[Rclark]

  I'll be sitting distances ranging between 6 feet and almost 9 feet from the diffusor surfaces (but often much closer to the 6). Plan is to place them behind each Maggie.

 The Gridfusor works from 600hz, the Qrd from 350hz. Apparently this difference can be a big deal depending on room size. Or, according to some, it makes no difference whatsoever 

 I'm assuming I can stack pairs of Gridfusors to get the full 4' by 2' of a standard single QRD. Anyway, never used diffusors, have read conflicting information, that the lower hz they work at, the further away you must sit from them, I've read here 3* longest wavelength minimum, so that would be almost ten feet away for the 350hz QRD, ...but on a competitor's video it was said about 1 foot per inch of depth is fine, so about five feet minimum distance for the 5.6 inch deep Gik QRD, and that QRD's are forgiving of distance anyway...  Which one is it?

 Would be concerned with hearing "artifacts", whatever those are. I'd prefer to use the QRD if I can get away with it though.

 However, the Gridfusor has more wells, so this presumably is better, right? Also, my plan is to get the Dspeaker Dual Core next month, and this provides correction to 500 hz, so perhaps Grifusors are the best option after all?

 Yours truly,

 confused.

[Rclark]

Just measured, hadn't done that before, between 7 to 10 feet from the diffusors, most of the time closer to 7 feet, underestimated the distance.

[jk@home]

Good questions. I am looking at the same products for the same use. 

Also, are the gridfusors fairly robust? I'll be mounting them to some closet doors and they may get bumped every now and then (guess I could do a frame around them).

[DTB300]

Go with the gridfusor to start to see what you think of diffusion in your room.

They are cheaper and lighter, hence, easier to play with many placements until you find the place you like (if you like them) in your room.   And since there are 4 of them, you can stack them for the 2x4 or use 2 on first reflection, and two behind speakers, or etc. etc. etc.

Then spend more $$$ on the QRD if you like the looks better than the Gridfusor.

[jk@home]

That's a good idea. A while back I posted a question regarding hanging diffusers on bass traps. Bryan responded but could only go so far due to it be a generic forum. I'm going to assume that the gridfusors would work in front of bass traps? If so then I have the option of using them there also/instead.

[bpape]

The Grid Fusors are cost effective option for MMG's since you don't need to go double wide. If you would have to do double like for 20.7's, then you'd want the QRD or Q7D set in mirror imaged pairs. You just don't want to repeat a diffusion pattern right next to itself.  It can cause more comb filtering problems.

Bryan

[jk@home]

Thanks Bryan. One question, how close can I put gridfuser horizontally next to each other (if not side by side)?
The reason I ask is I want to put some on the bass traps in the corners, and also the back wall (on the doors) next to the traps. They would look like this:       __   
                                                            /
Edit: found one of your previous posts stating: "Any time you repeat a pattern side to side, you're inviting lobing problems.  If you space them apart a bit (I prefer a minimum of 1/2 the width) then you minimize any potential issues."

Thanks.