phase grate diffuser deployment

[junkfoodandkombucha]

Hello all,
It's been a while since I've been around here and had to make a new account. During this time at home I've decided to install some acoustic treatment in my office/listening room/occasional mixing room and I have a few specific questions about phase grate or qrd diffuser deployment.
Here is a quick overview of my room with a few sketchup screenshots below. dimensions are 17 feet long 10 foot 8 inches wide and 8 foot ceilings. This room is mainly my office and listening room but I also mix some live multi track recordings in here. Mostly Bluegrass, Folk, Country string bands but often with drums, effects pedals and amps. I don't do any recording in the room. the absorption and binary amplitude diffusers are ordered but not installed yet.

I would like to do a quadratic residue diffuser on the rear wall. I realize this may not be the most practical approach but part of this project is also a learning experience for me and I would like to deploy one and see how well it works. my listening/mix position is 10 feet from the wall and I have 2 chairs 5 feet from the wall (the chairs are not critical listening spots) based on that I don't want to do well depths deeper than 5 inches (roughly 4 1/2 foot minimum listening distance)

My main question is about using multiple n7 qrd's vs fewer (or even 1) higher order qrd. I have read and seen different opinions on whether you want multiple periods to energize the lobes or arrange them to minimize the lobes. I will be building these so well width and depth can be whatever I choose. If anyone has any real world experience or advice it would be very much appreciated. current plan is to build standard qrd's with fins however I'm not opposed to trying a finless design. the back of my room is an active walkway in my home so no one will over sit closer than 4' from the diffuser.

Thanks everyone for your time. Once the main treatment is installed I plan to do new measurements and fine tune from there. This is a hobby project to treat my room and then change things and try new idea's to further my acoustic knowledge.

All the best,
Brady

[Gregwor]

I know you said you're 10 feet away but in my opinion, what really matters is that you're at least 3 full wavelengths of the low cut-off frequency from the device.

When it comes to the device design, personally I am a huge fan of Tim Perry's Leanfractal A1-Frac diffuser. You seem to have a good grasp on things so just make an educated decision on which design you want to go with. As long as your follow the guideline above, use any diffuser you want.

Greg