I received a PM from a couple of people asking about the acoustical benefits I noticed, if any, of the treatments behind the screen.
I have no measuring tools, but only practical information based off of what I hear.
Before the treatments, I could be talking to someone and as I showed them around the room and would simple walk towards where the screen was going (or is now), my voice would literally start sounding deeper and resonate more (boomy). It was really odd. Odd enough that my wife thought that I was "faking it" and making my voice deeper in an attempt to get her "approval" for the acoustical treatments.
I also noticed that the room was still a little bit too "live" for my tastes. I ran a couple of sound tests using an old CD I had that would simply play a series of tones at different frequencies in short bursts. You could hear a distinct (even though slight) echo of a bunch of the frequencies. This is something that would reflect nicely on a waterfall chart or whatever those with testing equipment call it.
Anyway, I could hear it, and I knew that this meant that audio was getting muddled and jumbled with itself (comb filtering?).
After the treatments, my "Barry White" voice went away. Now I sounds the same (good or bad) when moving around the room. I also popped in the test CD again, and alas, the amount of echo was GREATLY reduced. Keep in mind that it wasn't terrible to begin with, and really wasn't even noticeable when not running the test, but now, only a couple of frequencies even had a slight hint of echo.
So overall, I would say that they worked very well. MAYBE someday I will worry about first point reflections or treating the rear wall, but honestly, I doubt it. So much of this has turned out great from a sound perspective.
Things that were worth it:
*) Staggered stud wall/double wall construction
*) Double 5/8" drywall with GreenGlue for the inside of the theater
*) Hat Channel for the ceiling (plus the DD+GG mentioned above)
*) Kraft paper faced insulation in all wall/ceiling cavities.
*) Flexible duct for the air vents (kills all sound coming in or out of the room via the HVAC system)
*) Bass traps
*) Front wall treated
*) Solid core, steel exterior door. Some people build these massive doors by adding an inch of MDF, special (expensive) hinges, etc, but this worked better than expected and with the custom jamb to fit the staggered stud wall, cost me about $220 vs. at least $125 for the upgraded hinges alone going the other route).
*) VP180 center channel upgrade from VP150 (Wow!)
*) Second pair of QS8s to envelop the 2 rows of seats
*) Use "Wall Nuts" (I used ones made by WAGO). These make electrical connections SUPER easy and your fingers don't start to get sore or blister from twisting wire nuts on. NOTE: I did not have great success with stranded wire and these. It wasn't stiff enough, but that is usually just the last connecting piece of a light fixture and not a big deal. They look like this and come in a lot of different sizes. I used 4 and 8 connector versions mostly:
*) Use conduit for running speaker wires not so much for future expansion, although it is an option, but more for protection of the wire. Either this or run them between the two "walls" of your staggered stud our double stud wall. It will take a 5" screw to get to my speaker wires and what the heck would I be doing with that big of a screw.
*) Document EVERYTHING and take pictures with documentation IN the photo itself. This helps us to remember what exactly we did and why so that any future needs for modification can work out well the first time.
*) Monoprice.com is your friend for cables and connectors. (Please read comments in the next section about lessons learned too.)
*) You can be happy with some cheap seating. I went with about the cheapest home theater style seating I could, and it wasn't like there weren't some issues, or that they are the absolute most comfortable thing out there, but they work well, add to the look of the room, and are better than the simple couch setup we had before in that they recline and have a taller back for comfort.
Things that I am not sure helped or I would have done differently.
*) Putty pads (OK, I used a cheaper alternative) on the outlets. Just not sure that they actually did anything since the only thing that can escape through the small gaps are higher frequencies and those are generally stopped by the kraft faced insulation in the walls.
*) Acoustical caulk - Not that you shouldn't use it, but a good quality 100% latex "50-year" caulk seems to be about as good and is really cheap. This stuff should be used on the FIRST layer of drywall since it is a P.I.T.A. to mud/tape/paint over. It took a ton of primer that was "designed" for all surfaces before it could be finished. Also, caulking along where the drywall meets the floor took more caulk that everything else combined and I am not sure that it helped at much . You are filling basically a 1.25" deep area (lots of caulk) that isn't that thick, has the bottom plate for the stud wall, cement, and thick drywall surrounding it, and is blocked by the thick carpet pad, carpet, and baseboard trim. I think that as long as your drywall came down far enough that there wasn't a gap ABOVE the bottom stud wall plate and the drywall (which would be an incorrect installation of drywall), and there weren't any gaps UNDER the bottom plate when building the wall that this could be skipped. - Wow, that is a lot about the caulk.
