Originally Posted by BrolicBeast
I've just realized that had I known about AVS when I was in grad school, I probably would have flunked both tracks. Seriously, I wouldn't be able to get ANY research with AVS just a click away...
But on to the subject of the third drywall layer.....After giving it some thought, I am going to stick with triple layers. I had an extensive discussion with Ted about my audio requirements--he recommended triple layers on clips\channel w/ gg. It's best to stick with that recommendation, since he had the full understanding of my requirements when he gave that recommendation. But the last twenty posts reinforce my suspicion that the returns do diminish drastically with the third layer for most users. But...but...I am a bass-head....and not just that....I'm a reference-level bass head. I have a JRiver category JUST for Bass Demonstration material! So, any help with isolating bass frequencies is moreeee than welcome.
Well if you can swing it.. swing away!
At no point was anyone suggesting 2 layers was as good or better than 3 layers. This is a place you won't want to go back and re-do later if you get it wrong. If you can swing the cost of an extra layer of DW and some GG up front then there isn't much reason not to do it other than "value". But if the third layers get's you more what you really want then that is "value" in my opinion even if it costs you more.
My house has a noise floor of about 35db with the appliances off. I have a quiet neigborhood, I am second to last house on dead end street. There is no traffic. No planes overhead most of the time, and if they are they are way up in the sky. I don't have construction going, or big trucks driving around near my house. My neighbors are all quiet. The worst I need to contend with is a lawn mower, and let's be realistic it doesn't run more than an hour or so once a week. Aside from that it's crickets at night outside, and birds in the morning. My theater is above a 2 car garage that is seperated from the house with a two story breezway/mudroom and the attic space or any of the joists of my new construction don't directly couple or connect to any of the construction or walls of the main house. The kids rooms will be entirely on the other side as far away as possible from my theater, and even my wife and I bedroom has some space and rooms in between. I also won't share heating or cooling system or duct work. I thought really hard about 3 layers myself but for my needs and with my budget I decided I really just can't (or shouldn't). It's extra cost, extra work, and I wasn't sure I needed it. I think you are different though. Your design will require a bit more than mine given it's location and the size, and the kind of bass you want.
For me the priorities were different and at first I was really confused at "what is soundproofing" because it can either mean:
(A) Keeping sound from leaving the theater and bothering people
(B) Keeping sound out of the theater and bothering me while watching a movie.
These are very different. For me it was and is nearly 100% about keeping the sound from entering the theater and keeping my noise floor low so I can enjoy movies and music to the fullest extent possible and experience the full dynamic range. This also benefits in that I can watch a movie under reference volume (which I will do) and still enjoy a decent dynamic range. I want to be able to hear when actors whisper on screen without needing to turn on subtitles. If you noise floor is too loud this just isn't possible under reference listening volumes, and above reference volume is where the problem of too much noise from the theater presents itself the most too. But I think I decided that given my reasonable expectation and requirements for only moderate sound proofing results, and that my design already has a few elements going in it's favor that a basement build will not, two layers was "enough" for me.
At first I was specing three layers but the cost was insane and I wasn't making the differentiation between my real goal (low noise floor) from the less important goal (keeping sound in the theater). If I was trying to keep sound in the theater I would probably do 3 layers. My 8-10 year refresh I probably will add another layer
Do the third layer if you can swing it. No one ever regrets later when they make a decision to have something better. Once the check cashes and you are sitting in your theater blasting bass a year or two from now you will be happy.