Room Issues and Fixes
To be fair, this is an art and a science and one not for the faint of heart. Let’s keep things simple and just outline some of the considerations in a room…
Use the Triangle
The best speaker position involves making as close to an equilateral triangle between the two speakers and yourself. You want the distances to be the same with the speakers angled in towards you. This is covered in the text on pages 219-220.
Kill the 90s
No, this doesn’t mean burn all your grunge CDs and concert t-shirts. It means that you should try to deaden the hard 90 degree angles of the corners of your room.
Most rooms are square or rectangular with 90 degree corners. Low frequency sound loves to accumulate in these corners and if you’re listening position is near them, you’ll hear more bass than is actually in your room. Use corner bass traps (mass of fabric to absorb sound) to kill the corner-sound and help balance your low end.
Another issue with square and rectangular rooms is that all the surfaces face each other. This includes the ceiling and floor.
When two surfaces are directly opposite each other, sound can bounce back-and-forth repeatedly causing standing waves. These are extra frequencies that continue to vibrate even after the sound source has stopped. You can test for these with a simple clap - you’ll hear a “zipper” sound as the waves continue to bounce back and forth. Empty rooms are quite bad for this.
DEFN: Standing Waves. A result of parallel surfaces that amplify certain frequencies where sound reverberates excessively.
You’ll likely want to add absorption materials to these surfaces to kill wall-to-wall and floor-to-ceiling standing waves.
Reflecting on reflections
One of the last considerations here is to remove early reflections from your speakers.
Early reflections are the extra sounds that occur when sound leaves the speaker, bounces off a single surface (wall, floor, ceiling) and heads right to your ear. The problem is that this sound - while a version of what comes out of the speaker already - comes to your ear just a little bit later. When the same waves leaves the speaker and hits your ear AND bounces off the wall and hits your ear a bit late, phase shift occurs.
Phase shift from early reflections will cause either summing (too much sound) or cancellation (not enough sound) at particular frequencies, causing you to make EQ decisions that are inaccurate. We covered phasing and summing in the early sections of Audio Fundamentals I.
Use a mirror along each side wall at eye level to the listening position. Where you can see the speaker in the mirror, sound makes a direct reflection to your position. Add sound absorbing material there.