Spaceman Theater build - Page 8

Thanks Chase. Was your back wall poly between layers or on the surface? I'm going w/FSK on the rear wall surface so it's not too dead. My understanding on the poly sandwich on the front wall was that it still allows the 1st 1" to control the highs but provides a full 2" to control the lows. Without the poly, a full 2" would make it too dead. Am I understanding that correctly?

That's good to hear. For some time, that seemed to be the recommendation for the front wall (to make it as dead as possible). I was prepared to do the same until I started seeing the poly sandwich showing up again and again. I realize it's usually prescribed as a result of actual testing or modeling, which I'm not doing, so to say it is a good solution for my situation would be difficult. However, if it's one of those things that seems to help regardless of room-specific acoustics, I'd like to add it since I have the poly and it's easy to do. Choices, choices.

PM'd both Dennis and SierraMike today and both recommended the poly between the 2 layers of Linacoustic on the front wall. Actually, Dennis recommended it and Mike said it would be fine.

I got the 1st layer up today. Hope to have the poly and 2nd layer up tomorrow.

I've started installing linacoustic (actually it's cousin, JM Duct Liner PM) on the front wall. The 100' roll is a little cumbersome to handle so I did all my cutting outside.





Working outside also allowed some of the dead fish (formaldehyde) smell to wear off. I let the 4 pieces I needed for the front wall sit outside for about 6 hours before bringing them upstairs.



I didn't have any help today, so I had to use a few 2x4s to help hold things in place while I got the screws started.



I secured the first 1" layer with 2" drywall screws and 1/4" flat washers. I painted all of the washers flat black. These were a little cheaper than the bigger fender washers and seem to work ok. The hole size is just a tad smaller than the head of a drywall screw, although I did run into a few where the head slipped through the hole.



Nothing magical about the spacing of the screws. Just what felt right. Note that the surface of the Duct Liner PM is somewhat reflective. Does Linacoustic RC look the same? Will this be a problem?





With cutouts for speakers and boxes


In addition to 2 duplex outlets, I have a low voltage box under each of the 3 speakers for each of the speaker wire runs. I was originally planning on putting a scoop-style wall plate on each box after both layers of linacoustic were installed. I could then run the speaker wire up the face of the linacoustic to the bottom of each speaker. However, the low voltage box for the left speaker backs to the attic and a tremendous amount of heat is pouring into the room through that opening. I'm now thinking of abandoning the finished wall plate idea and using the insulating properties of the linacoustic to my advantage.

Option 1:
I could keep the first layer of linacoustic as is (with big squares cut out at each box) and run the speaker wire up the face of the first layer to the speaker. I could then cover the speaker wire and open box with the 2nd layer of linacoustic, trapping some of the heat. The only holes I would cut in the 2nd layer would be for the duplex outlets.

Option 2:
Same as option 1, but attempt to plug the openings in front of the low voltage boxes with small pieces of linacoustic. I would then punch the speaker wire through the linacoustic plug and run it up to the speaker before covering everything with the 2nd layer of linacoustic.

Option 3:
Same as option 2 but punch the speaker wire through both layers of linacoustic before running it up to the speaker. In this option, I would need to wrap the exposed section of speaker wire with black electrical tape since the jacket is white.

Do any of these options sound better than the others?

Mini-update:

Covering the first layer of linacoustic with 3.5 mil poly sheeting, after getting the green light from Dennis.






Added a 2nd layer of linacoustic on top of the poly sheeting, this time with 2 1/2" drywall screws and the same black washers. Note that I plugged the 3 low voltage boxes that were under each speaker and simply ran the speaker wire out of the box and up the wall behind the linacoustic. This kept the wire hidden and also kept heated air from the attic from pouring into the room through one of the boxes. Slack is temporarily thumb-tacked to the wall.







I was doing so well until hanging the last piece of linacoustic, when I obviously fell asleep at the wheel and mounted it so the Johns Manville product data is UPSIDE DOWN Come on, don't lie. It bugs you just a little bit.

Per Dennis, a non-pervious barrier between the two layers will increase absorption in the lower-mid frequency ranges.

With the poly being in the middle, the outer layer of linacoustic will still help with absorption of high frequencies.

To be honest, I would have used the same 2" material between the bass traps too except I had to find a home for all the extra Linacoustic. I think I'm only using half the roll for my side walls, so I decided to use the rest on the front wall.

Mine may be tidy, but it can't stop a runaway truck like yours can.

Seems to be a common trait around these parts.

Thank you.

Tips specific to the soffit? I just made simple frames out of 2x2s. Longer frames towards the middle of the curve, shorter frames towards the ends. Cross braces between each frame. 1/2" ply on the front. Pics below will give you an idea. FYI-A laser level has been my most valuable tool throughout the build.

Tips for overall planning? Given my skill set, I could not have built this room without designing the entire thing on paper first. Whether it be hand-drawn ideas on a napkin or detailed plans on the computer, my recommendation would be to plan everything out ahead of time. I don't have the ability to stare up at the ceiling and figure out in my head how to build a soffit. For one, I've never done it before. Two, my brain just doesn't work that way. I need to think it through on paper and fix all my mistakes long before I pick up the hammer. (Tip #2-I'm not very good with a hammer...use screws whenever possible)

My entire theater is designed in AutoCAD. After ripping down all of my existing drywall, I measured where every stud and joist were in the room. I drafted that on the computer and then designed where EVERY new piece of framing would go (walls, ceiling, soffits, riser, stage), every electrical box, drywall, all acoustic treatments, etc, etc. Anything that was added to the room was drawn to scale on the computer first, both in plan and elevation. I was able to catch 90% of the conflicts during the design phase instead of during the construction phase.

When it was time to build the curved soffit, I simply printed out an enlargement of the soffit area from my overall plan. The plan included dimensions on every piece of lumber I had to cut. I did the same thing for the riser, stage, and for all the modifications I made to the existing walls & ceiling. I have made a few tweaks during construction, but so far, the build has stayed true to the plans.

Here's a portion of the plan showing the curved soffit area (without any dimensions).


This is the area under construction






This is an example of what I printed out when it was time to build the riser. I already had the framing drawn. I just added some dimensions and I was good to go.

It's the Skil #8201-CL. It came with a cheap tripod, but I am using my own small and large camera tripods. I'm very happy with it.

The front wall looked a little naked with linacoustic but no speakers, so I made that my priority this weekend. I have very little room behind my AT screen, so I'm using in-wall speakers (Atlantic Technology IWCB-727 THX Select closed box). Rather than cut a hole in the drywall and recess the speakers 2" into the linacoustic, I built 3 simple speaker boxes that attached directly to the drywall.





I had at least one stud behind each box, so I secured the top and bottom of the box frame to the stud with 3" screws (see pencil lines on drywall). Where I didn't have a stud, I used 1/4" x 4" toggle bolts. Very sturdy.

I kept the bottom cross piece just off the wall so I could sneak the speaker wire up into the box.


All 3 frames installed


Added 3/4" OSB to the face of the frame with an opening sized to accept the speaker frame.




Boxes get 2 coats of Mouse Ears black for good measure. I also painted the frames holding up the corner traps


Once those dried, I installed the frames that came with the speakers. These were originally white, but I hit them with some flat black spray paint.




Once the frames were installed, the speakers slid right in.


They seem a little reflective. Should I use the grills that came with them. Like the frames, the grills are white, but could be painted flat black as well.