Whatever I Did, It Worked.

I've recently been playing around with a curved diffusor I bought from Acoustic Geometry:

https://www.acousticgeometry.com/products/curve-diffusor/

My room is well treated, and I can make it a bit more live or dead via moving some curtains.  My Left speaker has to be pretty close to the fireplace, placing it near a small area of ceramic tiles above the fire place.  Not a nice first reflection point so things get a bit hashy.  Hence I use a thick velvet cover for the fire place and that reduces any reflection hash beautifully.

But it can also sometimes take a bit of life out of the sound.

I bought the small, manageable diffusor to place at the first reflection point of the L speaker instead of there being the bare tiles.

Even though it was only used on one side, it livened up the whole sound of the system - making voices and instruments sound more direct and "in the room." That was cool.  But I also lost a bit of focus, and a bit of the beautiful, nuanced timbre of voices and instruments.

Then I started playing around, put the velvet back up over the fire place, and moved the diffusor around.  It turns out that I much prefer it when not in the first reflection point, and it still changes the sound at different points along the wall.  In fact, I now tend to put it on the fireplace wall beside the speaker, but pushed just behind the L speaker.  This both preserves most of the nuance I get with the fireplace covered, but it seems to add a bit more density and focus and palpability to the sound, especially central images.  

It also works well forward of the first reflection point, with a similar but slightly different effect.  Or even if I place it in the Right wall corner near me - there seems to be a large variety of places to put the thing allowing me to experiment and tune the sound as I wish.  Pretty neat for just one little diffusor!

Great explanation. Thanks, Erik.

I love GIK, and love their bass traps. I often say good room treatment can make speakers sound a lot bigger and more powerful.

You cleaned up the room modes, and helped the room drain off bass faster. This means smoother frequency response and less ringing or overhang.

Often in a room, those bass modes will increase the effective bass, making everything sound muddy. You can over-do it, but it sounds like you did it just right.

One thing people don't know also is how much off-axis room treatment can help. They think only first reflection points matter, but that's not the case.

Glad you found a good combination for you!

Best,

E