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For what it's worth, I'm not doing any sand in mine. No stage either. Speakers will just sit on the floor which is horse stall mats with 2 layers of subfloor with Green Glue. It's on a concrete slab.
 

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I'll throw my 2 cents in here also. I built the front area that is behind the screen false wall on top of rubber strips and the riser was built on rubber strips also....BUT...not on the sub floor. I did mine on the concrete first. Then I built the floor between the false wall and the riser using 2 layers of 3/4 OSB over rubber matting. I did not build the "stage" area or the riser on the subfloor. I thought I read that was a good way to do it from Jeff BIGmouthinDC, but maybe I am mistaken.
 

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Thanks Nicco. I actually just finished the last 3 sheets of drywall this last weekend and spent the rest of the weekend bagging up all the scrap and getting it up to the garage. Glad to be finally done with it! I think after I seal the inner corners up with acoustic sealant I will start to tackle the floor vs. the soffits. For the floor I was thinking of cutting 3 inch strips of 1/2 inch horse mat stall, 12 inches apart wall to wall. Then 3/4 T&G OSB on top, then green glue, then 5/8 OSB the other direction. I'm planning on doing this under the whole floor and then building the riser and stage on top with the thought of keeping as much tactical vibration as possible but insulating from the concrete slab. In doing that however, I'm not sure about putting sand in the stage due to the weight on the floating floor. What are peoples thoughts on this?
Putting horse mat stall on a concrete floor serves no purpose (it sort of does, but the purpose is neither acoustic nor the best regarding energy efficiency). Use 1" or thicker Owens Corning Foamular instead. Completely cover the floor and seal the seams and edges. This is the proper way to insulate the floor.
3044602


Next you have to decide if you want a resonant floor or non-resonant. If you want non-resonant, then screw down the plywood as shown above. Tapcons or Spax screws should be 8" apart. Hammer drill and then vacuum the holes. Using screws ensures that the entire floor is now a solid mass acoustically with the resonant frequency below 10 Hz if the concrete slab is on earth.

If you want a resonant floor, then decide what frequency you want it to resonate and design accordingly. A resonant floor will produce a resonate frequency and affect about 1.5 octaves above the resonant frequency and 1 octave below the resonate frequency. This will wreak havoc with the bass frequency response in your room. It is counter-productive to go to all the work to create a great acoustic starting point with the isolated walls and ceiling and then induce resonance with the floor. I also feel the same about the BOSS system in that it messes with the phase alignment of the subwoofer system, but at least it can be turned off or removed later if someone doesn't like it. The floor is basically impossible to fix. I recommend Crowson transducers for low bass tactile feel.

Regarding a stage, changing the room height also affects the bass height modes and reduces the ability to create a plane bass wave at the front of the room. I prefer to use the space as a bass trap (sand is not a bass trap ;)).
 

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Discussion Starter · #45 ·
I was following the standard from the sound proofing company, where they recommend "If you are serious about a floor that performs at the highest level, then install two layers of plywood with Green Glue in between and 3/8" Serena™ Underlay to create a floated floor system." I was just substituting 1/2" horse stall mats for the Serena Underlay. You are saying doing this will cause unforeseen bass issues? My large riser will be a bass trap already - sitting on top of the floating floor. I am very open to the idea of making the riser one as well.
 

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The Soundproofing Company advice for flooring is for floors that are over another room. You can see from the pictures that they are talking about flooring on joists. A long time ago someone decided to put Serena mat on their concrete floor and many have followed that pattern. It is a waste of money.

From the Soundproofing Company, "For soundproofing theaters and recording studios, all walls, ceiling, and floor (unless it’s a slab) need to be fully treated."

You were going to cut strips of horse mat with air space in between. Anytime you add an air layer in a floating floor you create a resonate system - unless the weight of the floor is sufficient. You would need quite a few inches of concrete above an air space to make the floor resonate at a low enough frequency.

When I said I prefer to use the stage area as a bass trap, I mean I don't like to have a stage. The front wall/floor junction behind the screen wall is a great place for insulation which then is a bass trap using velocity based absorption.
 

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Discussion Starter · #47 ·
Well the drywall and floor is done. I changed my floor plan slightly based on the advice above but I didn't have enough material to cover the concrete completely. I was able to cover about 90% of it with horse mat, then the 3/4" OSB, GG, and 1/2" OSB. Since almost 80% of the floor will also have stage or riser above it, I'm hoping it will work out.






I kept snapping drywall bits, so I went old school to cut out the speaker boxes.






Layer 1:


Had to get creative on getting the last pieces of t&g together:


Layer 2:


Here you can see the walk in height of the room:


Complete!


Now onto some fun stuff - soffits, HVAC, and wiring.
 

