After having experimented with absorption, diffusion, and nothing at all… I figured I’d chime in on this topic with my own personal findings. Upfront, I’m not looking to start any dispute, or discredit anyone else’s findings, but simply adding some helpful input based on my own personal experiences in my listening environment.
My listening room is basically my living room which shares a small dining room. The room is 20ft wide x 15ft deep and has a few jogs in the sides and rear wall for closets, windows, doors, hallway etc. The wall behind the Martin Logan Quest speakers is flat Sheetrock with no interruptions and the distance between the speakers and wall is 26 inches. The room is quite acoustically stable with the only acoustical treatment being three 2’ x 3’ broadband panels on the wall behind the listening position to eliminate a problem I had with a near-field reflection.
To be honest, I am very happy with the sound reproduction that my system offers in the room. If it was a perfect world, my only change would be moving the system to the left about three feet to get the right speaker further away from the wall. Unfortunately, there is a dining set to the left that does not allow for this so it is what it is. I do have some thick and heavy drapes on the wall close to the right speaker, and its close proximity to the wall does not seem to present a concern.
The reason for this post is that I have often seen pictures on the internet where Martin Logan owners have placed sound absorbing panels (as well as diffusion panels) behind the speakers. I also have read some conflicting information between forums and what is written in my owner’s manual to the Quest speakers. The owner’s manual goes into detail regarding room acoustics, bipolar speakers, dispersion, placement, anomalies, experimentation, etc. All this information lead me to contact Martin Logan in which I shared a pleasant conversation with someone there who reinstated what was indicated in the manual.
According to ML, the Quest speakers are designed to integrate the wall behind the speakers as part of the overall listening experience. If the speakers are placed 2.5 – 3ft from the wall, the reflection from the wall brings room ambience into play. They recommend the wall be flat without things like windows, doors, etc and that the surface not be too hard or soft for best results. If things are in your favor, the sound will seem natural (like having a quartet playing in your room vs being beamed at you).
I found this interesting and decided to try a few experiments. I tried absorption behind the speakers and found the results to be less than favorable. As the gentleman from ML expressed, the result was a very sterile music delivery (like wearing noise cancelling headphones). Although it was interesting, there was no room ambience, the sound was dry, lifeless, and unnatural. What I really found interesting was that if you stepped outside of the sweet spot, you were in a null. The speakers had a spotlight effect and the listening experience was limited to an area within the dispersion pattern of the speakers. This phenomenon is generally desired in professional applications (such as concert systems etc) but in a living room it was not my cup of tea. My first pair of premium speakers was a pair of Ohm Walsh F’s which radiated sound 360 degrees and filled the room with sound and made for a pleasant listening experience in virtually any seating position (something I’ve grown to enjoy). I further tried dispersion behind the speakers in which I found that the difference was minimal. If anything, I think the ambient sound was a bit smeared and wasn’t as good as without.
For me… my conclusion was less is more. Having the speakers perform in a stable room environment as instructed in the manual yielded the best results. However, sound can be subjective, and rooms can vary and all can have their own issues and anomalies. As the owner’s manual concludes; experiment and have fun! Placement, tilting, toe in, room treatment, etc all play a role in the outcome. Do what works for you and enjoy!