First Reflections

Probably one of the most important and overlooked parts of your system is the room. You can put the best equipment money can buy in a bad room or improperly placed within a room and it will sound terrible. Vice versa you can put moderately-priced (read affordable) equipment in a properly set-up room and it will sound like a million bucks!

There are plenty of articles online to discuss room layout & treatment so I won't rehash the details but to summarize:

- Listen across the longer dimension

- Place speakers 1/3 into the room

- Dispersion behind the speakers

- Absorbtion at first reflection points

- Absorbtion on the wall opposite the speakers

It is nice for all of the experts to agree on these basic principles but the reality is the architects of the world were not audiophiles! Sometimes we need to make choices and decisions that don't meet all of these criteria so be willing to experiment and at a minimum address first reflections.

Now, if you are anything like me, you are even lucky to have the SO allow you a dedicated music room! :) Unfortunately, my dedicated music room violates the first two requirements above whereas I need to listen across the short dimension and the speakers are against the wall in the far corners. I used to run Klipschorns which use the corner as the last leg of the bass horn but due to the near-field listening across the short dimension (~9' speaker to ear), I could never get accurate time alignment between the 3 drivers so I now run a full-range driver with subwoofer and super tweeter augmentation. The wall opposite my speakers has a large window which is again terrible for reflection so I added draperies and cloth blinds to absorb some of the sound waves. Now all that is left is 1st reflections which brings us back to the topic of this blog.

Think of sound waves as a line-of-sight wave of energy similar to light. The Law of Reflection states that the angle of incidence equals the angle of reflection.

To find the point of first reflection is as simple as the image shows! All you need is a mirror and an assistant. Simply sit in your normal listening position and have an assistant hold a mirror on all 4 surfaces (2 walls, floor & ceiling) and move it around until you can see the speaker driver(s) reflected in the mirror. My full-range drivers make this easy since I only need to focus on a single driver but you want to make sure you cover the first reflection of ALL drivers in your speaker. You also want to identify the first reflection for both the speaker nearest the wall and the speaker farthest from the wall and place absorption material on both locations. The picture below shows my farthest speaker in the reflection with the panel to the left of that for the reflection of the closer speaker.

You can buy fancy acoustic absorption panels or make your own like these which are simply a 2" pine frame with fabric stretched over it and then the pine frame is filled with Owens Corning 703 fiberglass panels.

The floor is much easier to address with the addition of a large area rug if you have a solid floor but if you already have carpet, you are already good to go.

For the ceiling I adhered a grid pattern of 1'x1' acoustic tiles for absorption using 3M foam squares. These can be purchased on Amazon for a reasonable cost and available in many colors to suit your decor.

Although not exactly first reflections, I also struggled with bass resonance so I also placed foam bass traps (also available on Amazon) in the open corners to help absorb some of the offending waves.

OK, this is all great ... how does it sound? Well, it was not subtle! Imaging become pinpoint precise, bass tightened up and the overall soundstage grew. All of this makes sense since now my ears are getting a more "clean" version of the sound waves by absorbing any reflections within the room allowing me to hear only the sounds and associated timing in the music medium instead of hearing the room. This can also be quantified by utilizing a reference mic and REW software to look at room modes before and after but I won't bore you with all of that. Just add a few absorption materials in strategic locations as described above and enjoy the newfound clarity!