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I love how you are making it personal with the fleur de lis theme. We went with more of an Art Nouveau style, which originally included a lot of floral and nature elements.

We used the sconces below and had leaded glass door panels made with a similar pattern. Other floral elements are in the chair fabric (just the edge of a recliner can be seen at lower left, and the floor lamps).


3046446



3046445
 

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Discussion Starter · #50 ·
2 month check in. Only been able to work on the room a little bit on the weekends, progress is slow but steady.
Starting the soffits / HVAC / Lighting. I started by drawing a laser line around the room for the header board.




I made sections of soffit wall with 2x3's and metal framing. These are glued up using construction adhesive, and screwed into the metal track when possible and to the drywall / osb layers when not possible. I also took the advice of folks here and did a rough mud / tape / primer for the section that will be inside the soffits.



Then I shirked lawn duties (again) and built some HVAC boxes. The two ends out 3/4" MDF which I then ran through the router table to cut a 1/2 inch rabbet so that the 1/2 MDF sides fit flush. Unfortunately due to bump outs in my room each HVAC box was slightly different sized, so took a bit of work to figure it all out.





Picked up 4 - 20x8 Aluminum grills at HVACQuick.com. Went with unpainted right now as I'm not sure what color the underside of my soffits will be. Went with 20x8 as its roughly 3x the area of my 8 inch supply and return soft ducts - so should slow the air down.



Finally completed all 4 HVAC boxes and all the soffits this last weekend. Next steps are wiring, insulating, and then covering them with osb and drywall.



 

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Discussion Starter · #55 ·
I've started drawing out my plans for the massive riser in my theater. It will have 5 steps total, dropping from the entrance of the theater down about 3 feet. The back row will be two steps down, the front row another two steps down, then a last step down to floor level for a few feet before it hits the stage. I know I eventually want to add some Crowsons or something similar, and I read on their website they get maximum attenuation under concrete or tile, less so on wood, and even less on carpet. With that being said, I was thinking of tiling the back sections of my riser where the chairs will sit - is that crazy? Carpet would run up to the chairs in both rows, then just tile tucked in the back sections of the riser platforms in row 1 and 2. Since the riser is two layers of 3/4 plywood, I figure I can just tile right on top?
 

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So if I understand the riser would be made of wood and have Crowsons on it? If correct I think using tile would be problematic, even if you caulk the grout lines (rather than grout) I would think cracking tiles or the glue that holds them down would be real issues.
 

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Discussion Starter · #58 ·
I was able to make some more progress over the holiday break, and finally got a chance to upload some photos.
Soffits were wired and stuffed with insulation, then a layer of OSB was run on the bottom with a 5 inch overhang for the light tray. I cut large squares where can lights and atmos speakers will be, since these really only need to grab onto the drywall that will be over the OSB.









Copying what others have done, I then glued and screwed a 1x4 poplar lip on the front of the OSB. I connected the inside corners with a kreg joint that will then eventually be covered in drywall mud.









And then some lightweight 1/2 drywall over the OSB. I'm going to wait to cut all the HVAC, atmos, and lighting holes until after mud, tape, and priming the room.







So happy not to hang another sheet of drywall or OSB. The final count was 145 sheets.
FYI, this says Lite on the bag, it is a lie.

 

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Discussion Starter · #59 ·
Slowly making some progress over the last few months, here is where I am at now.

Mud and Tape is complete. Went with a smooth level 5 finish where the whole room is skim coated.
Between coats:

Final coat:


Primed:


Here is what my wife and I agreed to as far as color scheme. Room will be Sherwin Williams Theatre Red (nice name! - ignore the other color swatch below - that was another color option we were looking at). Columns will be dark stained oak, with a grey brown speaker cloth in the center from Acoustimac. I ordered 10 Clark seats from HTMarket in a custom dark brown (see sample). HTMarket was amazing to work with, and we were able to visit their showroom and sit in a lot of their models. It will be two rows in a |OO|O|OO| configuration.

 

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Discussion Starter · #60 ·
For the stage, I copied a design that a bunch of previous builds have used. Drew it on graph paper, then to get the arch correct, the kids and I built a large compass with string and 2 pencils, and drew the arch on paper. Then we cut it out and traced it onto the floor. The stage is going to be about 13 inches to match the soffit height, so I cheated and stacked 2x10's on top of a sideways 2x3. This gives me close to 13 inches with two layers of plywood on top.





Installing the 2x3s


Sand and wood for the stage and riser delivered! I thought bringing down 70 60lb. bags of sand would be horrible, but it went pretty quick. Got it all down in a day. Then I took a lot of Ibuprofen. A lot. Wife led the painting effort and got the room done in a few days. She loves painting. I hate painting. Good match.

 
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