Hi, I'm running GIK absorbers and bass traps on front wall, the sound suffers a little without them. Considering moving to something like Acustica Applicata Daads or Stillpoints Apertures which offer a combination of diffusion and absorption.
On the front wall I prefer absorption panels with some kind of limiting reflecting front plate. The Alpha panels from GIK are very good for the price. I much prefer Apertures though. Apertures, although silly money, sound the best to me on the front wall and all reflection points. I have tried a bunch including pure absorption, pure diffusion and various mixes.
There is no right or wrong, experimentation is the only way. Buy a few panels of a different type and give them a try.
Advanced, how do you set up your Apertures?
Tima has been running his room with vertical columns of two panels on the front wall: central and maybe 3' to the R and L, so six Apertures in total on front wall; and at side wall first reflection points.
For me, I use the panels to cover windows but they are symmetrical. LR about 24” away from center. So no experimentation. I would say because of those windows, treatments at the front of the room are more important for me than they might be for someone with a solid wall.
There is a bit more going on inside of an Aperture. The patent is available online and will give you insight on the construction. Although this won’t tell you how they sound. For bass trapping, I would look elsewhere though. For reflection points, Apertures are my favorite.