*) Soffits - I was working with a limited height room already, and in order to keep up with the soundproofing efforts, needed "backer boxes" around my can lights that were going into the ceiling. The backer boxes took up so much space that the soffits are lower than I would have liked. They aren't so low to make people have to duck or anything, but I think that aesthetically, they would look better if they weren't as "tall". A solution would have been to drywall the entire room BEFORE putting in the soffits. This is the preferred method anyway when soundproofing, but it gets tricky when trying to go through inspections with a building permit like we did. It would have cost me another inspection fee, plus "red flagged" the room which probably wouldn't have been an issue, but still. Looking back, I probably would have just done the soffits last.
*) Plan for all audio wall plates (test fit) BEFORE drywall. I have some thick HDMI connections back by my equipment rack that do NOT want to bend to go inside the wall cavity and are thus pushing out about 1/8" the one side of the 3-gang wall plate. This will most likely never be noticed once the equipment rack is in place, but it bugs me.
*) Do NOT, EVER, under ANY circumstance, even REMOTELY believe that an existing wall (whether wood or poured concrete) is even slightly straight or square. Unfortunately I made this assumption and despite measurements being right in some areas (I didn't check *all* corners, etc when building), the one side of my theater is actually about 1.5" longer than the other. You don't "see" it, but when I was hanging drywall, it was evident.
*) Do NOT, EVER, under ANY circumstance, even REMOTELY believe that the floor joists above your room are even close to being the same distance from the floor or are parallel to each other. This one wasn't as big of a deal since I believe that it is because the concrete floor was SO unlevel, not that the joists had that much variance. They were far from parallel to each other though.
*) Realize that 12Gauge electrical wire is a pain to work with unless you put in 20 amp outlets and switches, and even then it doesn't "tuck" into the outlet box easily and you will end up monkeying around with outlets and switches in order to get them to lay flat and even once screwed down to the box. If going with at thick wall like I did, get the deepest, adjustable depth boxes you can. I had 1 choice, and if it was even 1/2" deeper it would have helped a lot.
*) If using in-wall rated speaker wire (like I did), remove the outer sheathing BEFORE drywall phase, this will help the speaker wire to hang straight down better instead of wanting to curl up and make it difficult to find later on once the drywall is up.
*) Do NOT get too gung-ho on your connection purchases before the build is almost done. I spent a LOT of money at MonoPrice on what I *thought* I would use for wall plate connections, just to find out things like my projector doesn't have a VGA connection, so there goes the VGA wall jacks and the long and heavy duty VGA cable that I ran. I also have a slew of HDMI wall plates and adapters that I will never use because the plans changed over time. I went from this:
and now have $25-$30 in the first type (both single and double connection) that are WAY beyond the 30 day return policy.
*) Test ALL cabling as soon as you receive it. My primary HDMI cable to my projector was DOA (or was it DOI - Dead On Install), but again, I had it for a couple of months before I even really needed it, so no return for me. Another $35 loss.
As I think of more things, I will post them.
Ask any questions you like about any of the things listed above. The point of this thread has evolved over time from something for me to keep me motivated to keep working into something that hopefully holds some documentation value for others.
There is still much more to do, but the last tip I will share:
AVS has a LOT of knowledgeable people that are willing to share their thoughts on a variety of different subjects, but just be aware that you get a whole gamut of things from people that just buy stuff because the advertising to people that dive so deep into the technical aspects of audio/video/construction that the only people that even understand what they are saying are those that already fully understand what they are saying...
A lot of people there also clearly have a LOT more money than I do and can drop $1000 per seat, or $900 on a "DIY" door, or $450 on a tool that they will use half a dozen times for their theater build and then never touch it again. It is the principle of diminishing returns. You can do a lot with a little bit of money, but to get that last bit will cost you the most. Think 80/20 rule. It takes 20% of your resources to get to 80% of the desired result, but to get the last 20% of the result, will cost you 805 of your resources. Of course, I only have about 25% resources, so I could never get above about 82.4% of the desired (ultimate) result anyway, but this is still 100x better than anything I've ever had in the past, even if I don't have flashy woodwork, 3 rows of seats, tiered 11 foot ceilings, 4 subs, 11.4 sound, etc...