Front or Back wall diffusers

Front or back wall diffusers, I have a 14' x 24' x 8' stereo audio room with Wilson Sasha DAW speakers. I want to know which wall to place it on. I have seen many photos with diffusers on the front wall, this is the most recommended, but I have doubts. Please some suggestions.


I would be embarrassed to show a picture as my room is such a cluttered mess (free diffusion, right?). 

Here are some good diagrams.

I made a lot of treatment mistakes until Michael Green Audio started saying things in the forum here that got me curious....he was right so I started digging deeper. I discovered the Anthony Gramani video series on the Audioholics YouTube channel during covid times. I followed his advice and it was GOLD for me. So now I just pass on what worked for me and warn people about what didn't work for me (mostly conventional wisdom from pro audio).  

@seanheis1 I think I may speak for many here that we care a lot more about sound than clutter, and since a picture is worth 1000 words I think many here (including me) may benefit from seeing what you’re talking about.  But, if it really makes you uncomfortable please just disregard. 

In some recording studios they go with a dead end / live end design approach. This is absorption behind the speakers and then extending it along the side walls approximately halfway down the rooms length. The last half is treated as reflective as it the rear wall. I've experimented with this design and found it killed the sound. The room became too dead and the music lost too much of it's liveliness for my taste. You however could hear all the fine detail within the music very easily which is what you would want when mixing music.

Someone up post mentioned keeping the side walls live as opposed to dampening them. If your speakers are not too close to the side walls this is a better approach than just dampening them like everyone else does. Those first early reflection points are typically treated for absorption because in most cases people have smaller listening rooms and cannot hold there speakers far enough off the side walls. If you do diffuse the side wall make sure the distance to your listening position is greater than 6 feet. The key is to stop the really early reflected sound waves. Those really early reflected sound waves are the ones that create distortion. There is a lag number that you can look up but designing for it requires special measuring equipment and programs so most everyone just use general rules of thumb picked up on forums, like this one or what can be read in the many articles on the subject or from a sales person you are thinking of buying panels from.

The basic rule I follow is to install absorption panels on the side wall right in front of the speakers, at that first reflection point, if your speakers are 36" or closer to the side wall. The front wall can be left fairly reflective if you can pull your speakers out into the room. My speakers are 53 inches out into the room so I felt absorption panels on the front wall was not necessary. The room's size of 12'Wx15'D with a 9' ceiling height. Due to this smaller size I added bass traps to the front two corners. Bass waves are huge and almost no one has a room large enough to allow them to fully develop, so in most cases the installation of bass traps is a good investment and will help. When using a small pair of two way bookshelf speakers then bass traps may not be as important as if you had a pair of full range speakers or if you use subwoofers. Bass traps alone are not the solution to great bass but are very helpful. Directly behind my speakers I placed my diffusion panels. In my opinion these panels are far enough from my listening position to not create an issue and they help make the sound more lively and create the illusion that the room is larger than it really is. The bass traps also help create the illusion of a larger space. Dead center between the speakers on the front wall there is no treatment. The speakers are far enough out into the room that treatment is not required and it helps keep the room sound lively. My listening position is pretty close to the rear wall. For that reason I was concerned about early reflection distortion so I installed three 6" thick absorption panels. Due to their thickness they absorb a wide frequency range. Thin absorption panels absorb mainly the high frequencies so be careful if you choose to use them. To the side walls in line with where I sit are CD racks. The CDs are placed at random spacing and some stick out further than others so I believe this helps with diffusion. I use a large wool area rug with thick padding between the listening spot and the speakers, again this aids in absorption.

When you walk into the room your ears feel a difference in pressure from the room you just left. If you clap your hands there is no slab echo. Some people may feel that would be a sign of an over damped room, but for me the room is lively enough and I have very clean and detailed bass

I hope my reasoning for how I treated my room gives you an idea on how you might think through how you might treat your room with both absorption and diffusion panels along with furniture and room features you have no ability to eliminate.

Thanks for sharing I think it's sound advice. I have never heard of a bass trap making a space feel larger...for me traps make my room feel smaller and more intimate. 

I have also never heard of putting diffusion directly behind a speaker. My thought is that the frequencies that wrap behind the speaker are too low to be diffused. 

All that matters is that it works for you and you're getting good sound. ;-) 

Definitely the front wall, in my opinion.

I've posted a photo of the front of my room in the Virtual System area. I've had three pairs of GIK Gotham Quadratic Diffusers deployed in the middle of the room boundary behind the speakers for over a year (I had a single pair before that) and have found they make a substantial difference—the perceived size of the room is larger and the sound is smoother. Because I'm a reviewer,  lots of speakers come and go, and I've  found the GIKs to be effective with various loudspeaker types—dynamic and electrostatic designs, ported and sealed box, floor standers and stand mounts. As room treatments go, they aren't expensive ($359 per pair) and even my wife doesn't find them unattractive.

In the photo, they are mounted in heavy wooden frames I had built. The speakers in the photo are JansZen Valentina P8s, which I own especially for use with the BACCH-SP crosstalk cancellation processor but the GIKs also are of considerable benefit when I'm listening to my Magicos.

Andy Quint