Listening Room Acoustics

Even with a non-perfect listening environment, you should aim to get the most out of your loudspeakers. once corretly placed and you'll get more out of this excercise than purchasing expensive amplifiers let alone exotic speaker cables. And did I already mention it doesn't cost anything?

Room Acoustic Basics

Let's face it - there isn't such thing as a "perfect room". Your listening room's dimensions with side walls, ceiling, floor and interiors are more or less given. All you want is to minimize your room's side effects and capture as much direct sound from your speakers as possible. In your room you are dealing with three major physical realities:

Room Modes

By definition, these are frequency resonances defined by the dimensions of your room. You can't avoid them (especially in rooms with an even geometric shape) but at least attenuate their effects by moving your speakers to another position or using specialized absorbers or reflectors. Room modes result in colored sound and an uneven frequency response - certain frequencies become either amplified or attenuated. Luckily, there are formulas to track them down (and possibly eliminate them).

Reverberation and Flutter Echoes

Whenever two opposing reflective surfaces of your room (wall to wall or wall to floor) meet, you might encounter flutter echoes. General reverberations are also highly disturbing. Typical sonic effects are a reduction in the speech intelligibility and other various colorations of music playback. In such cases, acoustic room treatments are necessary.
Minimalistic interiors of your listening room are never advisable as they are often a major contributor to this type of coloration. Instead, try to integrate thick curtains or wall carpets. A comfy armchair or a couch can also become a lifesaver. And they make your environment look nice, too.

Reflections and Absorbtions

Your room's side walls, ceiling, floor (and some interiors like mirros or glass doors/windows) reflect or absorb certain portions of the sound coming from your speakers. Indirect reflections arrive with a delay and merge with directly radiated sound. This results in your ears noticing poor spatial perception, non-centered presentation and a diffuse soundstage.

To minimize these effects and retain perfect channel balance, move your speakers further away from side walls or place diffusors (flowers or bookshelfs work well) at the side walls near your loudspeakers.
For reflections from tiled or wooden floors, try a carpet between the speakers and listening position.

As for taming reflections from the ceiling...well, there isn't much you can do unless your wife (or husband for that matter) agrees to decorating your room's ceiling with absorbers or carpets. If you've done your homework, you'll hear more from your speakers than your room.

I've barely touched the surface of room acoustics but the above steps are the precursor of succesful loudspeaker placement.

Speaker Placement Guide

Now we enter the experimental stage. Yes, experimental because there's honestly no perfect recipe for every situation although manufacturers want us to believe that software and a few algorithms do the job. Believe me, I've tried dozens of packages including the Cara software suite and Tact RCS 2.2x DSP processors but nothing beats moving around your speakers and getting firsthand experience with optimized speaker placement. Software never does magic. Sure, you might be able to measure room response and fix asymmetric speaker placement problems. However, reverberations, flutter echoes or room modes won't go away.

For perfect soundstage balance, it's suggested that your speakers are slightly angled in pointing to your listening position thereby forming an invisible triangle.

Our next requirement is an equi-distance of your speakers from your room's side walls and if possible - having a different distance from rear walls. Depending on your floor (carpet, tiles or wood), use spikes or vibration dampers under your speakers.

At this point you must determine the distance between left and right speaker.

Remember that bringing speakers closer together yields a narrower soundstage but better overall focus and definition while increasing the distance creates a much wider soundstage. I suggest you pick one of your favorite vocal recordings and move speakers carefully (inch by inch) while listening. I use Norah Jones' extraordinary album "Come Away With Me".

When Norah's voice loses definition and appears to be coming from two separate loudspeakers, I know I went too far and decrease the distance.

When the voice appears exactly centered between your speakers and all instruments are nailed into their acoustic space, you know you have succeeded. Depth and width of soundstage have the correct balance.

Next we tackle vertical positioning of your speakers.

Please mark the current position of your speakers. By moving your speakers further or closer to their real wall, you subjectively gain more bass end but soundstage depth suffers considerably. When moving your speakers further away from their rear wall, the bottom end becomes leaner but well defined. You might also notice an increase in depth. In the end it's all a matter of taste. Play around until you're completely satisfied. Sometimes only an inch or two will do the trick.

Finally, you're wondering how far your speakers should be angled in?

As a general rule, I always measure the distance from my listening position to the speakers. Let's assume 15 inches. Then I would add half of that distance to it which equals 15 + 7.5 = 22.5 inches.

Now from the center between the front side of your speakers, mark a position at 22.5 inches distance. This becomes your "reference" spot.

All that's left would be angling in your left and right speakers so they point to that reference spot. For some speakers it might not be the last word on proper placement but I've had extremely positive results. Try it!