1. Isolation — stop the sound from leaving
If your home theatre shares a wall with a bedroom, isolation is the first priority. MLV inside the wall (between two layers of drywall) is the highest-ROI upgrade. Skip it and every future acoustic treatment inside the room becomes cosmetic.
For a room in a basement or standalone shed, isolation matters less — jump straight to treatment.
2. Primary reflection points
Sit in the primary seat and have someone slide a mirror along the side walls. Anywhere in the mirror you can see the front speakers = a primary reflection point. Absorb there.
50–75 mm pyramid or wedge foam covered in acoustic fabric works. Or fabric-wrapped gripper panels with 50 mm PU foam infill for a premium finish.
3. Bass traps in the corners
Bass builds up in room corners. Corner bass traps — 100 mm PU foam wedges floor-to-ceiling in all four corners — dramatically clean up the low-end. This is the single treatment that separates a decent home theatre from a great one.
4. Rear-wall diffusion
The rear wall behind the seating position needs breakup, not absorption. Diffusion (or a mix of absorption + reflective bookshelves) prevents rear slap-echo without killing the sense of immersion.
Rough BOM for a 15×20 ft home theatre
This gets you 80% of the way to a fantastic-sounding room:
- MLV inside all four walls (~600 sq ft)
- 6 fabric-wrapped panels on side walls (2×4 ft each, 50 mm foam infill)
- 4 corner bass traps (100 mm PU foam, floor to ceiling)
- 2 ceiling clouds above front and centre listener
- 1 diffuser wall or mixed panel on rear wall