2 channel (listen music ... not studio)

[jwl]

In general I'm not a huge fan of diffusors on the ceiling, unless you have tall ceilings. For more on diffusion, see: RealTraps - All About Diffusion

[boggy]

Originally Posted by pompon

I have finished my acoustic traitment but now I start to think about add some diffusion.

I have some place on the side wall behind me and probably each side of my back panels (between them and the basstrap) and the ceiling.
......

I usually mount diffusers over all absorptive surfaces too: MyRoom Acoustic Design

[Glenn Kuras]

For side walls or back walls ... QRD or GridFuser are the best ?

The GridFuser is a QRD.


Just to clarify, unless the the ceiling is REALLY high you do not want to use diffusion in the early reflection points on the ceiling, but anywhere else can work very well. Just like using them on the side walls in the back of the room and or back wall works well.
GIK Acoustics: Early / First Reflection Points

[pompon]

I am at 8.5 foots from the back wall (22.5 foots total), the ceiling have 8 foots and my room have 14.5 foots wide.

Glenn: What is the difference between your QRD module and the gridfuser ? Only the look ? The module look very great btw.

[Glenn Kuras]

QRDs can be made at different roots. Like our normal QRD is 7 root where the Gridfuser is 13 root.

I am at 8.5 foots from the back wall (22.5 foots total), the ceiling have 8 foots and my room have 14.5 foots wide.

Like I said you just don't want to use them in the early reflection points. Another case might be above say vocals if you where doing them in the back of the room, which btw would then be a early reflection point.