First "real" movie I've watched down there. Overall I'm pleased, was able to watch at moderate volume and no one else in the house could hear it. I'm sure I could have cranked it up louder, but didn't need to. The sound is SO dynamic. With the room being basically dead silent you don't need to turn it up to hear the soft details/dialog. Similar story with the picture, the room is completely dark (and minimal reflection from the flat paint) so the contrast/black levels were stunning.

Still have some tweaks to make:
BFD hum due to ground loop from the BFD, past processor, and then out HDMI to the projector of all places... argh. Going to use optical connections for now, I'm not running a trueHD/MA capable processor yet. Then going to rewire projector outlet to feed from one of my isolation transformers. 

I built the sub box to fit a Shiva-X, but have a trusty Vifa in it for now (box specs are surprisingly similar, but with much higher roll off with the vifa). Hopefully will post my sub build thread soon.

Need to get my carpet down, and finish the material around the front screen wall. And then watch more movies...


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## 4U2NVME (Aug 20, 2010)

patchesj said:


> Projector mounted, wiring termination point in the equipment room, building the 2 dead vents.


Ok, I saw you mention a couple times about dead vents, I assume help with noise issues, but really what are they and how they work?

-NV


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## patchesj (Jun 17, 2009)

So the dead vent is basically a muffler. Because my room is completely isolated from the rest of the house, there is no connection to the HVAC system. In order to provide fresh air to the room I have an independant fan pulling air from another section of the basement and blowing it into the theater via a dead vent. Because the room is sealed I need to give the air somewhere to go, so there is a second dead vent that allows air to escape from the room back to the mechanical room of the basement. Air in, air out with minimal sound transmission in either direction.


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## hddummy (Mar 9, 2007)

So...i'm curious, what are you going to use to control the air transfer fan. Are you going to just have a manual control that you turn on when you are in there? Are you going to set a timer to run it for some hours every day? Can it be wired to a thermostat to control it based on in room temps?


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## patchesj (Jun 17, 2009)

I have a light switch in the theater wired to control the outlet near the fan. I can just flip it on when I need it. I have a variable speed controller on the fan so it is adjusted to provide the maximum airflow without causing noise.


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## 4U2NVME (Aug 20, 2010)

Thanks for the explanation Patchesj!!


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## patchesj (Jun 17, 2009)

Sorry for the dark pictures, taken on my blackberry this morning... Carpet is in, front wall is complete. Need to get seating and finish up my DIY surrounds.


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