If you’re fortunate enough to have a room with workable dimensions as described in this post, you’re already ahead of the game when it comes to good sound. Proper room dimensions enable the rule of thirds to work well (which is how we manage to get such good sound in our room).
I am assuming you followed the advice for live/dead in this post, and are now ready to place your speakers and equipment.
Do as little as required. We often figure if a little room treatment’s good, more is better. And, that’s simply not true. In fact, often the opposite is what happens. I can’t tell you the number of rooms I have improved by simply removing a lot of unnecessary clap trap.
Start with an empty room. To the best of your abilities (being respectful of your spouse) clear the room of anything unnecessary. Place the speakers and listening chair—using the rule of thirds if you’re able—where you’d like them and make big adjustments to rough in the sound.
Add back in what’s needed for decor and livability one at a time. Make note of the sonic changes with each addition. Adjust as necessary.
After all three primary rules have been completed, now it’s time to add the finishing touches.
Diffusion is better than absorption. It is almost always s better to diffuse sound than it is to absorb it. When you diffuse sound waves you scatter their reflections so the ear can’t localize them. When you attempt to absorb them, you capture some and leave the others, forming a type of filter that skews tonality.
If you absorb sound, keep it to the corners and rear wall. Some absorption is ok if you use it for specific frequencies like bass, which builds up in corners and the rear wall. If you’re going to have any area of your room acoustically deader than the other, it is the rear of the room (behind the listening position) that will benefit.
Speaker and seating placement are more effective than room treatment. In general, this is true. If you have a decent room without any treatment, moving speakers and listening position to best advantage often gets the best results.
Pull the speakers out from the front wall. Few speakers on the planet benefit from being close to the wall behind them. Pull them out into the room.
Use the last three posts as a type of guide to help your system bring life to music.