Treating a small room without rebuilding it

Small rooms have a specific set of problems and a specific set of fixes. The mistake almost everyone makes first is covering the walls in thin foam, which absorbs the high end, leaves the low end untouched, and produces a room that sounds dull and still boomy.

Corners first

Low frequency energy collects in corners. Thick porous absorbers running floor to ceiling in the vertical corners do more for a small room than any other single change. Thick is the operative word: the depth of the material matters more than the surface area, so four inches of mineral wool with an air gap behind it beats eight inches of foam.

Then first reflections

Sit in the listening position and have someone slide a mirror along the side walls. Anywhere you can see a speaker in the mirror is a first reflection point. Treat those, and the ceiling above and between you and the speakers. This is where the imaging comes from.

Then move the speakers

Free, reversible, and frequently the largest improvement of the three. Pull them away from the wall behind them. Get the tweeters to ear height. Make the triangle between the two speakers and your head equilateral. Then move your seat out of the exact centre of the room front to back, because that is where the worst nulls live.

Foam on every wall is the sound of a room that was treated by someone in a hurry.

What not to bother with

• Egg boxes. They do nothing measurable.
• Thin foam tiles. They absorb only the frequencies that were not the problem.
• Diffusion, in a very small room. There is not enough distance for it to work as intended.

Treat the microphone position too

Everything above is about the listening position, which is the right place to start if you mix in the room. If you mostly record in it, the other position that matters is wherever the microphone usually stands. A single thick absorber behind the singer, facing the mic, kills the reflection that makes a small room sound small on a vocal, and it costs one panel rather than a rebuild.

Then listen for a week

Do the three moves and then play music you know well for a week before changing anything else. Rooms take longer to judge than people expect, and the temptation to keep adding absorption is how a room ends up dead.

Then update the listing

If you rent the room out, treatment is worth saying out loud. Retake the photos once the corners are done, because the room genuinely looks different, and replace any vague adjective in your description with what you actually did. Treated with four inches of mineral wool in the corners tells a guest far more than warm does. There is more on that in writing a studio description.