Front or Back wall diffusers

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

Thanks for the helpful feedback. I never thought my untreated (other than a large area rug and bookshelves on one side) basement listening room sounded too bad — no frequencies seem emphasized or attenuated — and now thinking that might be largely because my speakers are 6’ out into the room and over 3’ from the sidewalls (ah the joys of a dedicated listening room with no WAF interference). That said, I know there are improvements to be had. I’d always thought I’d judiciously add some absorptive panels, but after hearing the feedback here and as I enjoy the spaciousness and reverb trails my system preserves/produces I’m thinking of skewing more to diffusion maybe mixed with some absorptive panels and bass traps as or if needed. One thing that seems assured is that to get it “right” for my room, system, and personal tastes there’s gonna be trial and error involved and that there’s no magic formula to achieve that, but I actually like that because that’s how I’ve learned many important audio-related lessons along the way. Anyway, great stuff and thanks again.

Andy @aquint : gorgeous room! Thanks for sharing and chiming in

Also, about 6 years ago, when drawing the original plans for the house of stereo, GIK told me that the front wall should be addressed last if at all. Just saying.

@baylinor GIK told me the same thing as it's the furthest reflection point for anything but bass. And I agree that audiophiles like to look at diffusion on front wall, especially Gotham diffusers.

However, the real disconnect is that GIK is pro audio and we are hi-fi. Diffusion on front wall will add depth and space to the sound stage...a nice hi-fi trick. Pro audio does not care about that. They want flat frequency response and to fight SBIR...so they will build their speakers into the wall or put them right up against the wall in a small mixing room.  

The main difficulty with setting up diffuse panels are you do not want them too close to your listening position. Six feet away is the minimum and at least eight feet away is the preferred. 

@axo0oxa 6-8 feet away for diffusion? To diffuse lower midrange absolutely yes...and you would need a well depth of like 6-10 inches as well. 

Most of us don't have that deep of wells or really deep poly diffusers that can diffuse lower midrange frequencies. Kind of the same challenge as "trapping bass" below 80hz...the panels have to be impractically thick. 

So most of us aren't diffusing lower-mids to begin with, even if we sit far enough way.

Scatter plates don't really scatter below the upper mid-range/lower treble but they still have benefit...they preserve higher frequencies by not allowing them to be absorbed into the foam or insulation that they are attached to. Scatter plates are a very smart way to prevent a dead room and still get low end absorption. 

A lot of us have quadratic diffusers and skyline diffusers and maybe some cylinders that are 4-7 inches deep. Again not going to do much diffusing in the lower midrange but still they are covering quite a bit of midrange...much more than scatter plates and they still diffuse, even if you're 5 feet away from them...though maybe you won't get diffusion at their lower limit if you are sitting too close.