QRD diffusor and centre fill

Hi folks, I have a question regarding the effect of QRD diffusors on left/right channel separation. I have three RPG QRD 734 diffusors that are located against the wall, between the speakers. When listening to music there is a very noticeable (and quite annoying) left/right channel separation. It's as if the distance between speakers is very large. After I removed the QRD diffusor that is the most centre-positioned (the other two are still standing at the same position), the left/right channel separation is a bit less pronounced, which gives the sound a more natural character. Does anyone have this experience also? What is the explanation of this acoustic phenomenon? Thank you.

Chris

[mattym]

I assume you have them infront of you when listening?

[mattym]

whats happening is that the units are working correctly, scattering the sound evenly back into the room, it sounds to me like you have them infront of your listening position, between the speakers, rather on the rear wall.

What depth are they and what size is your room