I'm renovating an apartment and I'm planning to use a small room for home theater:


This is how I'm planning to use it (the wall on the photo above is the south wall on the scheme below):

room schema

I'm gonna add sound proofing in order to be able to watch loud movies without annoying my neighbors. It's gonna be a 9 cm thick cocoon which is not touching the walls.

The goal

The purpose of the room is a home theater for movies and parties.

In addition to sound proofing, I would like to add sound treatment to minimize echoes, reflections, standing waves, etc.

I do realize that the room is too small, making perfect sound setup impossible. The fact that the couch is not in the middle of the room — also contributes to the problem.

My goal with this question is to find measures minimizing the flaws of the room and its arrangement.

The room

The screen wall is 3 meters wide, from corner to door. The side wall (south wall on the scheme) is 3.5 meters wide.

The ceiling is 2.8 meters tall.

The inner layer of the sound proofing cocoon is drywall.

Speakers setup

Initially I wanted a 7.1.4 setup with a floor-standing primary stereo pair.


  • I've discovered that a 7.1 setup in such a tiny room results in a tiny, single-person sweet spot in the middle of the room. Also, 12-channel receivers cost a fortune. Thus, I've decided to scale it down to 5.1.2.
  • Tall floor-standing speaker require placing them on the sides of the projector screen (120" 16:9). As a result, one of the speakers would end up in the corner. I assume that's undesirable. To move the speaker away from the side wall, I'll have to switch to large bookshelf speakers positioned under the screen.

The only audio component I've purchased already is a subwoofer. It's Mission MS-800, 12", quite powerful, closed box design, front-facing driver.

Measures I could think of:

  1. Do not position primary stereo speakers into the corner.
  2. Use a very thick curtain to cover the window, shown with green wavy line on the scheme.
  3. Cover the whole side (south) wall with sound treatment, shown with green zigzag line on the scheme. Note that using small patches of treatment in strategic spots is not an option because I'm trying to solve it for a party of movie watchers, not for a single person sitting in a predefined spot.


  1. What mistakes have I made and how do I fix them? Changing the arrangement of the room is not an option, it's settled.
  2. Should I use absorber or diffuser treatment to cover the side (south) wall? What is the difference?
  3. Which cheap material should I use? I've read that styrofoam is fraud. Is that true? I guess I could save a fortune by going with a handmade "pixel" diffuser made by cutting wooden beams. Is it the way to go?
  4. Should I add bass absorbers to both corners of the side (south) wall?
  5. What other measures can I take?
  6. Where should I position the subwoofer?
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  • 1
    Home theatre is off-topic, sorry.. but to throw you a bone. 1. You need mass & isolation [air-gapping] for soundproofing. Building a sealed floating box inside the room is a start, but unless it's heavy [& I mean concrete heavy] it will hardly stop any bass at all. 2. You can't know what acoustic treatment your room will need until the structure is completed & the room analysed. Also, it's best when building your 'box' to avoid any parallel walls & avoid similar dimensions. – Tetsujin Oct 16 at 9:33
  • Regarding sound proofing, accorting to my information, it's the change in density that is important. My sandwich is gonna be air, drywall, mineral wool, double drywall. But my question was about sound treatment inside the room, not about sound proofing the outside. – Andrey Mikhaylov - lolmaus Oct 16 at 10:05
  • Your lightweight construction will do almost nothing below 150Hz. You can't tune the room until it's built & measured. That kind of size you're going to get standing waves between maybe 95 & 130 Hz, but that's just a guess based on approx sizes. You won't know until you can measure it. – Tetsujin Oct 16 at 10:08
  • Regarding offtopic, there's no StackExchange section that is even remotely related. There's no Hi-Fi/audiophile section, no construction/renovation section. – Andrey Mikhaylov - lolmaus Oct 16 at 10:08