Axiom Home Page Forums General Discussion Home Theater Acoustic Treatments/ Soundproofing.

I just moved into a new townhouse and was going to put up a few acoustic panels in the theater room to counter all the framed posters I have on the walls. I was also considering adding any kind of soundproofing or sound reducing material so the neighbors don't completely hate us. I realize bass traps are more for room nodes than any kind of noise reduction, but would they help at all? Another thing I read about was decoupling the subwoofer from the floor/walls, which sounds like the most effective solution. Sorry if this subject has been brought up before, my search yielded nothing.

for a start, you could try here:
http://www.realtraps.com/art_room-setup.htm
http://www.ethanwiner.com/acoustics.html#diffusers and absorbers

i also think that decoupling the sub from the floor is a very good thing to do. this will give you cleaner sound, less distortion;
by that, i mean if everything in your HT room shakes, those sounds are ADDED to the original recorded sound, and they don't belong there; same as strong reflective walls for the high and medium frequencies. it muddies the sound.

Thanks for the links, I will peruse them. As a side note, for my sub decoupler, I'd like something that either comes in the size of the EP-350 or can be cut/modified to that size. The Auralex Subdude is 15" by 15", and I've seen another at 2' by 2'. Space is kind of an issue; I don't have too much wiggle room.

Soundproofing "after the fact" (after the room is already built) is really difficult. You are going to do more for sound quality in the room than anything else with what you propose.

However, decoupling the subwoofer might help with some of the sound going downstairs, but it won't do really anything for keeping those long wavelengths in the room.

Some cheapy DIY options are to take a piece of MDF (or even 3/4" plywood), and attach it to some thick foam pieces on two sides. This creates sort of an upside-down 'U' with the two foam pieces and the wood.

That will help reduce some of the transfer down below, but not much since it is still long soundwaves. It will, however, help with your bass quality in the room to some degree. This is the same thing that the Subdude is, only doesn't cost $60 plus shipping.

The theater is on the ground floor, and our bedrooms are upstairs. The neighbors in question are to the left of us; our townhouses are mirror images. I was hoping decoupling the sub would keep our shared wall from shaking too much. I realize the low frequencies will still travel through. Oh well, I guess my theater will sound awesome; just have to turn it down after quiet hours.

In your specific situation, i would recommend you watch the entire episode below, they will give you products and techniques that will help with your question specifically with regards to the neighbors.

I will warn you though, this is a holms on homes episode.. So, they pretty much tear everything up and make it arguably the best possible.


http://www.dailymotion.com/video/xd6yok_soundproofing-room-home-to-avoid-ne_people

Mike Holmes is great. He basically is taking the staggered wall that was built between the two "townhomes", put insulation in there, put putty pads around the outlets, and then QuietRock. QR is pricey for sure, but they nailed how it works. Two layers of drywall for the outside "sandwich" with a sheet of thin metal coated in a polymer. This is the same as doing two layers of 5/8" drywall yourself but before the second layer, you apply GreenGlue. The GreenGlue method can be a tad messy, but it is a lot easier hanging single sheets of drywall than hoisting up that QuietRock. Plus, some argue that GreenGlue with the two layers of 5/8" drywall is actually superior, and a lot cheaper, than QuietRock. What they show in the video is pretty much what I did in my theater and I have had amazing soundproofing results. I hear the tv in the living room next to our bedroom way more than any movie played in the theater right below our bedroom. Of course, I also had a door and air ducts to deal with too.

What you want to go for is three fold. 1 - decouple the common surfaces with a double studded wall or staggered stud wall. 2 - provide absorption with the insulation in the wall cavities. 3 - provide dampening with mass and elastic polymer via the mass of the drywall and the polymer of GreenGlue. Of course Plus and "holes" like they did, and you will be set.

Unfortunately, this means either building a whole additional stud wall with at least an inch gap between it and the current wall, or tearing it out like Holmes did and starting fresh...